Structure Rehabilitation Manual

STRUCTURE REHABILITATION MANUAL

POLICY, PLANNING AND STANDARDS DIVISION ENGINEERING STANDARDS BRANCH BRIDGE OFFICE MINISTRY OF TRANSPORTATION ISBN 0-7794-6430-3 © Queen’s Printer for Ontario, April 2004. Reproduced with permission.

To all users of this publication: The information contained herein has been carefully compiled and is believed to be accurate at the date of publication. Freedom from error, however, cannot be guaranteed. Enquires regarding the purchase and distribution of this manual should be directed to: Publications Ontario By telephone: 1-800-668-9938 By fax: (613) 566-2234 TTY: 1-800-268-7095 Online: www.publications.gov.on.ca

Enquires regarding amendments, suggestions, or comments should be directed to the Ministry of Transportation at (905) 704-2065.

CONTINUING RECORD OF REVISIONS MADE TO THE MANUAL STRUCTURE REHABILITATION MANUAL This sheet should be retained permanently in this page sequence in the Manual. All revised material should be inserted as soon as received and the relevant entries made by hand in the spaces provided to show who incorporated the Revision and the date it was done. If this practice is followed faithfully, it will be a simple matter to tell whether or not this copy of the Manual is up to date since all future Revisions will be numbered and dated. Revision No.

Entered By Date THIS REPRINT INCLUDES REVISION #9

Date

CONTENTS

PREFACE ACKNOWLEDGEMENTS FOREWORD PART 1:

CONDITION SURVEYS

PART 2:

REHABILITATION SELECTION

PART 3:

CONTRACT PREPARATION

PART 4:

CONSTRUCTION

i

PREFACE

The Bridge Deck Rehabilitation Manual was first published in 1983 and consisted of two parts: Part One, Condition Surveys and Part Two, Contract Preparation. In 1988, the Structure Rehabilitation Manual was published to supersede the Bridge Deck Rehabilitation Manual and included procedures for the condition survey and rehabilitation of all above-grade concrete components of highway bridges. It was issued in loose-leaf format to facilitate updating. Since then, the manual has undergone several minor revisions in various parts. The last revision was issued in 1996 as Revision No. 8. The present revision, Revision No. 9 of the Structure Rehabilitation Manual, is a complete rewrite of the entire manual and has incorporated many recent changes in the condition survey requirements in Part 1. Part 2 has been revised to include some of the recently developed rehabilitation treatments, for example, electrochemical chloride extraction and passive cathodic protection systems. It is also necessary to update Part 3 for the changes in special provisions and tender items.

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ACKNOWLEDGEMENTS

Staff from Concrete Section and the regional structural sections have provided many input and review comments for the draft and are gratefully acknowledged.

Special acknowledgement is also given to Rita Goulet for the formatting and editing of the tables and sketches.

Revision No. 9 of the Structure Rehabilitation Manual has been prepared by: David Lai, Head Rehabilitation Engineer Naran Patel, Senior Rehabilitation Engineer

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FOREWORD

The Structure Rehabilitation Manual covers the procedures in the preparation of contract documents for the rehabilitation of various structure components. The manual is written primarily for Ministry projects, but may also be used by Municipalities and Consulting Engineers engaged in structure rehabilitation. This manual is divided into four parts that reflect the following steps of structure rehabilitation: PART 1 PART 2 PART 3 PART 4

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Condition Surveys Rehabilitation Selection Contract Preparation Construction

Part 1, Condition Surveys, describes how condition surveys are to be carried out. Appendices 1A to 1E include consultant agreements, standard forms and standard legends. Condition surveys are normally carried out by consultants. Recommendations for the rehabilitation and contract documents may be prepared in-house or by a consultant. Other authorities, especially municipalities, frequently engage consultants to carry out the condition survey, make recommendations for repair, prepare the contract documents and supervise the construction. Occasionally, all the activities may be carried out by one consultant, but frequently, two or more consultants will be involved. The scope of the work needs to be clearly defined in the agreement with the consultant. Part 2, Rehabilitation Selection, describes methods of rehabilitation and shows how the information collected in the condition surveys is used to select the most appropriate method of rehabilitation for each different type of structure component. Although structural analysis is outside the scope of this manual, structure rehabilitation cannot be separated from an evaluation of the load carrying capacity of the structure. Therefore, before preparing the contract documents, the structure may have to be evaluated to ensure that all elements of the structure can support any additional loading and temporary loading conditions resulting from the rehabilitation. Part 3, Contract Preparation, covers most of the activities likely to be encountered in rehabilitation contracts. Only some of these activities will be included in any one contract. Consequently, considerable care is required in ascertaining what specific items are appropriate to the job in hand. Sample special provisions and reference drawings which can be used as a guide in preparing contract documents are to be developed and will be inserted in the Appendix to Part 3 in the future. Part 4, Construction, summarizes the construction procedures used for each of the rehabilitation or repair methods included in the manual. This part is to be developed in the future. It is expected the more experienced designer will use Part 4 for reference purposes only.

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The information contained in this manual is based on the Ministry’s Research and Development reports and Bridge Office reports published since 1975, as well as the Ministry’s experience in preparing and administering structure rehabilitation contracts. No attempt has been made to summarize research results. The interested reader is referred to the Ministry’s research reports and the numerous references listed in them. The Ministry’s Bridge Office or Concrete Section should be contacted for additional advice and guidance for rehabilitations not covered in this manual.

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PART 1 CONDITION SURVEYS CONTENTS 1. 1.1

1.2 1.3

1.4

2. 2.1 2.2

2.3

2.4

2.5 2.6

2.7 2.8 2.9 2.10 2.11 2.12

3. April, 2004

INTRODUCTION .............................................................................................. 1-1 General..................................................................................................... 1-1 1.1.1 Detailed Visual Inspection............................................................ 1-1 1.1.2 Detailed Condition Survey ........................................................... 1-1 1.1.3 Dart Survey................................................................................... 1-2 Common Defects in Materials .................................................................. 1-3 Protective Treatments for Structures in Ontario........................................ 1-3 1.3.1 General......................................................................................... 1-3 1.3.2 Superstructures ............................................................................. 1-4 1.3.3 Substructures ................................................................................ 1-5 Concrete Removal and Abrasive Blast Cleaning Policies........................ 1-6

REQUIREMENTS FOR DATA COLLECTION, SAMPLING AND TESTING.................................................................................................. 1-7 General..................................................................................................... 1-7 Delamination and Surface Deterioration Survey....................................... 1-7 2.2.1 Bridge Decks ................................................................................ 1-7 2.2.2 Concrete Components, Excluding Bridge Decks........................... 1-7 Corrosion Potential Survey....................................................................... 1-8 2.3.1 Bridge Decks ................................................................................ 1-8 2.3.2 Concrete Components, Excluding Deck Slabs .............................. 1-8 Concrete Cover Survey............................................................................. 1-8 2.4.1 Bridge Decks ................................................................................ 1-8 2.4.2 Concrete Components, Excluding Deck Slabs .............................. 1-9 Expansion Joint Survey............................................................................. 1-9 Concrete Coring and Testing .................................................................... 1-9 2.6.1 Bridge Decks ................................................................................ 1-9 2.6.2 Concrete Components Excluding Bridge Decks............................ 1-9 Asphalt Sawn Samples and Large Asphalt Strips................................... 1-10 Grid Layout............................................................................................. 1-10 Detailed Visual Inspections .................................................................... 1-11 Inspection of Cathodic Protection Embedded Hardware........................ 1-11 Conductive Asphalt Resistivity Test....................................................... 1-11 Investigation of Fire Damaged Concrete................................................. 1-11

PLANNING THE CONDITION SURVEY..................................................... 1-12 1-i

3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.7.1 3.7.2 3.8 3.8.1 3.8.2 3.8.3 3.8.4 3.9 4. 4.1 4.2 4.3

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General................................................................................................... 1-12 Sampling and Data Collection................................................................ 1-12 Plans and Previous Inspections............................................................... 1-12 Site Visit................................................................................................. 1-13 Traffic Control........................................................................................ 1-13 Manpower .............................................................................................. 1-14 Grid Layout............................................................................................. 1-14 General....................................................................................... 1-14 Post-Tensioned Decks with Circular Voids................................ 1-15 Equipment............................................................................................... 1-15 General....................................................................................... 1-15 General Tools and Materials...................................................... 1-15 Additional Tools and Materials for Asphalt Covered Deck....... 1-17 Tools and Materials For Resistance Test ................................... 1-17 Forms...................................................................................................... 1-17

FIELD PROCEDURES.................................................................................... 1-18 General................................................................................................... 1-18 Detailed Visual Inspection...................................................................... 1-18 Detailed Condition Surveys.................................................................... 1-18 4.3.1 General....................................................................................... 1-18 4.3.2 Photographs ................................................................................ 1-18 4.3.3 Traffic Control............................................................................ 1-19 4.3.4 Grid Layout................................................................................. 1-19 4.3.5 Cathodically Protected Components ........................................... 1-19 4.3.6 Equipment Calibration................................................................ 1-19 4.3.7 Corrosion Potential Survey......................................................... 1-19 4.3.7.1 Technique ....................................................................... 1-20 4.3.7.2 Procedure for Concrete with Uncoated Reinforcing Steel ............................................ 1-20 4.3.7.3 Procedure for Concrete with Epoxy Coated Reinforcing Steel............................................................ 1-22 4.3.8 Concrete Cover Survey............................................................... 1-22 4.3.8.1 Technique ....................................................................... 1-22 4.3.8.2 Procedure ....................................................................... 1-23 4.3.9 Delamination Survey .................................................................. 1-23 4.3.9.1 Technique ...................................................................... 1-23 4.3.9.2 Procedure ....................................................................... 1-24 4.3.10 Concrete Surface Deterioration Survey...................................... 1-24 4.3.11 Expansion Joint Survey - Bridge Decks...................................... 1-25 4.3.12 Drainage - Bridge Decks ............................................................ 1-26 4.3.13 Concrete Cores........................................................................... 1-27 4.3.13.1 General........................................................................... 1-27 4.3.13.2 Bridge Decks Riding Surface ......................................... 1-27 4.3.13.3 Curbs, Sidewalks, Barrier Walls and Approach Slabs... 1-30 4.3.13.4 Concrete Components, Excluding Bridge Decks............. 1-30 4.3.13.5 Repairs to Core Holes and Epoxy Coated Rebar............ 1-30 1-ii

4.3.14 4.3.15 4.3.16 4.3.17 4.4 4.4.1 4.4.2 4.4.3 5. 5.1 5.2

5.3 5.4

5.5 6. 6.1 6.2 6.3

6.4 6.5 6.6

7. 7.1 7.2 7.3 7.4

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Asphalt Sawn Samples ............................................................... 1-31 Removal of Large Asphalt Strips................................................ 1-32 Inspection of Cathodic Protection Embedded Hardware............ 1-33 Conductive Asphalt Resistance Test (Cathodic Protection) ....... 1-34 Sequence of Operations .......................................................................... 1-34 General....................................................................................... 1-34 Exposed Concrete Components and Exposed Decks .................. 1-35 Bridge Decks with Asphalt Wearing Surface ............................. 1-35

LABORATORY TESTING OF CORES ........................................................ 1-37 Photographs and Description.................................................................. 1-37 Physical Testing of Concrete .................................................................. 1-37 5.2.1 Compressive Strength................................................................. 1-39 5.2.2 Chloride Content......................................................................... 1-39 5.2.3 Air Void System......................................................................... 1-39 Resistivity Testing of Conductive Asphalt (Cathodic Protection) .......... 1-40 Significance of Test Results ................................................................... 1-40 5.4.1 Compressive Strength................................................................. 1-40 5.4.2 Air Content ................................................................................. 1-40 5.4.3 Chloride Content......................................................................... 1-40 5.4.4 Conductive Asphalt Resistivity (Cathodic Protection) ............... 1-42 Retention of Samples.............................................................................. 1-42 THE REPORT.................................................................................................. 1-43 Introduction............................................................................................. 1-43 Contents .................................................................................................. 1-43 Standard Forms....................................................................................... 1-43 6.3.1 Guide to Completing the Standard Forms ................................... 1-44 6.3.1.1 Structure Identification Sheet.......................................... 1-44 6.3.1.2 Detailed Condition Survey Summary Sheets................... 1-44 Text......................................................................................................... 1-45 Photographs ............................................................................................ 1-46 Drawings - Detailed Condition Survey................................................... 1-46 6.6.1 Requirements for All Concrete Components............................... 1-46 6.6.2 Exposed Concrete Components (Excluding Decks).................... 1-46 6.6.3 Exposed Concrete Decks ............................................................ 1-47 6.6.4 Asphalt-Covered Decks.............................................................. 1-47 REVIEW OF THE REPORT........................................................................... 1-49 Introduction............................................................................................. 1-49 Reference Data ....................................................................................... 1-49 Structure Identification Sheet.................................................................. 1-49 Summary of Significant Findings ............................................................ 1-49

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7.5 7.5.1 7.5.2 7.5.3 7.5.4 7.5.5 7.5.6 7.5.7 7.5.8 7.5.9 7.5.10 7.5.11 7.5.12 7.5.13 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14

8. 8.1 8.2

Detailed Condition Survey Summary Sheet(s)........................................ 1-50 Dimensions ................................................................................. 1-50 Cracking ..................................................................................... 1-50 Scaling........................................................................................ 1-51 Concrete Air Entrainment and Compressive Strength................. 1-51 Delamination and Spalling.......................................................... 1-51 Concrete Cover........................................................................... 1-51 Corrosion Potential..................................................................... 1-52 Adjusted Chloride Content at Rebar Level................................. 1-52 Defective Cores and Sawn Samples........................................... 1-53 Asphalt and Waterproofing......................................................... 1-53 Underside Deterioration (Deck Condition Surveys)................... 1-53 Expansion Joints (Deck Condition Surveys)............................... 1-54 Drainage (Deck Condition Surveys)........................................... 1-54 Survey Equipment and Calibration Procedures ..................................... 1-54 Core Log................................................................................................. 1-55 Sawn Samples (asphalt covered decks only).......................................... 1-56 Cathodic Protection Testing Summary Sheet .......................................... 1-56 Photographs ............................................................................................ 1-56 Drawings ................................................................................................ 1-56 OSIM Forms/OSIMS Output................................................................... 1-57 Acceptance of the Report........................................................................ 1-57 Maintenance Prior to Rehabilitation....................................................... 1-57

REFERENCE PUBLICATIONS ..................................................................... 1-58 Ministry's Publications ........................................................................... 1-58 Non-Ministry Reference Publications..................................................... 1-58

APPENDICES 1A

STANDARD CONSULTANT'S AGREEMENT FOR DETAILED CONDITION SURVEYS

1B

GRID LAYOUTS

1C

STANDARD FORMS

1D

STANDARD LEGEND

1E

CALCULATING AC RESISTANCE OF EPOXY COATED REBAR

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1.

INTRODUCTION

1.1

General

Condition Surveys involve carrying out a detailed visual inspection of the structure and detailed condition surveys of the various structure components. The purpose of the surveys described herein is to determine and document the deterioration in the structure so as to establish the type of rehabilitation and prepare contract documents. It may also provide information for an evaluation of the load carrying capacity of the bridge as described in the Canadian Highway Bridge Design Code, CHBDC, (2). Condition surveys shall be carried out with a plan for worker safety, and safety to the travelling public, and shall follow the guidelines given in “Safety Practices for Structure Inspections ”(3) and comply with the Occupational Health and Safety Act

1.1.1

Detailed Visual Inspection

A detailed visual inspection of all components according to the procedures given in the Ontario Structure Inspection Manual, OSIM (4), may be required, to determine if repairs of these components should be included in the rehabilitation contract. However, caution should be exercised when assessing the overall condition of the component using visual inspections as the visual observations do not reveal hidden defects or deterioration in concrete such as delaminations, rebar corrosion and low concrete cover to reinforcing steel.

1.1.2

Detailed Condition Survey

A detailed condition survey is generally carried out only after a concrete component has been identified for rehabilitation. The data collected is then used to establish the rehabilitation method and to prepare contract documents. The procedure for carrying out a detailed condition survey involves the observation and recording of surface defects and may also involve a delamination survey, a cover meter survey, a corrosion potential survey, coring of concrete components, asphalt sawn samples and physical testing of the concrete cores. Components that require rehabilitation are identified by the Regional Structural Sections in their routine detailed inspection reports, or in general inspections. Procedures for routine detailed inspections are given in the Ontario Structure Inspection Manual, OSIM (4). The need for structure rehabilitation is usually driven by the condition of the bridge deck. As most of the bridge decks have an asphalt-wearing surface, it is usually difficult to assess the condition of the concrete beneath the asphalt during an OSIM inspection. Therefore, candidates for a detailed condition survey should include the top surface of deck slabs included in paving contracts that have not been rehabilitated in the last 15 years. The scope of the detailed condition survey should be expanded to include other structure components such as piers, abutments and barrier walls when the OSIM inspection indicates that these components have deteriorations and a detailed condition survey is warranted. Detailed condition survey of a component may not be April, 2004

1-1

necessary if the need for replacement of a structurally deficient component is established by an evaluation of the load carrying capacity or by other means. The detailed condition survey usually should not be carried out on bridge decks containing epoxy coated steel that have been constructed in the last 20 years as these decks should still be in good condition. A Ground Penetrating Radar (GPR) (5) survey followed by a detailed condition survey should still be considered for these bridges if the asphalt wearing surface and deck soffit show signs of significant deterioration in more than 5% of the deck area. In the future, bridges requiring detailed condition surveys will be identified by the Ontario Bridge Management System program based on condition states of different components of the bridge. However, the program would allow the user to override any recommendations that the program recommends if they seem inappropriate. The detailed condition survey should preferably be carried out no more than two years prior to the proposed rehabilitation. Where a project is deferred, so that the detailed condition survey for bridge decks is more than four years old at time of construction, it would be necessary to update the original survey. Sufficient additional information should be gathered to update tender quantities and to ensure that the most effective method of repair is recommended. For exposed concrete components such as barrier walls, abutments and piers, the concrete delamination survey should be updated the year before construction for the portion of the components that are exposed to chlorides.

1.1.3

Ground Penetrating Radar Survey

Deck Assessment by Radar Technology used to be conducted by the Ministry's Bridge Office until 1998 when it was outsourced. Currently GPR survey is conducted by consultants specialising in radar technology. GPR can be used on asphalt covered decks to detect scaling, debonding, delaminations, concrete cover to reinforcing steel and asphalt thickness; it should not be performed on wearing surface containing steel slag. The older type of GPR previously used by the Ministry did not always reflect accurately the physical condition of the deck. The Ministry is currently investigating a new portable type of GPR that may provide more accurate results. If GPR survey is to be conducted, it should normally be carried out prior to the detailed condition surveys, especially on decks constructed with epoxy coated reinforcing steel. In order to minimize the survey cost per bridge, candidate bridges in the same region should be grouped in the same consultant’s assignment. The data from GPR surveys should be used to: • • •

Supplement data from visual and preliminary investigations to determine which asphalt covered decks should be rehabilitated; Determine the location of concrete cores and sawn samples during the detailed condition survey; Supplement data from detailed condition surveys for asphalt covered decks to finalise selection of rehabilitation method and to improve the design estimate for tender item quantities.

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1.2

Common Defects in Materials

The defects and deterioration that commonly occur in the materials used in structures are described in Ontario Structure Inspection Manual, OSIM. ( 4) Common defects in waterproofing membranes not covered by OSIM are, described below: • • • • • • • •

inadequate thickness at time of construction; excessive thickness resulting in shoving of the pavement; lack of adhesion to the bridge deck or asphalt; moisture present beneath the waterproofing; penetration of the membrane by aggregate from the bituminous overlay; migration of the membrane into the bituminous overlay; rotting of the fibreglass in some fibreglass-asphalt emulsion systems; embrittlement in mastic waterproofing.

1.3

Protective Treatments for Structures in Ontario

1.3.1

General

The type of protective treatments varied over the years. Changes in standards have resulted in some structures being prone to certain types of deterioration. Consequently, there is often a relationship between the age of a structure and its condition. The type of protective treatments are summarised in the subsections below. Since the time between design and construction varies, there may be some overlap between the dates and the construction methods. The dates for waterproofing are for original construction. Most of the deck slabs built before 1973 have since been rehabilitated as part of a highway resurfacing contract and are now waterproofed with hot rubberised asphalt or mastic waterproofing membrane. It should be noted that prior to 1988 waterproofing membrane was not always installed to the minimum thickness requirements and in some cases was installed over an excessively rough surface. Since 1988, the quality of the waterproofing membrane installation should have improved as acceptance is now based on a statistical approach according to end result specification and remedial measures have been implemented for repairing rough concrete surfaces to a surface acceptable for waterproofing. Occasionally, highways were resurfaced without removing the existing asphalt and a considerable build up of asphalt on older decks is not uncommon. 1.3.2 April, 2004

Superstructures 1-3

Constructed Prior to 1958 The deck slabs were not waterproofed at the time of construction. The concrete was not air-entrained. These decks are prone to salt penetration and to severe scaling due to freeze-thaw action. The condition of these older deck slabs varies considerably. Constructed Between 1958 and 1961 The concrete was specified to be air-entrained but the admixtures used did not produce a good air void system and the control of air content was poor. Many deck slabs were treated with silicone prior to the paving but this was not effective in preventing salt penetration. These decks are also prone to salt penetration and to scaling but their condition is generally better than pre-1958 structures.

Constructed Between 1962 and 1964 Deck slabs were waterproofed using mastic asphalt or glass fibre in an asphalt emulsion. Most membranes were ineffective after a few years in service. The concrete was air-entrained but the control on air content was not good. The condition of the decks is variable, but is generally fair to good. As there is no waterproofing treatment for the parapet walls, the parapet walls with low cover and severe exposure to chlorides are likely in poor condition.

Constructed Between 1965 and 1972 The decks were built with exposed concrete wearing surface and minimum cover to reinforcing steel was specified to be 40 mm, but the cover requirement was generally not met. Most decks exhibit corrosion induced distress. The concrete was generally properly air-entrained and of good quality. Many of these decks have now been waterproofed and paved. However, waterproofing and asphalt paving on these decks may now be due for replacement. As there is no waterproofing treatment for the concrete barrier walls, the barrier walls with low cover and severe exposure to chlorides are likely in poor condition.

Constructed 1973 to 1978 The deck slabs were waterproofed with a rubberised asphalt waterproofing membrane. Mastic asphalt was used on some rigid frames throughout the period and also on other types of structures

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until about 1976. A protection board was used with rubberised asphalt after 1975. Most decks are in good condition. As there is no waterproofing treatment for the concrete barrier walls, the barrier walls with low cover and severe exposure to chlorides are likely in poor condition. Constructed After 1978 The decks contain epoxy coated reinforcing bars as the top mat of steel and are waterproofed with rubberised asphalt membrane and protection board. Rigid Frame structures, waterproofed before 1986, might be waterproofed with either mastic or asphalt membrane waterproofing. The curbs and barrier walls also contain epoxy coated reinforcing steel. Specified cover is 70 + 20 mm. The decks are in good condition. As there is no waterproofing treatment for the concrete barrier walls, the barrier walls with low cover and severe exposure to chlorides may begin to exhibit some corrosion induced deterioration after 25 years in service despite the presence of epoxy coated reinforcing steel. Constructed After 1999 MTO began to use stainless steel for top reinforcement in decks carrying strategic highways with 100,000 AADT or more. Other superstructure components with direct salt splash ( barrier walls, sidewalks and expansion joint dams) also used stainless steel. High performance concrete also began to be used on selective structures while keeping the epoxy coated rebars. In all cases, rubberised asphalt waterproofing membrane and protection board continued to be used.

1.3.3

Substructures

Constructed Prior to 1958 The concrete was not air-entrained. The elements directly exposed to salt splash and/or roadway drainage are prone to spalling due to corrosion of reinforcing steel and to scaling due to freeze-thaw action. The quality of concrete was highly variable due to poor construction practices and high water cement ratio. Constructed Between 1958 and 1964 The concrete was air-entrained but the admixtures did not always produce a good air void system and control of air content was poor. The substructure is prone to scaling due to freeze-thaw action and spalling in areas exposed to chloride but the condition is generally better than pre-1958 structures. Constructed Between 1965 to 1981

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The concrete was generally properly air-entrained and of good quality. The resistance to scaling is good but the areas exposed to salt splash and roadway drainage are still prone to spalling due to the corrosion of the reinforcement.

Constructed After 1981 All reinforcing steel within 100 mm of a concrete surface directly exposed to salt splash and/or roadway drainage is epoxy coated. Reinforcing steel in areas that are indirectly exposed to salt, generally, through windblown roadway spray is uncoated. This reinforcing steel is considered to be adequately protected through the use of increased concrete cover and the designation of 30 MPa concrete in place of the 20 MPa concrete sometimes specified. Concrete aggregates in these structures have been tested for alkali reactivity and, therefore, possibility of alkali-aggregate reaction is remote. The substructures are in good condition. Constructed After 2000 Pier columns and shafts within splash zones ( less than 10 m from travelled lanes, and/or under expansion joints ) used stainless steel reinforcement. Structures that were selected for high performance concrete would have used HPC for all substructure components, except the footings. Epoxy coated reinforcement continued to be used for other substructure components. 1.4

Concrete Removal and Abrasive Blast Cleaning Policies

The performance of past rehabilitation treatments are also related to the policies that were in effect at the time of rehabilitation. Prior to 1987, abrasive blast cleaning reinforcing steel was specified with no acceptance criteria. The current requirement of a commercial blast cleaned finish has been specified since 1987. Prior to 1989, the policy was to remove concrete 25 mm below the reinforcing steel only in areas where more than 50% of the circumference of the rebar was exposed. The policy since 1989 has been to remove concrete to a uniform depth of 25 mm below the first layer of reinforcing steel and 25 mm locally around the second layer wherever reinforcing steel is exposed, and within spalled and delaminated areas. Also in 1989, the policy for concrete removal on bridge decks was changed to include removal of sound concrete in areas with corrosion potential more negative than –0.35 volts. This policy has generally not been applied to other components. However, in some cases, removal by corrosion potential criteria may have been specified for other components if the cause of chloride exposure cannot be eliminated and it is felt that concrete will continue to delaminate at a high rate if the high corrosion potential concrete is not removed.

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2.

REQUIREMENTS FOR DATA COLLECTION, SAMPLING AND TESTING

Section 2 gives guidelines for the preparation of the consultant agreement for the condition surveys.

2.1

General

The requirements for sampling and collecting data in the field and the number and type of tests to be performed in the laboratory on the samples taken, may vary from component to component for a variety of reasons. Guidelines are given in this section to assist in determining these requirements and in preparing the Consultant's Agreement. The type and extent of data to be collected and the requirements for the testing of samples shall be specified in the Consultant's Agreement. When detailed condition surveys of extremely large bridge decks (> 4000 m2) are required, consideration should be given to limiting the cores and sawn samples to a representative portion(s) of the deck. When access or traffic protection is a major consideration for detailed condition surveys of soffits and substructures, the survey could be limited to the area(s) where major deterioration is expected.

2.2

Delamination and Surface Deterioration Survey

2.2.1

Bridge Decks

A detailed condition survey of a reinforced concrete bridge deck shall always include a survey of the material defects and deterioration in the wearing surface (concrete or asphalt) and the deck soffit. In addition, a delamination survey shall also be carried out on all exposed concrete wearing surfaces of the bridge deck, curbs, medians, sidewalks, inside faces of concrete barrier/parapet walls and expansion joint end dams. A delamination survey should also be carried out on the deck soffit when more than 10% of the soffit, or more than 10 square metres is exhibiting deterioration and it is anticipated that major concrete repairs will be required. Deck soffit areas susceptible to deterioration include end of deck under expansion joints, areas adjacent to construction joints, cantilever edges and areas under round voids in post-tensioned structures.

2.2.2

Concrete Components, Excluding Bridge Decks

A delamination and concrete surface deterioration survey shall be carried out on all exposed concrete components that require concrete rehabilitation. If repairs to cracks using injection techniques are anticipated, the surface deterioration survey should also include measuring the depth of medium and wide cracks by coring.

2.3 April, 2004

Corrosion Potential Survey

1-7

2.3.1

Bridge Decks

The detailed condition survey for reinforced concrete deck surfaces with black reinforcing steel shall always include a corrosion potential survey. Normally a corrosion potential survey is not carried out on the deck soffit; however, a limited survey should be carried out in areas where the deck soffit is deteriorating due to leaking expansion joints, construction joints, salt splash, and where a delamination survey would be carried out as mentioned in 2.2.1. A corrosion potential survey shall also be carried out on the inside concrete faces of concrete barrier systems, curbs, sidewalks and medians where significant spalling and corrosion staining has been observed. On bridge decks with epoxy coated reinforcing steel, the regular type half-cell survey cannot be carried out as usually there is no electrical continuity between the different reinforcing bars. However, the half-cell readings should be taken at core and sawn sample locations where the rebar ground connection and the half-cell reading are at the same rebar. Along with localised half-cell readings, AC resistance measurements should be taken to assess the condition of the epoxy coating. On bridge decks that are cathodically protected with a conductive asphalt system, the corrosion potential survey shall be limited to the locations of the sawn samples as the conductive asphalt would affect the readings obtained at the drill hole locations. The cathodic protection system should be de-energised for a minimum of four weeks prior to the commencement of the survey to allow the reinforcing steel to depolarise.

2.3.2

Concrete Components, Excluding Deck Slabs

A corrosion potential survey should be carried out on piers and abutments that exhibit deterioration (spalling, delamination, rust-stained cracks etc.) for at least 10% of the total component area. Typically these components are located under open expansion joints, joints that are leaking and in areas where these components are exposed to salt splash. The survey can be limited to the area of chloride exposure.

2.4

Concrete Cover Survey

2.4.1

Bridge Decks

A cover meter survey shall be carried out for all exposed concrete bridge decks as part of the detailed condition surveys (excluding update surveys). The concrete cover survey should also be specified for concrete curbs, sidewalks, median and the inside faces of concrete barrier/parapet walls, and for deck soffit where corrosion potential survey has been specified. For asphalt covered decks, concrete cover survey shall be carried out at the sawn samples and large asphalt strips removal. 2.4.2 April, 2004

Concrete Components, Excluding Deck Slabs 1-8

A concrete cover survey should be carried out on components that exhibit deterioration for at least 10% of the component area. Deterioration could be a combination of delaminations, rust stains and cracking on the surface, or spalls with exposed reinforcing steel. The cover meter readings may also be required to calculate tender quantities.

2.5

Expansion Joint Survey

An expansion joint survey shall always be included with a first time detailed deck condition survey. In the case of update surveys, an expansion joint survey is not required if it has been completed as part of the original deck condition survey.

2.6

Concrete Coring and Testing

2.6.1

Bridge Decks

Concrete coring and testing shall always be carried out when a detailed condition survey is carried out on a deck for the first time. The need for coring and testing for update surveys shall be determined on an individual basis for each structure. The diameter of the cores shall be 100 mm and the number of cores required shall be determined in the field based on Table 4.3 in Section 4. Additional cores should be specified for the following: • • • •

where the rehabilitation work will involve removal of curb or sidewalk, at least one core shall be taken from each side of the bridge to establish the quality of the bond with the deck slab; a minimum of two core should be taken from curbs, sidewalks, medians and inside faces of barrier walls when a corrosion potential survey is specified. unless otherwise known, one core shall be taken to establish whether a concrete approach slab is present. If a large asphalt strip is removed for condition survey of a deck previously rehabilitated with an overlay, at least one core should be taken in an area that sounds hollow by chain drag in order to ascertain whether the overlay has debonded.

2.6.2

Concrete Components Excluding Bridge Decks

The requirements for coring shall be determined on an individual basis. Normally, no more than 3 cores are required from each component. The diameter of the cores shall be 100mm. However, 25mm, 50mm and 75mm diameter cores may be specified in areas of closely spaced reinforcing steel where it is structurally undesirable to core through the reinforcing steel. The following criterion shall be used to determine the number of cores required:

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•

• • • •

•

two core should be taken from the substructure for chloride analysis to determine chloride profile when a corrosion potential survey is carried out; the cores should not be specified for circular pier columns with spiral steel as these cores cannot be obtained without cutting through the spiral rebar; for skyway type substructures, two additional cores should be taken from each pier for chloride analysis when a corrosion potential survey is carried out on the pier; a minimum of one core shall be taken for air void determination if the surface of the component shows signs of extensive scaling and structure has been built after 1958; a minimum of one core shall be taken to determine soundness of concrete when the surface of the component is extensively disintegrated or exhibits signs of alkali-aggregate reaction; if crack repair work using injection techniques is anticipated, cores may be required to determine depth and orientation of the crack if this information cannot be obtained using feeler gauges or other methods. If the cracks are in the soffit of beams and where it is impractical to take cores due to the congestion of reinforcement or prestressing cables, concrete cover to the reinforcement or prestressing cables should be removed locally to ascertain their condition; if the condition of the ballast walls are suspect, at least one core should be taken from the ballast wall to assess the condition of the concrete in areas that cannot be visually assessed.

2.7

Asphalt Sawn Samples and Large Asphalt Strips

Asphalt sawn samples shall always be taken whenever a detailed condition survey is carried out on an asphalt covered deck. The number of sawn samples required shall be determined in the field based on Table 4.4 in Section 4. Removal of a large asphalt strip 1.50 m x 6.0 m shall be specified for decks based on the following guidelines: • Bridges showing significant areas of leaching, cracking and wetness at soffit. • Asphalt covered but no waterproofing. • Large structures where change in conditions and scope of work would have a large impact. • Post-tensioned decks with circular voids but without transverse post-tensioning.

2.8

Grid Layout

When a detailed condition survey includes a corrosion potential survey and/or cover meter survey the data shall be collected with reference to grid points marked on the component surface. A grid layout is optional when the detailed condition survey is limited to a delamination and surface deterioration survey or in areas where it is difficult to layout a grid.

2.9

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Detailed Visual Inspections

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The Regional Structural Sections should decide if the detailed visual inspection should be done by the Consultant as part of the condition survey.

2.10

Inspection of Cathodic Protection Embedded Hardware

The components to be tested shall be identified by the Bridge Office and Regional Structural Section. Guidelines for assessing the performance of embedded hardware are described in the Cathodic Protection Manual for Concrete Bridges (1). The components to be tested shall be listed in the Consultant's Agreement.

2.11

Conductive Asphalt Resistivity Test

When the anode AC resistance test is required on a structure protected with the conductive asphalt cathodic protection system, cores of the conductive asphalt layer should be tested for electrical resistivity. The number of cores to be tested is determined by Bridge Office and the Regional Structural Section and shall be identified in the Consultant's Agreement. The testing of the cores for electrical resistivity will be carried out by the Ministry. A two nail resistance check of the conductive asphalt shall also be taken at several locations. The number of resistance checks shall be determined by the Bridge Office and the Regional Structural Section and shall be identified in the Consultant's Agreement.

2.12

Investigation of Fire Damaged Concrete

The requirements for investigating fire damaged concrete are contained in ASTM Report STP 169B, "Significance of Tests and Properties of Concrete and Concrete-Making Materials" (12).

2.13

Sampling and Testing of Asbestos Ducts

When there are utility ducts embedded in the deck or sidewalk that may interfere with the rehabilitation work, the condition survey should include sampling and testing of the duct material wherever possible ( usually samples could be taken at expansion joint gap ) to confirm whether asbestos is present.

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3.

PLANNING THE CONDITION SURVEY

Section 3 gives guidelines for the preparations required prior to conducting a condition survey. The information in this section is to be used as a guide as the above requirements will vary with each individual project.

3.1

General

Prior to carrying out the condition survey, considerable preparation is required to ensure that the field investigation will be well organised. In advance of the field investigation, pertinent features of the structure should be identified and requirements for grid layout, sampling and data collection, equipment, manpower and traffic control should be determined. Arrangements should be made at least four weeks prior to the commencement of the condition survey with District Electrical Maintenance to turn off the electrical power supply on structures that are cathodically protected. The Consultant shall also make arrangements with the District to obtain a key to open the control cabinet. The District shall be also notified after completion of the investigation to re-energise the cathodic protection system.

3.2

Sampling and Data Collection

The sampling and data collection requirements of the condition survey are contained in the Consultant's Agreement; pertinent sections of a typical Consultant’s Agreement are given in Appendix 1A. If the Condition Survey is to be done by the Regional Structural Section staff, the sampling and data collection requirements shall be determined using the guide lines set forth in Section 2, Part 1, of this manual.

3.3

Plans and Previous Inspections/Surveys

The latest version of the existing structure plans and as constructed drawings should be reviewed for the following criteria: • • • • • • •

size and type of structure; unusual features in the design; structure location and topography at the site; direction and size of top reinforcing steel bars for covermeter check; location of utility ducts; location of stressing cables and void tubes on post-tensioned structures; year of construction - relationship between age and possible deterioration as detailed in subsection 1.3;

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• • •

number of separate grounds that will be required for potential measurements (a separate ground is required for each discontinuous slab); details of previous rehabilitations; location of all cables, anodes, probes and reference cells on structures that are cathodically protected.

The GPR Survey and previous Detailed Condition Surveys, if available, should be reviewed to determine location of samples. Previous routine detailed inspection files should be reviewed for history of deterioration and for details of any previous repairs. A copy of the latest inspection report should be obtained from the Ontario Bridge Management System, (6).

3.4

Site Visit

A preliminary visit to the site shall be made to establish: • • • •

traffic control requirements; general indications of the condition of the structure which can be used to establish the approximate duration of the survey and crew size; the extent of deterioration, including soffit condition of decks, and the need to arrange for a boat, ladder, bucket truck or other equipment; any unusual problems.

Where a Consultant is to carry out the condition survey, a reconnaissance trip may be required with Ministry staff so that the extent of inspection and sampling requirements can be generally agreed upon.

3.5

Traffic Control

Traffic control for condition surveys shall be in accordance with the Ontario Traffic Manual Book 7-Temporary Condition, (7). The responsibility for provision of traffic control may vary from Region to Region but should be identified in the Standard Consultant's Agreement. The order and number of lane closures required to carry out the survey in the most expedient manner and with the least disruption to traffic shall be determined and discussed with the Regional Structural Sections and the Districts involved. The local OPP detachment should be notified in advance when lane closures are required for the condition survey.

3.6

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Manpower

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In general, the crew will consist of a supervising Professional Engineer and two to four crew members. Additional personnel may be required for traffic control, concrete core drilling, and asphalt sawing operations. On large structures, the crew size may have to be increased for mapping cracks and operating additional cover meters or half-cells. If there are any time constraints involved in carrying out the survey (e.g. work permissible in off-peak hours only), they shall be identified in the Consultant's Agreement and may influence manpower requirements.

3.7

Grid Layout

3.7.1

General

When carrying out a detailed condition survey that involves a corrosion potential and concrete cover survey, data is collected with reference to grid lines. A 1.5 m x 1.5 m grid is used on most bridge decks; a 3 m x 3 m grid could be used on bridge decks with an area greater than 500 m2 that were constructed in 1975 or later. A 1.0 m x 1.0 m grid is usually used on other concrete components but the size of this grid may vary depending on the dimensions of a particular component. A proposed grid layout should be established using existing structure drawings prior to going to the site. Grid lines, whether longitudinal, transverse, vertical or horizontal shall run parallel to their respective reference lines. A minimum of 5 longitudinal lines are required when using a large grid spacing on bridge decks. When a GPR survey has been previously carried out, the orientation of the grid lines should correspond to the orientation of the grid lines in the GPR survey. The spacing for the longitudinal grid lines is measured perpendicular to the longitudinal reference lines. However, when laying out transverse grid lines, measurements must be made parallel to the longitudinal reference line. The spacing for the vertical grid lines is measured perpendicular to the vertical reference line. However, when laying out horizontal grid lines, measurements must be made parallel to the vertical reference line. Grid lines are usually placed 0.1 m from the edge of the component except on bridge decks where they are normally placed 0.25 m to 0.5 m from the curb, barrier or expansion joint end dams. On bridge decks with longitudinal or transverse construction joints, a grid line should be placed 0.1 m from each side of the construction joint. Examples of grid layout are given in Appendix 1.B. Letter size grid sheets of the component should be prepared for data collection. Each grid sheet shall include the grid lines and cover a convenient portion of the component. Copies of the grid sheets are used in the field to record data collected on surface deterioration, asphalt depths, half cell potentials, concrete cover to reinforcement and soffit deterioration.

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It should be noted, that even if the grid layout is not required when no corrosion potential and concrete cover surveys are specified, grid sheets should still be prepared, so that defects may be plotted in their approximate location. 3.7.2

Post-Tensioned Decks with Circular Voids

Based on past experience, half-cell readings are usually more negative directly over the voids than the adjacent areas. Hence, longitudinal grids for half-cell survey shall be located at every void and mid-point between them; additional grids to be at 0.25 m from curbs and then spaced at maximum 1.5 m until the first void. If the spacing of the voids is less than 1.5 m, spacing of the grids does not have to be less than 0.75 m, representative voids could be selected to reduce the total number of survey points. Transverse grids to be spaced at 1.5 m. Where a large asphalt strip is removed to expose the concrete surface, half-cell survey shall be conducted on the exposed surface using a grid of 0.5 m x 1.0 m with at least one grid line centred at the void; additional longitudinal grid lines shall be provided at cracks.

3.8

Equipment

3.8.1

General

A list of equipment and tools required to carry out a detailed condition survey has been prepared to provide some guidance as to the type and variety of equipment required. Vehicles required to transport equipment and personnel and special access equipment, such as a boat, ladder or bucket truck, are not included. The equipment list is divided into three categories: • • •

general tools and materials; additional tools and materials for asphalt covered decks; tools and materials for anode resistance test.

In some cases the sawing and coring is done by a subcontractor who specializes in that type of work.

3.8.2

General Tools and Materials

These general tools and materials are required for all condition surveys. • • • • •

gasoline powered electric generator capable of providing power simultaneously to a core drill, portable drill, and other equipment; extension cords; gasoline; electric core drill with 50 mm, 75 mm, 100 mm and 150 mm bits, core retrievers, water tank and necessary hoses to supply water to core drill; wet/dry vacuum cleaner;

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• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

a number of pieces of 13 mm plywood with wire attached suitable for using as forms when filling full depth core holes; Ministry approved concrete repair material for filling core holes; shipping crates; canvas sample bags; four wheel dolly; pachometer (or Cover meter); voltmeter and suitable lead wire as specified in ASTM C876 (9); for decks with epoxy coated steel, AC ohmmeter capable of measuring 0.1 to 1000 ohms and insensitive to AC and DC ground currents; for decks with epoxy coated steel, epoxy patching material, conforming to DSM 9.65.73(10), to repair damaged coating of epoxy coated bars; copper-copper sulphate half cell as specified in ASTM C876; portable electric drill with suitable 15 mm carbide bits; electric chipping hammer; thermometers for measuring air and concrete temperatures; sponges and rags; files; chisel; wire brush; screwdriver; vice grips; self tapping screws; rubber pails; nails; water; string and tape; camera, flash, telephoto lens and film; binoculars; flashlight; mirror on a pole; measuring tapes - 30 m and 5 m; measuring wheel; carpenter's level; plumb bob; crack comparator; prospectors pick-hammers heavy logging chain, typically 2 m long; blank forms; field books and scratch pads; field grid sheets; pens, pencils, pencil sharpeners and erasers; yellow marking crayons;

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•

personal safety equipment such as hard hats, safety shoes, safety vests, goggles, work gloves, safety belt, etc.; traffic control items such as signs, delineators (cones) and flags.

•

3.8.3

Additional Tools and Materials for Asphalt Covered Deck

The following additional tools and equipment are required for asphalt covered decks, in addition to those shown in Sections 3.8.2. • • • •

Portable breaker/compactor and attachments; Gasoline powered saw, suitable for dry sawing asphalt complete with 400 mm blades; Spray can suitable for applying wetting solution; Caulking gun and Bituthene caulking material for filling holes drilled in asphalt for half cell testing; Cold mix and Bituthene HDG waterproofing material for repairing core holes and sawn sample areas.

•

3.8.4

Tools and Materials For Resistance Test

The following additional tools and materials are required for measuring the resistance of anodes and probes on cathodically protected structures: • • • • • • • • •

cable locator; AC ohmmeter capable of measuring 0.1 to 1000 ohms and insensitive to AC and DC ground current; nails (100 mm long); #10 AWG stranded copper cable; compression connectors; soldering kit; heat shrink tubing; propane torch; self-amalgamating tape.

3.9

Forms

Standard forms required to carry out a detailed condition survey are described in Section 6.3 and are contained in Appendix 1.C.

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4.

FIELD PROCEDURES

Section 4 gives guidelines for procedures to be followed in the field and the amount of data to be collected in the field.

4.1

General

The Consultants' Agreement will indicate whether a detailed visual inspection of the structure is required and will specify the extent of field data collection and sampling requirements for components that require a detailed condition survey. All data recorded in the field shall be complete, legible and unambiguous to avoid errors in preparing the final report and the drawings. 4.2

Detailed Visual Inspection

The condition of structure components shall be visually assessed for material and performance defects as described in O.S.I.M. (4). The extent of the deterioration shall be estimated but not measured. No physical testing is required except that accessible areas shall be sounded in areas where delaminations are suspected. Colour photographs shall be taken of significant defects. Where a structure has been previously inspected according to O.S.I.M., the Ministry shall supply the consultant with the latest inspection data. The type and extent of deterioration shall be visually assessed and shall be compared to the previous conditions. Additional deterioration or repairs that have been made since the previous inspection shall be recorded, and the condition states of the components shall be adjusted accordingly. The changes in the O.S.I.M. inspection data will be entered by the Regional Structural Sections into the BMS database and updated reports will be produced. These shall be attached to the detailed deck condition survey reports. . 4.3

Detailed Condition Surveys

4.3.1

General

The Consultant Agreement shall specify the data and sampling requirements for each component to be surveyed. All areas of deterioration, and data from half cell, cover and delamination surveys shall be recorded on field grid sheets in such a manner that the final drawings can be prepared. 4.3.2

Photographs

Colour photographs are required and shall be taken with a digital camera. If at all possible, general views of the structure should be in a single photograph. Sawn sample photographs shall show the condition of the waterproofing membrane and the condition of the deck surface. For detailed deck condition surveys, a photograph is required of each expansion joint. Where extensive deterioration is evident, only typical areas need be photographed, e.g. a photograph of each spalled area is not required. Pictures of deteriorated asphalt over pancake anodes shall also be taken on cathodically protected bridge decks. April, 2004

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Pictures should also be taken of the deck soffit inside the voids of thick concrete decks that do not contain post-tensioning cables and have no provision for access to inspect the inside of the voids. The picture can be obtained by inserting the camera through a full depth core hole.

4.3.3

Traffic Control

Traffic control shall be implemented in accordance with the prescribed traffic control plan developed during the planning stage, see Section 3.5. 4.3.4

Grid Layout

When the grid layout is required, the grid points shall be laid out as detailed on the letter size grid sheets described in Section 3.7. The grid layout may be modified if the reference lines chosen from the drawings are not acceptable. The marking of the grid points on the concrete surface is normally carried out by three persons. A crayon or keel shall be used in marking the grid points. For areas where it is difficult to layout a grid system, reference rulers can be demarcated on the component at the appropriate locations. The data collected should be plotted on the field drawings as accurately as possible using the reference rulers as reference. 4.3.5

Cathodically Protected Components

Prior to the commencement of concrete coring and saw-cutting of asphalt, all embedded wires, anodes, probes and reference cells shall be located as per the layout given in the cathodic protection drawings. If possible, the location of cores and sawn samples shall be a minimum 2 metres from embedded wires or components; a cable locator should be used to confirm location of embedded wires if cores and sawn samples are to be taken within the 2 metre limit. Care shall be taken to avoid cutting the wires or damaging the cathodic protection hardware. Any damaged wiring shall be repaired. The system should be de-energized for at least four weeks prior to the commencement of the survey. 4.3.6

Equipment Calibration

Standard forms are provided to document the data required for calibration of the equipment used for checking concrete cover and corrosion activity. A description of equipment used and the temperatures at the time of the test is also required.

4.3.7

Corrosion Potential Survey

4.3.7.1

Technique

The corrosion potential survey is used to measure corrosion activity of reinforcing steel at the time of the test and is carried out in accordance with the requirements of ASTM C876-91 (9). Corrosion April, 2004

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activity shall be measured by comparing the potential of the reinforcing steel with the potential of a standard reference cell. A copper-copper sulphate half-cell is used because it is rugged and stable. The numerical values obtained using a copper-copper sulphate half-cell are indicative of conditions as listed below. •

If potentials over an area are numerically less than -0.20 V, there is a greater than 90% probability that no reinforcing steel corrosion is occurring in that area at the time of measurement.

•

If the potentials over an area are in the range -0.20 V to -0.35 V, corrosion activity of the reinforcing steel in that area is uncertain.

•

If potentials over an area are numerically greater than -0.35 V, there is a greater than 90% probability that reinforcing steel corrosion is occurring in that area at the time of measurement.

4.3.7.2

Procedure for Concrete with Uncoated Reinforcing Steel

The multimeter battery shall be checked at the start of the test. The location and concrete cover to the ground, the method of connecting to ground, the total resistance and voltage drop measured for electrical continuity check, and the resistance of lead wire shall be recorded. At least five potential measurements shall be checked at the beginning and the end of the test, and each time a new ground is used. Duplicate readings should differ by no more than 0.02 V. Where greater differences are recorded the test shall be repeated. Since corrosion activity is a function of temperature, readings shall not be taken when the air and concrete temperature is lower than 5o C. The concrete temperature shall be measured in a shaded area of the structure. For the results to be accurate, the concrete should have sufficient moisture to be conductive but should have no standing water at the time of the corrosion potential survey. Pre-wetting of the grid points is recommended for surveys carried out during prolonged dry spells. On exposed concrete decks the presence of contaminants may influence the readings obtained. Therefore, the concrete surface shall be removed to a 2 mm depth at each grid point using chipping hammers or by grinding. A positive ground connection shall be made directly to the reinforcing steel. The ground connection should be made with a self-tapping screw or compression clamp. When a compression clamp is used, all corrosive deposits should be removed at rebar ground location. The use of adhesive tape for grounding the reinforcing steel is not acceptable. A separate ground shall be used for each portion of the component that is not continuous. The reinforcing steel should be checked for electrical continuity by measuring the resistance (ohms) and voltage drop (mV's) between the ground and another rebar which is far as possible and April, 2004

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diagonally opposite from the ground connection. The resistance should be measured one way and then the polarity of the leads should be reversed and the resistance measurements should be repeated. When the above procedure is followed, discontinuity of the reinforcing steel will be indicated by any one of the following: • • •

any resistance reading more than 5 ohms or a negative number (after deducting the resistance of the test leads); resistance readings that are unstable; voltage drop readings greater than 3.0 mV's.

If electrical continuity cannot be established on the first attempt, the ground connection should be checked. If ground connection is secure and resistance and voltage drop is still high, the continuity check shall be repeated using different rebars for ground connection and/or resistance check. The survey should be subdivided into smaller areas on long bridge decks. In some older decks with black smooth round bars, it is not possible to carry out a half-cell survey as there is no continuity between the bars. Corrosion potential readings shall only be taken in the core and sawn sample locations on structures that are protected with the conductive asphalt CP system. Care shall be taken to avoid contact between the half-cell and the conductive asphalt when potential readings are made. Corrosion potential readings are required at all grid points on structures that are not cathodically protected. A 15 mm diameter hole shall be drilled through the asphalt and any waterproofing material to make contact with the concrete. The drilling dust shall be removed from the holes by vacuum or air blasting before adding the wetting solution to take the reading. Asphalt depths shall be measured in the holes drilled for corrosion potential tests. It is recognised that an exact measurement is not possible because of the difficulty in defining when contact is made between the drill bit and the deck surface. However, small errors are not significant in relation to the large number of readings taken. On decks with a latex modified concrete overlay treatment, an additional set of corrosion potential readings should be obtained at 5 grid point locations via 15 mm diameter holes that have been drilled through the latex modified overlay into the original concrete substrate to verify that the readings are the same as those taken at the top of the overlay. All drill holes shall be repaired by removing the wetting solution and caulking with bituthene caulking material for the full depth of the hole. Fine sand shall be sprinkled on the surface to prevent tracking.

4.3.7.3

Procedure for Concrete with Epoxy Coated Reinforcing Steel

A regular type of half-cell survey cannot be carried out on decks with epoxy coated reinforcing steel as there is no electrical continuity between the different coated reinforcing bars. However, April, 2004

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the condition of the reinforcing steel can be assessed by taking localised corrosion potential readings and measuring AC resistance and voltage (IR) drop between reinforcing steel at locations where rebars are exposed as part of the concrete coring operation. Only reinforcing steel in the top layer of the top mat should be tested. The AC resistance and IR drop testing should be carried out at 5 widely separated core locations where reinforcing steel is exposed. As failure of the epoxy coating is more likely along curbs and barrier walls, it is recommended that 3 of the readings be obtained in these locations. The connections to reinforcing steel shall be made with a self-tapping screw at each test location. An AC resistance and IR drop measurement shall be made between each pair of test points covering all possible combinations. When taking the IR drop measurement, it is important that the polarity of the connection and the sign of the reading be recorded. As the AC resistance measurement is actually the sum of the AC resistance of two rebars and the concrete, the AC resistance contributed by the individual bars will have to be calculated using the procedure in Appendix 1.E. Generally, a low AC resistance reading probably indicates that epoxy coating has failed to protect the steel from corrosion. However, as AC resistance is not only related to condition of coating but also to size and length of the reinforcement, the criteria for assessing the condition of coated reinforcing steel based on AC resistance cannot be finalised until more data is collected. Half-cell readings shall be taken at all locations where reinforcing steel is exposed by the coring operation. The connection to the rebar and location of the half- cell should be at the same rebar. A smaller type half-cell can be used for taking readings inside the core hole. The reading can be very unreliable when the half-cell location does not correspond to the same rebar as the ground connection. All data, both measured and calculated, shall be recorded on the Epoxy Coated Reinforcing Steel Summary Sheet and the Detailed Condition Survey Summary Sheet in Appendix 1.C.

4.3.8

Concrete Cover Survey

4.3.8.1

Technique

The concrete cover over the outer layer of reinforcing steel shall be measured using an approved cover-meter. The cover-meter measures the disturbance in a magnetic field and the magnitude of the disturbance is proportional to the size of the bar and its distance from the probe. The cover to the top bar in the top mat shall be measured nearest the grid point or by taking an average of the bars on either side of the grid point. The existing structure drawings shall be checked to determine orientation and the size of top bars (note if bar size is constant). The cover-meter shall be operated with the probe oriented parallel to the top bars. If the structure drawings are not available and the orientation of the top bars is not known, the probe shall be rotated at several locations until a sharply defined minimum reading

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(maximum deflection) is obtained. This indicates the probe is directly above a bar, and the orientation of the bar coincides with the longitudinal axis of the probe.

4.3.8.2

Procedure

A battery check shall be made at the start and end of the test. On some instruments the calibration tends to drift while in use. Therefore, the instrument shall be calibrated at a core hole where a bar location is known or at an exposed bar, and checked periodically (as per Equipment Calibration Form). This procedure will also identify if there are magnetic particles in the concrete for which a correction factor must be derived. On decks with exposed concrete surfaces, the cover shall be measured on a 3 m x 3 m grid. On decks with an asphalt surface, the cover shall be measured in areas where sawn samples have been removed. On other concrete surfaces the cover shall be measured at a maximum 1m x 1 m grid for components less than 50 m2 and on a 2m x 2m grid if the area of the component is greater than 50 m2. The value recorded shall be the cover to the uppermost bar nearest to the intersection of the grid lines. Reinforcing steel is tied together to form a relatively rigid mat. As a result, any significant change in the cover readings at adjacent points should be viewed with suspicion and additional readings taken to confirm the results.

4.3.9

Delamination Survey

4.3.9.1

Technique

Delaminations in concrete are detected by striking the surface and noting the change in sound being emitted. Several methods, using tools such as hammers, steel rods, chains and, more recently, electronic acoustical devices, radar and thermography, have been used for detecting delaminations in concrete. The chain drag method has been found to be the most suitable for detecting delaminations on the top surface of bridge decks. The chain is moved from side to side in a swinging motion along the surface of the concrete. A change in the normal ringing sound to that of a dull sound would normally indicate that a delaminated area has been encountered. A heavy chain (2.2 kg/m with 50 mm links) has proved to be most suitable, especially, in areas where there is interference from traffic noise. The chain drag is, generally, used in detecting delaminations on exposed horizontal concrete surfaces only. It can be useful, though, as a quick method of identifying potentially debonded areas in asphalt covered decks, that might require further investigation. However, these areas are not measured and recorded.

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Hammers and steel rods are used to detect delaminations on vertical and overhead surfaces. If the striking object is highly resonant, the difference between sound and delaminated concrete may be difficult to distinguish. Therefore, care must be taken when interpreting the sound produced.

4.3.9.2

Procedure

Delaminated areas shall be marked directly on the surface of the components using a red crayon. The areas are then measured (size and location) and recorded on the appropriate grid sheet.

4.3.10

Concrete Surface Deterioration Survey

The area and location of patches, spalls, exposed reinforcement, honey-combing, wet areas, scaling and other observed defects and deterioration shall be recorded on the field grid sheets. See OSIM, Part 1, Section 2, for description of defects commonly occurring in concrete. The severity of scaling shall be visually assessed and classified according to the categories given in Table 4.1.

Severity of Scaling

Depth, mm

light

0 to 5

medium

6 to 10

severe

10 to 20

very severe

over 20

Table 4.1 / Classification of Scaling

The width of cracks shall be measured using a crack comparator. The size and location of cracks shall be recorded with respect to the grid lines. On exposed surfaces the cracks are classified according to the scale given in Table 4.2 and the letter M or W is noted beside each crack on the grid sheet. Cracks that are leached or stained shall be labelled separately. For condition survey purposes the location and length of cracks narrower than 0.3 mm (shrinkage cracks) need not be recorded for most components; however, shrinkage cracks or pattern cracks shall be noted under the remarks column of the detailed condition survey summary sheet. Cracks wider than 0.25 mm should be recorded for concrete beams and girders.

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If measuring depth of the medium and wide cracks is specified in the consultant's agreement, the depth shall be measured using feeler gauges or fine wires. The crack surfaces should also be carefully assessed for degree of contamination and leakage.

Severity of Cracking

Crack Width, mm

Medium (M)

0.3 to 1.0

Wide (W)

> 1.0

Table 4.2 / Classification of Cracking

In the case of detailed condition surveys for decks, concrete surface deterioration of the deck soffit shall be recorded on a separate grid sheet on the same grid layout as the deck surface. The location of any void drains shall be noted. When a delamination survey is required for the deck soffit the areas of deterioration shall also be measured. On asphalt covered decks, the general condition of the asphalt and cracks wider than 3 mm shall be recorded. Sealed cracks shall also be recorded. Any defects in the surfacing which may be indicative of deterioration in the concrete deck slab shall be recorded. On decks with the conductive bituminous overlay system of cathodic protection, the condition of asphalt over the pancake anodes should be noted.

4.3.11

Expansion Joint Survey - Bridge Decks

The expansion joints shall be visually assessed for material and performance defects as described in O.S.I.M. (4) and the type and extent of the deterioration shall be recorded on the Detailed Condition Survey Summary Sheet for expansion joints. Although no physical testing is required, measurements to determine the joint dimensions shall be taken and recorded on the summary sheet.

The dimensions of each joint are required even where there is no armour or seal because new joints are usually installed as part of the rehabilitation contract. All joint gaps should be measured perpendicular to the line of the joint. Where the joint has been paved over, the asphalt must be removed at the curbs and at the centreline of the highway in order to measure the joint gap. There may be exceptional circumstances, such as the use of sliding plates where it is not possible to measure the joint gap. However, the engineer should be aware of this situation from the review of the plans and should make a note on the form in the section for remarks.

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The deck temperature shall be taken 50 mm below the surface on exposed concrete decks and at the asphalt-concrete interface on asphalt-covered decks. The ambient temperature shall be the shade temperature, usually taken below the structure. Sketches of typical sections of the expansion joint in the curb or sidewalk area as well as the driving lane area are required. The sections shall show any steel angles, steel cover plates, dimensions of concrete end dams and other pertinent information. The width of the top of the ballast wall shall be measured. If the ballast wall is paved over, the asphalt must be removed at one location for each abutment in order to measure this width. The thickness of asphalt at the concrete end dams shall be measured at the curbs and at the centreline of highway on the bridge deck. Asphalt shall be removed by coring or other suitable methods. The quality of concrete in the deck, curbs and ballast walls adjacent to the joint shall be noted under remarks.

4.3.12

Drainage - Bridge Decks

Deck drains shall be visually assessed for material and performance condition defects as described in OSIM and the type and extent of deterioration shall be recorded on the Detailed Condition Survey Summary Sheet for drainage. Although the deck drainage portion of the summary sheet is self-explanatory, additional instructions are given below: a.

The size of the drains shall be measured. The length and angle of inclination of the drains may be estimated.

b.

The boxes given for recording the location of catch basins is suitable for most structures. A separate sketch will be required for unusual alignments or complex geometry.

The deck soffit should be inspected for the presence of void drains on voided decks and asphalt drainage tubes on decks with transverse expansion joints.

4.3.13

Concrete Cores

4.3.13.1

General

A covermeter shall be used to avoid coring through the top mat of steel. However, in areas of high corrosion potential with sound concrete some cores should be taken through the steel to observe the condition of the rebar. Cores shall not be taken through pre-stressing steel, utility ducts, embedded cathodic protection components (including cables) or in areas immediately below or

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above the bearings. The cores shall be long enough to carry out the required tests and shall extend below the top mat of reinforcing steel. Where the concrete being cored is in poor condition and is broken into several fragments, the juxtaposition of the pieces shall be recorded, by either a sketch or identification of individual pieces, so that the core can be pieced together in the laboratory. Cracks in the concrete core caused by the coring operation should be identified as such. The inside of the core hole shall be examined carefully for horizontal cracks and the condition of the concrete. The condition and orientation of any rebar located in the side of the hole shall also be recorded. Each core shall be given a number that identifies the structure and its location in the structure. The location and the number (prefaced with 'C') of the cores shall be noted directly on the grid sheets and the core logs. It is a good practice to complete the dimensions and remarks section of the core log forms in the field, since this reduces the possibility of errors in identifying cores. The location of the cores shall be given with respect to the grid lines.

4.3.13.2

Bridge Deck Riding Surface

The number of cores required is specified in Table 4.3. Some cores may be taken before the completion of non-destructive testing. When this is done the coring operation shall be contained and any excess water shall be vacuumed frequently. Care shall be taken to prevent water from the coring operation interfering with the corrosion potential measurements and sawn sample operation. Cores shall be taken in areas where deterioration is suspected; i.e. near curbs, in areas of poor drainage, at cracks or wet spots in the soffit, in areas of high corrosion potential, in areas of delaminations identified by GPR survey (if available), and at cracks in the asphalt surface. However, it is also intended that the cores be representative of the condition of the concrete. Consequently, a sufficient number of cores shall also be taken from areas with lower corrosion potential (between 0.0 to –0.35 volts) to determine the extent of delaminated concrete in this area. Sound cores will, in any event, be required for physical testing. At least one core, free from reinforcing steel, shall be used for compression testing. At least two cores shall be taken from each span and where the structure has been widened, a sufficient number of cores shall be taken from old and newer portions of structures to carry out the physical testing. One of the cores shall be taken the full depth of a thin deck slab. At least 3 cores shall be taken full depth through the top slab of thick voided concrete slabs that are not post-tensioned and do not have provisions for access to inspect the inside of the voids. The cores should be taken in the areas of suspected deterioration for the purpose of photographing the underside of the slab. For post-tensioned decks with circular voids, all cores shall be taken at solid web areas between voids where the cables are sufficiently deep to avoid being damaged by coring. Furthermore, at least one core shall be taken at a longitudinal crack within the large asphalt strip removal area, just April, 2004

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deep enough to exposed the condition of the top reinforcement. If there is delamination of an existing overlay within the large asphalt strip based on sounding, then a core should be taken at the delaminated area to see if the overlay has debonded. On decks with uncoated reinforcing steel, the total number of cores required will not be known until the corrosion potential survey is completed. The additional cores required shall be concentrated in the areas that according to the GPR survey are delaminated or in areas with corrosion potentials more negative than -0.35 volts. On decks with epoxy coated reinforcing steel, the total number of cores shall be the minimum specified in Table 4.3 plus additional cores in delaminated areas identified by the GPR survey. For the AC resistance measurements, 5 cores are required directly over a reinforcing bar at 5 widely separated locations; they should consist of 3 cores along the curb/barrier wall and 2 cores towards the centre line of the deck. If necessary, these cores can be taken at sawn sample locations to facilitate locating the rebar. The cores shall be taken in such a way to expose the rebar without cutting through the bar.

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Wearing Surface

Deck Area (m2)

No. of Cores - First Time Survey Basic (Note 1)

Asphalt

Extra (Note 2)

Min

No. of Cores - Update Survey Max

Basic (Note 1)

Extra (Note 2)

Min

Max

< 300

6

1 per 25 m2 of HCP & delam area

6

10

3

1 per 50 m2 of HCP & delam area

3

5

300 to 1000

10

1 per 25 m2 of HCP & delam area

10

20

5

1 per 100 m2 of HCP & delam area

5

10

> 1000

1 per 100 m2 of deck area

1 per 50 m2 of HCP & delam area

15

n/a

1 per 500 m2 of deck area

1 per 100 m2 of HCP & delam area

7

n/a

< 500

6

1 per 50 m2 of HCP area

6

10

3

1 per 100 m2 of HCP area

3

7

> 500

1 per 200 m2 of deck area

1 per 100 m2 of HCP area

10

20

1 per 500 m2 of deck area

1 per 200 m2 of HCP area

3

10

Concrete

Note 1: The basic number of cores shall be uniformly distributed in areas outside of the HCP areas. Note 2: Extra number of cores are based on the area of high corrosion potential (HCP) more negative than -0.35 volts calculated statistically for decks with uncoated rebar and the area of delaminated (delam) concrete identified by GPR Survey. If area of HCP and delam exceeds 50% of the deck area, the number of extra cores shall be based on 50 % of the deck area.

Table 4.3 / Requirements for Coring Bridge Decks

When coring a deck with an asphalt wearing surface which has a poor bond between concrete and asphalt, it is advisable to remove the asphalt from the core bit before drilling the deck slab so that the asphalt is not broken inside the bit. Where asphalt thickness is in excess of 100 mm; it is sometimes necessary, in order to retrieve the concrete core, to remove a 150 mm diameter core from the asphalt prior to taking the 100 mm diameter core in the concrete. Normally, cores are not to be taken within the sawn sample areas except where a core without reinforcement (for testing compressive strength) cannot otherwise be secured. Also for decks with epoxy coated reinforcing steel, some cores may be required at sawn sample locations for the AC resistance testing. More cores are usually taken from asphalt covered decks because it is more difficult to establish the condition of the concrete deck slab. On bridge decks that are protected with the conductive bituminous overlay system of cathodic protection, the conductive asphalt layer in the cores must be completed intact for cores to be tested for electrical resistivity. One core sample should be taken next to an anode with high resistance. April, 2004

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4.3.13.3

Curbs, Sidewalks, Barrier Walls and Approach Slabs

Where cores are taken to confirm the existence of a concrete approach slab or from the sidewalk, or curb to determine the condition of the concrete and the bond with the deck slab, the cores shall be included in the Core Log but no physical testing is required. Cores for testing shall be taken in sound areas with high corrosion potentials; at least one of the cores for barrier walls and for the sidewalk shall be taken to expose the condition of the rebar. The core from the approach slab need not be retained but those from curbs, sidewalks or barrier walls shall be retained until advised by the Ministry.

4.3.13.4

Concrete Components, Excluding Bridge Decks

Cores shall be taken in sound areas to carry out the required testing and in deteriorated areas to determine the condition of the concrete substrate. The diameter of cores taken from columns should be sized to suit size and spacing of reinforcing steel to avoid cutting the bars. Cores taken to determine the condition of ballast walls shall be included in the Core Log but no physical testing is required. Cores to be tested for chloride content shall be from areas prone to chloride exposure from salt splash or leaking expansion joints; at least one of these cores shall be taken to expose the condition of the rebar. If cores are required in cracked areas, the width, depth and orientation of the crack should be noted on the core log. At least one core should be taken through cracks that visually appear contaminated. The presence of any calcite deposits, rust stains or any other deleterious material in the crack shall be recorded and photographed.

4.3.13.5

Repairs to Core Holes and Epoxy Coated Rebar

Prior to repairing the core holes, the sides of the hole must be cleaned and any water removed. The cut ends of epoxy coated bars or any damage areas of the coating shall be cleaned and repaired with an approved epoxy patching material. The core holes shall be repaired by tamping layers of a stiff mixture of approved concrete repair material until the hole is filled level with the concrete surface. On decks that have a waterproofing membrane, a disc of bituthene HDG preformed waterproofing material shall be cut to fit the core hole and shall be fastened with mastic to the concrete. Cold mix asphalt is then compacted to a level slightly above the bituminous surface.

4.3.14

Asphalt Sawn Samples

Sawn samples are removed from asphalt covered decks to establish the condition of the concrete deck, the presence and condition of waterproofing materials, and to check the cover to reinforcing steel. The size of the sawn samples shall be a minimum 250 mm x 250 mm. The sample shall be April, 2004

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removed by dry sawing in order to determine if and how much moisture is present beneath the asphalt. Sawn samples shall not be taken over embedded cathodic protection components, including cables, unless otherwise specified in the Consultant's Agreement. Prior to sawcutting, the depth of asphalt shall be established from adjacent drill holes for half-cell survey (allowance should be made for partial penetration of drill into concrete surface). The depth of saw cutting shall be such that there will be no damage to the concrete surface and reinforcing steel. The number of sawn samples required is specified in Table 4.4. As sawn samples provide considerably more information on the degree and type of surface deterioration than cores, some of the sawn samples shall be concentrated in areas of suspected deterioration. They can be especially useful in investigating the condition of the deck slab at cracks in the asphalt, above the areas of deterioration in the soffit, in areas of deterioration identified by GPR (if available) and in areas of high corrosion potential on decks constructed with uncoated reinforcing steel. At least one sample is to be removed from the area adjacent to the curb. As the sawn samples should be representative of the condition of the concrete, a sufficient number of sawn samples shall also be taken from areas with lower corrosion potential (between 0.0 to –0.35 volts) to determine the extent of delaminated concrete in this area. On structures that are protected with the conductive asphalt system of cathodic protection, at least two sawn samples shall be located in wheel paths. Sawn samples should also be taken in areas where the conductive asphalt has been patched to assess the type of patch and the condition of concrete. The total number of sawn samples required will not be known until the corrosion potential survey is completed on decks containing uncoated reinforcing steel. The additional sawn samples required shall be concentrated in areas that according to the GPR survey are scaled, delaminated or areas that have corrosion potentials more negative than -0.35 volts. The condition of the concrete and waterproofing are of greater significance than the condition of the asphalt. Consequently, photographs shall be taken to show clearly the condition of the concrete surface. This may involve cleaning the concrete surface of asphalt residue. Care should be taken during asphalt removal to ensure that concrete surface is not damaged by the breakers used for removal. Sawn sample logs shall be completed in the field. The location shall be given with respect to the grid lines. The concrete cover to the top layer steel in each removed area shall be measured using a covermeter. The depth of asphalt and waterproofing shall also be recorded. The concrete in the sample area shall be sounded for delaminations using both the hammer and chain technique. The depth of conductive asphalt shall also be measured and recorded on structures with the conductive asphalt system of cathodic protection. The concrete surface should be carefully examined for waterproofing or tack coating or other materials that may effect the performance of the conductive asphalt cathodic protection. April, 2004

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Sawn sample areas shall be repaired by compacting cold-mix asphalt to slightly above the level of the asphalt surfacing. On decks which have been waterproofed or are protected by cathodic protection, a piece of bituthene HDG waterproofing material shall be cut to fit the removed area and mastic shall be used to fix the membrane to the deck surface. Where the saw blade has accidentally cut into the concrete or asphalt surface, the resulting groove shall be sealed with bituthene caulking material.

Deck Area (m2)

No of Sawn Samples - First Time Survey Basic

Extra (Note 1)

Min

No. of Sawn Samples - Update Survey

Max

Deck Waterproofed

Deck Not Waterproofed

Basic

Extra (Note 1)

Basic

Extra (Note 1)

Min

< 300

6

1 per 25 m2 of HCP & delam area

6

10

3

1 per 50 m2 of HCP & delam area

3

1 per 35 m2 of HCP & delam area

3

300 to 1000

10

1 per 50 m2 of HCP & delam area

10

20

5

1 per 100 m2 of HCP & delam area

5

1 per 75 m2 of HCP & delam area

5

> 1000

1 per 200 m2 of deck area

1 per 100 m2 of HCP & delam area

15

n/a

7

1 per 150 m2 of HCP & delam area

7

1 per 100 m2 of HCP & delam area

7

Note 1: Extra number of sawn samples is based on the area of high corrosion potential (HCP) more negative than -0.35 volts calculated statistically for decks with uncoated rebars and the area of delaminated concrete identified by GPR Survey. If area of HCP and delam exceeds 50% of the deck area, the number of extra sawn samples shall be based on 50 % of the deck area.

Table 4.4 / Requirements for Sawn Samples

4.3.15

Removal of Large Asphalt Strips

On decks where removal of a large asphalt strip is warranted, the location of the large asphalt strip shall be selected to coincide with soffit deteriorations, suspected top surface deteriorations based on low cover, HCP, asphalt conditions etc., and centred over a void for post-tensioned decks with circular voids. Large asphalt strip removal area shall be repaired by placing hotapplied rubberised waterproofing, protection board, and hot-applied asphalt.

4.3.16

Inspection of Cathodic Protection Embedded Hardware

The resistance and voltage of anodes, voltage probes and cathode (ground) connections that are designated for inspection in the Consultant Agreement shall be measured and recorded. This test shall be carried out at the splice locations in the concrete fillet strip along the curb or in junction April, 2004

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boxes on newer installations. All work shall be done in accordance with the following procedures: 1.

A strip of asphalt (600mm X 200mm) shall be removed along the curb at the splice location. A cable locator may be useful in determining the location of the splice. The maximum depth of sawcutting shall be 25mm.

2.

The concrete around the cables shall be removed with hand tools. Extreme care shall be taken not to damage the cables.

3.

The condition of the concrete fillet strip and the exposed cables shall be photographed and recorded. The location of the removal areas and embedded components tested shall also be recorded.

4.

The AC resistance between an exposed rebar and the end of the anode (or voltage probe) lead wire at the curb shall be measured using an AC ohmmeter. The DC resistance and voltage in mV's between an exposed rebar and the end of the cathode (ground) connection lead wire shall be measured using a multimeter. The resistance test shall be repeated with the leads reversed. The wire at the curb will have to be cut for these tests; however a sufficient length of lead wire shall be left for splicing. The resistance of the test leads shall also be measured and deducted from the resistance readings. All readings shall be recorded.

5.

The embedded anode (or voltage probe) shall be located using a cable locator. A 100 mm long nail shall be driven through the asphalt to make contact with the anode. The resistance and voltage drop (mVs) between the anode (or voltage probe) and the end of the lead cable shall be measured using a multimeter. The readings shall be recorded after deducting resistance of the test leads.

6.

All lead cables shall be respliced using in line compression type connectors and soldered after installation. Each existing splice will probably have to be replaced with two new splices and a short length of cable.

7.

The cables running from the control panel to each exposed splice shall be checked with a multimeter to ensure that there are no defects in the cable. The test shall involve measuring the resistance and voltage of the cable between the splice and the control panel. The resistance should be compared to the theoretical resistance of the wire after deducting resistance of test leads.

8.

The contact surface of existing wiring should be thoroughly cleaned prior to installation of heat shrink tubing. A self amalgamating tape should be placed around wires that involve a Y-type splice. The splices shall then be sealed and insulated with heat shrink tubing.

9.

All sand and debris shall be removed from the splice locations and the cables shall be covered with concrete patching material. The concrete patch shall then be covered with asphalt cold mix to match the existing pavement.

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10.

After completion of all work on the deck, the District shall be contacted to arrange for re-energising the cathodic protection system.

4.3.17

Conductive Asphalt Resistance Test (Cathodic Protection)

When specified in the Consultant Agreement, the resistance of the conductive asphalt shall be measured in situ by measuring the AC resistance between 2 nails placed at a 600 mm spacing. The nails shall be driven full depth through the asphalt making contact with the concrete beneath the asphalt. Prior to measuring the AC resistance, the nails shall be checked to make sure that they are not loose to ensure good contact, full depth, is made with the conductive asphalt layer. The resistance shall be measured with an AC ohmmeter. The readings and location of the testing shall be recorded. Upon completion of the testing, the nails shall be removed and the holes shall be filled with bituthene caulking material.

4.4

Sequence of Operations

4.4.1

General

The first task is for the Engineer to carry out a visual appraisal of the condition of the structure particularly the components that require a detailed condition survey, if this has not been done on a previous site visit. This will enable the Engineer to determine the scope of the survey and any unusual features or deterioration which will require special attention. The typical sequence of operations for conducting a detailed condition survey of an exposed concrete surface and an asphalt surface is shown below. Some tasks can be performed simultaneously where crew size allows. Cores should not be taken until corrosion potential testing is complete so that the concrete surface remains dry. If cores are to be taken in wheel tracks, they should be done early so that the concrete used to repair the core hole can set before the lane is opened to traffic. In early spring or late fall when temperatures in the early morning are too low for corrosion potential measurements, the delamination survey and component inspection can be the first operation. The results of the corrosion potential survey and GPR survey shall be used to establish the locations for taking the additional cores and sawn samples and shall be used to determine the number of samples to be taken. The detailed visual inspection of components not requiring a detailed condition survey and photography may be carried out at the completion of the detailed condition survey or simultaneously, if crew size allows.

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4.4.2

Exposed Concrete Components and Exposed Decks

The following sequence of operations generally applies to a detailed condition survey of exposed concrete surfaces: • • • • • • • • • • •

set up traffic control; lay out grid; establish ground locations for corrosion potential survey on decks with uncoated reinforcing steel; carry out corrosion potential survey on decks with uncoated reinforcing steel; delamination survey; cover survey; inspect soffit and plot deterioration (deck condition survey only); take cores; measure AC resistance, voltage drop and half-cell potential at 5 core locations where epoxy coated rebars are exposed; plot concrete surface deterioration; carry out expansion joint survey and record drainage details (deck condition survey only).

4.4.3

Bridge Decks with Asphalt Wearing Surface

The following sequence of operations generally applies to a detailed condition survey of decks with an asphalt wearing surface: • • • • • • • • • • • • • •

set up traffic control; lay out grid; establish ground location(s) for corrosion potential survey on decks with uncoated reinforcing steel; anode resistance test, if applicable; conductive asphalt resistance test, if applicable; drill holes for corrosion potential survey and measure asphalt depths; carry out corrosion potential survey on decks with uncoated reinforcing steel; inspect soffit and plot deterioration; sawn samples and large asphalt strips measure AC resistance, voltage drop and half-cell potential at 5 core locations where epoxy coated rebars are exposed; take cores; delamination survey on curbs and sidewalks; plot deck surface deterioration; carry out expansion joint survey and record drainage details.

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5.

LABORATORY TESTING OF CORES

Section 5 gives guidelines for procedures to be followed for the testing of cores in the laboratory and for recording test results.

5.1

Photographs and Description

All cores shall be transported from the site for examination and testing. Each core shall be described and photographed, except those taken from approaches. Each photograph shall be in colour and shall include no more than one core. Photographs shall be taken using a digital camera in a studio environment against a neutral background. The cores shall be arranged to show significant deterioration, unusual features and, where possible, embedded reinforcement. Cores shall be photographed without the identification markings showing the core face. Multiple views (using mirrors) are not acceptable. In some cases, wetting the cores may improve the contrast and emphasise defects such as cracks and voids. It is good practice not to proceed with physical testing of the cores until the photographs have been printed and the quality is acceptable. A sketch is required to show the overall dimensions of each core, the location and orientation of reinforcement and significant defects (i.e. delaminations, breaks due to coring and type of cracking). The sketch shall illustrate the same view of the core as the photograph. The dimension for thickness of waterproofing membrane shall not include the thickness of protection boards. In most cases, the above description of each core is sufficient. However, where there is evidence of reaction, deleterious aggregates, extensive cracking or other types of physical distress, this shall be noted in the description so that the Ministry can consider the need for a petrographic examination.

5.2

Physical Testing of Concrete

The intent of the physical testing program is to obtain an assessment of the quality and durability of the concrete. This is done by testing cores for strength, chloride content, and, in some cases, air void system. The number of cores tested varies with the size of the component and in the case of decks, the degree of deterioration. All testing must be done in laboratories approved by the Ministry. A list of laboratories approved for testing cores can be obtained from the Ministry's Materials Engineering and Research Office. Specific requirements for core testing are given in Table 5.1. The number of cores to be tested may vary from component to component. The number of cores to be tested for bridge decks is given in Table 5.2. The number of cores requiring testing for components other than the deck is given in the Consultant's Agreement.

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Test

Compressive Strength

Chloride Content

Air Void System

Test Method

CAN3-A23.2-14C (moist condition) (reference 10)

Ministry *

ASTM C457 (Reference 11)

Laboratory Approval

C.S.A. or Ministry

Ministry

Ministry

Other Requirements

Choose core without steel and with L/D > 1.0. Preferably L/D > 1.5.

Core should be taken from area exposed to chlorides and areas of high corrosion potential. **

Only for structures built in 1958 or later.

Method of Testing for Acid Soluble Chloride Ion in Concrete ( 8) is available from the Materials Engineering and Research Office of the Ministry. Where significant deterioration exists on the deck soffit, the full length core shall be tested by measuring the chloride content in alternate 10 mm thick slices.

* **

Table 5.1 / Requirements for Testing Cores

No. of Cores Test

Deck Size

Compressive Strength Chloride Content Profile

Air Void ** * **

First Time Survey Update Survey

Min.

Max*

< 500 m2

1

2

500 to 2000 m2

2

4

> 2000 m2

4

6

< 500 m2

2

3

2

500 to 2000 m2

1 per 125 m2

12

3

> 2000 m2

10

15

3

< 250 m2

1

1

250 to 1000 m2

2

2

> 1000 m2

3

3

The maximum number will apply to decks in poor condition. Test on air void system to be carried out on decks built in 1958 and later.

Table 5.2 / Requirements for Testing Cores from Bridge Decks 5.2.1

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Compressive Strength

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1 (optional)

1 (optional)

The cores should be selected to represent the compressive strength of the concrete in the component. They should preferably be free from steel, though this may not always be possible. The cores must be conditioned in water for 48 hours prior to testing. Results shall be reported after correcting to an equivalent L/D ratio of 2.0 using the factors given in Table 1 of CAN3-A23.2-14C ( 10). The cores from bridge decks shall be selected to represent the range of compressive strength of the concrete. Where the concrete is of a uniform, good quality, only the minimum number of cores should be tested.

5.2.2

Chloride Content

Cores tested for acid soluble chloride determination shall be from areas prone to salt exposure as well as from other moderately exposed areas like waterproofed areas of decks. Only cores that do not contain delaminations and that are not required for other testing shall be tested for chloride content profile. When one core is specified for chloride content profile testing, the core should be from an area with corrosion potential < - 0.35 volts CSE . When two or more cores are specified for chloride content profile testing, 50% of the cores should be from areas with corrosion potential < - 0.35 volts CSE while the remaining cores should be from areas with corrosion potential in the -0.20 to -0.35 volt CSE range. For multi-spans decks, minimum two cores per span shall be tested for chloride content. The chloride content profile is measured on samples taken from alternate 10mm thick slices to a depth of 90 mm. The chloride content of slices near the 90mm depth should have similar values for at least one core. If values are not similar, additional slices should be tested beyond the 90 mm depth for one of the cores tested until values are similar in two consecutive slices. The chloride content of the concrete will usually be highest adjacent to an external surface. Where the test results produce an unexpected profile through the thickness of the concrete, a duplicate determination shall be made to verify anomalous values. For decks that have been overlaid, the chloride profile is to be established down to the level of the top reinforcement in the original concrete instead of terminating at 90 mm from the top of the overlay.

5.2.3

Air Void System

An air void determination is not required for structures built prior to 1958 because the concrete can be assumed to be non-air entrained. On decks with scaled concrete, at least one core should be tested in the area of scaling. Where an air void determination is required either the Linear Traverse or the Modified Point Count Method may be used. The values of air content, specific surface and spacing factor are to April, 2004

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be reported. Paste content may be determined by measurement (Modified Point Count Method) or from the original mix proportions. Where the paste content is not known it is to be assumed to be 27%, but this assumption must be noted.

5.3

Resistivity Testing of Conductive Asphalt (Cathodic Protection)

When specified in the Consultant Agreement, the conductive asphalt shall be tested for electrical resistivity. The tests shall be carried out on cores with the conductive asphalt layer completely intact. The number of cores to be tested shall be specified in the Consultant Agreement. The cores shall be submitted to the Ministry for testing.

5.4

Significance of Test Results

5.4.1

Compressive Strength

The compressive strength results shall be compared with the strength specified on the original drawings. Wide variations in strength may indicate local areas of deterioration. Values of less than 20 MPa represent poor quality concrete. It should be noted that concrete damaged by frost action, usually exhibited as horizontal cracks in the upper portion of the core, may register a high compressive strength but still be of a poor quality. 5.4.2

Air Content

Concrete is normally considered to be properly air entrained if the air content exceeds 3%, the spacing factor is less than 0.20 mm and the specific surface exceeds 24 mm2/mm3. 5.4.3

Chloride Content

The chloride threshold value necessary to depassivate embedded steel and permit corrosion (in the presence of oxygen and moisture) is usually taken to be 0.20% by mass of cement. For a typical cement factor of 300 kg/m3 this corresponds to a chloride content of 0.025% by mass of concrete. Interpretation of chloride values is complicated by the fact that all the mix ingredients contain chloride ions, some of which are not available to initiate corrosion. The subject is further complicated in southern Ontario because the dolomitic limestone aggregates from the Niagara Escarpment contain relatively large (typically 0.12% by mass of aggregate for aggregate from the Amabel formation and 0.08% for aggregate from the Lockport formation) amounts of chloride ion which does not enter into the pore water solution. The actual measured values of acid soluble chloride content shall be given in the report. However, the role of "background" chlorides, which are measured by the test method but do not contribute to corrosion, must be considered in preparing the summary of significant findings. Therefore, it is necessary to correct the results for the "background" chloride content.

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The background chloride content for the component surveyed shall be taken as the lowest value for all the cores tested for chloride content profile from that component. This lowest value should be similar in two successive slices of a core. If a previous condition survey has been carried out, the previous chloride data should be reviewed for comparison purposes. The lowest value should be compared with the anticipated background value taking into account the type of aggregate and admixture used, before it is accepted as the background value. Normally, the background value should not exceed 0.07% by mass of concrete. The background chloride content shall be deducted from all chloride content test results for that component to determine the depth of chlorides that contribute to corrosion. An example of determining the corrected chloride content is given in Table 5.3. In the example, the corrosion of reinforcing steel can occur if the concrete cover to reinforcing steel is less than 70 mm.

*

Horizon (mm)

Measured Value (%)

Corrected for Background Content (%)

0 - 10

0.307

0.268

20 - 30

0.207

0.168

40 - 50

0.101

0.062

60 - 70

0.064

0.025

80 - 90

0.049

0.010

100 - 110

0.040

0.001

120 - 130

0.039*

0.000

The background chloride content of 0.039 should be the lowest value from all cores tested.

Table 5.3 / Establishing The Corrected Value For Acid Soluble Chloride Ion Content It should be noted that the dolostone from the Amabel formation of the Niagara Escarpment will contribute approximately 0.05% CI- by mass of concrete to a mix and this chloride ion is not available to initiate corrosion. By comparison, if 2% calcium chloride dehydrate by weight of cement is used as an admixture, it contributes approximately 0.13% CI- by mass of concrete and a substantial proportion of this chloride ion is available to initiate corrosion.

5.4.4

Conductive Asphalt Resistivity (Cathodic Protection)

For proper performance of the cathodic protection system, the resistivity of the conductive asphalt should be less than 3 ohms-cm.

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5.5

Retention of Samples

All cores, pieces of cores and unused pulverized material shall be retained for six months after written acceptance of the Condition Survey report by the Ministry.

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6.

THE REPORT

Section 6 gives guidelines for the preparation of the condition survey report.

6.1

Introduction

The purpose of the report is to document the condition of the structure so that the results of the condition survey can be used to select the method of rehabilitation and prepare the contract documents. The prime requirement is that the report be concise and clear. Since the Ministry employs several consulting firms to carry out condition surveys, it is necessary that a standard format be used for the report. This format is also to be followed for reports produced in-house. In order to facilitate the use of a standard format, forms have been developed for recording the data. This enables specific information to be located quickly and reduces the length of the text. Four hard copies and an electronic copy of the report are required. The electronic copy of the report shall include photographs in a digital format.

6.2

Contents

The material in the report is presented in the following order: • • • • • • • • • • • • • •

Table of Contents; Structure Identification Sheet; Key Plan (showing location of structure); Summary of Significant Findings; Detailed Condition Survey Summary Sheet(s); Epoxy Coated Reinforcing Steel Summary Sheet Survey Equipment and Calibration Procedures; Core Photographs and Sketches; Core Logs; Sawn Asphalt Sample Photographs (asphalt covered decks only); Sawn Asphalt Sample Log (asphalt covered decks only); Cathodic Protection Testing Summary Sheet; Site Photographs; Drawings.

6.3

Standard Forms

Data is recorded on the following standard forms: •

Structure Identification Sheet;

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• • • • • •

Detailed Condition Survey Summary Sheets; Epoxy Coated Reinforcing Steel Summary Sheet Survey Equipment and Calibration Procedures; Core Log; Sawn Asphalt Sample Log; Cathodic Protection Testing Summary Sheet.

The forms are contained in Appendix 1.C.

6.3.1

Guide to Completing the Standard Forms

The following guide has been prepared to clarify the information to be shown on the standard forms.

6.3.1.1 • •

Structure Identification Sheet AADT is available from Ministry's Regional Structural Section.

The Ministry's District number and name can be obtained from the Regional Structural Sections.

•

All members of the survey team are to be listed.

•

The structure site number and other data can be obtained from the Regional Structural Sections.

•

The sheet shall be stamped by the Professional Engineer responsible for the work.

6.3.1.2

Detailed Condition Survey Summary Sheets

•

The dimensions of the concrete component shall be reported to the nearest 0.01 m.

•

Where the deck geometry is complex, the deck area is to be taken from the design drawings.

• • •

Total length of cracks shall be reported to the nearest 1.0 m. Areas of scaling, spalling and delamination and increments of concrete cover are measured on the drawings using a planimeter. Areas for the different ranges of corrosion potential are calculated statistically. The method involves counting the number of readings in each range of corrosion activity and then dividing by the total number of readings. On short span decks with expansion joints,

April, 2004

1-43

the readings along the expansion joint should not be included in the statistical calculation. It should be noted that the area of corrosion potential that is between –0.20 to –0.35 volts has been subdivided into two ranges on the summary sheets. The area between –0.30 to – 0.35 will be used to adjust the tender quantity estimate for condition surveys that are out of date. •

Areas of scaling, spalling and delaminations shall be measured in the field when a grid layout is not required.

•

In recording deck soffit deterioration the length of cracks which are leached and/or stained shall be tabulated separately from cracks which are not.

•

Where a structure has been widened, the test results for the old and newer portions of the structure shall be tabulated separately.

•

The form for expansion joints is designed for structures with up to four expansion joints, use additional forms for bridges having more than four expansion joints.

•

Most of the data used to complete the summary sheet for epoxy coated reinforcing steel is collected in the field. However, AC resistance of individual epoxy coated bars is calculated in the office using the field data and the procedure in Appendix E.

6.4

Text

The intent of the text is to summarise and explain significant deterioration or unusual findings. In this respect it can be compared to an executive summary. It is not necessary to describe test methods or field procedures since these are specified in the agreement and in this manual. The text should be a concise discussion of the salient features found in the condition survey and should explain any relationships or inconsistencies in the observations, test results and data collected by GPR survey and previous condition surveys. The text shall also discuss the significance of the readings obtained and any unusual findings on cathodically protected bridge decks. The monitoring and maintenance section of the Cathodic Protection Manual for Concrete Bridges (1) should be referenced for guidance in interpreting the readings obtained. Where the condition survey includes the detailed visual inspection of the structure, significant defects in components that are not designated for a detailed condition survey shall also be discussed briefly in the text.

6.5

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Photographs

1-44

The requirements for the photographs are contained in Sections 4.3 and 5.1. Colour photographs taken for the detailed visual inspection of the structure shall also be included in the report. The size of the photographs shall be 90mm x 125mm minimum.

6.6

Drawings - Detailed Condition Survey

6.6.1

Requirements for All Concrete Components

The drawings are prepared using a CAD computer program by transcribing the data from the field grid sheets. The following requirements apply to all concrete components; •

The scale shall be 1:100 except where another scale may be more suitable.

•

Core locations and numbers are to be shown on all drawings.

•

Cores that contain defects shall be clearly highlighted and labelled with the type of defect.

•

Grid lines are to be shown on all drawings.

•

The drawings of corrosion potentials and concrete cover measurements shall show distinct contrast between the different corrosion potential and concrete cover areas using the standard legend in Appendix 1.D.

•

Standard legends, as illustrated in Appendix l.D, shall also be used to identify other types of deterioration and features shown.

•

The location of all grounds and continuity checks for uncoated reinforcing steel, and location of AC resistance measurements for epoxy coated steel shall be shown on the corrosion potential survey drawings.

6.6.2

Exposed Concrete Components (Excluding Decks)

Separate plans are required for exposed concrete components to show the following three types of survey data: •

Deterioration and delaminations on the concrete surface. Crack widths shall be noted using the abbreviations M (medium) and W (wide) as given in sub-section 4.3. Crack depths, if measurements are required, shall be shown for each crack on the drawing in mm. Cracks that are leached or stained shall be labelled separately.

•

Concrete cover measurements at grid points and the 20 mm, 40 mm and 60 mm contour line. Areas between contour lines shall be shaded as per standard legend.

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1-45

•

Potential measurements at grid points (and intermediate points where taken) and the -0.20, -0.35, and -0.45 contour lines. Areas between contour lines shall be shaded as per standard legend in Appendix 1.D. For components with epoxy coated rebar, the half-cell potentials are recorded only at the cores with exposed top rebar. The AC resistance calculated for the individual bars should also be recorded on this drawing.

6.6.3

Exposed Concrete Decks

The following details shall be included on all drawings in addition to the requirements of Section 6.6.1. •

Deck drains are to be shown on all drawings.

•

Sidewalks, curbs, medians and joints together with the centreline of piers are to be shown on all drawings. The inside face of concrete barrier/parapet walls may be shown on a separate drawing.

Separate plans are required for exposed concrete decks to show the following four types of survey data. •

Deterioration and delaminations on the concrete surface of the deck, curbs, sidewalks, medians and inside faces of concrete barrier/parapet walls. Crack widths shall be noted by using the abbreviations M (medium) and W (wide) given in subsection 4.3. The location of longitudinal cracks shall be referenced to the location of the voids in thick slabs wherever possible.

•

Concrete cover measurements at grid points and the 20 mm, 40 mm and 60 mm contour line. Areas between contour lines shall be shaded as per standard legend.

•

Potential measurements at grid points and the -0.20, -0.35, and -0.45 contour lines. Areas between contour lines shall be shaded as per standard legend. For decks with epoxy coated rebar, the half-cell potentials are recorded only at the cores with exposed top rebar. The AC resistance calculated for the individual bars should also be recorded on this drawing.

•

Deterioration on the bottom surface of the deck slab. The locations of longitudinal beams and void drains shall be shown, where present. Cracks that are leached or stained shall be labelled separately.

6.6.4

April, 2004

Asphalt-Covered Decks

1-46

The following details shall be included on all drawings in addition to the requirements of Section 6.6.1. •

Sawn samples and numbers are to be shown on all drawings.

•

Sawn samples that contain defects shall be clearly highlighted with the type of defect.

•

Deck drains, sidewalks, curbs, medians and joints together with the centreline of piers are to be shown on all the drawings. The inside face of concrete barrier/parapet walls may be shown on a separate drawing.

•

The location of anodes, voltage probes, reference cells and cathode (ground) connections for bridges that are cathodically protected.

Separate plans are required for asphalt covered decks to show the following three types of survey data: •

Deterioration on the asphalt surface of the deck. Cracks wider than 3mm in the asphalt surface, the thickness of the asphalt at grid points and spalled, scaled and delaminated areas on the top surface of the curbs, sidewalks, medians and inside faces of concrete barrier/parapet walls (where present). Thickness of asphalt shall also be given at core and sawn sample locations.

•

Deterioration on the bottom surface of the deck slab. The location of longitudinal beams and void drains shall be shown, where present. Cracks that are leached or stained shall be labelled separately.

•

Potential measurements at grid points (and intermediate points where taken) and the -0.20, -0.35, and -0.45 contour lines. Areas between contour lines shall be shaded as per standard legend. For decks with epoxy coated rebar, the half-cell potentials are recorded only at the cores with exposed top rebar. The AC resistance calculated for the individual bars should also be recorded on this drawing.

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7.

REVIEW OF THE REPORT

Section 7 gives guidelines for reviewing the condition survey report.

7.1

Introduction

Condition Surveys are usually carried out by Consulting Engineers. When the report is received it is necessary that it be reviewed and formally accepted. Omissions and anomalies should be resolved prior to approving final payment for the work. The following guidelines have been prepared in the form of a checklist for each section of the report which will aid in the review and assist in identifying inconsistencies in the data. Some of the items apply only to either exposed concrete components or asphalt covered decks. The same guidelines should be applied in an independent review of any surveys carried out in-house. It is recommended that the reviewer mark off the material corresponding to each item in the checklist on one copy of the report.

7.2

Reference Data

The reviewer needs to be familiar with the following: • • • • •

existing structure drawings; Consultant's Agreement; sample reports; maintenance inspection file; ASTM C876.

7.3

Structure Identification Sheet

The following information should appear on this sheet: • • • • • •

structure data - type of structure, number of spans, widening details; etc.; date of survey - for realistic temperatures at time of year, and its relation to restrictions in temperature for half cell testing; time spent at site; year built/year of widening - significant points about age; last date of rehabilitation; stamped by the Engineer (P. Eng.) responsible.

7.4

Summary of Significant Findings

The findings should: April, 2004

1-48

•

Summarize all significant deterioration and also include references to forms and photo graphs.

•

Explain any relationship between spalling, delamination, cover and corrosion potentials.

•

Explain whether or not information collected by GPR survey correlates with the condition Survey.

•

For components with epoxy coated rebar, explain relationship between half-cell potential, AC resistance and chloride content at rebar level.

•

Include any relationship between scaling, air void system and year of construction.

•

Explain unusual defects, inconsistent data or unexpected results.

•

Summarize results for original structure and widenings separately.

•

•

Describe how acid soluble chloride content is adjusted for background chlorides and whether the acid soluble chloride content (adjusted) is above threshold value at rebar level. Discuss the significance of test results obtained on cathodically protected bridges.

7.5

Detailed Condition Survey Summary Sheet(s)

7.5.1

Dimensions

Check that: •

The dimensions are correct.

•

The photographs, captions and plans agree with the existing drawings of the structure.

7.5.2

Cracking

Check for:

•

Any relationships between significant cracks and structural problems (e.g. settlement, excessive deflection).

•

Consistency between total length of cracking in each category and the plan.

•

A written explanation in the summary of any significant or unusual cracks.

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7.5.3

Scaling

If scaling is present: •

Check the age of the structure and the air void system.

•

Confirm that there are photographs showing significant scaling if it is identified in the report or alternatively if photographs show scaling, it should be discussed in the report.

•

Verify that photographs of scaling do not show spalling, wear, grinding or erosion.

7.5.4

Concrete Air Entrainment and Compressive Strength

Check that: •

Confirm that the consultant has properly interpretted the air void measurements listed in the core logs;

•

Verify that the the average compressive strength is consistent with the strengths given in the core logs.

7.5.5

Delamination and Spalling

Check that: •

There are photographs of major spalls (typical).

•

The total areas agree with the plan.

•

There is a relationship between areas of delamination and spalling, low cover and high corrosion potentials. If not, is there an explanation.

7.5.6

Concrete Cover

Check that: • •

The cover measurements do not vary significantly at adjacent grid points. The areas within each increment agree with the plan, and the total area agrees with the deck area.

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1-50

•

There are no uniformly low, (< 30 mm), and uniformly high, (> 70 mm), readings. Read ings of 100 mm or more are uncommon, except on some rigid frames, and may indicate that the cover has not been measured to the uppermost bar.

•

Sudden variations in cover from one grid point to the next are explained.

•

Cover measurements on the plans agree with covers shown in cores at the corresponding locations.

7.5.7

Corrosion Potential

Check that: • •

Readings increase or decrease uniformly between adjacent grid points. The areas within each increment agree with the plan, and the total area agrees with the deck area.

•

Areas of high corrosion activity generally coincide with delaminations and spalls.

•

Chloride content (adjusted for background chlorides) is above threshold at rebar level in areas of high corrosion potential.

•

An explanation is provided for any suspicious uniformly low (> -0.20V) or uniformly high (< -0.40 V) readings.

•

For components with epoxy coated reinforcing steel, corrosion potentials should increase into the <-0.35 volt range when AC resistance of individual bars is low i.e. less than 1000 ohms.

7.5.8

Adjusted Chloride Content at Rebar Level

Check that: •

The average chloride values in each range of corrosion activity have been adjusted for background chlorides and are at the level of the top layer of reinforcing steel;

•

The chloride content is lower in the low ranges of corrosion activity and above threshold in area of high corrosion potential.

•

For decks with overlay, the chloride profile has been taken at sufficient depth in the original concrete.

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7.5.9

Defective Cores and Sawn Samples (Asphalt Covered Deck)

Check that: • •

The percentages of deteriorated areas are calculated based on the entire area of the deck; The defective cores and sawn samples are randomly distributed and not concentrated in one or two areas of the deck (the data would be considered reliable if a large number of samples are taken and the defective samples are randomly distributed; in other words, there should also be a representative number of samples taken in the area of corrosion potential that ranges from 0.00 to –0.35 volts as quite often there are delaminations outside the area of high corrosion potential).

•

If a GPR survey has been carried out, check if the areas calculated in the condition survey generally agree with the GPR data and the delaminations and scaling identified in the GPR survey have been confirmed by cores and sawn samples taken in the suspect areas;

•

There is a larger number of delaminated and spalled cores and sawn samples in the area of high corrosion potential vs the other areas verifying that the corrosion potential survey is reliable.

7.5.10

Asphalt and Waterproofing

Check that: •

The average depth of asphalt and waterproofing is consistent with the values given on the drawings, and, the core and sawn sample logs;

•

The overall assessment of the condition and bond of waterproofing is consistent with the core and sawn sample logs.

7.5.11

Underside Deterioration (Deck Condition Surveys)

Where there is underside deterioration, check that: • •

There are photographs of significant deterioration; The written summary is consistent with both the totals given in the Summary Sheet and the photographs;

•

The figures agree with the plan.

7.5.12 April, 2004

Expansion Joints (Deck Condition Surveys) 1-52

Check that: •

Dimensions and orientation agree with original structure drawings.

•

Deterioration or unusual features shown in the photographs appear in the remarks.

•

There is a relationship between gap, temperature and time of year.

•

Anomalies should be explained.

•

Joints are clearly shown on the plan.

7.5.13 •

Drainage

Check that the actual number of drains corresponds with number shown on the as built plans.

7.5.14

Epoxy Coated Reinforcing Steel

Check that: •

Check that the AC resistance that was calculated using field measurements and procedure in Appendix E is reasonably accurate.

•

Check if relationship between chloride content, AC resistance and half cell potentials corresponds to the Consultants analysis.

7.6

Survey Equipment and Calibration Procedures

Check that:

•

Equipment is suitable (Section 3.8).

•

Temperatures are high enough for corrosion potential testing.

•

Resistance to ground is less than 5 ohms both ways and voltage is less than 3 mV's, location is recorded and resistance of lead wire is given.

•

There is a separate ground location for each part of a component which is discontinuous (note location of all joints in deck slab).

•

Ground and resistance check locations are widely separated and diagonally opposite;

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•

On decks with latex modified concrete overlay, any significant variations between the initial readings and check readings (taken in drilled holes through the overlay) are discussed in the report.

7.7

Core Log

•

The number of cores conforms to the Consultant's Agreement.

•

The cores are well distributed over the concrete surface.

•

The additional cores are concentrated more in suspected areas of deterioration, cracking, high potentials and delaminations.

•

One core is full depth for thin slabs.

•

Core photographs are taken in a laboratory environment.

•

Photographs and dimensional sketches show the same view.

•

Photographs, sketches and the Core Logs agree.

•

Orientations of rebars relative to cover depths are clearly noted.

•

Testing is done by approved laboratories.

•

Compression tests are done on cores with L/D ratio > 1.0 and containing no reinforcement.

•

Air void measurements are done only on structures built in 1958 and later, and the spacing factor, specific surface and air content are reported.

•

Number of acid soluble chloride measurements conforms to the agreement and any anomalous values are explained.

•

Where requested, approach slab, curb, sidewalk or ballast wall cores have been taken.

7.8

Sawn Samples (asphalt covered decks only)

Check that: •

The number conforms to Consultant's Agreement.

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•

The samples are well distributed over the deck surface.

•

The majority of additional sawn samples are located in areas of suspected deterioration (e.g. high potential areas, cracks or wet spots on underside).

•

There is dry sawing (examine photographs carefully).

•

Asphalt thickness agrees with photographs and thickness shown at adjacent grid points (cores should also be checked this way).

•

Photographs and description of concrete deck slab agree.

•

Concrete surface is not damaged by sawing equipment.

7.9

Cathodic Protection Testing Summary Sheet

Check that: •

Tests have been carried out in conformance with the agreement.

7.10

Photographs

Check that: •

These conform to the agreement.

•

The clarity is acceptable.

7.11

Drawings

Check that: •

These conform to the agreement and are clear and legible.

•

Drawings have a standard legend.

•

Deck drains, cores and sawn samples for asphalt covered decks are shown on all drawings.

•

Cores and sawn samples that contain defects are clearly highlighted and labelled with the type of defect.

•

Void drains where present are shown on soffit drawing.

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•

Contours have been drawn properly.

•

Asphalt thickness is shown at grid points and values reasonably agree with thickness measured from cores and sawn samples.

•

The location of anodes, voltage probes, reference cells and cathode connections are shown on cathodically protected bridges.

Where it is stated that the values given in the Survey Summary Sheet should agree with the drawings, it is intended that the reviewer will check that the figures are reasonable but will not measure the drawings.

7.12

OSIM Forms

Although the OSIM Forms are submitted separately from the report, they should be reviewed to ensure that defects for other components are photographed and discussed in the written summary of the report. The photographs of the defects shall also be included in the report. 7.13

Acceptance of the Report

Where the reviewer identifies errors, omissions or unexplained anomalies, then clarification and correction shall be sought from the Engineer responsible. In some cases, this may involve additional field work. Where the work is done by a Consultant Engineering firm, any unsatisfactory work should be identified when completing the Consultant's appraisal.

7.14

Maintenance Repair Prior to Rehabilitation

In addition to reviewing the report for conformance with the agreement, the reviewer should be alert for conditions which may require maintenance repair prior to the rehabilitation contract. Where necessary, appropriate action shall be taken.

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8.

REFERENCE PUBLICATIONS

8.1

Ministry's Publications

1.

Cathodic Protection Manual for Concrete Bridges, Manual SO-14, 1993

2.

Canadian Highway Bridge Design Code (CHBDC), CAN/CSA-S6-00

3.

Safety Practices for Structure Inspections, Bridge Office Guidelines, 2001

4.

Ontario Structure Inspection Manual (OSIM), 2000

5.

The Application of Radar and Thermography to Bridge Deck Condition Surveys, 90-11

MAT-

New Impulse Radar Strategies For Bridge Deck Assessment, 1993 6.

Ontario Bridge Management System

7.

Ontario Traffic Manual Book 7 – Temporary Condition, 2001

8.

Method of Testing for Acid Soluble Chloride Ion in Concrete

8.2

Non-Ministry Reference Publications

9.

ASTM 876-91 - Standard Test Method for Half Cell Potentials of Uncoated Reinforcing Steel in Concrete

10.

Can 3-A23.2 - 14 C - Obtaining and Testing Drilled Cores for Compressive Strength Testing

11.

ASTM C457 - Standard Practice for Microscopical Determination of Air-Void Content and Parameters of the Air-Void System in Hardened Concrete

12.

ASTM Report STP 169B - Significance of Tests and Properties of Concrete and Concrete Making Materials

April, 2004

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APPENDIX 1A

STANDARD CONSULTANT’S AGREEMENT FOR DETAILED CONDITION SURVEYS

April, 2004

1A-1

The Ministry’s standard Request for Quotation document consists of the following parts: Part A

Terms of Reference - Instructions for Completion of Quotation - Introduction - The Assignment - General Information - Appendices

Part B

Terms and Conditions

Part C

Forms and Notices

Most of the project specific requirements would be described in “The Assignment” and the Appendices. The following are typical requirements to be stipulated: Consultant’s Services The Consultant shall provide the services to carry out the detailed condition survey in accordance with the Structure Rehabilitation Manual, Ministry of Transportation, 2004; and detailed visual inspections in accordance with Ontario Structure Inspection Manual, OSIM; and such work shall include: - Providing direct supervision on site by a Professional Engineer registered in the Province of Ontario, experienced in the inspection and condition survey of bridges; the Engineer shall direct the investigation, determine the number and location of samples and modify the course of the investigation as necessary. -

Carry out detailed condition surveys on components designated for these surveys in the Appendices of the agreement.

-

Carry out detailed visual inspections of structures designated for such inspections in the Appendices of the agreement.

-

Liaise with the appropriate local utility companies to identify and locate in the field any of their facilities on or near the bridge structure, where precautionary measures are required to avoid damage as a result of the work.

-

Identify all facilities on or near the bridge structure. Location of the facilities shall be clearly shown on a drawing with sufficient information for construction purpose.

-

Hazardous materials such as asbestos ducts shall be identified and sampled for bridge rehabilitation design and construction disposal.

-

Repairing all areas damaged by destructive testing with Ministry approved repair materials.

-

Arranging for the laboratory testing of cores designated for testing .

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1A-2

-

Preparing, and supplying to the Ministry, 5 hard copies and 1 electronic copy of the detailed condition survey report on the condition of each structure listed in the Appendices of the Agreement.

Traffic Control The Consultant’s services shall include the provision of flagmen, temporary traffic signals, signs and other devices specified for the control of traffic and lane closure on the bridge deck and adjacent portions of the highway conforming to the `Ontario Traffic Manual-Book 7 Temporary Condition’ The Consultant shall co-ordinate with local municipalities for traffic control and road closures. The Consultant shall provide the Ministry with a schedule of his program at least two weeks prior to carrying out the condition survey. Ministry’s Responsibilities The Ministry shall provide the following: -

Designation of the structures to be surveyed (Appendices).

-

Designation of the components requiring detailed condition surveys and the extent of the surveys and testing required for each component (Appendices).

-

Designation of the structures requiring detailed visual inspections (Appendices).

-

Designation of the traffic control requirements and operational constraints.

-

Designation of the Consultant’s working hours.

-

Copies of the original design drawings and rehabilitation drawings of the structures, where available.

-

Copies of the latest routine biennial inspection report, where available.

-

Dart survey report, if available.

Additional Investigations Where the Consultant identifies a need for further investigation, over and above the work specified in the Agreement, the Consultant shall contact the Head, Regional Structural Section, for approval prior to carrying out the additional work.

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1A-3

LIST OF STRUCTURES

1)

The Consultant is required to carry out condition surveys on the following structure(s):

Structure Name

2)

Site No.

Highway No.

District No.

The extent of the condition surveys is described for each structure in the following Tables.

April, 2004

1A-4

STRUCTURE NAME:

SITE NO.:

HWY. NO.:

Detailed Visual Inspection Required?

Yes

No

Type of Detailed Deck Condition Survey?

First Time

Update

TABLE 1 – DETAILED CONDITION SURVEY REQUIREMENTS – SUPERSTRUCTURE: Exposed Component Asphalt Deck Beams & Curbs & Approach Barrier Covered Concrete Extent Type Soffit Girders Sidewalks Slabs Walls Deck Deck Of Survey Area (m2) N/A Grid Layout Delaminations Surface Deterioration Conc. Cover Corrosion Potentials Conc. Cores No. of Cores Core Diameter Expansion Joint Survey Sawn Samples Number of Sawn Samples

N/A N/A

N/A

N/A N/A

N/A N/A

* 100mm

*

* 100mm

100mm

100mm

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

TABLE 2 – NUMBER OF CONCRETE CORES TO BE TESTED – SUPERSTRUCTURE Component Asphalt Exposed Number of Cores Test Type Covered Concrete Deck Beams & Curbs & Approach Barrier Slabs Walls Type Deck Deck Soffit Girders Sidewalks Compression * * N/A Air Content

*

*

N/A

Chloride Ion

*

*

N/A

Legend: (N/A) = Not Applicable, (Y) = Applicable * See Sections 4 and 5, Part I, Structure Rehabilitation Manual for number required.

April, 2004

1A-5

STRUCTURE NAME:

SITE NO.:

HWY. NO.:

TABLE 3 – DETAILED CONDITION SURVEY REQUIREMENTS – SUBSTRUCTURE: Component Test Type Type Area (m2)

Piers

Abutments

Ballast Walls

Retaining/ Wing Walls

Grid Layout Delaminations Surface Deterioration Conc. Cover Corrosion Potentials Concrete Cores Core Diameter

TABLE 4 – NUMBER OF CONCRETE CORES TO BE TESTED - SUBSTRUCTURE:

Test Type

Component Type

Number of Cores Piers

Abutments

Compression Air Content Chloride Ion REMARKS:

Legend: (N/A) = Not Applicable, (Y) = Applicable

April, 2004

1A-6

Ballast Walls

Retaining/ Wing Walls

APPENDIX 1B GRID LAYOUTS The examples of grid layouts in Appendix 1B are for some of the more common configurations for decks and other components that may be included in a detailed condition survey.

April, 2004

1B-1

APPENDIX 1C STANDARD FORMS

Standard forms contained in Appendix 1C are to be used for detailed deck condition surveys.

April, 2004

1C-1

STRUCTURE IDENTIFICATION SHEET GENERAL INFORMATION STRUCTURE NAME DISTRICT NUMBER

SITE NUMBER HIGHWAY

above

below

TYPE OF STRUCTURE SPAN LENGTHS

NUMBER OF SPANS ROADWAY WIDTH

YEAR BUILT

DIRECTION OF STRUCTURE TOWNSHIP NUMBER

SEQUENCE NUMBER

BRIDGE NUMBER (MUNIC.)

LHRS NUMBER

JURISDICTION

LOCATION INSPECTOR'S NAME PARTY MEMBERS DATE OF INSPECTION TEMPERATURE

0

C

WEATHER AADT

MTO REGION DECK RIDING SURFACE YEAR LAST REHABILITATED

ENGINEER'S STAMP

April, 2004

1C-2

DETAIILED CONDITION SURVEY SUMMARY SHEET Page 1 of 4 ASPHALT COVERED DECK DECK RIDING SURFACE Site No. _________ OSIM Identifier ________ 1.

Dimensions and Area of Survey

Width between N/E abutment curbs ________m Width between S/W abutment curbs __________m Area of deck riding surface ________________m2

Length between abutment joints ___________m

Remarks 2.

Asphalt Surface Cracks Orientation

3.

Unsealed

Sealed

Transverse

m

Longitudinal

m

Random

m

Asphalt Condition and Depth

Condition *

Depth Min

Max

Avg mm

*

G - Good F - Fair P - Poor V - Variable Good to Poor

4.

Waterproofing

Type

*

Condition *

Conc. Bond *

Thickness (mm) Min

Max

Avg

G - Good F - Fair P - Poor V - Variable Good to Poor

April, 2004

1C-3

DETAILED CONDITION SURVEY SUMMARY SHEET Page 2 of 4 ASPHALT COVERED DECK DECK RIDING SURFACE Site No. ______ Remarks 5.

Concrete Cover – Cores and Sawn Samples Minimum

Maximum

Average mm

Note: Only include covers for top upper layer of rebars.

6.

Corrosion Activity Minimum

Maximum

Average V

-0.20 to –0.30

0 to -0.20

-0.30 to -0.35

-0.35 to -0.45

< -0.45

V

m2 %

7.

Defective Cores and Sawn Samples

Corrosion Activity (Volts)

Total in Each Area

Cores and Sawn Samples Delaminated, Medium Spalled, Severe Scaling * Scaling and Disintegration * No.

m2

%

No

m2

%

0 to -.20 -.20 to -.35 ≤ -.35

*

The percent calculation should be of the entire deck area investigated. The values obtained should be used with caution as large errors may occur when a small number of samples are used for the calculation or when the samples are not randomly distributed over the entire deck area.

April, 2004

1C-4

DETAILED CONDITION SURVEY SUMMARY SHEET Page 3 of 4 ASPHALT COVERED DECK DECK RIDING SURFACE Site No. __________

8.

Adjusted Chloride Content Profile

Corrosion Activity at Core Location (volts)

0 to -.20

≤ -.35

-.20 to .35

0-10 mm

Chloride Content *

20-30 mm 40-50 mm 60-70 mm 80-90 mm 100-110 mm

*

Average chloride content as % chloride by weight of concrete after deducting background chlorides for all cores taken in each range of corrosion potential.

9.

Chloride Content at Level of Rebar

Core No. Chloride Content * *

Chloride content as % chloride by weight of concrete after deducting background chlorides

10.

AC Resistance Test Data of Epoxy Coated Rebar

Connection #1 G1 G2 G3 G4 G5 *

Measured AC Resistance between Connection #1 and #2 Connection #2 G1 G2 G3 G4 N/A N/A N/A N/A

N/A

See Appendix 1E for calculating AC resistance contributed by individual rebar

April, 2004

G5

1C-5

Calculated AC Resistance *

DETAILED CONDITION SURVEY SUMMARY SHEET Page 4 of 4 ASPHALT COVERED DECK DECK RIDING SURFACE Site No. __________

11.

IR Drop and True Half Cell Potential Measurements of Epoxy Coated Rebar

IR Drop Between Connection #1 and #2 Connection Connection #2 (negative) #1 G1 G2 G3 G4 G5 (Positive) G1 N/A G2 N/A G3 N/A G4 N/A G5 N/A * Half cell reading taken on the same rebar with the ground connection

12.

Concrete Air Entrainment

Concrete Air Entrained?

13.

Yes ___

No ___

Marginal ___

Compressive Strength

Average Compressive Strength ________ MPa

April, 2004

1C-6

True Half Cell Potential *

DETAILED CONDITION SURVEY SUMMARY SHEET Page 1 of 4 EXPOSED CONCRETE COMPONENTS ( Exposed Deck, Deck Soffit, Curbs, Medians, Sidewalks, Barrier/Parapet Walls etc. ): Use separate form for each component Site No.__________ Component Type _________________ & Location 1.

OSIM Identifier _____________________

Dimensions and Area

Width ________m _________m

Height _______ m __________m

Total Area Surveyed ________________m2

Diameter _________m

2.

Length _______m

Cracks (medium and wide)

Type

Trans.

Remarks

Long’inal

Other

Total

Clean Medium Width

Stained

m

Clean

Wide Width

Stained

m

3. Alkali aggregate reaction Area of component with severe to very severe aggregate reaction _______m2

4.

Concrete Cover Minimum

Maximum

Average mm

0 - 20 mm

m2

40 - 60 mm

% 20 - 40 mm

m2

over 60 mm

%

April, 2004

1C-7

DETAILED CONDITION SURVEY SUMMARY SHEET EXPOSED CONCRETE COMPONENTS

Page 2 of 4

Site No. __________ Component Type & Location :_____________________ Remarks 5.

Corrosion Activity Minimum

Maximum

Average V

-0.20 to –0.30

0 to -0.20

-0.30 to -0.35

-0.35 to -0.45

< -0.45

V

m2 %

6.

Delaminations and Spalls Defect Type

Delaminations

Spalls

Patches

Area (m2) Total Delaminations and Spalls m2

7.

Total Delaminations and Spalls in Areas ≤ -0.35 V

%

m2

Scaling Light

Medium

Severe to Very Severe m2 %

8.

Honeycombing

Total Area __________ m2

April, 2004

1C-8

%

DETAILED CONDITION SURVEY SUMMARY SHEET Page 3 of 4 EXPOSED CONCRETE COMPONENTS Site No. __________ Component & Location:_______________ 9.

Adjusted Chloride Content Profile

Corrosion Activity at Core Location (volts) 0-10 mm Chloride Content *

0 to -.20

-.20 to .35

< -.35

20-30 mm 40-50 mm 60-70 mm 80-90 mm 100-110 mm

•

Average chloride content as % chloride by weight of concrete after deducting background chlorides for all cores taken in each range of corrosion potential.

10.

Chloride Content at Level of Rebar

Core No. Chloride Content * *

Chloride content as % chloride by weight of concrete after deducting background chlorides

11.

AC Resistance Test Data of Epoxy Coated Rebar

Measured AC Resistance between Connection #1 and #2 Calculated AC Connection Connection #2 Resistance * #1 G1 G2 G3 G4 G5 G1 N/A G2 N/A G3 N/A G4 N/A G5 N/A * See Appendix 1E for calculating AC resistance contributed by individual rebar

April, 2004

1C-9

DETAILED CONDITION SURVEY SUMMARY SHEET Page 4 of 4 EXPOSED CONCRETE COMPONENTS Site No. __________

Component & Location : ___________________

12.

IR Drop and True Half Cell Potential Measurements of Epoxy Coated Rebar

Connection #1 (Positive) G1 G2 G3 G4 G5

IR Drop Between Connection #1 and #2 Connection #2 (negative) G1 G2 G3 G4 N/A N/A N/A N/A

N/A

*

Half cell reading taken on the same rebar with the ground connection

13.

Concrete Air Entrainment

Concrete Air Entrained?

14.

Yes ___

No ___

Marginal ___

Compressive Strength

Average Compressive Strength ________ MPa

April, 2004

G5

1C-10

True Half Cell Potential *

DETAILED CONDITION SURVEY SUMMARY SHEET EXPANSION JOINTS Site No. __________ Remarks Abutments Joint 1 Dimension

N

Intermediate Joint 2

E

S

W

Joint 3

Joint 4

a (mm) b (mm) b' (mm) c (mm) d (mm) d' (mm) e (mm) Depth of Asphalt @ Deck Side

N/E

S/W

N/E

S/W

S/W

N/E

S/W

1 (mm) 2 (mm) 3 (mm) Width: Top of Ballast Wall and End Dams N/E

S/W

N/E

S/W

N/E

1 (mm) 2 (mm) 3 (mm) Gap Dimensions 1 (mm) 2 (mm) 3 (mm) Misc Joint Details

Skew Angle

Exp. Fixed Type Leaking Angle Size Temp oC N/E

a

Deck

Ambient Joint Dimensions

b

X

C/L

d

X

b’

d’ c

Typical Sections at Joints

X-X

April, 2004

S/W

Y-Y

1C-11

e

Y

Y

DETAILED CONDITION SURVEY SUMMARY SHEET DRAINAGE

Deck Drains *

Number

Length

Angle

Depth *

For asphalt covered decks, recess depth in mm between top of asphalt and top of drain

Catch Basins *

Type

Site No. __________

Yes

*

*

No

*

*

Identify location of catch basins as N/E, N/W, S/E etc. using the same direction of north as shown in the drawings

Drainage Tubes

April, 2004

Yes No

Void Drains

Yes No

1C-12

SURVEY EQUIPMENT AND CALIBRATION PROCEDURES Component Type: _______________________ 1.

Site No: _______________

Delaminations: Weight of Chain: _______kg/m Other Equipment:_______________________________________________________

2.

Concrete Cover: Covermeter Make & Model: _______________________________________________ Battery Check: Reading at Start of Test: ________ Reading at End of Test: ________ Concrete Cover Check: Location of Check: _____________________________ Actual Depth & Rebar Dia: ______________________ Reading Before Test: _______ Readings Each 30 min During Test: _______________ Reading End of Test: ________

3.

Corrosion Activity: Half Cell Make & Model: __________________________________________________ Multimeter Make & Model: ________________________________________________ Length and Gauge of Lead Wires:___________________________________________ Deck Temp: Start of Test: _____oC End of Test: _____oC o Ambient Temp: Start of Test: _____ C End of Test: _____oC Battery Check: _______ Ground Check: Method of Connection: ____________ Ground Location: ________ Check Location: ___________ Lead Resistance:_________ Voltage Drop (mV's): _______ Resistance: _____________ Resistance Reversed: _______ Grid Point Potential Readings Check - See Table Below Location

* **

Initial Reading

Check Reading*

Check Reading - Latex Concrete Overlay **

Check at least 5 readings at beginning of test and each change in ground. On decks with latex modified concrete overlay, check at least 5 locations by drilling holes through the latex concrete overlay into the original concre te substrate.

April, 2004

1C-13

CORE LOG ASPHALT COVERED BRIDGE DECKS Page

of

Site no.

Core No. Location Diameter, mm Thickness of Asphalt, mm Thickness of Asphalt @ nearest grid point Thickness of Concrete, mm Full Depth, (yes/no) Condition of Asphalt (1) Waterproofing (W/P) type Condition of W/P (1) W/P Thickness, mm Bond of Asphalt or W/P to Concrete Defects in Concrete (2) Condition of Rebar (3) Corrosion Potential Compressive Strength, MPa Total

Chloride Content % Chloride by Weight of Concrete

Air Voids

Corrected

Total

Corrected

Total

0-10mm 20-30mm 40-50mm 60-70mm 80-90mm

Air Content, % Spec. Surf.,mm2/mm3 Spacing Factor, mm

Testing Laboratory Remarks - Orientation of rebars and cover - Presence of overlay, patch, and thickness - Other observed defects 1. 2. 3.

Condition - G = Good, F = Fair, P = Poor. Defects - C = Cracked, D = Delamination, R = Rough, Sc = Scaling, S = Spalling. Condition Rebar - LR = Light Rust, SR = Severe Rust, N/A = No rebar exposed. Condition of Epoxy Coating – ECG = Good, ECF = Fair ECP = Poor - rusted & debonded areas

April, 2004

1C-14

Corrected

SAWN ASPHALT SAMPLE LOG Page

of

SITE NO. _________

Sample No. Location

Size, mm X mm Thickness of Asphalt, mm

Thickness of Asphalt @Nearest Grid Point Condition of Asphalt (1) Waterproofing (W/P) Type W/P Thickness, mm Condition of W/P (1) Bond of W/P to Asphalt Bond of Asphalt or W/P to Concrete Concrete Cover to Reinf., mm (Note orientation of rebar) Defects in Concrete Surface (2) Corrosion Potential @Nearest Grid Point Remarks

1. 2.

Condition - G = Good, F = Fair, P = Poor. Defects - C = Cracked, D = Delamination, R = Rough, Sc = Scaling, S = Spalling

April, 2004

1C-15

CORE LOG FOR EXPOSED CONCRETE Page

of

SITE NO. _________ Component Type and Location ________________________________

Core No. Location Diameter, mm Length, mm Full Depth (Yes/No) Defects in Concrete (1) Condition of Rebar (2) Corrosion Potential (At Closest Grid Point) Compressive Strength, MPa Total

Chloride Content

Corrected

Total

Corrected

0-10mm

% Chloride by Weight of Concrete

20-30mm 40-50mm 60-70mm 80-90mm

Air Content, % Air Voids

Spec. Surf., mm2/mm3 Spacing Factor, mm

Test Laboratory Remarks

1. 2.

Defects - C = Cracked, D = Delamination, R = Rough, Sc = Scaling, S = Spalling Condition Rebar - LR = Light Rust, SR = Severe Rust, N/A - No rebar exposed

April, 2004

1C-16

Total

Corrected

CATHODIC PROTECTION TESTING SUMMARY SHEET SITE NO. TESTING OF EMBEDDED COMPONENTS AND CABLES Component ID No.

AC Resistance (ohms) Between Component and Rebar at Splice Location

Resistance and Voltage of Cables & Connection Component Lead Cable DC Resistance ( ohms)

Volts (mV's)

Cable to Control Panel DC Resistance (ohms)

Volts (mV's)

RESISTANCE OF CONDUCTIVE ASPHALT Laboratory Tests on Cores Sample No.

April, 2004

Location

Field Tests Using 2 - Nail Method

Resistivity (ohm-cms)

1C-17

Location

AC Resistance (ohms)

APPENDIX 1D STANDARD LEGEND The standard legend illustrated in this Appendix should be used when preparing the drawings for detailed condition surveys. Less common types of deterioration should be brought to the attention of the Bridge Office for inclusion in this Appendix. When stick-on type patterns or a computer is used to prepare the drawings, the patterns chosen do not have to match the patterns given herein but should be similar.

April, 2004

1D-1

APPENDIX 1E CALCULATING AC RESISTANCE OF EPOXY COATED REBAR

The AC resistance measurement in the field is actually the sum of the AC resistance of two rebars and the resistance of the concrete. This data is difficult to interpret as high resistance readings can be obtained when the coating of one of the rebars is in excellent condition. The AC resistance contributed by the individual rebars would provide more meaningful information. The procedure for calculating the AC resistance contributed by the individual bars is described below using the sample measurements in Table E1.

Measured AC Resistance (ohms) between Connection #1 and #2 Connection #1 G1 G2 G3 G4 G5

Connection #2 G1

G2

G3

G4

G5

N/A 8200 6000 6900 4800

8200 N/A 6100 7000 4900

6100 6100 N/A 4800 2800

6900 7000 4800 N/A 3600

4800 4900 2800 3600 N/A

Table E1 / AC Resistance Measurements AC Resistance calculation to determine resistance contributed by individual bars is summarised below: (RG1 + RG2) + (RG1 + RG3) = 8200 + 6100 = 14300 ohms 2RG1 + (RG2 + RG3) = 14300 ohms 2RG1 + 6100 = 14300 AC Resistance of G1 = (14300-6100)/2 = 4100 ohms Using value for RG1, the resistance for other bars is calculated as follows: RG1 + RG2 = 8200 AC Resistance of G2 = 8200 – 4100 = 4100 ohms RG1 + RG3 = 6100 AC Resistance of G3 = 6100 – 4100 = 2000 ohms RG1 + RG4 = 6900 ohms AC Resistance of G4 = 6900 – 4100 = 2800 ohms RG1 + RG5 = 4800 AC Resistance of G5 = 4800 – 4100 = 700 ohms

April, 2004

1E-1

April, 2004

1E-2

PART 2 REHABILITATION SELECTION CONTENTS 1. 1.1 1.2

1.3

1.4 1.5

April, 04

GENERAL .............................................................................................. 2-1 Introduction .............................................................................................. 2-1 Review of Data........................................................................................... 2-1 1.2.1 General............................................................................................. 2-1 1.2.2 Condition Surveys ............................................................................ 2-1 1.2.3 DART Surveys ................................................................................. 2-2 1.2.4 Existing Structure Drawings ............................................................. 2-2 1.2.5 Evaluation Reports ........................................................................... 2-3 1.2.6 Inspection, Maintenance and Rehabilitation Reports ........................ 2-3 1.2.7 Site Conditions ................................................................................. 2-3 Factors That Influence the Selection of the Rehabilitation Method............. 2-4 1.3.1 Defects and Deterioration................................................................. 2-4 1.3.1.1 General................................................................................. 2-4 1.3.1.2 Concrete with High Chloride Content................................... 2-4 1.3.1.3 Excessive Removal of Material............................................ 2-5 1.3.1.4 Partial or Complete Replacement of Components ................ 2-6 1.3.2 Load Carrying Capacity.................................................................... 2-7 1.3.2.1 Loads Induced by the Rehabilitation..................................... 2-7 1.3.2.2 Rehabilitation for Restricted and Limited Use...................... 2-7 1.3.3 Functional Adequacy and Staging Requirements .............................. 2-8 1.3.4 Financial Analysis............................................................................ 2-8 1.3.5 Importance of Structure..................................................................... 2-9 1.3.5.1 General................................................................................. 2-9 1.3.5.2 Heritage Bridges................................................................... 2-9 1.3.5.3 Bridge Aesthetics ............................................................... 2-10 1.3.6 Type of Structure ............................................................................ 2-10 1.3.7 Type of Component......................................................................... 2-10 1.3.8 Structure Service Life..................................................................... 2-10 1.3.9 Highway Construction Program...................................................... 2-11 1.3.10 Contractor Expertise....................................................................... 2-11 1.3.11 Social and Environmental Concerns ............................................... 2-11 Finalizing Structure Rehabilitation Selection ........................................... 2-12 Deferred Projects ........................................................................... 2-12

2-i

2. 2.1 2.2 2.3 2.4

3. 3.1 3.2 3.3

April, 04

CONCRETE STRUCTURE COMPONENTS -REPAIR AND REHABILITATION METHODS.................................................................. 2-13 General ............................................................................................ 2-13 Concrete Materials - General Considerations .......................................... 2-13 Preparation of Concrete Surfaces and Reinforcing Steel.......................... 2-14 Concrete Repair and Rehabilitation Methods........................................... 2-14 2.4.1 Patch Repairs.................................................................................. 2-14 2.4.1.1 Concrete Patches ................................................................ 2-14 2.4.1.2 Shotcrete Patches................................................................ 2-15 2.4.1.2.1 Silica Fume Shotcrete................................................ 2-16 2.4.1.2.2 Normal Shotcrete....................................................... 2-16 2.4.1.3 Concrete Patches Form and Pump....................................... 2-17 2.4.1.4 Proprietary Product Patches ............................................... 2-17 2.4.1.4.1 Trowel Applied Patching Materials .......................... 2-18 2.4.1.4.2 Non-Shrink Proprietary Products............................... 2-19 2.4.1.4.3 High Early Strength Proprietary Products.................. 2-19 2.4.1.4.4 Self-Levelling Proprietary Products .......................... 2-20 2.4.2 Concrete Refacing or Encasement .................................................. 2-20 2.4.3 Concrete Overlays .......................................................................... 2-21 2.4.3.1 Normal Concrete Overlay................................................... 2-21 2.4.3.2 Latex Modified Concrete Overlay...................................... 2-22 2.4.3.3 Silica Fume Concrete Overlay............................................ 2-23 2.4.4 Concrete Sealant............................................................................. 2-23 2.4.5 Waterproofing and Asphalt Paving................................................. 2-24 2.4.6 Cathodic Protection ........................................................................ 2-25 2.4.6.1 Conductive Bituminous Overlay System............................. 2-26 2.4.6.2 Titanium Mesh System - Bridge Decks............................... 2-26 2.4.6.3 Titanium Mesh System - Substructures ............................... 2-27 2.4.6.4 Arc Sprayed Zinc System................................................... 2-27 2.4.7 Electrochemical Chloride Removal................................................ 2-28 2.4.8 Steel Jacketing................................................................................ 2-29 2.4.9 Fibre Reinforced Polymers Wrapping............................................ 2-29 2.4.10 Galvanic Cathodic Protection System............................................. 2-30 2.4.11 Partial or Complete Replacement................................................... 2-31 2.4.12 No Action....................................................................................... 2-31 CONCRETE STRUCTURE COMPONENTS SELECTION OF REHABILITATION METHOD...................................... 2-33 General ............................................................................................ 2-33 Concrete Removal Criteria....................................................................... 2-33 Bridge Decks ............................................................................................ 2-35 3.3.1 Bridge Deck Riding Surfaces ......................................................... 2-35 3.3.1.1 General............................................................................... 2-35 3.3.1.2 Selection of Method Prior to Condition Survey.................. 2-35 3.3.1.3 Selection of Method Based on Condition Survey ............... 2-35 3.3.2 Bridge Deck Soffits ........................................................................ 2-38 3.3.3 Bridge Deck Facia.......................................................................... 2-38 2 - ii

3.3.4 3.4 3.5 3.6 3.7 3.8 3.9 3.10 4. 4.1 4.2

4.3

5.

Bridge Deck Replacement Option .................................................. 2-38 Concrete Beams, Girders and Misc. Superstructure Components............. 2-39 Substructure Components.......................................................................... 2-40 Railing Systems and Walls ....................................................................... 2-41 Sidewalks ............................................................................................ 2-43 Curbs and Medians ................................................................................... 2-43 Ballast Walls ............................................................................................ 2-43 Approach Slabs ........................................................................................ 2-44

CRACKING IN CONCRETE........................................................................ 2-45 Introduction ............................................................................................ 2-45 General Considerations ............................................................................ 2-45 4.2.1 Cause of Cracking........................................................................... 2-45 4.2.2 State of Activity.............................................................................. 2-46 4.2.2.1 Dormant Cracks .................................................................. 2-47 4.2.2.2 Active Cracks ..................................................................... 2-47 4.2.3 Extent of Cracking .......................................................................... 2-47 4.2.4 Moisture and Contaminants............................................................. 2-47 Crack Repair Methods.............................................................................. 2-47 4.3.1 General........................................................................................... 2-47 4.3.2 Crack Injection ............................................................................... 2-47 4.3.3 Routing and Sealing Cracks ............................................................ 2-48 STRUCTURAL STEEL COMPONENTS.................................................... 2-50

5.1 5.2 5.3

Repairs to Damaged Steel Members......................................................... 2-50 Protection of Existing ACR Girders ......................................................... 2-50 Existing Shear Connectors........................................................................ 2-50

6.

TIMBER COMPONENTS............................................................................. 2-51

7.

ALUMINUM COMPONENTS...................................................................... 2-52

8.

MASONRY COMPONENTS ........................................................................ 2-53

9. 9.1 9.2

9.3 9.4

April, 04

EXPANSION JOINTS, BEARINGS AND DECK DRAINAGE.................. 2-54 General ............................................................................................ 2-54 Expansion Joints ....................................................................................... 2-54 9.2.1 Strip Seal Joints.............................................................................. 2-54 9.2.2 Open Joints ..................................................................................... 2-55 9.2.3 Ethylene Vinyl Acetate (EVA) Foam.............................................. 2-55 Bearings ............................................................................................ 2-55 Deck Drainage .......................................................................................... 2-56 9.4.1 General........................................................................................... 2-56 9.4.2 Deck Drains.................................................................................... 2-56 9.4.3 Drainage Tubes............................................................................... 2-57 9.4.4 Void Tubes ..................................................................................... 2-57 2 - iii

10.

STREAMS, EMBANKMENTS AND SLOPE PROTECTION................... 2-58

11.

11.3 11.4 11.5 11.6 11.7 11.8

MISCELLANEOUS DESIGN CONSIDERATIONS................................... 2-59 General ............................................................................................ 2-59 Traffic Control.......................................................................................... 2-59 11.2.1 General ........................................................................................... 2-59 11.2.2 Construction Staging....................................................................... 2-59 11.2.3 Methods of Traffic Control and Protection..................................... 2-60 11.2.4 Notification of External Agencies................................................... 2-60 Roadway Protection ................................................................................. 2-61 Jacking ............................................................................................ 2-61 Environment ............................................................................................ 2-61 Utilities ............................................................................................ 2-61 Engineering Survey................................................................................... 2-61 Widening Highway Bridges...................................................................... 2-62

12.1 12.2

REFERENCE PUBLICATIONS ................................................................... 2-63 Ministry Reference Publications............................................................... 2-63 Non-Ministry Publications........................................................................ 2-63

11.1 11.2

12.

APPENDICES

2.A

FORMS – STRUCTURE REHABILITATION RECOMMENDATIONS

2.B

GUIDELINES FOR SELECTING PATCH MATERIALS FOR REPAIR OF CONCRETE COMPONENTS

2.C

GUIDELINES FOR SELECTING REHABILITATION METHODS FOR CONCRETE BRIDGE DECKS

2.D

GUIDELINES FOR DELECTING REHABILTITATION METHODS FOR CONCRETE SUBSTRUCTURE COMPONENTS

2.E

GUIDELINES FOR SELECTING REHABILITATION METHODS FOR CONCRETE BARRIER/PARAPET WALLS

2.F

GUIDELINES FOR SELECTING CRACK REPAIR METHOD FOR CONCRETE COMPONENTS

April, 04

2 - iv

1.

GENERAL

1.1

Introduction

Part 2 of this Manual provides guidelines on the selection of the methods and the appropriate strategy to be used in the repair, rehabilitation or replacement of structure components. The selection of the rehabilitation method to be used is a critical factor in the rehabilitation of a structure. It is often a difficult process, which involves consideration of a large number of factors, some of which are technical, some economic, and others that are purely practical.

1.2

Review of Data

1.2.1

General

Prior to developing and finalizing the rehabilitation strategy, the Engineer should study all available data on the structure to become familiar with the condition of the structure and to determine which factors will influence the method of rehabilitation and carrying out of the work at the site. The selection process should take into consideration the data collected from inspections, evaluations, condition surveys and the cost of various options. The past performance of rehabilitation methods and materials, previous rehabilitation /repair works carried out as well as any other available and relevant data on the structure should also be considered. The more important items of information that should be reviewed are discussed below.

1.2.2

Condition Surveys

Particular attention should be paid to the following items in the condition survey report on the structure: • • • • • • • • • • •

corrosion potential survey results; locations and size of delaminations and spalls in concrete; locations and size of cracks and patched areas; location of scaled concrete; type and location of other defects and deterioration; condition of concrete in cores and sawn samples; core test results for chloride content, air voids and strength; concrete cover to reinforcing steel; curb heights; depth of asphalt; presence and type of waterproofing;

April, 04

2-1

• • •

details of expansion joints, bearings and drainage; structure type and visible details; identification of previous rehabilitation/repair treatments.

The results from the condition survey and the DART survey, if available, should be compared and any anomalies should be resolved. When the data contained in the condition survey report is considered to be insufficient or unreliable, further investigation should be carried out before finalizing the method of rehabilitation. Examples of anomalies include: • extremely high overall corrosion potential readings but small standard deviation; • mixing of cover for top and bottom mat of rebars; • lack of data at original concrete surface for previously overlaid decks. 1.2.3

DART Surveys

Particular attention should be paid to the following items in the DART survey report on the structure: • • • •

locations of delaminations; concrete cover to reinforcing steel; locations of scaling; depth of asphalt.

When the data contained in the DART report is considered to be insufficient or unreliable, further investigation should be carried out before finalizing the method of rehabilitation.

1.2.4

Existing Structure Drawings

All available structure drawings (design drawings, shop drawings and as-built drawings) and other sources should be reviewed to determine: • • • • • • • • •

structure dimensions; design details and unusual design features; depth, location, size and spacing of main reinforcement; as-built details; roadway widths (for staging); expansion joint details; utilities located in the structure; utilities in ducts located in the structure or suspended from the structure and the presence of asbestos in the duct material; previous rehabilitation/repair treatments.

April, 04

2-2

1.2.5

Evaluation Reports

Evaluation reports, where available, should be reviewed to determine: • •

the load carrying capacity of components and the structure; effect of the proposed work on the load carrying capacity of the structure and it's components during and after the rehabilitation; • required strengthening of components.

1.2.6

Inspection, Maintenance and Rehabilitation Reports

Available reports and data on the inspection, maintenance and previous rehabilitation of the structure should be reviewed to determine: • • • • • •

history of deterioration and rehabilitation; materials and methods used in previous repairs and rehabilitation; performance of previous repairs and rehabilitation; history and extent of maintenance; history and underwater inspection and condition of components underwater; history of flooding, scour and ice damage and conditions at low water level.

1.2.7

Site Conditions

A visit to the site should be made to determine: • • • • • • • • • • •

extent of defects and deterioration and correlation with the findings in the condition survey report and other available data; accessibility of components in need of repair; differences between as-built condition and as-designed information; modifications made subsequent to original as-built construction; traffic conditions; geometry of the approach and highway beyond the ends of the structure; options for staging and detours; any unusual features that may affect the rehabilitation; such as, the presence of utilities and facilities for drainage, clearance restrictions; environmental considerations; the need for liaison with other authorities, such as: utility companies, railways, conservation authorities, municipalities, and private property owners; hydraulic conditions and improvements where flooding is a problem.

April, 04

2-3

1.3

Factors That Influence the Selection of the Rehabilitation Method

The following factors typically influence the selection of the rehabilitation method.

1.3.1

Defects and Deterioration

1.3.1.1

General

The type, extent, location and causes of the defects and deterioration must be established in order to select an appropriate method of rehabilitation. The types of defects commonly occurring in structure materials are described in the Ontario Structure Inspection Manual (1). If the causes of the defects and deterioration are likely to remain active after the affected area is repaired, then the rehabilitation strategy should include consideration of ways of overcoming contributing factors. The choices of repair and rehabilitation methods are at times limited due to the extent and location of the deterioration and the availability of suitable repair materials. Some materials and methods for concrete repairs have been specifically developed for vertical and overhead surfaces. Areas with poor access may require special considerations.

1.3.1.2

Concrete with High Chloride Content

Chlorides are a primary contributing cause of rebar corrosion. For components where chlorides have not reached the threshold value at the level of the reinforcing steel, it may take a number of years for the chlorides to diffuse down to the level of reinforcing steel and initiate corrosion activity. Therefore, these components will likely remain in good condition until a second generation rehabilitation is required. However, measures should be taken to minimize further exposure to moisture and chlorides by the application of waterproofing membranes or sealers and sealing of expansion joints. Furthermore, improvement of drainage from the structure should be carried out if it is an issue. If the chloride content at the level of reinforcing is above the threshold value to initiate corrosion, then consideration should be given to removing this chloride contaminated, but otherwise sound concrete since there could be active corrosion of the reinforcement. Corrosion potential readings more negative than -0.35 volts taken in accordance with ASTM C-876 are usually a good indication of a high probability of corrosion of the reinforcing steel. The mean and standard deviation of the corrosion potential readings should also be considered since corrosion is generated by differences in potentials, and by experience a standard deviation greater than 0.075 volt is generally associated with decks that are performing poorly. Since 1989, it has been the Ministry’s policy to remove concrete in bridge decks where the corrosion potential readings are more negative than –0.35 volt. This policy also applies to other components where corrosion potential survey has been carried out as part of detailed condition survey. The decision to remove concrete by corrosion potential criteria for a particular component with uncoated reinforcing steel should take into account the following factors: April, 04

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• • • • • •

expected rate that concrete will delaminate if high chloride content concrete is not removed in areas with corrosion potential < -0.35 volts CSE; the implications on rideability, structural adequacy and public safety if corrosion of reinforcing steel and concrete delaminations continue; implications on user costs if lane closures are required for additional maintenance repairs that may be required if concrete continues to delaminate at a high rate; the estimated remaining service life of the component; extent of delaminations in areas with corrosion potential < -0.35 volts CSE; where excessive concrete removal affects the structural capacity and it is not practical or cost effective to stage the concrete removal or provide temporary supports.

For components where chlorides have reached the threshold value at the level of reinforcing steel, the rate of concrete delaminations will vary depending on the concentration, depth, and area of chloride contamination as well as concrete cover, concrete resistivity, rebar diameter, rebar spacing and moisture availability. For example, concrete pier columns with closely spaced spiral reinforcing steel can delaminate at a rate of up to 8% per year if chloride contaminated concrete is not removed and the cause of chloride exposure is not eliminated; see Bridge Office Report BO 96-11 (2). A similar study on concrete barrier walls indicated that concrete can delaminate at a rate of up to 8% per year if chloride contaminated concrete is not removed and there is a continuing high exposure to chlorides/moisture due to narrow shoulders; see Bridge Office Report BO-98-02 (3). For components with high concrete cover ( > 100 mm) or light reinforcing steel, it may not be cost effective to remove the chloride contaminated concrete based on corrosion potential as the rate of delaminations is likely to be low. In this case, consideration should be given not to remove concrete by corrosion potential criteria; however, past and current inspection records should be examined to confirm the site specific delamination rate. The concrete removal by corrosion potential criteria may also have to be waived when excessive removal of concrete is required in critical areas of the structure as described in Section 1.3.1.3.

1.3.1.3

Excessive Removal of Material

Rehabilitation of bridges typically involves the removal of deteriorated material to the point where the material is sound and, in some cases, the removal of sound concrete in areas with corrosion potential < -0.35 volts. Concrete in the areas more negative than -0.35 volts is removed to a depth of 25 mm below the first layer of reinforcing where the concrete is otherwise sound. In areas of unsound concrete, the depth of removal may extend beyond the 25 mm limit until sound concrete is reached. This may result in extensive concrete removals and deactivation of reinforcement over large areas of a component and the bridge. The consequences and sequence of removals and need for temporary support systems has to be carefully assessed and accounted for in the rehabilitation design where excessive removals, deep removals or removals in critical areas are involved. Excessive removal of material or removal in the wrong sequence can seriously affect the capacity, stability and April, 04

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behaviour of a component and the bridge, depending on the location and extent of the removals and type of component involved. Measures, such as placing the component and bridge on temporary supports, may have to be taken to ensure adequate strength and stability during removals. Where such removals would adversely affect the capacity of the component and bridge, or result in expensive or impractical staging and temporary support systems, then it is advisable to consider alternative practical methods of rehabilitation that do not involve such removals. Material must not be removed to the extent that the main reinforcing steel is not adequately anchored, embedded or surrounded by sufficient concrete to transfer loads to the reinforcing steel or develop the strength of the reinforcing steel. Material must not be removed under any circumstances to the point where the capacity of the component and the structure is reduced to less than adequate to support the applied loads, unless adequate temporary supports are provided. Accordingly, exceptions to the current policy for concrete removal by corrosion potential should be considered or other acceptable rehabilitation methods should be adopted in the following locations and circumstances: a) Extensive removal of concrete in slender compression components, such as around the circumference and through the depth of pier columns and shafts. b) Extensive removal of concrete in the compression zones of reinforced and prestressed concrete (girders, T-beams, and slab) bridges. c) Extensive removal of concrete directly over bearings and supports, and in concrete bearing seats. d) Extensive removal of concrete which exposes prestressing steel or ducts, particularly at anchorages. e) Extensive removal of concrete which exposes main tension reinforcing steel over a significant length, in the following areas: -

1.3.1.4

at anchorage zones and over its development length; around the negative moment region in rigid frame bridges (slab and T-beam); over the top of concrete girders in negative moment regions at supports in continuous cast-in-place reinforced concrete bridges; in the positive moment regions in concrete beams and slabs;

Partial or Complete Replacement of Components

Consideration should be given to full-depth removal and to replacement of part or all of a component in those circumstances where partial depth removal and repairs are impractical or not cost effective, such as in the following circumstances:

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• • • • •

component has inadequate capacity and requires significant strengthening; expensive temporary support systems are required during rehabilitation but which may be avoided or significantly reduced if the component were removed and replaced; there is removal of material through the depth, or over parallel, or intersecting surfaces of the component such that the removals may overlap; there is the possibility of breakthrough or there would be relatively thin sections of inadequate strength remaining after removals; access to the deteriorated area is difficult, impractical or requires the construction of expensive scaffolding and repairs could be carried out from other more readily accessible surfaces.

The decision to carry out full-depth removals and replace part or all of the component(s) should be based on a thorough analysis of practicable options.

1.3.2

Load Carrying Capacity

1.3.2.1

Loads Induced by the Rehabilitation

Components of bridges may be required to carry additional loads during or after rehabilitation, either as a result of additional loads applied directly to the component or through re-distribution of loads from other components. The rehabilitation may result in changes to the behaviour or articulation of the bridge as a consequence of removal or addition of material, and freeing or fixing of restraints or bearings at supports. These factors can result in loads and stresses in components that were not accounted for in the original design of the bridge. Where the load carrying capacity or the applied loads on the structure is affected due to either defects or deterioration or the method of rehabilitation, an evaluation of the structure shall be carried out to ensure that the bridge and its components have adequate capacity to carry the loads applied during and after rehabilitation and are stable during all stages of rehabilitation. All significant changes in loads and capacity shall be included.

1.3.2.2

Rehabilitation for Restricted and Limited Use

Over the years structures have been designed and built to different load levels and standards. As such there are many existing structures designed to other loads and standards than are presently specified for new structures. An evaluation of the load capacity and assessment of other details of an existing structure may therefore indicate that it does not meet some or all of the current design criteria for new structures. In those cases, the owner must decide whether or not to upgrade the structure capacity and rehabilitate other components to the current standards. In some cases, it may not be necessary for an existing bridge to be able to carry the loads specified April, 04

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for new bridges in the Canadian Highway Bridge Design Code (4). An existing bridge may be rehabilitated to lower loads depending on the proposed use and planned service life of the bridge. Such bridges may typically be on low volume roadways, which serve only light local traffic, and bridges that are planned for replacement in the near future. In those cases, the bridge may be rehabilitated to lower load levels as detailed in Section 15 of the Canadian Highway Bridge Design Code (4). The bridges would be posted and signed for restricted use accordingly. The possible adverse effects on public safety and future work must be carefully assessed before any such lower standards are incorporated in the rehabilitation design. Consideration should be given for the bridge to have adequate strength to carry emergency vehicles and road maintenance equipment.

1.3.3

Functional Adequacy and Staging Requirements

The functional adequacy of the structure should be reviewed; functional improvements and methods of correcting deficiencies should be considered in the selection of rehabilitation method. Traffic staging and access requirements may affect the choice of rehabilitation method. For soffit repair works, the designer should review the existing vertical clearance under the bridge and select a rehabilitation method that would not adversely affect the clearance for traffic, either temporarily during construction or in the permanent condition. Certain repair treatments, like silica fume shotcrete patches, would require continual access to the area during the curing period and it must be reviewed with the traffic management requirements; alternative treatments that require a shorter duration of access for curing should be considered if it is justified. 1.3.4

Financial Analysis

The procedures and requirements for carrying out a financial analysis are given in the Structural Financial Analysis Manual (5). The Ministry’s HICO program provides up-to-date cost information based on MTO projects. In many cases, there is more than one acceptable method of rehabilitation for each type of component of a structure. In such cases, a financial analysis of alternative rehabilitation strategies should be carried out to determine the most cost effective rehabilitation option over the life of the bridge. The financial analysis should take into account local conditions such as the availability of materials and contractor expertise, as well as other repairs and rehabilitation expected during the remaining life of the structure. As some repair/rehabilitation methods have a shorter service life, it is important that the cost of access, traffic control, environmental protection and user costs be taken into consideration when options with different life cycles are being considered. The financial analysis should include the options for replacement of part or all of the structure where there is extensive deterioration and removal of material or where other factors have to be considered as described below: April, 04

the structure requires significant strengthening to carry applied loads; 2-8

-

functional improvement is needed; the structure does not meet current standards or code requirements

The financial analysis should consider the option of allowing the component(s) to deteriorate to the point where replacement is required. In this case, the condition of the bridge should be monitored to ensure that the safety of the public is not compromised. The size of the structure influences the economics of the various rehabilitation strategies. Where cathodic protection is a suitable method of rehabilitation, but where the area of the component is small, usually less than 500 m2 for deck slabs, the cost of concrete removal and overlay are often comparable to cathodic protection. In such cases an overlay is the preferable alternatives to avoid the additional requirements and costs for routine monitoring and maintenance associated with cathodic protection installations. Where deterioration is minor, some methods of rehabilitation may not be cost effective due to the high cost of mobilization, difficult access or traffic disruption. In such cases, the consequences of not doing the work should be carefully assessed. In emergency situations, public safety and downtime are more important factors than cost effectiveness. In such cases, the strategy may be to carry out sufficient repairs required to maintain the structure in a serviceable condition until a proper rehabilitation can be carried out in a timely manner.

1.3.5

Importance of Structure

1.3.5.1

General

The importance of the structure is determined by traffic volume at the site, importance of the highway and availability of alternative routes, and sometimes the size of the structure, as this affects the total cost of the work. Consequently, structures meeting these requirements may warrant selection of a combination of protective treatments (even though this may involve additional costs) in order to maximize service life. Traffic volumes and available alternative routes also influence the choice of rehabilitation method as they determine the requirements for staging and the number of lanes which can be closed and the length of time for which they can be closed.

1.3.5.2

Heritage Bridges

Where a bridge is designated as a heritage bridge, it may have to be repaired or rehabilitated even though it may be more economical to replace it with a modern design. Any work done on a heritage bridge should preserve the integrity and original appearance of the bridge where possible. When a heritage bridge is to be replaced, the engineer should consider various conservation April, 04

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strategies given in the Ontario Heritage Bridge Program

1.3.5.3

(6)

.

Bridge Aesthetics

Consideration should be given to the appearance of the completed rehabilitation work. Patchwork that protrudes or is of substantially different appearance than the surrounding original material should be avoided, particularly for highly visible components. Where possible, efforts should be made to match the rehabilitation work with the original construction.

1.3.6

Type of Structure

Some types of structures present particular difficulties. Structures where the deck is an integral part of the superstructure, such as solid or voided thick slabs, concrete box girder and T-girder bridges, may be difficult and costly to rehabilitate, and more difficult and costly to replace, and thus may warrant additional treatment to ensure long term durability. Also, some rehabilitation methods may not be practical for bridges and components with complex or unusual geometry.

1.3.7

Type of Component

The performance of primary components of bridge decks, superstructures and substructures is dependent on their ability to support and transmit imposed live and dead loads as described in OSIM (1). Furthermore, some of the primary components are exposed to heavy application of deicing salts and, in the case of bridge decks, the performance is also related to the quality of the riding surface. Therefore, the rehabilitation strategy for the primary components should consider materials and methods that would ensure structural adequacy, prevent chloride penetration and minimize corrosion of reinforcing steel in concrete components and provide a smooth riding surface on bridge decks. The method of rehabilitation would also depend on the type of material used to construct the component. Although the rehabilitation strategy for the secondary components can be less stringent, the life expectancy of the rehabilitated secondary component should preferably be consistent with the rehabilitation life cycle of the primary components and the safety of the motoring public should not be compromised. 1.3.8

Structure Service Life

The rehabilitation strategy should be compatible with the remaining service life of the structure. A structure may require replacement where it does not meet current design criteria for geometry or load capacity, or where other deficiencies are present in components of the structure that will otherwise limit its service life. In such cases, the most cost effective rehabilitation strategy that keeps the structure in service until it is replaced should be chosen. Sometimes, the actual date of replacement of the structure, or a part thereof, extends significantly April, 04

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beyond the expected date of replacement. Where this date is uncertain, it is advisable to select a method of rehabilitation whose life expectancy is somewhat longer than the expected date of replacement, otherwise the rehabilitation method may not be adequate and further rehabilitation may be required before replacement.

1.3.9

Highway Construction Program

The planned construction program for highways has a major influence on the timing of structure rehabilitation. Often, the structure rehabilitation is included with highway improvement contracts. Therefore, the future plans for the highway and other proposed structure contracts in the vicinity should be investigated. Where future re-alignment or geometric improvements to the highway are anticipated, a minimum amount of work should be carried out to maintain the structure in service until the future improvements are carried out. However, any postponement in necessary structure rehabilitation work may result in increased deterioration whose effect should be assessed. Conversely, it may be justified to rehabilitate nearby structures not in serious need of rehabilitation in a road surfacing contract by savings on the costs of mobilizing equipment and manpower. An attempt should be made to ensure that the structure rehabilitation is compatible with other activities in the contract. Where the scheduling of a resurfacing contract is not known, the rehabilitation of the structure should be carried out as a separate contract.

1.3.10

Contractor Expertise

Consideration must also be given to the expertise of local contractors and available construction equipment. Rehabilitation methods and materials for use on small contracts that require a specialized contractor from outside the area may not be cost effective. In such cases, alternative rehabilitation methods that can be carried out by local contractors should be considered.

1.3.11

Social and Environmental Concerns

Social and environmental concerns may affect the method and timing of rehabilitation. The rehabilitation strategy should minimize inconvenience to the public and should, where possible, be scheduled to avoid creating traffic congestion during peak traffic periods. The justification for programming a structure for rehabilitation should always take into account public safety. Seasonal timing constraints or other protection may be dictated when working in an environmentally sensitive area. Otherwise, a suitable rehabilitation method that has the least impact on the environment should be chosen in these areas.

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1.4

Finalizing Structure Rehabilitation Selection

The recommendations for the method of rehabilitation are to be prepared by the Regional Structural Section or by their Consultant. Forms contained in Appendix 2.A could be used to document the different rehabilitation options considered and the final option selected. 1.5

Deferred Projects

Where a project is deferred, such that the detailed condition survey is more than 4 years old, the Regional Structural Section should review the recommendations before advertising. Also, appropriate update condition surveys should be carried out to determine if the condition of the component investigated has substantially changed and if the original recommendations require revision accordingly.

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2.

CONCRETE STRUCTURE COMPONENTS -REPAIR AND REHABILITATION METHODS

2.1

General

The repair and rehabilitation of deteriorated concrete structure components involves the replacement of defective concrete with a suitable material and correcting any deficiencies in the original design or construction to restore or upgrade the structure capacity and to prevent the deterioration from recurring. This section describes the various rehabilitation materials and methods, their advantages and disadvantages and conditions for use. Crack repair is not included in this section as it requires a different category of repair method and materials for which guidelines are set forth in Section 4. The Ministry’s current standards and specifications include the best practices known to maximize service life. If the standards or specifications for a particular treatment could not be met, then an alternative treatment or product should be specified rather than relaxing the standards or specifications requirements.

2.2

Concrete Materials - General Considerations

The following factors must be considered when selecting a material for use on a repair/rehabilitation project. a) Where possible, repair like with like. It is best to repair concrete with ready-mixed concrete where this is possible. Use of proprietary and special mixes should be reserved for those locations where exceptional material properties are required, or where it is not economical nor practical to bring in ready-mixed concrete. b) The material and the substrate should respond similarly to changes in temperatures, load and moisture to avoid large differences in movement. c) The material must bond thoroughly to the substrate. d) The material must be sufficiently low in permeability to prevent moisture migrating through to the substrate. e) Components that are to be cathodically protected should not be repaired with epoxies or other materials that are non-conductive. f) The material must also be resistant to salt scaling and freeze thaw conditions. g) The material should be approved by the Concrete Section. h) Do not specify premium materials where it is not possible to enforce proper placement and April, 04

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curing methods.

2.3

Preparation of Concrete Surfaces and Reinforcing Steel

The durability of the repair/rehabilitation method depends on the quality of the preparatory work carried out prior to placement of the new materials. Concrete in areas of corrosion related delaminations and spalls should be removed to 25 mm below the top layer of reinforcing steel, except for rebars larger than 25mm in diameter where depth of concrete removal should be to sound concrete only. In any case, rebars with more than half of the perimeter exposed should have concrete removed to 25mm below the rebars. The exposed reinforcing steel should be thoroughly cleaned to ensure that all chlorides have been removed to prevent continuing corrosion of the reinforcing steel. In areas where corrosion damage of the existing concrete is expected to continue, consideration should be given to removing concrete in areas with corrosion potential more negative than -0.35 volts as discussed in Section 1.3.1.2, or using methods that mitigate the corrosion of the reinforcing steel. All existing concrete surfaces in contact with the material used for repair/rehabilitation must be thoroughly abrasive blast-cleaned and, if necessary, roughened to ensure that there is a good bond between the existing concrete and new material. Current specification requires the existing concrete surface to be adequately pre-wet prior to placing the new concrete.

2.4

Concrete Repair and Rehabilitation Methods

There is a wide range of repair and rehabilitation methods that can be used for the rehabilitation of a concrete component. The methods that are currently used by the Ministry and their advantages and disadvantages are described below.

2.4.1

Patch Repairs

This method of repair is used where extent of surface deterioration is not sufficient to warrant a concrete overlay, refacing or replacement of the component. The deteriorated concrete is removed and replaced with either normal concrete, normal shotcrete, silica fume shotcrete or proprietary products. It should be noted that in the unpatched areas of the component, delaminations might continue if chloride contaminated concrete is not removed. The corrosion activity around the perimeter of the repaired area may actually increase due to macro-cell effect.

2.4.1.1

Concrete Patches

Concrete is suitable for patching of vertical and horizontal surfaces. The minimum depth of repair is 50 mm for horizontal surfaces. For vertical surfaces the minimum depth of patch should be 100 mm in areas with exposed reinforcing steel and 75 mm in areas with no exposed reinforcing steel. The concrete patch should be reinforced with wire mesh if no reinforcing steel is exposed. April, 04

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Normal concrete should be used. Advantages Normal concrete is readily available and economical to place. The material is most compatible with the concrete structure and is not prone to shrinkage cracking. The patch can be fairly durable in areas exposed to chlorides provided that adequate concrete cover is provided. Disadvantages Normal concrete is relatively permeable to chlorides. If source of chloride exposure is not eliminated, corrosion activity of reinforcing steel will be reinitiated once chlorides migrate down to the level of the reinforcing steel. This method is not particularly aesthetic in areas where overbuilding of the patch is required to provide adequate concrete cover. Furthermore, placing and compaction of concrete by gravity for vertical surfaces with congested reinforcement would be difficult. Where to Use The use of normal concrete as a patch material is suitable for all concrete components except for overhead applications involving partial depth concrete removal and also in areas where there is poor access to place the concrete. The addition of a superplasticizer should be specified in areas congested with reinforcing steel. In areas with inadequate concrete cover to reinforcing steel, the use of concrete sealers or concrete overlays and concrete refacing should be considered.

2.4.1.2

Shotcrete Patches

Shotcrete is a mixture of water, cement and sand that is pneumatically applied to the repair area. The mix proportions are controlled so as to limit shrinkage and cracking while maintaining workability. The shotcrete must be placed in layers 25 mm to 50 mm thick to prevent sagging. To minimize shrinkage cracking, a galvanized wire mesh is fastened to the reinforcing steel in the patch area. This method of repair is particularly economical for large and shallow repair areas as no formwork is required. Shotcrete is suitable for both vertical and overhead applications and in some cases may be the most practical method of repairing deck soffits, diaphragms, pier caps, beams, etc. It may not be possible to use shotcrete to patch components with closely spaced reinforcing or where removal has extended a great depth behind the steel. Moreover, shotcrete cannot be properly applied where there is insufficient room to position the nozzle at right angle to the surface. Normal shotcrete, silica fume shotcrete and latex modified shotcrete have been used by the Ministry. However, the use of latex modified shotcrete has been discontinued due to poor quality control by the Contractor. The Ministry has a certification program to qualify nozzleman for MTO contract works.

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2.4.1.2.1

Silica Fume Shotcrete

Advantages Silica fume shotcrete is relatively impervious to water and chlorides and has a good bond to the existing concrete substrate. It is more cohesive than normal shotcrete and, therefore, thickness can be built up faster. Disadvantages The cost of shotcrete is more expensive than normal concrete type repairs. The quality of the final product is dependent on the expertise of the nozzleman. There may be voids on the backside of reinforcing bars as shotcrete is difficult to place in this area. The silica fume shotcrete is susceptible to shrinkage cracking if not properly wet-cured, especially in areas exposed to the elements; standard requirement is four days of moist curing. The colour of silica fume shotcrete is darker than normal concrete and therefore the patches would be more noticeable. Furthermore, although the finishing is greatly improved compared with latex modified shotcrete, it is still not as good as a formed surface. Where to Use Silica fume shotcrete can be specified for shallow overhead patches except for surfaces where cathodic protection is to be applied. The silica fume shotcrete can also be specified for vertical surfaces of substructures when the project involves both vertical and overhead repairs and the combined quantity for the work is more than 1 cubic metre. Superplasticized concrete by the form and pump method instead of shotcrete should be specified for areas congested with reinforcing steel and where the depth of patch extend more than 60 mm behind the galvanized wire mesh.

2.4.1.2.2

Normal Shotcrete

Advantages The resistance in the patched area of normal shotcrete is comparable to the surrounding existing concrete, which is an important consideration for cathodic protection installations. It does not require extended wet curing, as silica fume shotcrete does, and can be cured by means of a curing compound. Normal shotcrete is not usually as susceptible to plastic shrinkage cracking as silica fume shotcrete. The colour is consistent with normal concrete. Disadvantages Normal shotcrete is less durable than silica fume shotcrete, and is also much more permeable to water and chloride penetration. Since the mix is less cohesive than silica fume shotcrete, it may take longer time during application to build up the same thickness.

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Where to Use Normal shotcrete should normally be restricted to partial depth patches for deck soffit or substructure components where cathodic protection is to be installed. The galvanized wire mesh should not be installed on surfaces to be cathodically protected. It may also be used for emergency or temporary repairs where durability is not a requirement.

2.4.1.3

Concrete Patches Form and Pump

This method of patching involves forming the surface and filling the patch area with concrete by means of low pressure injection. The concrete mix would be designed by the contractor; material and construction requirements are contained in a standard special provision. Advantages It can be applied in the overhead position, in areas congested with reinforcing steel and in areas where the depth of patch is too deep for shotcrete. Disadvantages There is no long term experience with the performance of this method. This method could be more susceptible to shrinkage cracking due to higher cement and fine content of the concrete grout. Furthermore, the formwork would have to be left in place during curing, which would limit the vertical clearance for soffit repairs. Where to Use This method can be used to patch soffits of concrete girders, deck slabs and arches, and in areas congested with reinforcing steel. This method should also be considered for patching the soffits of thick deck slabs where the depth of repair is too deep for shotcrete application or where the access is poor for shotcrete application.

2.4.1.4

Proprietary Product Patches

Manufacturers have developed proprietary products for a variety of applications. The basic ingredients of proprietary products are cement, sand and special additives or modifiers that are necessary to enhance specific properties (e.g. increase early strength or reduce chloride permeability) and that make the product suitable for the particular application described below. Concrete Section maintains a list of approved proprietary materials for a number of common applications. These include general repairs, repairs where high early strength is required etc. The list also identifies properties such as suitability for overhead application. The list is updated on an ongoing basis as new products are introduced to the market, and is based on laboratory testing of the physical and chemical properties of the material.

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Repairing concrete with proprietary patching material is a suitable approach for applications that are small in terms of overall volume, or may be significant in terms of volume but consist of a large number of small patch areas. It is also suitable for patching areas where materials must be placed by hand. In general, a premium price is paid for proprietary materials relative to conventional concrete. Some general principles regarding the use of proprietary materials are: • • •

Specify repair materials using the lists of approved products maintained by Concrete Section. Choose the appropriate list depending on application (i.e. overhead or vertical, chloride permeability etc.). Avoid identifying a single source or a specific proprietary product in the contract document.

2.4.1.4.1

Trowel Applied Patching Materials

These products can be applied to vertical and overhead surfaces without the use of formwork. Advantages Trowel applied patching materials are suitable for patching vertical and overhead surfaces where the total quantity of material is too small to justify the use of concrete or shotcrete, or where the repair consists of numerous small but randomly distributed patches. Disadvantages Some of these products are prone to severe shrinkage cracking, especially in areas exposed to the elements. Hence, the repair may not be as durable as concrete or shotcrete. The products are expensive when large quantities are involved. The material has to be placed in layers and, therefore, the patch may not be monolithic if Manufacturer's specifications are not followed. Where to Use Trowel applied proprietary products could be considered when: a. shotcrete and concrete cannot be placed due to poor access and placing formwork is difficult; b. the greatest dimension of the patch is less than 300 mm and the total quantity is less than 0.5 cubic metres (standard special provision would allow contractor this option); c. repairs require thinner section than normal concrete due to scaling or freeze-thaw damage. Only products that have are proven to have low shrinkage in the plastic and hardened state should be allowed.

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2.4.1.4.2

Non-Shrink Proprietary Products

Non-shrink proprietary products contain additives that compensate for shrinkage in both the plastic and hardened state. Acceptable products for this application are listed in the Ministry’s Designated Sources for Materials. Advantages The repair could be more durable than conventional proprietary products due to less shrinkage cracking. Furthermore, the load carrying capacity of the patch is not reduced as there is no shrinkage relative to the parent concrete. Disadvantages The patch has to be formed for vertical surfaces and cannot be used for partial depth repairs in deck soffit. The products are more expensive than conventional concrete. Performance and characteristics of different materials are variable. Where to Use Non-shrink proprietary products could be used as an alternative to concrete patches for horizontal and vertical surfaces when the total quantity involved is less than 0.5 cubic metres. A non-shrink product should also be specified where support beneath mechanical bearings is required. The non-shrink product should only be 5 - 15 mm thick; otherwise, concrete should be used. Non-shrink grout should not be used beneath laminated or plain elastomeric bearings. 2.4.1.4.3

High Early Strength Proprietary Products

High early strength proprietary products could have a compressive strength of 8 MPa at 4 hours. Advantages These products are particularly useful for minor maintenance repairs when it is necessary to minimize the disruption to traffic. Disadvantages These products are a lot more expensive than conventional concrete. They may have reduced long term durability, and increased shrinkage cracking, especially when a large area is involved. Where to Use These products could be used for patching areas where it is desirable to minimize the time for lane closures. The products are more applicable to maintenance repairs rather than long term repairs. Products containing calcium chloride should not be used for permanent repairs where corrosion of April, 04

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reinforcing steel is a concern.

2.4.1.4.4

Self-Levelling Proprietary Products

These materials flow readily and will spread out to fill a cavity. Only shrinkage compensated proprietary products should be used. Advantages Self-levelling products are suitable for horizontal surfaces in hard to reach areas. Disadvantages These products are more expensive than conventional concrete and may not be as durable. Where to Use Self-levelling proprietary products could be used as an alternative to superplasticized concrete for very small patches.

2.4.2

Concrete Refacing or Jacketing

Concrete refacing or jacketing involves placing a layer of new concrete over a properly prepared existing surface. Localized areas of delamination and spall should have concrete removed to 25 mm behind the first layer of rebars wherever practical; other sound areas should be either roughened or a uniform depth of removal could be specified. When a uniform depth of removal is required, the contract documents must specify the following conditions to be met: (a) the concrete must be removed to the specified depth; (b) all delaminated concrete must be removed; (c) if the reinforcing steel is exposed for more than half the diameter of the bar, then the concrete must be removed 25mm uniformly around the bar. For horizontal surfaces, the minimum thickness of the refacing is 50 mm. For vertical surfaces the refacing/jacketing should be reinforced with a galvanized wire mesh or reinforcing steel equivalent to 0.2% of the sectional area of the refacing in each direction in order to control shrinkage and temperature cracking; the minimum thickness is 75 mm with wire mesh and 125 mm with reinforcing steel, maintaining a minimum cover of 50 mm in both cases. The concrete refacing should be anchored to existing concrete with new dowels. The wire spacing for welded wire mesh shall be no greater than 150mm x 150mm, and 300mm for reinforcing steel. Stainless steel should only be specified where a minimum cover of 50mm cannot be provided to the steel, or areas where repair would be subjected to salt splashing and the required service life is longer than 35 years. Advantages

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This method of rehabilitation is suitable when the delaminations and spalls cover large areas of the component (see Flow Charts in Appendices for guidance). It may also be used to reface surfaces that are delaminating due to low concrete cover or where the surfaces are deteriorating due to erosion and scaling. The rate of delaminations is slowed down due to the increased concrete cover. Increasing the cross section of the component by encasing it with reinforced concrete may strengthen a structurally deficient concrete component. The appearance of the rehabilitated component is much more aesthetically pleasing than if it were repaired using patch materials. Disadvantages Although the rate of corrosion damage may be substantially reduced, this method will not stop corrosion damage if chloride contaminated concrete is not removed. The life expectancy of the refacing depends on how much chloride is left, concrete cover, rebar spacing, and the continual supply of moisture and oxygen. Wide or active cracks in the existing concrete will be reflected in the refacing or encasement. Where to Use Concrete refacing and encasement can be used as a rehabilitation method for most components exhibiting extensive deterioration, except deck soffits and bridge deck riding surfaces (for bridge deck riding surfaces refer to concrete overlays). In areas with severe chloride exposure, consideration should be given to using high performance concrete instead of normal concrete.

2.4.3

Concrete Overlays

This method involves placing a layer of new concrete on a properly prepared concrete deck. The Ministry uses either normal 30 MPa concrete, latex modified concrete or silica fume concrete overlay. Placement of the concrete in patches and the overlaying of the deck are done in one operation. The specified thickness, from the scarified surface, is 60 mm for normal concrete and silica fume concrete, and 50 mm for latex modified concrete. The specifications for concrete overlays are contained in a standard special provision replacing Ontario Provincial Standard Specification, OPSS 930. Concrete overlays provide additional cover to reinforcing steel and are well suited to repair of extensively spalled and scaled decks. The rate of corrosion and corrosion damage is slowed down due to the increased concrete cover and possible upward migration of chloride from the original concrete into the overlay. However, if the chloride content at the rebar level is very high (> 2 times threshold), this method may not stop active corrosion if the chloride contaminated concrete is not removed in areas indicating corrosion activity. Wide cracks in existing concrete would likely be reflected in the concrete overlays.

2.4.3.1

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Normal Concrete Overlay

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A waterproofing membrane with asphalt paving is required with this method. Advantages Normal concrete is significantly less expensive than latex modified concrete and it does not require a specialized subcontractor. The overlay provides a smooth surface that is acceptable for waterproofing. Although wide cracks in existing concrete may be reflected in the concrete overlay, the waterproofing membrane should bridge these cracks. Disadvantages The concrete overlay requires a waterproofing membrane as normal concrete is relatively permeable to chlorides. The combination of overlay and asphalt increases the dead weight. Where to Use Normal concrete overlay can be used as a rehabilitation method for bridge decks provided that it is waterproofed and paved.

2.4.3.2

Latex Modified Concrete Overlay

A waterproofing membrane with asphalt paving may not be required with this method for secondary highways. Advantages The addition of latex makes latex modified concrete relatively impermeable to chloride penetration and provides a better bond to the existing concrete substrate. Hence, latex modified concrete overlay could be used as the riding surface and thus reducing the dead load on the deck. For major freeways, a waterproofing membrane could also be provided to achieve the longest service life possible. Latex modified concrete overlay only requires one day of wet curing, therefore, the total construction period for a multi-stage project could be shortened. This method could also be used for isolated rehabilitation contracts because it is mixed on site, though there would be a premium for transportation of materials and equipment to remote areas. Disadvantages It requires specialized Contractor expertise and is significantly more expensive than normal concrete overlays. Materials need to be stockpiled on site together with the batching equipment, which could take up a lot of work space. Latex modified concrete overlay is difficult to finish to the required grade on flexible structures with slopes or cross-fall greater than 4% unless the slump is carefully controlled. The permeability of the latex modified concrete is greatly affected if it is not placed according to April, 04

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MTO's specifications, especially if the latex is diluted. There is limitation on the temperature range over which it can be produced and cured. Since the number of contractors experienced in latex modified concrete have become very few, MTO currently would have to design the mix and execute full quality assurance; this is counter to the way MTO is proceeding with most other specifications. Where to Use Latex modified concrete overlay can be used as an exposed wearing surface for bridge decks of secondary highways where the bridge cannot carry the extra dead load of asphalt; it could also be used with waterproofing for decks carrying major freeways in order to achieve the longest service life. It should not be used for decks that are to be treated with the titanium mesh system of cathodic protection.

2.4.3.3

Silica Fume Concrete Overlay

Advantages The addition of silica fume makes silica fume concrete less permeable to chloride penetration than normal concrete. The bond strength to original concrete surface is likely to be higher than normal concrete due to its cohesiveness. Disadvantages Immediate fog misting during placement and a wet curing period of seven days is required to prevent shrinkage cracking. Silica fume concrete can be more difficult to finish and would require a contractor experienced in placing, finishing and curing of the silica fume concrete to do the job. There is limited experience with the long term performance of this material in the Ministry. Where to Use Silica fume concrete overlay can be used for most bridge decks except decks that are to be treated with the titanium mesh cathodic protection system. It is considered a low permeability overlay and therefore could be considered for major freeways with waterproofing to achieve the longest service life.

2.4.4

Concrete Sealer

This method consists of applying a surface treatment to the concrete to prevent the penetration of de-icing salt and water. Sealers are expensive and should only be used when there is a reasonably high probability that the concrete will scale or corrosion of reinforcing steel will occur prematurely without some protection. The sealer selected should allow the concrete surface to breathe to relieve water vapour pressure build up under the sealed surface (i.e. a penetrating silane and/or siloxane based sealers). Designers should refer to the Materials Engineering & Research Office, Concrete Section, for a April, 04

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list of recommended products for different applications. Ministry Report MI 127 provides additional information on sealers. Advantages If properly applied, concrete sealers will reduce the ingress of chlorides and moisture, which in turn will prevent corrosion of the reinforcing steel and increase the scaling resistance of the concrete. Sealants can also be used on concrete undergoing light to medium alkali-aggregate reaction. Alkali-aggregate reaction will slow down when moisture is eliminated by sealing the exposed surfaces. However, in the case of abutments and retaining walls, moisture will still penetrate through the faces covered by earth and, in this case, the sealing of the exposed face may be less effective. Disadvantages Sealers have to be applied within a certain range of temperature and moisture conditions; the concrete substrate could not contain excessive amount of moisture. The sealer is not effective in reducing corrosion if chlorides are above threshold value at the level of the reinforcing steel. While a one-time application of a sealer may be helpful, for continued effectiveness it must be reapplied, typically after about 5 to 7 years. Where to Use Sealers can be used on all components requiring this treatment except bridge deck surfaces. Sealers do not totally prevent water penetration into the surface of concrete bridge decks and, therefore, a rubberized asphalt membrane, latex modified concrete or silica fume concrete is normally used for bridge decks. Sealers applied as part of a rehabilitation contract could be relatively cost effective. However, the re-application every 5 to 7 years would be impractical for many bridges due to the high cost of traffic protection, which would limit the benefit of its use.

2.4.5

Waterproofing and Asphalt Paving

This method involves placing a layer of rubberized asphalt membrane after the deteriorated concrete in the deck has been patched or overlaid. The waterproofing membrane is then protected with an asphalt impregnated protection board and paved with asphalt paving. The specifications for waterproofing are contained in Ontario Provincial Standard Specification, OPSS 914 and associated special provisions. Advantages This is one of the more economical methods of rehabilitation when the extent of deterioration is not excessive. The waterproofing membrane can bridge active cracks and is impermeable to April, 04

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chloride and water penetration if properly applied. Corrosion activity may decrease once moisture and oxygen ingress is prevented. Further salt scaling and freeze thaw damage would also be reduced. Disadvantages The performance of this method is variable if proper surface preparation is not carried out; rough or textured deck surfaces must be ground or overlaid. If ingress of moisture into concrete continues due to improper installation of waterproofing or due to other reasons, corrosion activity will continue in areas with chloride contaminated concrete around the reinforcing steel. Where to Use This method can be used for bridge deck rehabilitation except when the structure cannot support the additional dead load; any structure specific concerns with respect to dead load should be dealt with on an individual basis.

2.4.6

Cathodic Protection

The concept of cathodic protection is to apply sufficient current to the surface of the reinforcing steel to prevent it from discharging electrons so that corrosion does not occur. This method of rehabilitation is suitable for components that have small areas of delaminated or deteriorated concrete but large areas of reinforcing steel with corrosion potential readings more negative than -0.35 volts. Cathodic protection is not suitable for protecting prestressing strands in post-tensioned bridges because of the cable ducts. Cathodic protection systems for bridge deck surfaces used the conductive asphalt system from the late 1970’s until the late 1980’s. Since 1991, the titanium anode mesh system has been used. The systems for concrete substructures use either titanium mesh or sprayed zinc anodes. The Ministry mostly used impressed current systems in the past, however, sacrificial type cathodic protection systems are being developed and may be allowed in the near future if trial installations perform well (see 2.4.10). Advantages Corrosion activity could be stopped. Chloride contaminated concrete and areas with corrosion potential <-0.35 V, if otherwise sound do not have to be removed. Thus, structural integrity could be preserved by avoiding excessive removal. For post-tensioned decks and rigid frames, this could avoid complex removal sequences and temporary support. Disadvantages The impressed current system would only be cost effective when large areas are involved. Ongoing monitoring of the system is required to ensure the current is in the required range and an electrical power source is required. Specialized contractors are required for installation and maintenance repairs. April, 04

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2.4.6.1

Conductive Bituminous Overlay System

This system uses a 40 mm thick layer of electrically conductive coke mix to distribute the current over the entire deck surface. The conductive mix is overlaid with normal asphalt. This system should only be installed on sound; properly air entrained concrete decks. On decks where concrete is not air entrained or with low concrete cover to reinforcing steel, a concrete overlay is required prior to installation of the conductive bituminous overlay system. Advantages This is the least expensive cathodic protection system. Disadvantages A waterproofing membrane cannot be used with this system, therefore, deterioration of concrete surface due to scaling may continue even when concrete is properly air entrained. The eventual replacement of the surface course asphalt overlaying the conductive mix may be difficult as anodes can be damaged during removal. Also, water may penetrate through cracks in the deck due to lack of waterproofing. This conductive asphalt is not a structural component of the deck slab. On decks with low concrete cover, the sawing required for installation of the system may interfere with the rebars. Low concrete cover may also cause short circuits between the cathodic system and the rebars if there is no concrete overlay. The conductive asphalt may have to be replaced after 15 years due to scaling beneath the asphalt and due to increase in resistance of the conductive mix in the vicinity of the anodes. This system is not suitable on post-tensioned decks as chlorides continue to penetrate below the reinforcing steel. Where to Use This method should no longer be used for new installations due to its poor performance.

2.4.6.2

Titanium Mesh System - Bridge Decks

The current is distributed over the entire concrete surface by a titanium mesh anode embedded in a normal concrete overlay. The bridge deck is then waterproofed and paved. Advantages The presence of waterproofing will prevent deterioration of concrete due to scaling and will bridge active cracks in concrete. This is suitable for post-tensioned decks since the waterproofing would prevent water and chloride from reaching the prestressing cables. Since the anode is buried April, 04

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underneath the overlay, it is not susceptible to damage during resurfacing. Disadvantages This is an expensive method of rehabilitation and there is only one supplier of the anode mesh. Although the concrete overlay is a structural component of the deck slab, the waterproofing and asphalt increases the dead load. Low concrete cover could result in poor current distribution or shorts between the anode mesh and the rebar. It requires a continuous source of AC power and ongoing monitoring to ensure maintenance of power supply and appropriate current level and distribution. Where to Use This method of rehabilitation can be used for large bridge decks on high volume roads and for post-tensioned bridge decks.

2.4.6.3

Titanium Mesh System - Substructures

The current is distributed over the entire concrete surface by a titanium mesh anode embedded in a modified cementitious overcoat. Advantages The system is expected to have a service life of 20 to 25 years due to better long term current distribution of the continuous anode mesh. Disadvantages There has been a problem due to acid attack damage, which was related to the acrylic cementitious overcoat that was used and the current density was set excessively high. The Ministry is currently evaluating a silica fume/carbon fibre type of overcoat that should perform more effectively. Low concrete cover could result in poor current distribution or shorts between the anode mesh and the rebar. Application This method of rehabilitation can be used on substructure applications where total areas are large enough to justify the cost of electrical hardwares and long term maintenance.

2.4.6.4

Arc Sprayed Zinc System

A 300 micron thick layer of zinc that is sprayed over the entire surface distributes the current. Advantages

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The system is easier to apply in the overhead position than the titanium mesh. Disadvantages It probably will have a shorter life cycle than the titanium mesh system due to the build up of zinc chloride compounds at the zinc/concrete interface, which will increase circuit resistance; life expectancy of this system is about 20 years. Thickness of the Zn on a rough surface may be difficult to control and the life of the system will be reduced if insufficient thickness is applied. Environmental requirements are more stringent than for the titanium mesh system. Low concrete cover could result in poor current distribution or shorts between the zinc and the rebar. Where to Use This method of rehabilitation can be used for substructure and soffit applications where large areas are involved.

2.4.7

Electrochemical Chloride Removal

The theory for this method is similar to cathodic protection except the system is a temporary installation and it is operated at a much higher current density than cathodic protection. The electric field that is created causes chloride ions to migrate away from the reinforcing steel towards the anode electrolyte system that is fastened to the concrete surface. Simultaneously, alkali ions move from the electrolyte back into the concrete raising the pH of the concrete in the vicinity of the reinforcing steel. The entire process can be completed in a couple of months. Advantages If properly applied corrosion activity of the reinforcing steel will return to the passive state. There is no need for long term monitoring and maintenance of equipment as is the case with cathodic protection. Disadvantages The method is not suitable for applications where chlorides have penetrated beyond the first layer of reinforcing steel. The Ministry has limited experience in the long term performance and cost effectiveness of this method. The method may not be suitable for bridge decks on high volume roads, as lane closures would be required for a longer period of time. Contrary to what is implied by the name of this method, the ECR process does not actually remove all the chloride ions from the concrete; the chloride ion concentration at some distance in front of the steel may still be above threshold and given time may migrate back towards the reinforcing steel. The oldest MTO installation was in 1989 and indications to-date (year 2004) are that chloride has not moved back to the steel which remains passive. Since there is only one applicator for this method in Ontario, and it is subject to profit mark-up by the contractor, recent Ministry’s contracts have shown that this method is very expensive. April, 04

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Where to Use Electrochemical chloride removal can be used for substructure applications. However, long term evaluation is required to determine whether this method is more cost effective than cathodic protection.

2.4.8

Steel Jacketing

This method involves encasing a circular concrete column with a steel jacket. On columns with closely spaced reinforcing steel, delaminated concrete is removed to the spring line of the spiral reinforcing steel or sound concrete, whichever is deeper. The space between the steel jacket and the concrete column is pressure grouted with a silica fume modified grout. Advantages The steel jacket forms a structural component of the pier. The concrete is not expected to delaminate as readily as the steel jacket confines the concrete. Corrosion activity may decrease as the jacket seals moisture out. Concrete does not have to be removed behind the reinforcing steel. The steel jacket could replace any loss in confinement due to section loss of the spiral. Disadvantages There is limited experience with the long term performance of this method. Corrosion of reinforcing steel may continue if extensive chloride contaminated concrete remains behind the reinforcing steel. Stiffness of the columns are modified by this method, which could affect the substructure’s response to lateral loads. Where to Use This method could be considered for seriously deteriorated columns where the space between spiral reinforcing steel is less than 70 mm, or where concrete cannot be removed to behind the steel due to structural considerations.

2.4.9

Fibre Reinforced Polymers Wrapping

This method involves wrapping a repaired concrete column with either glass fibre or carbon fibre fabric embedded in epoxy resin. On columns with closely spaced reinforcing steel, delaminated concrete is removed to the spring line of the spiral reinforcing steel or sound concrete, whichever is deeper, and the removal area is patched with concrete prior to installation of the fibre wrapping. The fibre wrapping is then painted over with a coating system to prevent the epoxy resin from UV degradation and for aesthetics. Advantages

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The fibre wrapping seals out moisture, which could slow down the corrosion activity. The fibre wrapping may also confine the concrete when reinforcing steel corrodes and, therefore, slow down the rate of delaminations. The wrapping could be designed to strengthen the column for inceased loading or to replace corroded spirals. It is easier to apply than concrete encasement or the use of steel jackets. This method does not alter the stiffness of the columns significantly as opposed to steel jacketing; the load capacity and ductility of the column is enhanced due to the confining effect of the wrapping. Disadvantages There is limited industry knowledge and experience with the long term performance and cost effectiveness of this method from a corrosion standpoint; it is not certain whether corrosion activity would be stopped or slowed down if chloride contaminated concrete is not removed. Maintenance of the coating system is also a concern. Where to Use This method can be considered for rehabilitation of circular columns with closely spaced spiral rebar and for strengthening circular columns that suffer excessive section loss of the spirals. However, due to maintenance requirements of the coating, and potential on-going corrosion if chloride contaminated concrete is not removed, this method should only be used for columns adjacent to secondary highways.

2.4.10

Galvanic Cathodic Protection System

These are surface applied systems that make use of the electropotential difference between black steel and the surface applied metal (usually Zinc) to mitigate corrosion; external power supply is not required. Trial applications of two systems have been conducted on bridges: • 3M Zinc-Hydrogel in 1999 • CORRPRO arc sprayed Al-Zn-Indium in 2000, 2002 and 2003 Monitoring data of both systems to-date shows good current output and good projected life expectancy. Advantages • • • • • •

It is simple to apply, no need of power supply, rectifier nor extensive wiring It can be applied at relatively cold temperature Minimal maintenance and monitoring Cost is about 75% of an impressed current system Reasonable service life of about 15 years It can tolerate a short circuit

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Disadvantages • •

These are proprietary systems, each system only has a single source The effectiveness diminishes over time due to consumption and polarisation of the anode

Where to Use Galvanic CP systems can be used on all exposed structural components, except bridge decks top, on a project specific basis. Continual monitoring of their performance would be carried out to refine materials and work procedure. The specifications for these systems could be obtained from Concrete Section or Bridge Office.

2.4.11

Partial or Complete Replacement

The concrete in the affected area of the component is replaced full depth or the component is completely replaced depending on the extent of the deterioration. Where extensive removal of concrete is required, it may be more economical to replace the component because larger or heavier equipment may be used to remove concrete more cost effectively. Advantages The work is easier to bid by the contractors and there should be no overruns in the tender quantity during construction if the extent of the removal is well defined. Strengthening of the bridge may be carried out more cost effectively when the component is removed. There may be better access to some areas of the structure to facilitate repairs if part of a component is removed. The component should have a longer service life, as it will be built using the latest standards and specifications. It may also be more acceptable visually. Disadvantages In some cases, staging of work is more difficult when replacement is involved. Also some substructure components are expensive to replace if the superstructure is to remain in place. Where to Use The replacement option is always a consideration for any component that is in poor condition.

2.4.12

No Action

This option is suitable when the component is in good condition or where the deterioration is not causing any current problems for the structure and the cause of the deterioration has been eliminated or will not contribute to future deterioration. This option is also used when the structure has deteriorated to such an extent that it would have to be replaced within a short period of time and minimum maintenance is expected to address or mitigate any problems in the April, 04

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meantime. Advantages The funds allocated to repair the bridge can be allocated to another structure requiring rehabilitation. Disadvantages If source of chlorides is not eliminated, chlorides will continue to diffuse to the level of the reinforcing steel and the life cycle of any subsequent rehabilitation will be reduced. Also deterioration of the component may accelerate to the point that replacement is warranted. Where to Use Always a consideration when it is cost effective and the safety of the public is not compromised.

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3.

CONCRETE STRUCTURE COMPONENTS - SELECTION OF REHABILITATION METHOD

3.1

General

In this section, guidelines are given for selecting the most suitable method of repair and rehabilitation for each type of component. The guidelines take into account: • • •

factors that influence the selection of rehabilitation methods described in Subsection 1.3; relative advantages and disadvantages of the different repair and rehabilitation methods summarized in Section 2; concrete removal criteria described in Section 3.2.

Crack repair is not included in this section as it requires a different category of repair methods and materials for which guidelines are set forth in Section 4. One option common to all types of concrete components is simply patching the removal area with a suitable patch material. The flow chart and decision matrix contained in Figure 2.B-1 and Table 2.B-1, Appendix B, provides guidelines for selecting patch materials suitable for a particular application.

3.2

Concrete Removal Criteria

The major factor that will influence the method of rehabilitation is the extent of concrete removal required. In addition to removing concrete in areas where concrete is delaminated, spalled and scaled, the extent of concrete removal will depend on whether or not chloride contaminated concrete that is otherwise sound is designated for removal in areas with corrosion potential < -0.35 volts for components with uncoated reinforcing steel. As a full scale corrosion potential survey is not feasible on concrete components with epoxy coated reinforcing steel, new condition survey procedure and removal criteria has to be developed for chloride contaminated concrete on components with epoxy coated reinforcing steel. An interim procedure for assessing the electrical continuity and true corrosion potential of epoxy coated reinforcement has been included in Part 1 of this manual, this is expected to be revised in the future once the Ministry establishes an official protocol for condition survey of epoxy coated reinforcement. Factors to take into consideration for removing concrete by corrosion potential criteria from components with uncoated reinforcing steel are discussed in Subsection 1.3.1.2. Guidelines for removing concrete by corrosion potential criteria are summarized in Table 3.1. It should be noted that chloride contaminated concrete does not have to be removed in areas with corrosion potential < -0.35 volts when cathodic protection is the method of rehabilitation. However, a financial analysis should be carried out to compare the cost of cathodic protection versus conventional methods that include concrete removal in areas < -0.35 volts. Increasing the April, 04

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cover with concrete refacing will also slow down the rate of delamination, and in some cases this may be a preferred option compared with concrete removal by corrosion potential criteria; however, more studies are required to evaluate the effectiveness of this option. Type of Component

Guidelines for Removing Concrete by Half Cell potential Criteria for Components with Uncoated Reinforcing Steel

Bridge Deck Top Surface

All deck surfaces except for post-tensioned decks and decks where concrete cover is greater than 100 mm.

Deck Soffits

In areas beneath leaking expansion joints or construction joints where significant delaminations or spalling is evident.

Deck Facia

In areas over travelled lanes of the highway beneath the structure where spalling and delaminations are evident.

Approach slabs, sidewalks, curbs or median

Removal by corrosion potential criteria not practical since exposed horizontal surfaces would likely have extensive high corrosion potential.

Barrier Walls and parapet walls

Removal by corrosion potential criteria should be considered on concrete walls that exhibit significant corrosion related deterioration and if chloride content exceeds threshold at the rebar, especially on bridges with narrow shoulders. For refacing option, removal by corrosion potential criteria may be waived if refaced concrete is reinforced with new doweled in reinforcing steel.

Ballast Walls

In most cases there is no access to carry out corrosion potential survey and to repair ballast wall. Removal by corrosion potential criteria not required. As concrete is likely chloride contaminated, remove entire ballast wall if extensive spalling and cracking is evident.

Abutment and Pier Walls

Removal by corrosion potential criteria should be considered if walls exhibit significant corrosion related deterioration and chloride/moisture exposure has not been eliminated. For refacing option, removal by corrosion potential criteria may be waived if refaced concrete is reinforced with new doweled in reinforcing steel.

Pier columns

Columns with spiral rebar at greater than 80 mm spacing Removal by corrosion potential criteria on columns that exhibit significant corrosion related damage provided the removal does not affect structural integrity. Columns with spiral rebar at less than 80 mm spacing Concrete cannot be removed below the rebar; in this case concrete should be removed to the spring line in areas <-0.35 volts and the column should be rehabilitated by cathodic protection, concrete encasement or steel jacket.

Table 3.1 / Guidelines for Removal By Corrosion Potential Criteria

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3.3

Bridge Decks

3.3.1

Bridge Deck Riding Surfaces

3.3.1.1

General

The strategy for rehabilitating the top surface of bridge decks is fairly complex due to the variety of options available. Therefore, a decision matrix and flow charts contained in Appendix 2C have been developed to assist the designer in selecting the most appropriate rehabilitation strategy. The designer should be thoroughly familiar with the rationale given in the decision matrix when using the flow charts. All flow charts are for structures with adequate load capacity and with a remaining service life of more than 10 years.

3.3.1.2

Selection of Method Prior to Condition Survey

In some cases, it is desirable to predict the most likely method of rehabilitation prior to the condition survey. As the condition of the concrete surface beneath the asphalt is difficult to assess visually, the method would be more related to the age of the bridge deck, type of deck, condition of deck soffit and previous rehabilitation history. Therefore, the flow chart in Figure 2C-1, Appendix 2C provides some guidelines for predicting method of rehabilitation prior to the condition survey. After the condition survey is carried out, the method of rehabilitation should be reviewed and revised, if necessary.

3.3.1.3

Selection of Method Based on Condition Survey

The flow chart in Figures 2C-2 and decision matrix in Table 2C-1, Appendix 2C, provide guidelines for selecting the method of rehabilitation based on the detailed condition survey. The criteria contained in the flow charts and tables are not meant to be rigid because of the complexity of the decision-making process, but the tables are a useful starting point and are applicable to most reinforced concrete structures. Where areas of deterioration are concentrated in one portion of the deck, consideration should be given to using a different treatment for that portion. Where the concrete deck and waterproofing are in good condition, there is no need to rehabilitate the deck even if the structure falls within the limits of a resurfacing contract. The method of rehabilitation should also be reviewed for cost effectiveness if expensive staging and temporary supports are required when excessive removal of concrete is required in the following locations and circumstances: a)

Extensive removal of concrete that exposes prestressing steel or ducts, particularly at anchorages.

b)

Extensive removal of concrete which exposes main tension reinforcing steel over a significant length, in the following areas:

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• • • • • •

at anchorage zones and over its development length; around the negative moment region in rigid frame bridges (slab and T-beam); over the top of concrete girders in negative moment regions at supports in continuous castin-place reinforced concrete bridges (girder and T-beam); in the positive moment regions in concrete beams and slabs; along the curb of a cantilevered thin deck slab; extensive top and soffit removal in a thin deck.

Where expansion joints and end dams are judged to be satisfactory and in good condition, the method of rehabilitation of the deck should be compatible with the elevations of the existing expansion joints and end dams. This may result in overlay and asphalt thickness of slightly more or less than normal. This thickness should not be reduced to below the minimum acceptable for strength and durability. Where the deck is in good condition but the joints are to be rehabilitated, it is recommended that they be set at the elevations of the existing roadway surface, but not less than 90 mm above the existing concrete deck surface. This is recommended so as to accommodate at least a future deck rehabilitation treatment of waterproofing and paving. This will involve an increase to the existing thickness of asphalt where it is less than 90 mm. It is desirable to limit the thickness of asphalt on a bridge to 90 mm. On some bridges the depth of asphalt has been built-up over the years due to re-paving and, in some cases, may be in excess of 200 mm. Removing the excess asphalt may involve lowering the profile of the approaches and extensive excavations and replacement of curbs, gutter, guiderail and other works beyond the bridge. In such cases, the method of bridge rehabilitation should consider replacing the underlying asphalt with a concrete overlay (reinforced if thicker than + 125 mm) followed by the normal thickness of waterproofing and paving. On decks where the extra depth of asphalt is due to recesses in the travelled lane portion of the concrete deck, the recess in the deck should be filled with a concrete overlay to improve the drainage. The bridge should also be evaluated whenever the depth of asphalt significantly exceeds the design thickness, and where concrete overlays are added. The decision tables and matrices are suitable for reinforced concrete components. For other types of structures and components other rationale may have to be used to assess the appropriate method of rehabilitation, as follows: Post-Tensioned Decks with black reinforcement Concrete removal shall not be according to corrosion potential criteria, removal shall be limited to delaminations and spalls only. The following are guidelines for selecting appropriate rehabilitation treatments based on conditions and rehabilitation history of the post-tensioned deck: I.

Decks that have not been rehabilitated to date: (i) If the chloride content exceeds 0.03% by mass of concrete at the rebar level:

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HCP + Delam < 5% of deck: Normal concrete overlay, waterproof and pave HCP + Delam > 5% of deck: Titanium mesh cathodic protection system + normal concrete overlay, waterproof and pave

(ii)

If chloride content is less than 0.03% by mass of concrete: HCP + Delam < 5% of deck: Patch, waterproof and pave HCP + Delam > 5% of deck: Normal concrete overlay, waterproof and pave

II.

Decks that were previously rehabilitated with overlay: (i) HCP + Delam < 10% of deck: Patch, waterproof and pave (ii)

HCP + Delam > 10% of deck: Remove overlay, install titanium mesh cathodic protection system + normal concrete overlay, waterproof and pave

III.

Decks that were previously rehabilitated with patch, waterproof and pave: Use same treatments as in I.

IV.

Decks that were previously rehabilitated with conductive asphalt cathodic protection: Since there is no waterproofing on the deck, the chloride content would undoubtedly exceed threshold greatly. The only long-term solution to stop further corrosion of the rebars would be to replace the existing conductive asphalt with the titanium mesh cathodic protection system, plus normal concrete overlay, waterproof and pave.

Composite Wood/Concrete Decks On composite wood/concrete decks the area of corrosion potential more negative than -0.35 volts may cover a large portion of the deck, although the extent of delamination may be relatively small. This can be attributed to the fact that composite wood/concrete decks contain little reinforcement, typically one layer of small diameter widely spaced bars. For these decks, the method of rehabilitation should be based on the condition of the concrete or wood surface. It may be difficult to remove the concrete from the wood, and in some cases the concrete tends to debond or separate over larger areas than intended when it is removed. In this regard total removal and replacement of the deck should be considered in the rehabilitation when large areas of removal are involved.

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Bridges Without Deck Slabs Some bridges, such as side-by-side precast box beams or T-beams, were constructed with no separate concrete deck slab (the top slab of the beams acts as the deck slab). In addition to normal removal of concrete and patching, the rehabilitation of these bridges typically includes the construction of a 150 mm concrete slab with one layer of longitudinal and transverse reinforcement followed by waterproofing and paving. The bridge should be evaluated for the extra load of the concrete slab. Depending on the deterioration that has occurred in the beams, it may also be necessary to remove and replace some of the beams.

3.3.2

Bridge Deck Soffits

The options for repairing deteriorated areas of the deck soffit are usually limited to silica fume shotcrete and low pressure concrete grouting using the form and pump method. However, in areas where the removal for the deck soffit coincides with the removal area for the deck top surface, serious consideration should be given to carrying out full depth repair of the deck in this area. Low pressure grouting of removal areas may be the most suitable method of patching areas where access is poor to properly place shotcrete or when the depth of the patch is too deep for shotcrete.

3.3.3

Bridge Deck Facia

The options for repairing the deck facia is usually limited to concrete patches or refacing the entire concrete facia. Refacing or rebuilding the deck edge should be seriously considered over travelled lanes when removal is expected to extend over 50% of the facia area. If a new concrete barrier wall is to be installed, it may be appropriate to replace the entire edge of deck to the centre line of the exterior beam if the facia and/or soffit is in poor condition or if excessive removal of concrete is required along the existing curb gutter line on a cantilevered thin deck slab.

3.3.4

Bridge Deck Replacement Option

Although the flow charts and decision matrix are useful in selecting the most suitable method of rehabilitation for a bridge deck, the deck/structure replacement option should be given serious consideration for bridge decks which require extensive concrete removal or when extensive repairs are required to other components of the bridge. The replacement option assures a longer service life and as a result future maintenance and user costs could be reduced significantly, especially on high traffic volume roads. Providing composite action between the concrete slab and steel beams by means of steel shear connector can usually strengthen decks supported by steel beams. The cost of rehabilitation can escalate on asphalt covered decks due to much more April, 04

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extensive deterioration than was anticipated whereas the replacement work can be clearly defined in the contract. Repairs/replacement of substructure components and bearings and coating of structural steel can be carried out more cost effectively with the deck removed. Factors, which should be considered in finalizing the decision to rehabilitate or replace the deck, are listed below: • • • • • • • • •

expansion joints to be eliminated; new barrier walls or parapet walls are required; the deck edge is to be replaced to centre line of exterior beam; extensive repairs to substructure and bearings required; bridge is to be widened within 10 years; superstructure requires strengthening; structural steel requires recoating within 10 years; repairs to soffit or facia extend over 20% of the total area and expensive access, traffic control and/or environmental protection required; concrete removal from deck surface is more than 50% of the total area.

Most of the above factors apply to thin deck slabs. The replacement of thick deck slabs like posttensioned decks and rigid frames are more complex and may involve complicated staging, temporary support and alternative structural arrangement etc. In any case, the final decision should be based on a life cycle cost analysis that should include traffic management and user cost. The financial analysis should be based on rehabilitating the deck in 1 year versus replacement in 5 years or more depending on the condition of the bridge; financial analysis is not required if the deck is in such poor condition that replacement is the only option. The replacement option can often be postponed provided necessary maintenance is carried out to maintain traffic safety on/under the deck. As the cost of rehabilitation is more likely to escalate during construction compared to the replacement option, the deck/structure replacement option should be considered even when the present value life cycle cost of replacement is up to 10% higher than that of rehabilitation.

3.4

Concrete Beams, Girders and Misc. Superstructure Components

Normally concrete beams, girders and miscellaneous concrete superstructure components are in good condition and repairs are not often required. However, some of these components may be susceptible to collision damage and localized corrosion damage beneath leaking expansion joints. The condition of beams that are damaged by collision damage or where cracking or significant section loss is observed should be thoroughly investigated to determine the extent of the damage. The extent of concrete removal in the compression zones of reinforced and prestressed concrete girders and in areas directly over bearings and supports should be assessed. A repair procedure using such methods as patching, epoxy injection and strengthening by fibre reinforced polymers should be developed based on the findings of a structural analysis. Spalls at the end of beams caused by corrosion damage due to leaking expansion joints are April, 04

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difficult to repair properly due to poor access for concrete removal and cleaning of reinforcement steel. Where possible, the beam end should be protected by sacrificial cathodic protection or concrete encasement. The soffit of beams and some arches are difficult to patch with shotcrete due to tightly spaced reinforcing steel. These areas should be patched using low pressure concrete grouting. The replacement of the superstructure should be considered as an option if the following is applicable: • •

deck replacement and strengthening of the superstructure is required; deck replacement and coating of the structural steel is required within 10 years.

3.5

Substructure Components

The strategy for rehabilitating substructures can be fairly complex due to the variety of options available. Therefore, a decision matrix and flow chart described in Table 2.D-1 and Figure 2D-1, Appendix D, has been developed to assist the designer in selecting the most appropriate rehabilitation strategy. The designer should be thoroughly familiar with the rationale given in the decision matrix when using the flow charts. All flow charts are for structures with adequate load capacity and with a remaining service life of more than 10 years. The criteria contained in the tables are not meant to be rigid because of the complexity of the decision-making process, but the tables are useful guidelines. The tables are more applicable to abutment and pier walls whereas Figure 2D-1, Appendix D, is also applicable to pier columns. The rehabilitation options are more limited for slender pier columns as described in Figure 2D-1 and as discussed below. Where removal of concrete by corrosion potential criteria would result in extensive removals adversely affecting the capacity of slender compression components and result in expensive staging and temporary support systems, consideration should be given to removal of deteriorated and unsound surface concrete followed by a rehabilitation method that does not require the removal of chloride contaminated concrete, such as electrochemical chloride extraction, cathodic protection, concrete or steel jacketing. A similar treatment would also be applicable to circular columns where it is difficult to remove concrete behind the tightly spaced spiral reinforcing steel. The method of rehabilitation should also be reviewed for cost effectiveness if expensive temporary supports are required when excessive removal of concrete is required in pier caps and in concrete bearing seats. The replacement of the substructure should also be considered as an option for financial analysis if the following is applicable • •

substructure rehabilitation involves refacing or cathodic protection; superstructure replacement is required.

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3.6

Railing Systems and Walls

The decision to rehabilitate or replace the existing concrete walls and railing systems should be made at the individual project level taking the following into consideration: • • • • • •

an appropriate investigation of the condition of the concrete walls and railing systems; incidence of accidents; conformance with crash testing standards and safety considerations; speed and volume of traffic; geometrics of the highway at the structure; a detailed financial analysis.

In Ontario, bridge railings were first required to conform to crash tested railing standards when the 3rd edition of the Ontario Highway Bridge Design Code was implemented in 1993. Depending on the site specific exposure index, a bridge railing had to meet the appropriate performance level required by OHBDC and standard drawings were developed for crash tested railings for all the three performance levels ( PL1, PL2 and PL3). In May 2002, the Canadian Highway Bridge Design Code CAN/CSA S6-00 was implemented to supersede OHBDC as the required bridge design code in Ontario. CHBDC has retained the crash testing and performance levels requirement for traffic railings similar to OHBDC, except that the loadings for the design of the railing anchorage and the cantilever deck have been redefined for different performance levels, the design load for PL3 is substantially higher than before. Revised standards for PL2 and PL3 concrete barriers meeting the requirements of CHBDC have been implemented together with the code. The amount of reinforcement required for the cantilever deck to resist the loading on PL3 barrier would be increased, the design aid in the Structural Manual for cantilever deck has been withdrawn and a new design aid would be developed in the future. The current bridge railing inventory on the provincial system can be categorized as follows: • • • • •

Railings that do not conform to any past or present crash tested standards. Railings that conform to the previous crash tested standard according to OHBDC, but do not conform to the current standard according to CHBDC. Railings that conform to the current standard. Railings on low volume roads that conform to the Low Volume Road Guidelines. Railings on low volume roads that do not conform to the Low Volume Road Guidelines.

Upgrading and replacement of railings a)

Railings that do not conform to any past or present crash tested standards shall be upgraded or replaced to meet the current standard at the same time when the deck is programmed to be rehabilitated, unless site specific accident record justifies earlier replacement. Programmed deck rehabilitation work includes patching or overlay,

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waterproofing and paving, but excludes shave and pave of the wearing surface. b)

Railings that were designed previously to meet the requirements of OHBDC do not need to be upgraded to meet the current standard, unless the current traffic volume and accident record justify a higher performance level than before; in such cases, the railing shall be upgraded as part of deck rehabilitation. Furthermore, if the material condition of the railing is such that a major rehabilitation would cost more than 60% of replacing with a current standard railing, then the railing shall be upgraded or replaced to meet the current standard as part of the overall rehabilitation strategy of the bridge.

c)

Structural adequacy of existing bridge to support new barrier shall be investigated. Details of slab and curb reinforcement of the existing bridge and wingwalls shall be reviewed to determine if the deck edge is capable of resisting loading from the new railing, and whether there is enough room to accommodate the new railing detail. Deck cantilevers shall be evaluated for railing loads according to CHBDC, but no greater than the requirements for PL2; a reliability index of 2.75 according to Section 14 of CHBDC shall be used.

d)

Historical bridge sites and aesthetic concerns shall be considered on a case-by case basis. Variation to the crash tested standards could include the following options: • Place an approved traffic railing inboard of the existing railing, leaving the existing railing in place. • Remove the existing railing and incorporate it into a new acceptable railing. This could be appropriate where an existing railing is especially decorative. • Design a special railing to match the appearance of the existing railing provided the geometry and calculated strength equal or exceed a crash tested railing.

e)

Occasionally, an upgrade to railing on an existing structure could degrade rather than improve safety due to limited sight distance and shoulder width, narrow lanes or other factors. In such cases, the railing should not be upgraded on its own without addressing the other safety factors.

f)

If a bridge is proposed to be widened on one side only, any existing non-conforming railing on the other side shall also be upgraded to match the new railing on the widened side, unless it at least meets the previous crash tested standard according to OHBDC. The new railing on the widened portion of the deck shall meet the current standard.

Railings on low volume roads that do not conform to the Low Volume Road Guidelines shall be assessed on a case-by-case basis and engineering judgement shall be used to determine the warrant for their upgrading or replacement. If existing railing systems and concrete walls are to be replaced, the new barrier or railing system should meet the requirements of the CHBDC (4). g)

The capacity of the structure and need to modify existing details to carry loads from the concrete barrier should also be assessed. Where the roadway profile is raised through resurfacing, the height of walls and handrails should be reviewed to determine if suitable adjustments are consequently required. April, 04

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If the existing concrete barrier wall or parapet wall is to be maintained, the rehabilitation options are limited to concrete patches or concrete refacing. As concrete patches are not particularly aesthetic, treating of the entire inside face of the walls with a sealer should be considered. The use of a sealer should also be considered for barrier walls that are scaling. Refacing the entire area of a panel should be considered if area of concrete deterioration extends over 20% of the panel area. The refacing at each end of the panel should be tapered gradually to meet the existing surface of adjacent panels. Guidelines for selecting method of rehabilitation for barrier/parapet type walls are given in the flowchart in Figure 2E-1, Appendix E.

3.7

Sidewalks

If the bridge deck rehabilitation will result in a curb height of less than 150 mm for sidewalks, or where the existing curb height of a sidewalk is less than 150 mm prior to bridge deck rehabilitation, then the sidewalk should be refaced to provide a minimum curb height of 150 mm or other means of protection should be provided for pedestrian safety, or both. The height of handrails should also be reviewed when the sidewalk is refaced to determine if adjustments are required.

3.8

Curbs and Medians

A curb height of less than 150 mm may be acceptable for medians and curbs with solid concrete parapet walls provided that the height of the parapet wall meets the requirements of CHBDC. The rehabilitation design should not result in a curb height of less than 150 mm for existing curbs with metal lattice or open railing systems. Where it is not possible to avoid reducing the curb height, the curb should be refaced to restore the curb height to 150 mm and the railing should be raised accordingly. Alternatively, the curb or railing may not need to be raised where the face of the railing system is built out so as to be flush with the edge of the curb. The design of such a modified railing system shall conform to the requirements of CHBDC, (4).

3.9

Ballast Walls

Accessible areas of ballast walls can be patched with concrete. Ballast walls that are severely deteriorated should be replaced. Partial replacement of the approach slab and excavation of the backfill may also be necessary to facilitate removal and reconstruction of the ballast wall. The replacement of a ballast wall in poor condition will also provide better access to repair ends of soffits of thick deck slabs and the ends of concrete girders. Where deterioration is due to pressure exerted by the approach concrete pavement, relief joints should be provided in the approach pavement to prevent this from recurring. It is also good April, 04

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practice to install relief joints where concrete pavement butts up against ballast walls.

3.10

Approach Slabs

Some existing structures have no approach slabs. This is typical of bridges where the deck or superstructure is covered with fill (with or without paving). Some examples of structures without approach slabs are filled spandrel arches, soil-steel structures, barrel arches and culverts. Other cases are bridges on unpaved roads. Approach slabs should be installed to reduce the dynamic load effects onto the deck and the potential hazard for loss of control when vehicles drive onto and off the bridge where there are no approach slabs, where there is no fill on the bridge and where the approaches are paved. The bridge maintenance files should be reviewed to determine if and when the approaches were padded, and if the settlement has stabilized. At bridges where the fill under existing approach slabs has settled, the condition of the approach slab and severity of settlement should be assessed to determine if remedial action is necessary.

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4.

CRACKING IN CONCRETE

4.1

Introduction

Almost all concrete components are subject to fine and hairline cracking and, in most cases, this cracking is not a cause for concern and no treatment is needed. Therefore, before cracks are designated for repair, the designer shall determine if remedial measures are necessary and if an effective repair is feasible and economical. Cracks should be repaired when the structural load carrying capacity or durability is affected. Structure durability is affected by wide cracks that allow access of air and moisture resulting in corrosion of the reinforcement. In either case, the cause of the cracking should be determined and eliminated, if practical, and the most effective repair method should be selected. The different types of cracking and their causes are described in the Ontario Structure Inspection Manual OSIM (1) .

4.2

General Considerations

There are a number of factors to consider when selecting the most suitable material and method for repairing cracks. Considerations shall include the cause of cracking, the crack's current state of activity, the extent of cracking and the presence of moisture and contaminants in the crack.

4.2.1

Cause of Cracking

The cause of cracking should be determined in order to select the most suitable and permanent repair method. The investigation should also ascertain whether the mechanism that caused the cracking is still active or will reoccur in the future. Following is a list of different types of cracks and the most appropriate remedial measure that should be taken. a)

Plastic Shrinkage/Drying Shrinkage Cracks caused by plastic or drying shrinkage that are less than 0.3 mm in width normally do not require any type of treatment. Cracks wider than 0.3 mm would affect durability, and depending on the location in a structural component, may also affect structural integrity.

b)

Settlement Cracks Fine cracks above reinforcement caused by settlement of formwork require no treatment. Wide cracks caused by differential movements due to foundation or support settlement should be repaired to prevent localized corrosion of reinforcing steel.

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If settlement is still occurring, the movement should be stabilized before repairs are carried out. If it is not feasible to prevent further movements, then a flexible sealant should be considered if the crack is exposed to moisture. c)

Structural Cracks Fine and hairline cracks, less than 0.3 mm in width, caused by externally applied loads and external restraint forces require no treatment. The structure may require strengthening if the cracking has been caused by forces that will recur in the future. If cracking is due to hydrostatic pressure, provisions should be made to provide proper drainage of the subsoil. The cause of restraint forces should be determined and eliminated, if practicable. An evaluation of structural cracks should be carried out prior to undertaking repairs.

d)

Cracks Due to Alkali Aggregate Reaction There is currently no method that is suitable for repairing cracks caused by reactive aggregates. The policy at the present time is to permit the cracking to continue to a point where the component has to be partially or completely replaced. A concrete sealer may be used to prevent the ingress of moisture and, as a result, slow down the alkali-aggregate reaction. Guidelines for use of concrete sealers are given in Section 2.

e)

Cracks Due to Corrosion of Reinforcement These cracks are usually associated with shallow cover. Repairing or sealing the crack alone may not be a long term solution since spalling or delamination of the concrete cover may be imminent. Proper repair treatment would involve removal of concrete to 25 mm behind the reinforcement and then patch with concrete or proprietary products described in Section 2. The concrete cover should be increased to current requirements where practicable, which may require refacing of the entire surface.

f)

Cracks Due to Freeze Thaw Cracks that are due to freeze thaw damage are usually found in components that have poor drainage. The component should be replaced if the freeze thaw damage extends through the full depth of the component and provisions for proper drainage should be made.

4.2.2

State of Activity

Cracks can either be categorized as active or dormant, depending on whether the mechanism that caused the cracking is still active or not. If the state of activity cannot be determined by a visual inspection, movement can be monitored with a crack measuring device, which gives a direct reading of crack displacement and rotation. In addition to this, structure cracks should be recorded and monitored to determine whether the number and width of cracks have stabilized.

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4.2.2.1

Dormant Cracks

Dormant cracks are cracks that remain constant in number, width and length. These cracks occurred in the past and are not currently active. A rigid material may be used to fill these cracks.

4.2.2.2

Active Cracks

Active cracks are cracks that are currently increasing in number, width or length because the mechanism(s) that caused the cracking is still active. The repair material used to repair active cracks must be flexible enough to allow for movement, or the cause of the cracking must be eliminated.

4.2.3

Extent of Cracking

The extent of cracking must be defined to select the most suitable repair method. Width and depth can be determined using a feeler gauge, crack comparator or other suitable measuring devices. Cores shall be taken where it is difficult to determine the depth of a crack using feeler gauges or fine wires. The number, width and depth of cracking in the component shall be measured if a detailed condition survey has not been carried out.

4.2.4

Moisture and Contaminants

The presence of moisture and contaminants in a crack may reduce the effectiveness of the repair by preventing the penetration or proper bonding of the repair material. Therefore, moisture insensitive materials and flushing out of the cracks with water or solvents should be specified. Also, some repairs may not be feasible if there is excessive hydrostatic pressure present.

4.3

Crack Repair Methods

4.3.1

General

This section describes the different methods of repair currently used by the Ministry for repair of cracks less than 5 mm in width. Cracks wider than 5 mm that do not affect structural capacity should be repaired using non-shrink grout, concrete or shotcrete and, therefore, should be treated as a concrete patch. The decision matrix given in Table 2.F-1 and the flow chart in Figure 2.F-1 in Appendix F can be used to select the most suitable crack repair method. The specifications for crack repair are contained in Ontario Provincial Standard Specifications OPSS 932.

4.3.2

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This method of crack repair involves sealing the surface of the crack(s), installing entry ports and pumping epoxy resin or polyurethane resin into the crack(s) by means of a positive displacement pump. It should be noted that cathodic protection might not function properly in areas repaired with epoxy or polyurethane resins as resins may insulate the underlying reinforcement. Epoxy Resin Epoxy injection is suitable for cracks from 0.1 mm to 5 mm in width and is the most suitable method for restoring structural strength and water tightness of a component, provided that the cause of cracking is eliminated and where there is no high waterhead. Epoxy is not effective for active cracks as new cracks will likely occur adjacent to the injected crack. The epoxy resin selected for injection should conform to ASTM C-881, Type I and IV, Grade 1, Class B and C. The resin selected should be moisture insensitive. Polyurethane Resin The polyurethane resin should be selected for active cracks where it is not necessary to restore structural strength. As the term polyurethane is sometimes applied to prepolymers, which can be rigid, it is important that the product selected is flexible. A water compatible hydrophobic polyurethane elastomer is recommended for most applications. The product should be able to displace water in the cracks and have a good bond to wet or dry concrete. For applications where there is serious water leakage, a hydrophobic flexible foam prepolymer may be more suitable. However, the Manufacturer should be consulted to provide advice on materials and techniques for sealing cracks that are seriously leaking due to high waterhead.

4.3.3

Routing and Sealing Cracks

This method of crack repair involves the routing of a crack and sealing with either a hot applied or cold applied joint sealing compound. OPSS 932 specifies a 15 + 5 mm wide chase with a 1:1 width to depth ratio. The dimensions of the chase should be increased if the elasticity of the sealing material is insufficient to accommodate the movement of the crack for the dimensions given in OPSS 932. A bond breaker is required at the bottom of the recess to allow the sealant to accommodate the full range of movement without cracking. Although a rigid type sealant would be suitable for dormant cracks, there usually is some thermal movement. Therefore a flexible sealant should always be specified.

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Hot Applied Joint Sealing Compound Hot applied joint sealing compound should be specified for horizontal surfaces that are to be treated with waterproofing membrane. Approved suppliers are given in the Designated Sources List. Cold Applied Joint Sealing Compound Cold applied joint sealing compound should be specified for horizontal surfaces that will not be treated with a waterproofing membrane and for vertical surfaces. Normally, the material selected should be an elastomeric joint sealant conforming to ASTM C920, Type S, Grade NS, Class 25 Type M sealant should be specified where depth of chase exceeds the Manufacturer's recommendations for a Type S sealant.

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5.

STRUCTURAL STEEL COMPONENTS

5.1

Repairs to Damaged Steel Members

Guidelines for evaluation and repair of damaged steel bridge members are contained in the National Co-operative Highway Research Program Report No. 271, "Guidelines for Evaluation and Repair of Damaged Steel Bridge Members" (9). The rehabilitation of steel structures may include the supply of additional steel components or the replacement of existing steel components with new steel components. For new structures, atmospheric corrosion resistant, ACR steel is specified for this purpose. However, the use of ACR steel should not be specified for rehabilitation when the new steel will be coated by an approved coating system or hot-dipped galvanized or metallized, unless ACR steel is required to match the existing steel for durability and notch toughness.

5.2

Protection of Existing ACR Girders

If the ends of existing ACR girders are corroding due to leaking expansion joints, all structural steel, including diaphragms and bracing should be coated with an approved field applied coating system for a distance of 3000 mm from the ends of the girders. For the mid-span area of ACR girders over travelled lanes, there is not enough information at this moment to determine if coating is warranted.

5.3

Existing Shear Connectors

If the existing deck is to be replaced, the existing shear connectors should be maintained where possible. Additional shear connectors should be added in conformance with the Canadian Highway Bridge Design Code (4).

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6.

TIMBER COMPONENTS

To be developed.

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7.

ALUMINUM COMPONENTS

To be developed.

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8.

MASONRY COMPONENTS

To be developed.

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9.

EXPANSION JOINTS, BEARINGS AND DECK DRAINAGE

9.1

General

Details on the selection of expansion joints and bearings are described in the Structural Manual (7). This section covers additional considerations for rehabilitation of expansion joints and bearings, as well as requirements for deck drains, catch basins, drainage tubes and void tubes to facilitate deck drainage.

9.2

Expansion Joints

9.2.1

Strip Seal Joints

Expansion joints must be able to accommodate the movement of the structure and should be sealed to prevent water leaking through the joint, which in turn may cause deterioration of components beneath the joint. Expansion joints that cannot perform these functions, including those that have loose anchorages or steel angles, should be repaired or replaced. Where the problem is due to a damaged seal and the expansion joint armouring meets current requirements, replacement of the joint seal should be specified. Expansion joints are an ongoing maintenance problem. Serious consideration should be given to eliminating expansion joints at abutments with semi-integral abutment and at pier locations with either flexible link slab or semi-continuous details, provided that modifications are feasible and can be made economically. Existing expansion joints without steel armouring should be replaced with an armoured joint. Wherever possible, existing open fingerplate joints should be replaced with a suitable sealed expansion joint. Where practical, the existing armouring could be utilized. However, most of the existing anchorages are of the stud or strap type and may not be suitable for modifications. Furthermore, care must be taken to ensure that the alignment of the top of the joint across the width of the deck is compatible with the proposed elevation of the rehabilitated deck surface. It is rarely practical to insert shims of different thickness. Where the existing joint armouring is inadequate or the structure carries high volume freeway traffic, a new joint assembly and end dams should be constructed in accordance with current Ministry standards. Mechanical friction-type anchor bolts or anchor bolts embedded in a sleeve of grout have been found unsatisfactory and should not be used in high traffic volume areas. All existing black or epoxy coated reinforcing steel in the expansion joint blockout should be replaced with stainless steel in accordance with the Corrosion Protection Policy of the Ministry. An expansion joint anchored in elastomeric concrete could be specified when the design of the structure does not allow sufficient depth or width for the expansion joint blockout and, therefore, prevents proper installation of the expansion joint anchorage. However, since an armoured strip April, 04

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seal joint is preferred, the designer should first investigate if the anchorage detail could be modified to suit the width and depth of the end dams. Polystyrene foam and other formwork, which has been left at the abutment or at the pier, should be removed since it traps moisture and accelerates deterioration of the concrete.

9.2.2

Open Joints

Where existing open joints are to be maintained, the drainage system should be inspected to ensure that water and sand are being properly directed away from the joint. Where the water discharging through the open joint causes deterioration of other components or undermining of the slope protection, then replacement with a sealed joint or modification to the drainage system should be carried out.

9.2.3

Ethylene Vinyl Acetate (EVA) Foam

Longitudinal joint between adjacent structures where drainage through the joint is causing damage to the components beneath the joint should be sealed. A strip seal embedded in elastomeric concrete should be used wherever possible; a less durable solution would be to install ethylene vinyl acetate (EVA) foam, which would require periodical maintenance. EVA foam should also be specified for sealing expansion joints in parapet or barrier walls where it is not practical to place armoured expansion joints through the parapet or barrier wall.

9.3

Bearings

Bearings must be able to accommodate the movements of the structure and transfer all loads from the superstructure to the substructure. With the exception of jacking a structure to restore a bearing to its neutral position or lubrication of steel rockers or rollers, there are few maintenance procedures for bearings other than keeping them clean by maintenance. The bearing surfaces must have complete and uniform contact with each other and with the superstructure and bearing seats in order to prevent damage to the bearing, supports and superstructure. Where bearing seats and superstructure are of concrete construction, full contact may be achieved by concrete patching. For other types of construction shim plates may have to be used to restore full contact provided that they are properly attached to the bearing. Shim plates should not be used with laminated bearings as they may walk out.

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Steel bearings under deck joints or exposed to drainage may have to be blast cleaned and coated at more frequent intervals than the overall structure coating. Defective, deteriorated or frozen bearings should normally be replaced; however, non functional bearings may be left alone if the Engineer determines that it is not necessary or practical to replace them. Sometimes, due to other design considerations, it may be economically viable to rebuild the bearings. The sliding surfaces of tetraflouraethylene (TFE) bearings are considered as wearing parts and should be replaced when the TFE surface is scored or damaged. Anchor bolts and guidebars that are broken should also be replaced.

9.4

Deck Drainage

9.4.1

General

Surface drainage of bridge decks is provided by a minimum of 2% cross-fall and a longitudinal profile that allows water to run to deck drains, if present, or off the structure. Drainage tubes are used at the low points of the deck to drain water that accumulates beneath asphalt. Void tubes are used on the soffit of voided decks to drain any water that may have penetrated into the voids through cracks in the deck concrete, or due to condensation.

9.4.2

Deck Drains

Consideration should be given to replacing drains in poor condition or less than 150 mm diameter. However, there are some situations where a large number of small-diameter drains are functioning properly and replacement is not warranted. Deck drains on existing exposed concrete decks will require an extension upward to match the new surface elevation. Similarly, deck drains on asphalt covered decks where the new profile will be lower will require a reduction downward to match the new surface elevation. Deck drains discharging on beams, piers or other components should be extended downward or have the point of discharge diverted. Where deck drains are a continuous maintenance problem or are causing accelerated deterioration of concrete in the vicinity of the drain, consideration should be given to reducing excessive numbers of drains by plugging surplus drains, consolidating drainage into new higher capacity drains, or routing surface drainage off the structure. The lateral spread of the ponding water shall be verified for compliance with CHBDC. Existing deck drains should also be checked to determine if there are provisions for draining water that may accumulate beneath the asphalt. Drainage slots should be provided at the concrete deck and asphalt interface if they are not present.

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9.4.3

Drainage Tubes

The drainage tubes installed to drain moisture accumulating beneath the asphalt may also cause deterioration by discharging on beams or even inside box girders. Where such conditions exist, the tubes should be diverted, extended or replaced. New drainage tubes should be installed where none exist. This is especially important for a cathodic protection system with no waterproofing membrane. Drainage tubes are not required on structures without expansion joint concrete end dams, provided that the profile of the deck is such that moisture beneath the asphalt will flow off the deck.

9.4.4

Void Tubes

Most structures have provisions for draining of the voids in the deck. If the drainage system is absent or ineffective, new void tubes should be installed or holes should be drilled into the soffit at the low points of the voids to facilitate drainage.

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10.

STREAMS, EMBANKMENTS AND SLOPE PROTECTION

To be developed.

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11.

MISCELLANEOUS DESIGN CONSIDERATIONS

11.1

General

All factors that affect the rehabilitation contract must be investigated before the contract package is assembled. The offices charged with responsibility for road design, environment, traffic control, etc., must be contacted so their requirements can be incorporated in the contract. When developing the preliminary design, miscellaneous factors that must be considered are described in this section.

11.2

Traffic Control

11.2.1

General

The objectives of any traffic control plan for construction or maintenance operations should be to adequately warn motorists in advance of the ensuing activity and to guide them through the work area efficiently with the safety of the motorists, pedestrians and workers kept in mind. Where a convenient detour exists, it is often advantageous to close a bridge to traffic during repair because this allows the contractor to operate with maximum efficiency. However, the opportunity to detour traffic is rarely available and most rehabilitation contracts are carried out in stages. Concern has frequently been expressed about the effect of traffic-induced vibrations on the fresh concrete in bridge deck overlays and widenings. This concern focuses on the fact that the vibrations may cause an uneven riding surface or induce cracks and impair bond of the concrete, thereby reducing the service life of the rehabilitation. There is, however, substantial evidence that the quality of the construction is not adversely affected when traffic is maintained on a structure undergoing repair provided that good concreting practices are followed. Consequently, the elimination of vibrations is not sufficient reason to close a bridge to traffic to carry out rehabilitation. It is prudent, however, to minimize the effects of traffic-induced vibrations. Since these vibrations result from the excitation of vehicles by irregularities such as spalls and joints in the pavement, maintaining a smooth approach pavement and a smooth transition at expansion joints by providing temporary patches and ramps are more effective in reducing the amplitude of traffic-induced vibrations than speed and weight restrictions.

11.2.2

Construction Staging

On two lane highways, one lane of traffic should be maintained in each direction where possible by making use of shoulders to carry traffic. If necessary, shoulders may have to be strengthened to carry this traffic. Temporary traffic control signals may be required where two way traffic cannot be maintained and traffic will be restricted for any length of time. On bridges with more than two lanes of traffic, particularly those on freeways, the situation can be much more complex. The requirements for design and construction are that the number of stages be April, 04

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kept to a minimum. It is also important to avoid a longitudinal joint in either a concrete overlay or a bituminous surfacing that coincides with a wheel track in the finished pavement. On structures with complex geometry, staging may be influenced by the position of the crown line, depending upon the method of rehabilitation selected. The traffic control plan for construction staging and lane closures should be determined jointly by representatives from the Regional Planning and Design, Traffic, and Structural Sections. The Regional Construction Office should be invited to review staging plans at the preliminary design stage. In formulating the plan, analysis of the structure may be necessary to ensure that the proposed staging is feasible. This is most commonly required when a portion of the structure is removed or when the shoulder area is used as a traffic lane thereby resulting in either a reduction in load-carrying capacity or an unbalanced loading for which the structure may not have been designed. On curved decks, the low side of the deck should be rehabilitated first, especially when adding dead load to the deck. On curved bridges that are rehabilitated in stages, uplifting of the bearings should be evaluated and prevented for uneven dead and live loading introduced during the rehabilitation. This is especially true for curved bridges on single columns, but can also occur for curved bridges on shafts and twin columns. The traffic control plan should be finalized before detailed design work begins.

11.2.3

Methods of Traffic Control and Protection

The Traffic Section makes the decision on whether signing, flagging, or temporary signals are required for traffic control. In all cases, traffic control measure must conform to the requirements of the Ontario Traffic Manual Book 7 – Temporary Conditions, 2001 (7). The decision to use temporary concrete barriers is made by the Regional Traffic Section and the Regional Structural Section on the basis of site conditions and the volume and speed of traffic.

11.2.4

Notification of External Agencies

Once the traffic control plan has been formulated, the Project Manager should prepare a schedule for informing all interested parties including emergency services and the media. If night work is to be carried out, an exemption from the noise bylaws of local municipalities may be needed. Where construction is to take place over a railway, the appropriate railway authority shall be contacted to determine the type of track protection, clearance and flagging requirements, etc. Generally, it is also necessary to obtain an order from a National Transportation Agency when there is a change in geometry such as clearance, widening etc.

April, 04

2 - 60

11.3

Roadway Protection

The excavation required to reconstruct wingwalls, abutments, piers, etc., may result in undermining of adjacent roadway and structure to remain in place. Where there is no practical way to do the work without protection, a protection scheme must be developed.

11.4

Jacking

Jacking of the superstructure is required for the replacement of bearings and possibly for other structure components. The structure should be investigated to ensure that there are adequate provisions for jacking. Structural components may have to be analysed to determine if modifying or strengthening is required to accommodate the jacking forces. For replacement of abutments, pier, pier caps, etc., temporary bents will have to be installed to accommodate the jacking and to support the structure.

11.5

Environment

If the proposed method of rehabilitation has a potential impact on the environment (i.e. rehabilitation over streams), the Environmental Unit of Planning and Design should be informed. The Environmental Planner will assess the effect of proposed construction on the environment. The methods and materials used for construction, along with the timing of the work, may have to be altered to reduce adverse environmental effects.

11.6

Utilities

The location of existing utilities and ducts should be identified to determine the effect of the rehabilitation on the utilities, particularly if jacking of the superstructure is required. The expansion/deflection fittings may not be able to accommodate the vertical and horizontal movements needed for the rehabilitation. Where proposed construction cannot be altered to accommodate existing utilities and ducts, the District and Utility Companies involved shall be contacted to inform them that the proposed rehabilitation may result in the temporary or permanent relocation of the utilities. If ducts are not used, then a decision must be made with the utility company involved as to whether the ducts should be removed, repaired or replaced. Abandoned ducts in sidewalks and curbs should be filled with grout if dowels for barrier walls are to be installed at that location.

11.7

Engineering Survey

An engineering survey should normally be carried out to determine existing alignment, profile and cross-section. It is especially important that such a survey be performed where the drainage is April, 04

2 - 61

poor or the geometrics are unusual or deficient. The data is used to: • • • • • • • • •

specify finished elevations to ensure adequate drainage (existing deficiencies can often be eliminated); calculate extensions to the top of drainage pipes; specify joint elevations; improve vertical alignment; identify where the approach pavement needs modifying; calculate screed elevations to ensure that the minimum thickness requirements for overlays are satisfied; calculate quantities of materials; identify the need for modifications to such items as curb height and guiderail height for reasons of safety; to verify data on existing structure drawings.

The extent of the survey will vary with the site conditions and should be specified in the request from the Project Engineer to the Surveys and Plans Section. Circumstances may exist, particularly on urban freeways, where it is not practical to carry out the engineering survey. In such cases, elevations will not be specified on the contract drawings and the responsibility for setting profiles in the field is assumed by staff of the Regional Construction Office.

11.8

Widening Highway Bridges

When a bridge requires widening, the designer should refer to ACI Structural Journal Title No. 89-S45, "Guide for Widening Highway Bridges" (10) for general design considerations and construction details.

April, 04

2 - 62

12.

REFERENCE PUBLICATIONS

12.1

Ministry Reference Publications 1. 2.

3. 4. 5. 6. 7.

12.2

Ontario Structure Inspection Manual, OSIM, Bridge Office, Ministry of Transportation, St. Catharines, Ontario, 2000 Performance and Cost Effectiveness of Substructure Rehabilitation/Repair Strategies, Structural Office, Ministry of Transportation, St. Catharines, Ontario, (1996), SO-96-11 Performance of Concrete Barrier Wall Rehabilitation/Repair Methods, Bridge Office, Ministry of Transportation, St. Catharines, Ontario, (1996), BO-98-02 Structural Financial Analysis Manual, Structural Office, Ministry of Transportation, St. Catharines, Ontario, (1990), SO-11 Ontario Heritage Bridge Program, Ministry of Transportation and Ministry of Citizenship, Culture and Recreation, (1983) Structural Manual, Structural Office, Ministry of Transportation, St. Catharines, Ontario Ontario Traffic Manual Book 7 – Temporary Conditions, 2001

Non-Ministry Publications 8. 9.

10.

April, 04

Canadian Highway Bridge Design Code, (CHBDC), CAN/CSA-S6-00 Shanafelt, G.O., and Horn, W.B., "Guidelines for Evaluation and Repair of Damaged Steel Members", National Co-operative Highway Research Program, 1984, Report No. 271, ACI Structural Journal,, "Guide for Widening Highway Bridges", 1992, Title No. 89-S45

2 - 63

APPENDIX 2.A FORMS - STRUCTURE REHABILITATION RECOMMENDATIONS

The forms, Structure Rehabilitation Recommendations, are to be completed by the rehabilitation design engineer and included in the structural design report.

April, 2004

2.A-1

STRUCTURE REHABILITATION RECOMMENDATIONS Structure Name ____________________________ Hwy. No. _______ 1.

Page 1 of 3

Site No. _____________ Date _______________

District ______

Rehabilitation Methods Considered

Component

Option No. 1 Method

Option No. 2 Cost

Method

Deck Surface Deck Soffit Deck Edge/Facia Barrier Walls/Railings Curbs/Median Sidewalks Expansion Joints Approach Slabs Beams/Girders Bearings Abutments Ballast Walls Piers Pier Caps Access Environmental Traffic Protection Roadway Protection Design Constr. Supervision Total Cost

*

Use Standard Abbreviations for Rehabilitation Methods Listed on Page 3.

Remarks:

April, 2004

2.A-2

Cost

STRUCTURE REHABILITATION RECOMMENDATIONS

Page 2 of 3

Site No. _____________ 1.

Rehabilitation Methods Considered (continued from Page 1) Component

Option No. 3 Method

Deck and Approach Slabs

Option No. 4 Cost

Method

Cost

Replace REPLACE BRIDGE

Beams/Girders Bearings Abutments Ballast Walls Piers Pier Caps Access Environmental Traffic Protection Roadway Protection Design Const Supervision Total Cost

Remarks:

2.

Additional Considerations

Financial Analysis Results:

Anticipated future modifications, conditions and expenditures:

Additional Investigation Required:

3.

Recommended Rehabilitation Option No. ____ and Scheduled Year of Construction: 20_____

April, 2004

2.A-3

STRUCTURE REHABILITATION RECOMMENDATIONS

Page 3 of 3

4. Standard Abbreviations for Rehabilitation Methods 4.1 Do Nothing NONE RASC -

Do Nothing Replace Asphalt Surface Course

4.2 Patching / Concrete Sealing PWAP CONC PROP SHOT PGRT SEAL -

Patch, Waterproof and Pave Bridge Deck Partial Depth Concrete Patch Patch with Proprietary Product Patch with Silica Fume Shotcrete. Patch Using Pressure Grouting Technique Seal Component with Penetrating Sealer

4.3 Concrete Overlays / Concrete Refacing LMCO SFCO NSCO NCWP RFCE -

Latex Modified Concrete Overlay Silica Fume Concrete Overlay Normal Slump Concrete Overlay Normal Concrete Overlay + Waterproof and Pave Reface or Encase the Entire Face of the Component with Concrete

4.4 Cathodic Protection CPAM CPAM/ NCWP CPCA CPCA/NSCO CPZC -

Continuous Anode Mesh Cathodic Protection Continuous Anode Mesh Cathodic Protection Embedded in a Concrete Overlay including Waterproofing and Asphalt on Bridge Decks Conductive Asphalt Cathodic Protection without Concrete Overlay Conductive Asphalt Cathodic Protection with Normal Slump Concrete Overlay Zinc Sprayed Cathodic Protection

4.5 Coat/Galvanize COAT Coat Structural Steel or Railings GALV Galvanize Structural Steel or Railings ENCP - Coat Portions of Structural Steel Girders that are Corroding 4.6 Repair, Replace, Strengthen or Eliminate Component REPR REPL ELIM STRN -

Repair Component Replace Component Eliminate Component Increase Strength of Superstructure

4.7

Crack Repair

CRKI CRKR

April, 2004

Repair Cracks by Pressure Injection Techniques Using Epoxy or Polyurethanes Repair Cracks by Routing and Sealing Techniques

2.A-4

APPENDIX 2.B

GUIDELINES FOR SELECTING PATCH MATERIALS FOR REPAIR OF CONCRETE COMPONENTS

April, 2004

2.B-1

Total quantity of patch material required is less than 1.0 cubic metres

Select most suitable patch material. Allow contractor to use proprietary product as an option if area < 300 mm in dimension.

Y

N

Y

Bridge deck riding surface

High early strength required

N

Y

Proprietary products or high early strength concrete

N

Overhead repair

N

Concrete

Y

Access too restrictive for application of shotcrete

Y Form and pump concrete

N

Y Y Removal area congested with reinforcing steel N

Depth of repair extends more than 60 mm beyond front face of rebar

N

Shotcrete or form & pump concrete

Figure 2.B-1 / Flow Chart for Selecting Patch Repair Material

April, 2004

2.B-2

APPENDIX 2.B

CRITERIA

Concrete

Shotcrete

Form and Pump Concrete

Proprietary Products

COMMENTS

Access restrictions for placement

Yes

No

Yes

*

Shotcrete should be applied at right angles with nozzle 600 to 1000 mm from surface

Horizontal and vertical repairs

Yes

*

*

*

Where possible repairs should be made with concrete as it is the most compatible patch material.

Overhead repairs

No

Yes

Yes

*

Superplasticized concrete may be used sometimes if access for placement by gravity can be provided.

Areas congested with reinforcing steel

Yes

No

Yes

No

Depth of repair extends more than 60 mm behind front face of rebar

Yes

No

Yes

*

Shotcrete can not be properly placed in deep repairs requiring more than 1 layer due to galvanized mesh.

Bridge deck riding surface

Yes

No

No

*

Concrete is the most compatible material.

Quantities less than 0.5 cubic metres for all components

Yes

Yes

No

Yes

Shotcrete or concrete should be specified. The Contractor should be given the option to use proprietary products if quantity is small.

*

No

*

Yes

This would only be applicable to the top surface of bridge decks. Generally, normal concrete is preferred on a bridge deck, but if high early strength is required, then high early strength concrete can be used. If repair volume is small or consists of scattered small areas, a high early strength proprietary material can be used.

High early strength required to minimize traffic disruption

*

Although these methods may be used, their selection should be based on other controlling criteria.

Table 2.B-1 / Guidelines for Selection of Patching Materials

April, 2004

2.B-3

It is difficult to properly place shotcrete behind closely spaced rebar.

APPENDIX 2.C GUIDELINES FOR SELECTING REHABILITATION METHODS FOR CONCRETE BRIDGE DECKS

April, 2004

2.C-1

Deck is less than 10 years old

Y

Do Nothing

N Deck was rehabilitated in last 10 years

Y

N Deck built after 1978

Patch, waterproof and pave

Y

N Type of last rehabilitation treatment

Deck built after 1972

Conc. Overlay, W.P. & pave Patch, W.P & pave

Y

No treatment

N

More than 20% of soffit area is in poor condition N Cathodic protection system previously installed

Select most appropriate rehab method. Carry out financial analysis for deck rehab versus replacement

Y

N

Concrete Overlay previously installed Y Conc. Overlay installed after 1988

Y

Concrete overlay, waterproof and pave

N

Y

Patch, waterproof and pave

N Replace overlay

Conductive Asphalt System? N

Y

Y

Post-tensioned deck? N Deck thickness > 300 mm

Continuous anode mesh C.P., concrete overlay, W.P. & pave Y

Concrete overlay W.P. & pave

N Replace Deck

Figure 2.C-1 / Prediction of Probable Rehabilitation Method for Asphalt Covered Deck Prior to Condition Survey

April, 2004

2.C-2

Flow Chart I – Deck in Good Condition Appendix 2.C

Total combined area of delams, spalls, medium to very severe scaling and corrosion potential < 0.35 volts is between 0 to 5% of deck area – Area of overlapping defects shall not be double counted counted N

Go to Flow Chart II and III

Y

Area of deck with concrete cover to reinforcing steel less than 20 mm extends over 10% of the deck surface area

Y

Go to Flow Chart III

N

Highway to be resurfaced

N

Exposed concrete wearing surface

Y

N Maintenance Repairs

Y

Medium cracks in concrete

N

Y Exposed concrete wearing surface

Y

Patch, waterproof and pave

N N

Mill off 40 mm asphalt and resurface

Deck is waterproofed Y N

N

Waterproofing is in good condition

Asphalt is in good condition Y

Y

Do nothing – Treatment of the wearing surface may be required for other reasons

Figure 2C.2 / Selection of Deck Rehabilitation Methods Based on Condition Survey

April, 2004

2.C-3

Appendix 2.C

Flow Chart II – Deck in Fair Condition

Total combined area of delams, spalls, medium to very severe scaling and corrosion potential < -0.35 volts is between 5% to 10% of deck surface – Areas of overlapping defects shall not be double counted N

Y

Area of deck with concrete cover to reinforcing steel less than 20 mm extends over 10% of the deck surface area

N

Concrete deck recess in travelled lanes

N

Y

Y

Go to Flow Chart III

Go to Flow Chart I and III

Figure 2.C-2 / Selection of Deck Rehabilitation Methods Based on Condition Survey

April, 2004

Patch, waterproof and pave – If concrete overlay or cathodic protection is a consideration go to Flow Chart III

2.C-4

Flow Chart III – Deck in Poor Condition Appendix 2.C

Total combined area of delams, spalls, medium to severe scaling and corrosion potential < 0.35 volts exceeds 10% of deck area - Areas of overlapping defects shall not be double counted. or Area of deck with concrete cover to rebar less than 20 mm extending over 10% of the deck surface area

Y

Deck surface and deck soffit show extensive medium to wide cracking

Y

N

Select rehab method(s) – Cost and strength analysis required for deck rehab vs replacement

Y

Y

Total combined area of concrete removal will extend over 30% of deck surface area

N

Replace deck/structure N

Combined area of spalls, delams, honeycomb and severe scaling extend over 20% of soffit area N

Y

Severe alkali aggregate reaction

N

N

Go to Flow Chart I and II Area of deck has concrete cover to rebar less than 20 mm after scarifying

Corrosion potential < -0.35 volts exceeds 20% of deck area and majority of the area contains sound concrete Y

N

Y

AC Power Supply Available

Y

Area of deck is less than 500 m2

N

Y

Grade or crossfall is greater than 4% on very flexible structures or 6% on other structures

April, 2004

Exposed low permeability concrete overlay

N N

Y

Y

Select most suitable rehab method based on dead load capacity of structure, condition of expansion joints, sidewalk height and amount of approach work

N

Wide cracks in deck

N

Titanium mesh cathodic protection, concrete overlay, waterproof & pave – Cost analysis required to compare cost of above treatment vs most suitable type of concrete overlay treatment without cathodic protection

Post-Tensioned deck Y

N

AADT greater than 10000/lane Y

Figure 2.C-2 / Selection of Deck Rehabilitation Based on Condition Survey 2.C-5 2.C-5

Normal concrete overlay, waterproof & pave

Appendix 2.C

CRITERION

Patch, Waterproof and Pave

Silica Fume or Latex Modified Overlay Only

Normal Concrete Overlay Plus Waterproofing

Cathodic Protection *

COMMENTS

Total combined area of delaminations, spalls, medium to very severe scaling and corrosion potential more negative than -0.35 volts is between 0 to 5% of the deck area.

No

No

No

No

General maintenance repairs. In some cases patch, waterproof and pave may be considered.

Total combined area of delaminations, spalls, medium to very severe scaling and corrosion potential more negative than -0.35 volts is between 5 to 10% of the deck area.

Yes

No

No

No

Patching of small areas is much more economical than constructing a concrete overlay.

Total combined area of delaminations, spalls, medium to very severe scaling and corrosion potential more negative than -0.35 volts exceeds 10% of the deck area.

No

Yes

Yes

Yes **

Patching of large areas is not economical.

Corrosion potential more negative than -0.35 volts over more than 20% of the deck area.

No

No

No

Yes **

When the corrosion potentials are high, cathodic protection is needed to reduce the potentials.

Table 3.1 continued on next page. * Titanium mesh cathodic protection anode embedded in a normal concrete overlay with waterproofing and asphalt. ** Cathodic Protection should be considered when areas of delaminations and spalls are less than 10% of deck area, and area of corrosion potential more negative than -0.35 volts exceeds 20% of deck area.

TABLE 2C-1 / Decision Matrix for Selection of Deck Rehabilitation Method

April, 2004

2.C-6

Appendix 2.C

CRITERION

Patch, Waterproof and Pave

Limited load capacity. Structure will not be replaced or strengthened to current bridge code requirements.

No

Yes

No

No

Silica Fume and Latex overlays add the least weight and are a structural component. Capacity after rehabilitation must be verified. Additional strengthening may be necessary.

Areas of the deck with concrete cover to reinforcing steel less than 20 mm extend over 10% of the decks surface area.

No

Yes

Yes

Yes

Additional concrete cover required to slow down ingress of chlorides. Increasing cover to current requirements will provide additional protection.

Remaining life of structure less than 10 years.

No

No

No

No

Do minimum amount of work.

Wide cracks in deck slab.

Yes

No

Yes

Yes

Waterproofing membrane is required to bridge cracks.

Deck not waterproofed, or waterproofing system in poor condition, or exposed concrete wearing surface.

Yes

No

No

No

Waterproofing will prevent ingress of chlorides to rebar level.

Electrical power unavailable.

Yes

Yes

Yes

No

Power required for rectifier.

Silica Fume or Latex Modified Overlay Only

Normal Concrete Overlay Plus Waterproof & Pave

Cathodic Protection *

COMMENTS

Table 3.1 continued on next page. * Titanium mesh cathodic protection anode embedded in a normal concrete overlay with waterproofing and asphalt.

TABLE 2C-1 / Decision Matrix for Selection of Deck Rehabilitation Method (cont.)

April, 2004

2.C-7

Appendix 2.C

CRITERION

Patch, Waterproof and Pave

Concrete deck recessed in travelled lanes.

No

Yes

Yes

Yes

Concrete overlay will improve drainage of deck.

Epoxy injection repairs previously performed.

Yes

Yes

Yes

No

Epoxy insulates underlying reinforcement from cathodic protection.

Yes Use with caution.

Yes Use with caution.

Yes Use with caution.

Yes

CAUTION: Latex modified concrete may be difficulty to finish at required grade unless the slump is carefully controlled. Bituminous concrete may shove.

Post -tensioned bridge decks

Yes

No

Yes

Yes

Waterproofing membrane ensures that no chlorides penetrate down to level of prestressing.

AADT > 10,000 per lane

Yes

No

Yes

Yes

Asphalt wearing surface is easier to maintain on high volume roads.

Grade or crossfall is greater than 4% on very flexible structures or 5% on other structures.

*

Silica Fume or Latex Modified Overlay Only

Normal Concrete Overlay Plus Waterproofing

Cathodic Protection *

COMMENTS

Titanium mesh cathodic protection anode embedded in a normal concrete overlay with waterproofing and asphalt.

TABLE 2C-1 / Decision Matrix for Selection of Deck Rehabilitation Method (cont.)

April, 2004

2.C-8

April, 2004

2.C-9

APPENDIX 2.D GUIDELINES FOR SELECTING REHABILITATION METHODS FOR CONCRETE SUBSTRUCTURE COMPONENTS

April, 2004

2.D-1

Y

Remaining life of bridge less than 15 years

Minimum maintenance repairs

N

Y

Alkali-Aggregate Reaction N

Strengthening Required

Y Y Area of concrete removal >40% of component area

N Y Extensive severe scaling, disintegration or erosion

N

N Area of spalls and delam’s is greater than 30% of component area

Concrete Refacing or steel jacketing. Financial analysis required if replacement is a consideration

Column with delam’s & spiral steel at less than 80 mm spacing c/c Y

N

Concrete is exposed to moisture after rehab

N Area of sound concrete with corrosion potential < -0.35 volts is > than 30% of component area

Concrete Patch with galvanic CP system

Y

Concrete Patch & Sealant

Y

N N Area of concrete to remain is chloride contaminated

Y

N

Concrete Patch

Y Concrete cover is less than 20 mm in some areas

Y Concrete is lightly scaled or not properly air entrained

N

N

Chlorides are above threshold value at rebar level Y

Y Power supply is not available or epoxy repairs previously carried out. Y

N

Area of components >1000 square metres

Y

Cathodic Protection or ECR Financial analysis required to confirm

N

Concrete Patch with Galvanic CP system

April, 2004

N

Figure 2.D-1 / Flow Chart for 2.D-2 Substructure Rehabilitation Selection

APPENDIX 2.D

CRITERIA

SEALANT PATCHING * **

REFACING CATHODIC*** JACKETING PROTECTION

COMMENTS

Chlorides at rebar level are above threshold values for corrosion

****

****

****

Yes

Sealers would reduce the ingress of moisture and would slow down deterioration. However, it’s effectiveness is limited to 5 to 7 years if not reapplied.

Chlorides are present but below threshold value at rebar level

Yes

****

****

No

Sealant would only be specified if there is exposure to chlorides.

Concrete cover is less than 20 mm in some areas and concrete is exposed to chlorides

****

****

Yes

No

Low cover increases the possibility of short circuits for the cathodic protection option.

Concrete surface has extensive areas of severe scaling, disintegration or erosion

****

No

Yes

No

If corrosion of reinforcement is extensive, replacement of the component should also be considered.

Area of spalls and delaminations is less than 30% of the component area

Yes

Yes

****

Yes

Concrete should generally be sound for cathodic protection to be cost effective.

Area of spalls and delaminations is greater than 30 % of the component area

****

****

Yes

No

Refacing would likely be the most appropriate method if concrete removal will also includes areas with corrosion potential < -0.35 volts.

Concrete to be removed by half cell potential criteria and area of sound concrete with corrosion potential < -0.35 volts is between 0 to 30 % of component area

Yes

Yes

****

No

It would be less expensive to remove and patch the area with corrosion potentials < -0.35 volts than to install cathodic protection.

Concrete to be removed by half cell potential criteria and area of sound concrete with corrosion potential < -0.35 volts is more than 30 % of component area

****

****

Yes

Yes

Sealing and patching would likely not be a consideration as the component will likely also be delaminated which would make the total removal area too large to justify patching.

Table 2.D-1 continued on next page

Table 2.D-1 / Guidelines for Selecting Rehabilitation Methods for Substructure Components April, 2004

2.D-3

Table 2.D-1 continued from previous page APPENDIX 2.D

CRITERIA

SEALANT PATCHING * **

REFACING CATHODIC*** JACKETING PROTECTION

COMMENTS

The total area of spalls and delaminations and areas of sound concrete with corrosion potentials< 0.35 volts (only if concrete is to be removed by half cell potential criteria) is more than 40 % of the component area

No

No

Yes

Yes

A financial analysis should be carried out to compare cost of cathodic protection, refacing and replacement options. If area of removal exceeds 70% for refacing option, than removal over entire area should be specified.

The total area of spalls and delaminations and areas of sound concrete with corrosion potentials< 0.35 volts (only if concrete is to be removed by half cell potential criteria) is less than 40 % of the component area

Yes

Yes

No

****

Refacing could be considered for other reasons.

Remaining life of bridge is less than 15 years

Yes

Yes

No

No

Do minimum amount of work.

Concrete undergoing alkali-aggregate reaction

Yes

Yes

****

No

Sealant should be considered in areas exposed to moisture to slow down the alkali-aggregate reaction. Refacing may be a consideration for piers based on other criteria.

Deterioration extends full depth into the component

No

Yes

****

****

When a major part of the component is deteriorated, replace entire component.

Strengthening of the component is required

No

No

Yes

No

Replacement should also be considered.

****

****

****

No

Impressed current system is not cost effective on small bridges due to the large fixed costs associated with the system. The galvanic CP systems may be used for small applications.

Area of component is less than 1000 square metres and there is no cathodic protection for the bridge deck. Table 2.D-1 continued on next page

Table 2.D-1 / Guidelines for Selecting Rehabilitation Methods for Substructure Components (continued) April, 2004

2.D-4

Table 2.D-1 continued from previous page APPENDIX 2.D

CRITERIA

SEALANT PATCHING * **

REFACING CATHODIC*** JACKETING PROTECTION

COMMENTS

Electrical Power unavailable

****

****

****

No

AC power supply required for rectifier

Epoxy injection repairs previously performed

****

****

****

No

Epoxy insulates underlying reinforcement from cathodic protection

Sound areas of chloride contaminated concrete have light scaling - Exposed to moisture after rehab

Yes

****

****

****

A breathable concrete sealant should be specified.

Sound areas of chloride contaminated concrete not air entrained - Exposed to moisture after rehab

Yes

****

****

****

A breathable concrete sealant should be specified.

* Sealant can be used in combination wi th patch treatment but not with refacing or cathodic protection. ** Additional guidelines for patch treatment are described in Table 2.B-1 *** When considering the cathodic protection option, the area of concrete removal for cathodic protection should not include areas with corrosion potential < -0.35 volts. This applies to both impressed current or galvanic CP systems. **** Although these methods may also be applicable, their selection should be based on other controlling criteria.

Table 2.D-1 / Guidelines for Selecting Rehabilitation Methods for Substructure Components (continued)

April, 2004

2.D-5

April, 2004

2.D-6

APPENDIX 2.E GUIDELINES FOR SELECTING REHABILITATION METHODS FOR CONCRETE BARRIER/PARAPET WALLS

April, 2004

2.E-1

Total combined area of spalls, delam’s, severe scaling and corrosion potential <-0.35 volts exceeds 30% of f/face area

N

Concrete Patches and seal entire wall

Y

N Total combined area of spalls, delam’s and severe scaling exceed 20% of f/face area

Area of wall with concrete cover less than 40 mm exceeds 20% of f/face area

N

Y

Y

Back face of wall is in good condition with less than 5% deteriorated concrete

Y

Existing wall meets requirements of OHBDC

N

Replace wall or reface with doweled in reinforcing steel

N

Y Total combined area of spalls, delam, severe scaling and HCP less than 50% of front face

Y Concrete Refacing

N Replace wall

Figure 2E-1 / Flow Chart for Barrier/Parapet Wall Rehabilitation Selection April, 2004

2.E-2

Appendix 2.E

CRITERIA

Total combined area of spalls, delams, severe scaling and corrosion potential <-0.35 volts is less than 30% of front face area Total combined area of spalls, delam’s, severe scaling and corrosion potential < -0.35 volts is greater than 30% of front face area. Total combined area of spalls, delam’s and severe scaling is less than 10% of front face area

CONCRETE PATCH & SEALANT

CONCRETE REFACING

REPLACE

COMMENTS

Removal of concrete by half cell potential criteria should be considered to extend life of treatment. The final decision would be based on extent of Yes Yes Yes concrete deterioration, concrete cover, condition of back face etc. If area of deterioration is relatively small, it is Yes No No likely that delaminations are occurring at a slower rate and refacing or replacement is not warranted. Total combined area of spalls, delam’s and severe scaling Yes Yes Yes The final decision should be based on concrete is between 10 to 20% of front face area. cover and condition of back face. Total combined area of spalls, delam’s and severe scaling The final decision should be based on condition is over 20% of front face area. No Yes Yes of back face and whether existing wall meets OHBDC/CHBDC requirements. * The final decision should be based on condition Total area of the wall with concrete cover less than 40 No Yes Yes of back face and whether existing wall meets mm exceeds 20% of the front face and at least 10% of the OHBDC/CHBDC requirements. * wall is deteriorated Total combined area of spalls, delam’s, severe scaling No No Yes Rehabilitation is expensive, life-cycle cost and HCP is more than 50% of front face area. would approach that of replacement. The existing wall is in poor condition and does not meet No No Yes Conversely if wall is in good condition but OHBDC requirements does not meet requirements of OHBDC refacing with doweled in reinforcing steel may be a consideration * * The decision to replace or to strengthen to CHBDC requirements should be based on site specific conditions. Barriers that conform to the OHBDC requirements do not have to be replaced or upgraded unless warranted by material condition. Yes

No

No

Table 2.E-1 / Guidelines for Selecting Rehabilitation Methods for Parapet/Barrier Walls

April, 2004

2.E-3

APPENDIX 2.F GUIDELINES FOR SELECTING CRACK REPAIR METHOD FOR CONCRETE COMPONENTS

April, 2004

2.F-1

Y

Repair of cracks to restore structural strength required

N

Crack width is less than 0.3 mm

Y

No Action

N

N

Crack to be covered with waterproofing membrane

Y

Crack width is greater than 5 mm

Crack width is less than 1 mm

Y

Repair with concrete or non-shrink grout patches

N

Rout and seal with hot applied joint sealing compound

Y

N

Cracks with seepage

N

Cracks exposed to exterior moisture

Y

N

Y

Rout and seal with cold applied joint sealing compound

Seepage is very serious (high water head)

Inject with hydrophobic flexible prepolymer. Consult Manufacturer for advice

Y

N Y

Inject with polyurethane (hydrophobic elastomer)

Active crack N

Inject with epoxy

Figure 2.F-1 / Flow Chart for Selecting Crack Repair Method April, 2004

2.F-2

APPENIX 2.F

Criterion

Crack Injection Epoxy

Polyurethane

Routing and Seal Cold Applied Joint Compound

Yes

Yes

Crack is greater than 5.0 mm in width Restore Structural Strength.

Remarks

Hot Applied Joint Compound

Crack is less than 0.3 mm in width. Crack is 0.3 mm to 5.0 mm in width.

No Action

Yes

Very fine and hairline cracks do not require any treatment as ingress of moisture will be minimal.

Yes

Yes

Yes

Most suitable method should be selected based on other criterion and cost.

Yes

Yes

Yes

Concrete or non-shrink grout patching should be carried out before routing and sealing cracks.

Yes

Cause of cracking should be eliminated to prevent further movement.

Cracks not exposed to moisture

Yes

Cracks exposed to moisture on exterior face.

Yes

Yes

Cracks with minor seepage.

Yes

Yes

Suitable for low waterhead. The polyurethane should be a water compatible hydrophobic elas tomer.

Cracks with serious seepage.

Yes

A hydrophobic flexible prepolymer may be suitable for cracks with serious seepage. Consult Manufacturer for material & technique.

Active Cracks

Yes

Yes

Yes

Yes

Epoxy will not accommodate movement.

Yes

Yes

Yes

Yes

Use most economical method if there are no other considerations.

Yes

Hot rubberized asphalt membrane will bridge cracks that are less than 1 mm in width

Dormant Cracks

Yes

Yes

Yes

Corrosion of steel is minimal due to lack of moisture.

Cracks < 1.0 mm wide & to be covered with hot waterproofing Cracks > 1 mm wide and to be covered with hot waterproofing

Yes

Use most economical method if there are no other considerations.

Hot rubberized joint sealing compound is compatible with waterproofing membrane.

Table 2.F-1 / Decision Matrix for Selecting Crack Repair Method April, 2004

2.F-3

April, 2004

2.F-4

April, 2004

2.F-5

PART 3 CONTRACT PREPARATION CONTENTS

1.

GENERAL ............................................................................................................ 3-1

2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7

CONTRACT DRAWINGS..................................................................................... General ..................................................................................................... General Arrangement Drawing..................................................................... Detail Drawings.......................................................................................... Profiles and Elevations................................................................................ Existing Structure Drawings......................................................................... Structure Condition Survey ......................................................................... Key Plan ...................................................................................................

3.1 3.2

TENDER ITEMS AND SPECIAL PROVISIONS.................................................... 3-5 Tender Items ............................................................................................. 3-5 Special Provisions ...................................................................................... 3-5

3.

3-2 3-2 3-2 3-3 3-3 3-4 3-4 3-4

4.

CONTRACT PREPARATION SCHEDULING AND REVIEW................................ 3-6

5.

REFERENCE PUBLICATIONS............................................................................. 3-8

APPENDIX A A1 1.1 1.2 1.3 1.4 1.5

ESTIMATING QUANTITIES AND CONTRACT DOCUMENTATION ............ 3A-1 CONCRETE REMOVAL .................................................................................... General .................................................................................................. Scarifying ............................................................................................... Partial Depth Removal............................................................................. Full Depth Removal................................................................................ Structural Component/ Complete Deck ....................................................

3A-2 3A-2 3A-2 3A-3 3A-11 3A-13

A2

STRUCTURE REMOVAL AND MISCELLANEOUS REMOVAL ...................... 3A-16

A3

ABRASIVE BLAST CLEANING........................................................................ 3A-18

A4

CONCRETE PLACEMENT............................................................................... 3A-20

A5

CONCRETE OVERLAYS.................................................................................. 3A-23

April, 2004

3-i

A6

CONCRETE REFACING / CONCRETE REFACING, FORM AND PUMP.......... 3A-26

A7 7.1 7.2 7.3 7.4 7.5

PATCHING OF CONCRETE COMPONENTS................................................... General ................................................................................................. Concrete................................................................................................ Shotcrete ............................................................................................... Concrete Patches- Form and Pump.......................................................... Proprietary Products...............................................................................

3A-28 3A-28 3A-28 3A-30 3A-32 3A-33

8.1 8.2 8.3

CONCRETE CRACK REPAIR .......................................................................... General ................................................................................................. Routing and Sealing................................................................................ Crack Injection ......................................................................................

3A-35 3A-35 3A-35 3A-36

A8

A9

CONCRETE SEALERS ..................................................................................... 3A-38

A10 10.1 10.2 10.3

STEEL REINFORCEMENT .............................................................................. General ................................................................................................. Reinforcing Steel.................................................................................... Mechanical Connections .........................................................................

3A-39 3A-39 3A-39 3A-40

A11

INSTALLATION OF DOWELS......................................................................... 3A-42

A12

STEEL BARRIER RAILING/ PARAPET WALL RAILING................................. 3A-43

A13

EMBEDDED WORK IN STRUCTURE ............................................................. 3A-44

A14

EXPANSION JOINTS....................................................................................... General ................................................................................................. Deck Joint Assemblies ............................................................................ Repairs to Existing Deck Joints................................................................

14.1 14.2 14.3

3A-46 3A-46 3A-46 3A-49

A15

BEARINGS....................................................................................................... 3A-51

A16

CATHODIC PROTECTION .............................................................................. General ................................................................................................. Tender Items ......................................................................................... 16.2.1 Conductive Bituminous Overlay System..................................................... 16.2.2 Continuous Anode Mesh System ............................................................... 16.2.3 Arc Sprayed Zinc ..................................................................................... 16.2.4 All Systems ............................................................................................. Contract Drawings..................................................................................

16.1 16.2

16.3 A17

3A-53 3A-53 3A-53 3A-53 3A-54 3A-54 3A-54 3A-56

ACCESS TO WORK AREA............................................................................... 3A-57

A18 18.1 18.2

TEMPORARY SUPPORT AND JACKING ........................................................ 3A-58 General ................................................................................................. 3A-58 Temporary Support ................................................................................ 3A-58

18.3

Jacking.................................................................................................. 3A-59

A19

April, 2004

DECK DRAINAGE ........................................................................................... 3A-61

3-ii

19.1 19.2 19.3 19.4

General ................................................................................................. Deck Drains and Drainage Tubes............................................................. Modification of Deck Drains ................................................................... Deck Drain and Drain Tube Extensions....................................................

3A-61 3A-61 3A-63 3A-63

A20

STRUCTURAL STEEL..................................................................................... 3A-65

A21

BRIDGE DECK WATERPROOFING ................................................................ 3A-67

A22 22.1 22.2 22.3 22.4 22.5 22.6 22.7 A23

PLANNING AND DESIGN ITEMS ................................................................... General ................................................................................................. Hot Mix................................................................................................. Removal of Asphalt Pavement from Concrete Surfaces ............................. Roadway and Track Protection ............................................................... Temporary Concrete Barrier ................................................................... Traffic Control....................................................................................... Earth Excavation for Structure.................................................................

3A-69 3A-69 3A-69 3A-69 3A-69 3A-70 3A-70 3A-70

DEVELOPMENTAL REHABILITATION METHODS ....................................... 3A-71

APPENDIX B NON-STANDARD SPECIAL PROVISIONS…. [To be developed]........................ 3B-1

April, 2004

3-iii

1.

GENERAL

Part 3 of this manual discusses the preparation of contract drawings and documents that make up the structural portion of a rehabilitation contract. General requirements for the preparation of a contract are given in the Contract Design Estimating and Documentation Manual (2). The preparation of contract documents should not commence until the rehabilitation methods selected are determined and agreed by the Ministry. The general policies, procedures and responsibilities for rehabilitation designs and preparation of contract documents are described in PHY Directive B-147 (3) as amended by the streamlining document.

April, 2004

3-1

2.

CONTRACT DRAWINGS

2.1

General

Structural drawings required as part of a rehabilitation contract include a general arrangement drawing together with detail drawings as required. The requirements for the preparation of drawings for the other parts of the contract (grading, electrical, etc.) are detailed in other MTO manuals. General design and drafting requirements for structure drawings can be found in the MTO Structural Manual, (4). For major rehabilitation designs where an independent design check is mandatory, each drawing shall be stamped by two professional engineers. In general, a second P. Eng. stamp is required on the rehabilitation design drawings if one or more of the following conditions prevail: • • • •

increase in loading of more than 10% of the original loading; rehabilitation work would result in change in structural behaviour or change in load distribution; rehabilitation work would upgrade the bridge to meet the functional and structural requirements of the current code; construction method or staging would result in critical load cases.

2.2

General Arrangement Drawing

The following is a list of views and details that should be included when preparing a general arrangement drawing: • • • • • • •

plan of the structure; side elevation of the structure; cross-section or sections of the structure showing the existing conditions and the proposed treatment; suggested construction sequence (scope of work) and staging; general notes to the contractor; list of structural drawings; list of applicable standard drawings.

The general areas of removal for the soffit and substructure should be shown on the side elevation of the structure so that the Contractor can estimate the cost of access requirements. The side elevation of the structure may be omitted if there is no work to be carried out on the soffit or substructure. In addition to the general notes described in the Structural Manual, (4), the following notes to the Contractor are required for structure rehabilitation. a)

The Contractor shall verify all dimensions of the existing work and all details on site and report any discrepancies to the Engineer before proceeding with the work.

b)

The Contractor shall check all relevant dimensions and elevations of existing work prior to fabrication of the joint assemblies. Dimensions and elevations shall be adjusted as required to suit the proposed work.

April, 2004

3-2

The Suggested Construction Sequence and Staging Notes will vary depending on the type of work and the complexity of the rehabilitation. The notes should conform to the following guidelines: • • • • • • • •

the work operation should be listed as clearly and specifically as possible; all of the details of a particular operation do not have to be listed if they are understood to be part of the work; i.e. abrasive blast cleaning is always required prior to placing of a concrete overlay and therefore does not have to be listed as an operation; work should be listed in the order of construction; separate notes are required for each stage; scarifying of the deck should be carried out before the concrete removal for the deck is started; the jacking of the superstructure should be carried out after the removal of concrete for expansion joint block-outs and before placement of the new expansion joints, and before the dead load of the structure is increased due to the rehabilitation; the removal of concrete from the surface of thin deck slabs should be carried out prior to the removal of concrete from the deck soffit, where practical; the high side of a super-elevated structure should be rehabilitated in the first stage to facilitate drainage, if practical.

2.3

Detail Drawings

It is not practical to list in this manual all the details required on Contract drawings for each type of rehabilitation contract. The extent and number of details will vary with the complexity of the individual project. Appendix A provides guidance for the details required on drawings for structural items. The detailing information for road design items is given in the Contract Design Estimating and Documentation Manual (2). The applicable Ontario Provincial Standard Drawings should also be listed on the detail drawings.

2.4

Profiles and Elevations

In order to correct or avoid problems associated with uneven riding surfaces, poor drainage, insufficient or excessive thickness of concrete overlays and improper joint settings, it is preferable that new profiles and elevations be provided. This is done by analysing the data collected as per requirements of Section 11.7 of Part 2. Normally, it is only practical to establish the new profile and elevations on decks with existing concrete wearing surfaces. The new profile and elevations should be established to satisfy the following conditions: • • • • • • •

eliminate existing drainage deficiencies and provide adequate cross-fall, super-elevation and grade; ensure that the required thickness of bituminous concrete surfaces are satisfied; ensure that the requirements for minimum concrete overlay thickness are satisfied while keeping overlay quantities to a minimum; ensure that the thickness of the concrete overlay and bituminous concrete does not result in the maximum allowable loads being exceeded; specify joint elevations so that concrete end dams are recessed 3 mm below the pavement surface; specify deck drain elevations to provide proper drainage; provide a smooth transition between the new pavement and the existing approach pavement.

When it is not practical or economical to specify profile data on the drawings for asphalt covered decks, the responsibility for establishing profiles must be assumed by field staff.

April, 2004

3-3

2.5

Existing Structure Drawings

Existing structure drawings should be made available to the Contractor so that unusual situations or difficulties can be anticipated; and to provide data on concrete cover and reinforcing steel diameters for concrete removal by the volume measurement for payment method. If the existing structure drawings do not represent the "as-built" condition, the Contract drawings should show the "as-built" condition from field measurements and observations when appropriate. The drawings should be made available for inspection at a specified location. SP 109F10 has been written to cover this situation.

2.6

Structure Condition Survey

Where the contract involves removal of concrete, the structure condition survey report should be made available for viewing during the tendering period so that the Contractor can get some information on the condition of the concrete, location of the deterioration and areas of corrosion potential more negative than -0.35 volts. The structure condition survey should be made available for inspection at a specified location. SP 109F10 has been written to cover this situation. A note should be attached to the report requesting the return of the report and existing structure drawings to the Regional Structural Section after the Contract is awarded.

2.7

Key Plan

A key plan showing the location of the Contract is usually prepared by the Regional Planning and Design Section. The work project number and site number of each structure to be rehabilitated as part of the Contract should be shown on the key plan.

April, 2004

3-4

3.

TENDER ITEMS AND SPECIAL PROVISIONS

3.1

Tender Items

The tender items most frequently required in rehabilitation Contracts, and the conditions for their use are described in Appendix A. The sequence of the tender items and their descriptions should be as per the list of tender items in the Contract Preparation System, [CPS]. Abbreviations are not permitted. Guidelines for estimating quantities and the requirements for contract drawings and special provisions are contained in Appendix A. Applicable specifications are identified by their Ontario Provincial Standard Specification [OPSS] numbers. In preparing Contract documents, only those items, specifications and special provisions that apply to the Work are to be quoted. When it is known that the quantity of Work is very small, it may be more appropriate to carry out the Work under extra Work provisions of the General Conditions of Contract. The method of dealing with small quantity tender items is covered in Directive C-86 (5).

3.2

Special Provisions

When a standard special provision is required, the number given in Appendix A should be selected against the appropriate tender item, where applicable. The special provisions listed in Appendix A are either item specific special provisions or general special provisions that amend the appropriate specification for the tender item. There are other general special provisions listed in Chapter E of the CDED Manual that apply to the material specifications and to the Contract in general; these may be required in the Contract when warranted. Appendix A provides some guidelines for cases when a non-standard special provision is required against an item. Examples of non-standard special provisions are contained in Appendix B. The non-standard special provisions are given as samples and are not intended to be used verbatim. Appropriate job specific modifications should be made as required. Examples of non-standard special provisions for the removal and reinstallation of various structural components are contained in the Structural Steel Coating Manual, [6]. These special provisions may be applied to general rehabilitation work when removal and reinstallation of a component is required to carry out the rehabilitation. A non-standard special provision should always be prepared when clarification of Work under a tender item is required. A non-standard special provision applying to the Contract in general may be required to address: • • •

environmental requirements; public protection requirements; disconnection of power supply temporarily on cathodically protected bridges while arc welding is being carried out.

4. April, 2004

CONTRACT PREPARATION SCHEDULING AND REVIEW 3-5

The time taken to prepare Contract documents will vary with the complexity of the project. Table 4.1 provides a check list of those activities which must be completed, and indicates the approximate time required to complete each activity. The "Time" column allows for the activity to be incorporated into the Work schedule of the section involved but does not represent the actual time spent on the activity. Also some of the activities listed in the table can be carried out simultaneously; therefore, the time required to prepare the Contract may be less than the total time of all activities. The schedule is presented in a general format for information only; the procedure for scheduling and reviewing of Contract documents vary from Region to Region. The Bridge Office undertakes a detailed review of the Contract documents for cathodic protection and bridge coating Contracts. The remaining rehabilitation contracts are monitored and a detailed review is carried out if deemed necessary. A design check is also carried out on structures where safety and adequacy is a concern. After the original documents are revised incorporating the Regional technical review, they are submitted to the Contract Preparation and Control Section by the "Delivery Date" shown on the schedule of PreContract Engineering Clearance Dates.

April, 2004

3-6

Activity Condition Survey Select Rehabilitation Method Design Criteria Approval Engineering Profile Survey Traffic Staging, Approach, and Surface Treatment Recommendations Comments - External Agencies Structural Design Report (if required) Structural Design and Drawings Structural, Grading and Electrical Documents Assemble Tender Documents Submit Documents to Bridge Office and to Regional Offices Assemble all Replies Regional Technical Review and Revisions Regional Executive Review Submit Contract Documents to Contract Preparation and Control Section Printing and Advertisement Tender Opening and Award

Responsibility Regional Structural and Consultant Regional Structural and Consultant Project Manager Surveys and Plans and Consultant Regional Structural, Traffic, Geotechnical and Consultant Regional Structural and Project Manager Regional Structural and Consultant Regional Structural or Consultant Regional Structural, Planning & Design and Electrical and Consultant Project Manager Project Manager

Time 2 -6 months 4 weeks 6 - 8 weeks 2 -6 months 8 weeks

Contract Review Unit Regional Structural, Planning and Design and Consultant Project Manager Project Manager

2 weeks 6 weeks

Construction Office Construction Office

2 -3 months 2 weeks

Table 4.1 / Contract Preparation Scheduling

April, 2004

3-7

4 weeks 4 weeks 1 - 9 months 4 weeks 4 weeks 5 weeks

2 weeks 1 week

5.

REFERENCE PUBLICATIONS

5.1

Ministry Publications

1. 2. 3. 4. 5. 6.

Cathodic Protection Manual for Concrete Bridges, Manual SO-14 Contract Design Estimating and Documentation Manual Provincial Highways Directive B-147 "General Policies, Procedures and Responsibilities for Structures" Structural Manual Provincial Roads Directive C-86 "Small Quantity Tender Items" Structural Steel Coating Manual, 2004

April, 2004

3-8

APPENDIX 3A ESTIMATING QUANTITIES AND CONTRACT DOCUMENTATION

April, 2004

3A-1

A1

CONCRETE REMOVAL

1.1

General

For MTO projects, OPSS 928, May 1994 has been deleted in its entirety and replaced with the special provision SP109S49 in 2004. This section is divided into the following subsections depending on the type of concrete removal involved. 1.2 Scarifying 1.3 Partial Depth Removal 1.4 Full Depth Removal 1.5 Concrete Removal- Structural Component Concrete Removal- Complete Deck

1.2

Scarifying

1.2.1

General

Scarifying is required prior to the placement of a concrete overlay on bridge decks and sidewalks. Scarifying is done to remove surface concrete, which may be contaminated; and to provide a surface texture suitable for the application of the overlay. 1.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Scarifying [0928-0050]

m2

928

109S49

Always in conjunction with overlays.

This tender item may be used for the removal of scaled concrete from bridge decks provided that the extent of scaling is known and there is adequate cover to the reinforcing steel; otherwise the removal of scaled concrete shall be administered under the tender items for partial depth removal of concrete described in Subsection 1.3. The tender item is not to be used for the work of roughening of existing surfaces for the purpose of concrete refacing or for the uniform concrete removal of existing surfaces other than top surface of deck.

1.2.3 April, 2004

Special Provisions 3A-2

A non-standard special provision is required when: •

a concrete overlay is required for sidewalks and curbs and the work of scarifying is to be included under this item;

•

there is very low concrete cover to reinforcing steel and a concrete covermeter survey is required to identify areas with less than 15 mm cover to prevent damage to scarifying equipment and rebar. The Designer should modify SP109S49 to specify that the covermeter survey shall be done prior to the scarifying operation instead of after the first pass of the equipment.

1.2.4

Quantity Calculations

Scarifying quantities are computed from the Contract Drawings or field measurements. The calculation should be compared with areas given in the detailed deck condition survey report. The area of existing expansion joint end dams shall not be measured for payment. Quantities for scarifying are to the nearest square metre.

1.2.5

Contract Drawings

A note on the drawings shall be included to indicate the extent and required depth of scarifying. Where documentation of scarifying is complicated by the requirements that some locations require an extra depth of removal, the Contract Drawings should show the extent of these areas along with the required depth of removal for each area. The drawings should also have a note if the Designer wants to specify a lighter scarifier. The special provision limits the weight to 26 tonnes unless a lesser weight is shown on the Contract Drawings. 1.3

Partial Depth Removal

1.3.1

General

The partial depth removal of concrete applies to the removal of delaminated and unsound concrete, and concrete in areas of high corrosion potential. This removal is administered under special provision 109S49. Concrete removal over voids on post-tensioned round voided decks shall also be administered by the partial depth removal tender items, even though the full depth of concrete above the void may be removed. 1.3.2 Tender Items

April, 2004

3A-3

Item Description [CPS Code] Concrete Removal Partial Depth -Type A [0928-0060] [0928-0061]

Concrete Removal Partial Depth -Type B [0928-0065] [0928-0066] Concrete Removal Partial Depth -Type C [0928-0070] [0928-0071]

Unit

OPSS

Standard Special

Conditions For Use

928

109F10 109S49 928F01

Typically applies to the top surface of decks; including removals over round voids on post tensioned structures, the top and inside faces of concrete barrier walls and parapets walls, sidewalks, curbs and the floor slabs of culverts and tunnels

928

109F10 109S49

Typically applies to deck soffit and fascia of bridge decks; soffit of the top slab of culverts and tunnels; girders; diaphragms; outside face of concrete barrier walls and parapet walls.

928

109F10 109S49

Typically applies to abutments and wingwalls; pier columns and caps; bearing seat; retaining walls; vertical walls of culverts and tunnels. Type C also means concrete removals other than the ones specified for Concrete Removal – Partial Depth – Type A and Type B.

m3 m2

m3 m2

m3 m2

The partial depth concrete removal items should normally be paid by volume. At locations where a uniform depth of removal is required, the designer may choose to pay for the uniform removal by area; however, this does not apply to deck top surface. For partial depth removal from a thin deck, when a large surface area of deck is removed and the depth of removal is over 100 mm, the designer shall evaluate and ensure that the load carrying capacity of the deck remaining is adequate to sustain construction live loads and dead loads including superimposed dead loads of any wet overlays; otherwise, a full depth removal shall be considered. If the total volume of each type of partial depth removal in the bridge is less than 1.0 m3, the removal of concrete shall be administered under "Extra Work" procedures.

1.3.3

April, 2004

Special Provisions

3A-4

If there is the risk of punching through of the deck during Type A removal and concrete debris could fall onto live traffic below, a NSSP should be included in the Contract Documents to require traffic protection under the non-standard item, “Traffic protection”. A punching through may occur in existing thin decks when the existing condition reported from deck condition survey shows signs of deterioration at the soffit. A standard special provision should be completed to designate the components, usually the top surface of bridge decks, that require concrete removal based on half-cell potential criteria. As a guide, removal based on half-cell potentials is not required on the following components. • • • • • • •

components with epoxy coated reinforcing steel. components with concrete cover to reinforcing steel greater than 100mm; components that are to be cathodically protected; concrete/timber composite decks; substructure components that did not have half cell survey carried out as part of the condition survey; components where half-cell survey data in the condition survey is unreliable or is known to not accurately represent the condition of the deck. post-tensioned decks with circular voids.

Standard special provision 109F10 should be completed to indicate where the original structure drawings and the condition survey report are available for viewing during the tendering period. 1.3.4

Quantity Calculations

1.3.4.1

General

Concrete removal quantities are calculated from the data given in the condition survey report, field measurements and original structure drawings. The condition survey report should be updated if necessary to improve the accuracy of the estimate. 1.3.4.2

Adjustment Factors

When calculating quantities for concrete removal, the volume of concrete removed is increased by an adjustment factor for every year between the year of the condition survey and the year of construction to take into account any deterioration that takes place during that period. The type of adjustment factor used depends on whether concrete is to be removed by half-cell corrosion potential criteria and on whether or not the rebar is epoxy coated. Concrete Removal based on Corrosion Potential and Delamination Survey The adjustment factor for areas to be removed by half-cell potential shall be based on area of corrosion potential between –0.30 to –0.35 volts. As condition surveys should be updated if they are more than 4 years old, the area between –0.30 to –0.35 volts shall be averaged out for a 4year period. This averaged quantity shall then be multiplied by the number of years that the condition survey is out of date as described in Table A1-1.The area of delaminations shall be increased by 10 % per year. The adjusted areas shall then be increased by 10% to account for April, 2004

3A-5

variability of the half-cell survey, delaminations that are undetected by the cores and sawn samples and, squaring up of the areas for sawcutting. Concrete Removal Based on Delamination Survey Where removal of concrete is based on the sounding method only, the initial quantity is increased by 25% to take into account imminent delaminations in areas of sound concrete where corrosion potential is more negative than -0.35 volts. Additional removal of concrete due to corroded reinforcing steel beyond the delaminated area is also taken into account by this adjustment factor. Concrete removal based on delamination survey applies primarily to exposed concrete components, it is fairly easy to update the data for out of date condition surveys for most components. Therefore, the designer should update the tender quantity by carrying out an updated delamination survey prior to the preparation of contract quantities. If the update delamination survey is not practical due to poor access, an adjustment factor of 10% to 20% per year of the delaminated area of the component exposed to chlorides shall be applied to concrete components with uncoated reinforcing steel as per Table A1-2. For concrete with epoxy coated rebar, the volume of concrete removal is increased 10% per year as per Table A1-3. 1.3.4.3

Average Depth of Removal

The average cover to reinforcing steel and the diameter of the rebar is required to calculate the average depth of removal. The average cover should be determined from covermeter readings taken in the largest areas of removal. Concrete cover may also be determined from concrete cores provided that the Designer is reasonably confident that the cores have been taken through the upper layer of reinforcing steel in the top mat. If the covermeter readings or cores are unavailable and cover measurements cannot be taken in spalled areas, then the cover given in the original structure drawings may be used. The average rebar diameter should be determined from the original structure drawings. The reinforcement diameters in the top layer of the reinforcing steel in the largest areas of removal should be used in the calculation. For refacing or patch repairs of vertical faces and soffit without over-built, the depth of concrete removal shall be no less than 90 mm in order to minimize shrinkage, and the removal quantity shall be calculated accordingly.

1.3.4.4

Notations

The notations that represent or are used to calculate the areas and depths for different types of deterioration and the number of years between condition survey and construction are described April, 2004

3A-6

below. The values for these notations should be determined for each component before proceeding with calculations for concrete removal. ADLM area, m2, of delaminations and spalls outside the high corrosion potential areas. (include areas of very severe scaling where reinforcing steel will probably be exposed during concrete removal). In the case where concrete is removed based on delaminations survey only, ADLM is the area of delaminations and spalls over the entire surface AHCP

area, m2, of component with high corrosion potential readings more negative than -0.35 volts.

AACP

area, m2, of component with corrosion potential readings between –0.30 to -0.35 volts (this area to be used to calculate an adjustment factor for out of date half cell surveys).

ASCL

area, m2, of medium to severe scaling (exclude areas that will be removed by scarifier for concrete overlays or are included in ADLM and AHCP).

DAVG Average theoretical removal depth, for ADLM and AHCP in metres; calculated as follows: (i)

When average concrete cover is calculated from field measurements. DAVG [(average concrete cover, mm) + (average top bar diameter, mm) + (25 mm under top bar) – (8 mm scarifying, if applicable)] x 0.00l.

(ii)

When the concrete cover to the reinforcing steel is taken from original structure drawings. DAVG [(theoretical concrete cover, mm) + (average top bar diameter, mm) + (25 mm under top bar) – (8 mm scarifying, if applicable)] x 0.001.

n

the number of years between the latest condition survey and construction.

V

volume, m3, of concrete to be removed.

1.3.4.5

Calculations

For asphalt covered decks, the area ADLM can be determined from the table for defective cores and sawn samples contained in the Detailed Condition Survey Summary Sheet. Alternatively, for decks

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3A-7

where DART survey is available, the areas for ADLM can be determined from the surface deterioration surveys. For exposed concrete components, the areas for ADLM can be determined from the delamination surveys. Sound judgement has to be used in calculating quantities and, if necessary, additional investigation shall be carried out if insufficient number of samples are likely to result in a gross overestimate or underestimate of the quantity of removal. Also additional investigation should be carried out if there is a large discrepancy between the area of deterioration identified in the DART survey versus the area determined from cores and sawn samples. The procedure for calculating the volume of concrete removal for bridge deck surfaces and other concrete components is given in Tables A1-1 to A1-3. A separate calculation is required for each component.

Table A1-1:

Concrete Removal Based on Corrosion Potential and Delamination Surveys (Table shall not be used for cathodic protection rehabilitation)

Calculate ARBR, the area, m2, of concrete to be removed below rebar. * ARBR = {AHCP + (ADLM x 1.10 n) + (AACP ÷ 4) x n} x 1.10 V = (ARBR x DAVG) + (ASCL x 50 mm) * * * **

When removing concrete over the entire face of the component, ARBR shall not exceed the surface area of the component. The quantity calculation for ASCL is required for patching jobs only and not for overlay.

Table A1-2: Concrete Removal Based on Delamination Surveys Uncoated Reinforcing Steel

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Calculate ARBR, the area, m2, of concrete to be removed below rebar. * Pier Shafts, Abutments, deck top and soffit, and similar Components that are exposed to chloride with a lower rate of delaminations: ARBR = ADLM x 1.25 x 1.10 n Pier Columns, Pier caps, Barrier Walls and similar Components that are exposed to chloride with a higher rate of delamination: ARBR = ADLM x 1.25 x 1.20 n V = (ARBR x DAVG) + (ASCL x 50mm) * * * **

When removing concrete over the entire face of the component, ARBR shall not exceed the surface area of the component. The quantity calculation for ASCL is required for patching jobs only and not for overlay.

Table A1-3: Concrete Removal Based on Delamination Surveys Epoxy Coated Reinforcing Steel Calculate ARBR, the area, m2, of concrete to be removed below rebar.* ARBR = ADLM x 1.25 x 1.1n V = (ARBR x DAVG) + (ASCL x 50mm) * * * **

When removing concrete over the entire face of the component, ARBR shall not exceed the surface area of the component. The quantity calculation for ASCL is required for patching jobs only and not for overlay.

The quantities calculated in Tables A1-1 to A1-3 are combined under the separate tender items as described below and in Subsection 1.3.2. Quantities for concrete removal are to the nearest 0.1 m3. (a)

Concrete Removal Type A:

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Calculate VA , the volume, m3, of concrete to be removed from: the deck surface (VDK), sidewalks (VSW ), curbs (VCRB) and front face of barrier walls and parapet walls (VFBW ) VA = VDK + VSW + VCRB + VFBW (b)

Concrete Removal Type B: Calculate VB, the volume, m3, of concrete to be removed from the deck soffit (VDS), beams, girders and diaphragms (VBM), back face of barrier walls and parapet walls (VBBW) and the underside of other components. VB = VDS + VBM + VBBW

(c)

Concrete Removal Type C: Calculate VC, the volume, m3, of concrete to be removed from the structure excluding the quantities for concrete removal Types A and B. VC = (VC1 + VC2 ... + VCN ) where each number represents a different component.

1.3.5

Contract Drawings

The typical locations of the deterioration should be shown on the contract drawings especially for areas where access to work area is a consideration. The areas of concrete removal should be the areas calculated using Tables A1 to Table A3 and not the area given in the condition survey report. Drawings shall indicate that the perimeter of the removal area shall be saw cut. Sawcutting is required where the method of concrete repair is by concrete patches only without an application of concrete overlay or refacing. No sawcutting is required if the concrete surface is to receive concrete overlay, refacing. SP109S49 covers removal requirements for scaled areas; therefore, additional details are not required to be shown on the Contract Drawings. For refacing or patch repairs of vertical faces and soffit without over-built, the Contract Drawings should show the depth of concrete removal not less than 90 mm in order to minimize shrinkage, and the removal quantity shall be calculated accordingly. The depth and extent of removal may affect the behaviour of the structure if the concrete is removed in one operation. Where this is a concern, the contract drawings should indicate that these areas should be repaired in stages or requirements for a temporary support during removal should be specified in the contract. April, 2004

3A-10

Any precautions to be taken for concrete removal around prestressing cables should also be noted on the drawings. The Contract Drawings shall indicate areas where traffic protection is required for concrete removal over live traffic.

1.4

Full Depth Removal

1.4.1

General

The full depth removal of concrete is defined as the partial or complete removal of a concrete component and may include components other than concrete. The partial depth removal of delaminated and unsound concrete and concrete in areas of high corrosion potential should be administered by the items in Subsection 1.3.

1.4.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Concrete Removal - Full Depth [0928-0078]

L.S.

928

109S49

This item typically refers to full or partial length removals of entire thickness of curbs, sidewalks,

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3A-11

medians, wingwalls, barrier walls, parapet walls, ballast walls and approach slabs including removal of elements other than concrete. Concrete Removal - Full Depth [0928-0075]

m3

928

109S49

This item typically refers to localized removals extending the full thickness of thin slab decks and culverts. when final dimensions of removal are to be determined during construction.

Concrete Removal - Deck Joint Assemblies [0928-0085]

L.S.

928

109S49

Removal of existing joint assemblies including concrete to create blockout.

1.4.3

Special Provisions

A non-standard special provision is required to: • • • • •

include the “Scope” of the work to identify components or portions of components to be removed under the "Concrete Removal - Full Depth" item; include minor excavation and/or backfill with the lump sum items; clarify requirements for salvage of any materials; include roughening of the surface if there is full depth removal by sawcutting; include the removal of existing expanded polystyrene in joint gaps if this material extends within 300 mm below the limits of removal or if the limits of removal beyond 300 mm are known, include this removal under the item, “Concrete Removal - Deck Joint Assemblies”.

1.4.4

Calculating Quantities

The main sources of information are the original structure drawings, the detailed condition survey report and field notebooks. For full depth removal of localized areas of thin decks, the designer shall review both the detailed soffit condition survey and the deck top condition survey to estimate the areas of overlaps, and to locate the full depth removals. If the detailed soffit condition survey is not available, the designer shall access the condition of soffit based on visual soffit survey. When the measurement for payment is by m3, the computation for concrete removal will be made from field measurements, concrete cores and dimensions shown on original structure drawings. The quantities for concrete removal are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. April, 2004

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1.4.5

Contract Drawings

The Contract Drawings should show: • • • • • • • • •

removal details; location and extent of the full depth removal; where necessary, layout and description of concrete removal sequences and temporary supports; components to be removed under concrete removals – structural component; location of sawcuts; treatment of existing reinforcing steel; excavation required to facilitate removal; type of backfill; any utilities that may restrict the removal operation.

The Contract Drawings should indicate a sawcut along the perimeter of the removal when a neat joint is required on surfaces that will be exposed and to provide close control on the extent of removal. Wherever old curbs and sidewalks are removed full depth, the condition of existing concrete underneath may not be acceptable for waterproofing directly. Hence, the surface needs to be treated and likely would require concrete overlay over the entire area. When removing concrete from thin deck slabs for the purpose of joint modification, the thickness of the concrete to remain at the bottom of the blockout should be at least 75 mm. Concrete less than 75 mm thick at the bottom of the blockout should be designated for removal as it would be difficult to keep this concrete intact during the concrete removal operation and this remaining concrete may not always be adequate for "formwork". Any precautions to be taken for the removal of concrete around prestressed cables and anchorages should be noted on the drawings. The Contract Drawings should show the limit of removal of existing expanded polystyrene below the limit of removal of the deck joint assembly. 1.5

Concrete Removal- Structural Component Concrete Removal-Complete Deck

1.5.1

General

These items are different than the Concrete Removal- Full Depth item because they require consideration of structural adequacy, stability and integrity of component adjacent to the removals, which are removed in full or partial length of entire thickness. Working drawings showing loading conditions for removal of these components are required to be submitted according to SP 109S49. April, 2004

3A-13

1.5.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Concrete Removal - Structural Component [0928-0090]

L.S.

928

109S49

The concrete removals that typically apply to full or partial length removals of entire thickness of decks, girders, diaphragms, pier columns and caps which have an impact on the structural adequacy, stability and integrity of a structure.

L.S.

928

109S49

Concrete Removal - Complete Deck [0928-0080]

1.5.3

Replacement of the entire bridge deck including removal of components other than concrete.

Special Provisions

A non-standard special provision is required to: • • • • •

include the “Scope” of the work to identify components or portions of components to be removed under the “Concrete Removal - Structural Component” item; and “Concrete removal- Complete Deck” item; include minor excavation and/or backfill with the lump sum items; clarify requirements for salvage of any materials; include roughening of the surface if there is full depth removal by sawcutting;

1.5.4

Calculating Quantities

The main sources of information are the original structure drawings, the detailed condition survey report and field notebooks. The quantities are calculated for estimating purposes only; therefore, they should not be shown on the quantity sheet of the Contract Drawings.

1.5.5

Contract Drawings

The Contract Drawings should show:

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• • • • • • • • •

removal details; location and extent of the full depth removal; where necessary, layout and description of concrete removal sequences, temporary supports and loading restrictions on adjacent structural components; components to be removed under concrete removals – structural component; location of sawcuts; treatment of existing reinforcing steel; excavation required to facilitate removal; type of backfill; any utilities that may restrict the removal operation.

The Contract Drawings should indicate a sawcut along the perimeter of the removal when a neat joint is required on surfaces that will be exposed and to provide close control on the extent of removal. Any precautions to be taken for the removal of concrete around prestressed cables and anchorages should be noted on the drawings.

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A2

STRUCTURE REMOVAL AND MISCELLANEOUS REMOVAL

1.1

General

This section covers the complete removal of structures. The removal and reinstallation of appurtenances such as barrier rails to facilitate rehabilitation of a component are also covered. It should not be used for partial removal of structure or structural components where concrete removal needs to be controlled to prevent damage to structural components to remain. The removal of waterproofing from concrete surfaces is a Planning and Design item and is covered under Appendix A22.

2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Removal of Bridge Structure [0510-9010]

L.S.

510

109F10

Removal of Bridge Footings [0510-9015]

m3

510

109F10

Removal and Reinstallation of Appurtances [0510-9075]

L.S.

510

109F10

Removal and Reinstallation of Steel Handrails [0510-9055]

L.S.

510

109F10

Removal and Reinstallation of Diaphrams [0510-9065]

L.S.

510

109F10

Removal and Reinstallation of Railway Blast Deflection Plates [0510-9070]

L.S.

510

109F10

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Conditions For Use When entire structure is to be removed.

Item Description [CPS Code] Removal of Appurtances [0510-9080]

Unit

OPSS

L.S.

510

Standard Special 109F10

Removal of Sign Support Structure [0510-9035]

Each

510

109F10

Removal of Temporary Modular Bridge [0510-9183]

L.S.

510

109F10

Removal of Temporary Modular Bridge Substructures [0510-9184]

L.S.

510

109F10

2.3

Conditions For Use

Special Provisions

A non-standard special provision is required for miscellaneous removals to: • • •

identify appurtenances to be removed and reinstalled; identify parts for disposal and new parts that may be required; describe procedure for removal and reinstallation.

2.5

Contract Drawings

The appurtenances requiring removal and reinstallation should be identified on the Contract Drawings; the metric size and length of new bolts, nuts and spacers should be listed.

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A3

ABRASIVE BLAST CLEANING

3.1

General

This section applies to the requirements for abrasive blast cleaning concrete surfaces for concrete overlays and abrasive blast cleaning of all exposed reinforcing steel for the different rehabilitation treatments. The cost of abrasive blast cleaning concrete surfaces for those concrete removal areas where the removal is only to sound concrete and does not expose any reinforcing steel, is included with the concrete placement items. For other concrete patch repairs where the reinforcing steel is exposed, a separate tender item, “Abrasive blast cleaning of reinforcing steel” is required. However, a separate tender item for abrasive blast cleaning of concrete surfaces is not required since concrete surface is blast cleaned at the same time as exposed reinforcing steel in the patches and paid under an item, “Abrasive blast cleaning of reinforcing steel”. Abrasive blast cleaning of concrete surface prior to concrete refacing is paid under the item, “Concrete Refacing”. All existing epoxy coated reinforcing steel that is exposed during concrete removal is also required to be abrasive blast cleaned to remove the epoxy coating; however, new epoxy coated reinforcing steel just placed in the vicinity of the abrasive blast cleaning operations should be protected from damage.

3.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Abrasive Blast Cleaning of Reinforcing Steel [0929-0030]

m2

929

929S01

Applies to all exposed reinforcing steel to be patched, refaced or overlayed by treatments administered under OPSS 904, 920, 930 and 931.

Abrasive Blast Cleaning for Overlays [0929-0040]

L.S.

929

3.3 April, 2004

Applies to bridge decks receiving concrete overlay treatment.

Quantity Calculations 3A-18

The area of exposed reinforcing steel on the bridge requiring abrasive blast cleaning is ARBR as determined in the calculations for concrete removal described in Tables A1-1 and Table A1-2 of Appendix A1. Areas of existing exposed reinforcing steel in areas for the purpose of deck widening and expansion joint block-outs can also be included with this item. The quantities for the different components are combined and the total area is rounded off to the nearest square metre.

3.4

Contract Drawings

On projects where epoxy coatings are to be removed from epoxy coated rebars, the designer shall specify on the Contract Drawings the components where this is required. The contract drawings should show typical locations of repair areas. The original structure drawings and condition survey report should be made available for viewing, if available, during the tendering period.

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A4

CONCRETE PLACEMENT

4.1

General

This section applies to placement of concrete in structure components when the concrete and the reinforcement of the component is to be partially or completely replaced. When the existing reinforcing steel is to remain intact, the patching of this component is normally administered under the tender items in Appendix A7.

4.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Concrete in Structure [904-0075]

L.S.

904

904 S11 929S01

Concrete in Deck [0904-0105]

L.S.

904

904 S11 904 S12 929S01

Concrete in Substructure [0904-0085]

L.S.

904

904 S10 904 S11 929S01

Concrete in Approach Slabs [0904-0135]

L.S.

904

904 S11

Concrete in Barrier Walls [0904-0115]

L.S.

904

904 S11 999 S03 929S01 109 S37

Concrete in Parapet Walls [0904-0125]

L.S.

904

904 S11 929S01 109 S37

The work under the above tender items includes the following: • • •

construction of formwork and falsework; abrasive blast cleaning of existing concrete surfaces; the supplying, placing and curing of concrete.

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Conditions For Use

The placement of new reinforcing steel may be included with the above tender items when a small quantity is involved. The abrasive blast cleaning of reinforcing steel may be included with the above tender items when there is no separate tender item for abrasive blast cleaning of reinforcing steel. 4.3

Special Provisions

SP929S01 is to be included in the Contract if existing epoxy coated reinforcing steel is required to be abrasive blast cleaned. A non-standard special provision is required if the abrasive blast cleaning of reinforcing steel is to be included with the above tender item. The designer should refer to the Contract Design Estimating and Documentation Manual for special provisions series that apply to concrete materials.

4.4

Quantity Calculations

The volume of concrete should be calculated from the information on the contract drawings for estimating purpose and need not be shown on the Quantities - Structure sheet. 4.5

Contract Drawings

4.5.1

General

The Contract Drawings should indicate the limits and details of new construction. The type of bonding agent required for construction joints should be specified in the Contract Drawings if it is not covered by the specifications. The drawings should specify superplasticized concrete for areas congested with reinforcing steel and for areas of limited accessibility. The drawings should be reviewed to ensure that sufficient access has been provided to install formwork, place concrete and backfill material. Standard drawing OPSD 4670.000 for construction joint details, contained in the Structural Manual, should be included with the Contract Drawings as appropriate.

4.5.2

Concrete Barrier Wall and Parapet Wall

Standard drawings SS110-54 and SS110-61 for the design of barrier walls and, SS110-56 and SS110-57 for the design of parapet walls using stainless steel reinforcing are contained in the Structural Manual.

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The standard drawings may require modifications to show the following: • • •

anchorage details when the barrier wall/parapet is to be anchored to the existing concrete; details for closing off ends of the barrier/parapet wall or details of concrete slope at back of barrier/parapet wall when a wide ledge exists, [to discourage people from sitting on ledge]; details of drainage when a wide ledge is to be left behind the barrier /parapet wall.

Standard drawing OPSD-4010 that applies to guide rail and channel anchorages for concrete barrier/parapet wall end treatments should be listed in the drawing section of the D4 tender form. The construction notes should indicate that the construction of new barrier/parapet walls should be carried out prior to the placement of the concrete overlay. 4.5.3

Approach Slabs

Standard drawings SS 116-1 for the design of the approach slabs are contained in the Structural Manual. The standard drawings may require modifications to show anchorage details to the abutment. Elevations at all corners of the approach slab should also be shown. 4.5.4

Bridge Decks

Standard drawing OPSD-3922 and OPSD-3923 for supporting reinforcing steel should be listed under the drawings section in the D4 Tender Forms when the bridge deck is to be replaced. The deck slab constructed over precast beams laid side by side shall be 150 mm thick and reinforced with one layer of 15M @ 300 mm spacings each way.

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A5

CONCRETE OVERLAYS

5.1

General

This section applies to the placing, finishing, texturing and curing of latex modified, silica fume and normal slump concrete overlays. For MTO projects, OPSS 930, May 1994 has been deleted in its entirety and replaced with the special provision SP109S50 in 2004. However, due to specific material and quality control requirements for latex modified overlay, a separate special provision has been developed to administer latex modified concrete overlays.

5.2

Tender Items

Item Description [CPS Code] Place Concrete Overlay [0930-0065]

Unit

OPSS

m3

930

Standard Special 109S50

Place Silica Fume Concrete Overlay [0930-0070]

m3

930

109S50

Use when silica fume concrete is used for the overlay.

Finish and Cure Concrete Overlay [0930-0095]

L.S.

930

109S50

Use when normal concrete is used for the overlay.

Finish and Cure Silica Fume Concrete Overlay [0930-0100]

L.S.

930

109S50

Use when silica fume concrete is used for the overlay.

Place Latex Modified Concrete Overlay [0999-0XXX]

m3

N/A

[999SXX]

Use when latex modified concrete is used for the overlay.

L.S.

N/A

[999SXX]

Use when latex modified concrete is used for the overlay.

Finish and Cure Latex Modified Concrete Overlay [0999-0XXX]

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Conditions For Use Use when normal concrete is used for the overlay.

The placing of concrete in the areas of patch removal shall normally be included with the concrete overlay item. When there is extensive full depth removals or when a continuous anode mesh cathodic protection system is used, the placement of concrete in the removal areas would have to be completed prior to the overlay. A separate tender item for placement of concrete in the removal areas described in Appendix A4 and A7 should be used accordingly. 5.3

Special Provisions

A special provision 109S50 is always required with OPSS 930 for normal and silica fume concrete overlays. A special provision 999SXX is required for latex modified concrete overlay item when it is specified in the Contract Documents, Concrete Section is currently developing this special provision. The designer should refer to the Contract Design Estimating and Documentation Manual for special provisions, in the 113 series, that apply to concrete materials. 5.4

Quantity Calculations

Quantity of concrete overlay required is determined from concrete removal calculations and information given on Contract Drawings. The volume of concrete overlay required is calculated as follows. Review calculations for concrete removal described in Tables A1-1 to A1-3 of Appendix A1 to determine volume of concrete removal, VDK, m3, for the deck. Estimate VO the total volume, m3, of concrete overlay. VO = 1.2 (0.001 h A) + VDK Where A = Area of overlay in m2 h = Nominal thickness, mm, of overlay from the scarified surface. The volume of concrete overlay is increased by 20% to allow for corrections to the grade and to eliminate drainage deficiencies. When the existing crossfall is to be revised, the quantities should be increased accordingly. When the existing elevations of the deck are known, the screed elevations should be calculated and the volumes should be calculated using the end area method. The quantities for concrete overlay are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3.

5.5 April, 2004

Contract Drawings 3A-24

Contract Drawings should show the overlay thickness from the scarified surface and the limits of the concrete overlay in plan and cross section. Normally, the nominal thickness of normal and silica fume concrete overlay is 60mm and latex concrete overlay is 50 mm. Any geometric conditions which may affect the contractor's operations, choice of equipment, or number of placing operations shall also be detailed. Screed elevations should be calculated and shown on contract drawings when existing elevations of concrete surface are known. On asphalt wearing surfaces, screed elevations may be calculated from elevations of the top of asphalt and thickness of asphalt at the grid points; provided that the depth of asphalt at grid points in the detailed condition survey reasonably agrees with depths of asphalt for cores and sawn samples. If the depth of the concrete overlay is greater than 125 mm, the concrete overlay shall be reinforced as per Ministry’s corrosion protection policy. Where the final profile of the wearing surface is higher or lower than the existing approaches to the structure, the treatment required for approaches shall be detailed on the drawings by the Planning and Design Section.

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A6

CONCRETE REFACING CONCRETE REFACING, FORM AND PUMP

6.1

General

This section applies to refacing or encasing of concrete components for vertical and some overhead applications. For MTO projects, OPSS 930, May 1994 has been deleted in its entirety and replaced with the special provision SP109S50 in 2004.

6.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Concrete Refacing [0930-0125]

m3

930

109S50

Applies where concrete components are encased generally vertically.

Concrete Refacing, Form and Pump [0930-0130]

m3

930

109S50

Applies where concrete components are encased in overhead and vertical applications

The placing of concrete in the areas of patch removal shall normally be included with the concrete refacing items. The abrasive blast cleaning of existing concrete surfaces is also included with the above items. 6.3

Quantity Calculations

The quantity of concrete required is determined from concrete removal calculations and information given on Contract Drawings and is calculated as follows: Review calculations for concrete removal described in Tables A1-1 to A1-3 of Appendix A1 to determine the volume of concrete removal, VC, m3, for the component. Estimate VT, the total volume, m3 of the concrete refacing. VT = 1.2 (A x D) + VC where A = the area of refacing D = nominal thickness of refacing The quantities for concrete refacing are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. 6.4 Contract Drawings April, 2004

3A-26

Contract Drawings should show the following details: • • • •

thickness and limits of the refacing; indicate if superplasticizer is required; location of the work; details of the reinforcing steel or wire mesh.

A7 April, 2004

PATCHING OF CONCRETE COMPONENTS 3A-27

7.1

General

For MTO projects, OPSS 930, May 1994 has been deleted in its entirety and replaced with the special provision SP109S50 in 2004. This section applies to the patching of concrete surfaces in the areas of partial depth concrete removal. The section is divided into the following subsections based on the type of material used to fill the void: 7.2 7.3 7.4 7.5

Concrete Shotcrete Concrete Patches- Form and Pump Proprietary Products

7.2

Concrete

7.2.1

General

Concrete is usually the most economical patch material and is compatible with the concrete structure. It is suitable for horizontal and vertical repairs. 7.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Concrete Patches Unformed Surface [0930-0135]

m3

930

109S50

Applies to concrete patches to top surfaces of decks, sidewalks and curbs where no formwork is required. For thin decks, the designer shall verify that the concrete remaining after the removal is structurally adequate to sustain dead loads of wet concrete if it is used as temporary formwork.

Concrete Patches Formed Surface [0930-0145]

m3

930

109S50

Applies to concrete patches where at least one face of the patch requires formwork, including area over circular voids of posttensioned deck when punching through to the void occurs. (See note below).

For post-tensioned deck with circular voids where a reasonable probability of punching through exists, the designer should proportion the quantity of concrete that would require fomwork for placing of concrete.

April, 2004

3A-28

The placing of concrete in deck patches is usually included with the concrete overlay item, if an overlay item is specified in the Contract Documents. If a continuous anode mesh system of cathodic protection is specified in the contract or if the patch turns out to be a full depth, the volume for concrete in patches and in full depth is covered under concrete patches item. The abrasive blast cleaning of existing concrete surfaces is included with the above item. 7.2.3

Special Provisions

SP 109S50 allows the Contractor the option to use proprietary patching product instead of normal concrete in areas where the greatest dimension, of the width and length, is less than 300 mm and therefore, the contractor may submit a proposal to use a proprietary product. SP 109S50 does not cover the requirements for proprietary product and as such there is no tender item. However, if a designer chooses to use proprietary product for specific project, reference should be made to Section 7.5 for proprietary product. 7.2.4

Calculating Quantities

7.2.4.1

Concrete Patches - Unformed Surface

Review calculations for partial depth concrete removal described in Tables A1-1 to A1-3 of Appendix A1 to determine the volume VDK, VSW , and VCRB in m3, of concrete to be removed from the surface of the deck, sidewalk and curb. Calculate VT, the total volume, m3, of concrete required to patch the deck including sidewalks and curbs. VT = VDK + VSWK + VCRB The quantities for concrete patches are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. 7.2.4.2

Concrete Patches - Formed Surface

Review data used to determine concrete removal quantities for components that are to be patched with normal concrete requiring formwork. The item may include full depth deck patches where formwork is required. The calculations for concrete removal are described in Tables A1-1 to A1-3 of Appendix A1; calculations should also include concrete to patch areas where concrete is removed full depth. Determine AR, the area, m2, and DAVG, the depth in metres, for each component that is to be repaired with normal concrete. Adjust the value for DAVG, if necessary, to ensure 50 mm cover is achieved. Calculate VT, the total volume, m3, of concrete required for concrete patches - formed surface.

April, 2004

3A-29

VT = AR1 x DAVG1 + AR2 x DAVG2 + ..... + ARN x DAVGN Where each number represents a different component to be repaired with concrete. The quantities for concrete patches shall be given separately on the contract drawings for each component and shall be combined into one total for the tender item "Concrete Patches - Formed Surface". The quantities for concrete patches are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. 7.2.5

Contract Drawings

The Contract Drawings should show the treatment over voids if it is suspected that the voids may be exposed during concrete removal on post-tensioned round voided decks. The slab over the voids should be reconstructed to a minimum depth of 150 mm by partially forming into the voids. The drawings should identify the reinforcing steel that may be cut and replaced with new steel to facilitate placement of the formwork inside the voids. The main reinforcing steel that would affect the behaviour of the structure should not be cut for this purpose. The Contract Drawings should show the typical locations of the repairs with concrete patches for soffit, fascia, substructure work and barrier walls so that the bidder can determine the access, and formwork and falsework requirements. A typical repair detail should be shown on the drawings when the final surface of the patch differs from the original lines of the structure. It is the Contractor’s option under SP109S50 to use superplasticizer for concrete patches. However, if the Designer sees the need to use of superplasticized concrete for certain areas that are congested with reinforcing steel or with poor access for placing of concrete; such areas should be identified on the Contract Drawings.

7.3

Shotcrete

7.3.1

General

Shotcrete should be used mainly for repairs to overhead concrete surfaces where the total quantity of repairs is more than 1.0 m3. Repairs to vertical surfaces should normally be made with normal concrete. However, shotcrete could be considered where the concrete surface is difficult to form. When specifying shotcrete as the repair material, the Designer should make sure that all areas of repair could be made accessible for proper application of the shotcrete. Areas that are congested with reinforcing steel may require patching with form and pump concrete. 7.3.2

Tender Items

Item Description April, 2004

Unit

OPSS

Standard 3A-30

Conditions For Use

[CPS Code]

Special

Silica Fume Shotcrete [0931-0030]

m3

931

Normal Shotcrete [0931-0015]

m3

931

Normally always used. It requires continual access to the area of repair for 4 days for wet curing. NSSP

Used in conjunction with cathodic protection only or where full concrete curing could not be provided because of lack of continual access or need to minimize interruption to traffic. However, normal shotcrete would require longer time to apply in multiple layers.

The abrasive blast cleaning of existing concrete surfaces is included with the above items. 7.3.3

Quantity Calculations

Review data used to determine concrete removal quantities for components that are to be repaired with shotcrete. The calculations for concrete removal are described in Tables A1-1 to A1-3 of Appendix A1. a)

Determine AR and ASCL, the area, m2, of concrete to be removed for each component to be repaired with shotcrete.

b)

Determine DAVG, the depth of removal in metres for each AR. Adjust the value for DAVG, if necessary, to ensure that 50 mm cover is achieved.

c)

Calculate VSCL, the volume, m3, of shotcrete required to repair scaled areas. VSCL = (ASCL1 + ASCL2 + ........ ASCLN) x 0.050

d)

Calculate VT, the volume, m3, of shotcrete required for all repairs. VT = VSCL + [(AR1 x DAVG1) + (AR2 x DAVG2) + .... ARN x DAVGN)] where each number represents a different component to be repaired with shotcrete.

The quantities for shotcrete are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. 7.3.4

Contract Drawings

The Contract Drawings should show the typical location of repair areas with shotcrete. If the soffit and substructure repairs involve a combination of concrete and shotcrete patching, a typical April, 2004

3A-31

detail for the concrete patch should be shown on the drawing to clarify the Designer's intent. Sawcutting the perimeter of the demarcated removal area is not permitted for shotcrete patching.

7.4

Concrete Patches- Form and Pump

7.4.1

General

Concrete Patches- Form and Pump is recommended for areas where shotcrete is not practical due to restricted access and areas congested with reinforcing steel. Concrete Patches- Form and Pump should also be considered in lieu of shotcrete for deep repair areas (depth of repair r extends more than 60 mm behind galvanized mesh). 7.4.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Concrete PatchesForm and Pump [0930-0150]

m3

930

109S50

areas where shotcrete is not practical due to restricted access, areas congested with reinforcing steel and for deep repair areas (depth of repair extends more than 60 mm behind galvanized mesh).

The abrasive blast cleaning of existing concrete surfaces is included with the above item. 7.4.3

Quantity Calculations

Review data used to determine concrete removal quantities for components that are to be repaired with Concrete patches- Form and Pump method. The calculations for concrete removal are described in Tables A1-1 to A1-3 of Appendix A1. Determine AR, the area, m2, and DAVG, the depth in metres, for each component that is to be repaired with Concrete Patches- Form and Pump.

Adjust the value for DAVG, if necessary, to ensure 50 mm cover is achieved. Calculate VT, the volume, m3, of concrete required for Concrete Patches- Form and Pump. VT = AR1 x DAVG1 + AR2 x DAVG2 + ..... + ARN x DAVGN Where each number represents a different component to be repaired with Concrete Patches- Form and Pump. The quantities for concrete are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. April, 2004

3A-32

7.4.4

Contract Drawings

The drawings should show the typical locations of repair areas with Concrete Patches- Form and Pump.

7.5

Proprietary Products

7.5.1

General

Proprietary products could be considered when: • • • •

shotcrete and concrete cannot be placed due to poor access and placing formwork is a problem; high early strength is required for bridge deck surfaces; areas to be patched consist of small, numerous and randomly distributed where it is not practical to place formwork; where the greatest dimension of the width and length shall be less than 300 mm; the quantities of removal of concrete are less than 1.0 m3.

7.5.2

Special Provisions

When the option of using the proprietary products is exercised by the Designer, the special provision SP999S10 should be used to cover the requirement of the work. Also, a non-standard special provision is required to identify the patching areas, proprietary product and the names of the manufacturers of the proprietary product. Avoid identification of a single source or specific proprietary products in the contract documents. Only products approved by the Concrete Section should be used. The Designer should obtain such a list from the Concrete Section.

7.5.3

Tender Items

A non-standard tender item #0999-9051 for “Concrete Patches – Proprietary Product” should be used. Where self-levelling material is required beneath bearings, this should be included with the item for bearing repairs. 7.5.4

Quantity Calculations

The quantities for concrete proprietary products are to be calculated to the nearest 0.01 m3 and then shown on the quantity sheet to the nearest 0.1 m3. April, 2004

3A-33

April, 2004

3A-34

A8

CONCRETE CRACK REPAIR

8.1

General

This section is divided into the following subsections based on the repair methods to be used. 8.2 Routing and Sealing Cracks 8.3 Crack Injection The cause of cracking should be determined and eliminated as part of the rehabilitation.

8.2

Routing and Sealing Cracks

8.2.1

General

This subsection applies to the routing out and sealing of cracks with hot poured rubberized joint sealing compound and cold applied joint sealing compound. It does not apply to very wide cracks that are to be repaired using cement based grouts or concrete; this type of repair is considered to be a concrete patch. 8.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Routing and Sealing - Hot Poured Rubberized Joint Sealing Compound [0932-0020]

m

932

Routing and Sealing - Cold Applied Joint Sealing Compound [0932-0030]

m

April, 2004

932

Standard Special

Conditions For Use Used for horizontal surfaces that are to be waterproofed.

NSSP

3A-35

Used for horizontal surfaces that will not be waterproofed and for vertical applications.

8.2.3

Special Provisions

A non-standard special provision is required to specify the type of cold applied joint sealing compound to be used including the address and phone number of the Manufacturer(s), if not listed in the Designated Sources Manual. 8.2.4

Quantity Calculations

The total length of cracks is calculated from field note books and/or condition survey reports. If the cracks are still growing, the quantities should be increased by 15%. The quantities of crack repair are to be calculated to the nearest 0.1 m length and then shown on the quantity sheet to the nearest m. 8.2.5

Contract Drawings

If the condition survey does not adequately address the location and size of cracks, the Contract Drawings should show those details. When more than one material or method is used for crack repair, the contract drawings should clearly indicate which areas apply to each item.

8.3

Crack Injection

8.3.1

General

This section applies to filling of cracks full depth with epoxy resin or polyurethane by means of a positive displacement pump. 8.3.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Crack Injection [0932-0010]

m

932

NSSP

8.3.3

Conditions For Use

Special Provisions

A non-standard special provision is required to specify the type of material to be used including the address and phone number of the Manufacturer(s). 8.3.4

Quantity Calculations

The total length of cracks is calculated from field note books and/or condition survey reports. If the cracks are still growing, the quantities should be increased by 15%. April, 2004

3A-36

The quantities for crack repair are to be calculated to the nearest 0.1 m and then shown on the quantity sheet to the nearest m.

8.3.5

Contract Drawings

If the condition survey does not adequately address the location and size of cracks, Contract Drawings should be prepared showing these details. When more than one material or method is used for crack repair, Contract Drawings should clearly indicate which areas apply to each item.

April, 2004

3A-37

A9

CONCRETE SEALERS

9.1

General

This section applies to the sealing of concrete surfaces to prevent the penetration of de-icing salt. The Designer shall consult the Concrete Section for current list of acceptable products and shall specify appropriate product to be used in the Contract.

9.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Concrete Sealer [0999-9100]

m2

N/A

NSSP

9.3

Conditions For Use

Special Provisions

A non-standard special provision is required to address the following: • • • • • • •

type of sealers to be used and the address and the phone number of the manufacturer to be included. The approved list can be obtained from the Concrete Section; include provision of access if there is no separate tender item for access; requirements for surface preparation [light duty abrasive blast cleaning may be required]; temperature, drying times and application instructions as per Manufacturer's recommendations; environmental protection requirements; include disposal of debris and waste material; include measurement for payment and basis of payment clauses.

9.4

Quantity Calculations

The total area requiring treatment should be calculated from field note books, condition survey reports and original structure drawings. The quantities for concrete sealers are to be calculated to the nearest 0.1 m2 and then shown on the quantity sheet to the nearest m2. 9.5

Contract Drawings

The contract drawings shall identify the area of the structure requiring concrete surface sealing.

April, 2004

3A-38

A10

STEEL REINFORCEMENT

10.1

General

This section applies to reinforcing steel and mechanical rebar splices used in concrete construction. 10.2

Reinforcing Steel

10.2.1

General

New reinforcing steel is usually required when a concrete component is to be partially or completely replaced. 10.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Reinforcing Steel Bar [0905-0010]

L.S.

905

109S42

Coated Reinforcing Steel Bar [0905-0020]

L.S.

905

109S42

L.S.

N/A

905S04 109S42

Reinforcing Stainless Steel Bar [0905-0025]

Conditions For Use

Applies to splash zone and bridge decks of strategic highways as defined in, “Corrosion Protection Policy” contained in Structural Manual.

For reinforcing stainless steel, always use a separate tender item. Reinforcing steel and coated reinforcing steel are usually separate tender items. However, when the total quantity for both types of reinforcing steel for all work on the structure is less than 3 tonnes, then the steel quantity may be included with the applicable concrete placement item; and an NSSP would be required to include payment for reinforcing steel in the concrete placement item. The addresses and phone numbers of the Manufacturers of the reinforcing stainless steel are as listed in the Designated Sources Manual.

April, 2004

3A-39

10.2.3

Quantity Calculations

The quantity for reinforcing steel is calculated in kilograms and converted to tonnes. The procedure for calculating the quantities is described in the Structural Manual. The quantities are calculated for estimating purposes only; quantities are not shown in the Contract as the Contractor is responsible for preparing reinforcing steel schedule. 10.2.4

Contract Drawings

The location, size, cover and lap length of the reinforcing steel are to be shown on the Contract Drawings. A note on the drawing is required when field bending of reinforcing is allowed to facilitate stage construction. The general notes and detailing of the reinforcing should be according to the Structural Manual. 10.3

Mechanical Connections

10.3.1

General

Mechanical rebar splices may be specified when there is insufficient room to lap the reinforcing steel for staged construction. The use of mechanical rebar splices should also be considered for the following applications: • •

abutment reconstruction in stages when the requirements for roadway protection are to be minimized; for structure widening when it may be more economical to remove the edge of the existing deck by using large concrete saws.

Acceptable mechanical rebar splices are according to DSM for normal and coated mechanical connections. 10.3.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Mechanical Connections [0905-0030]

each

905

109S42

Coated Mechanical Connections [0905-0040]

each

905

109S42

April, 2004

3A-40

Conditions For Use

Item Description [CPS Code]

Unit

OPSS

Standard Special

Stainless Steel Mechanical Connections [0905-0045]

each

N/A

905S04 109S42

Conditions For Use

Currently, the DSM does not cover stainless steel mechanical connections. The designer should contact bridge office for specific products that can be used. (e.g. Lenton couplers can be used with threaded connections). 10.3.3

Special Provisions

A non-standard special provision is required to specify stainless steel mechanical connectors including the address and phone number of the Manufacturer, if not in the Designated Sources List. 10.3.4

Quantity Calculations

The number of mechanical connections required is determined from the structure drawings. 10.3.5

Contract Drawings

The locations and details of mechanical rebar splices should be shown on the contract drawings.

April, 2004

3A-41

A11

INSTALLATION OF DOWELS

11.1

General

This section applies to the installation of dowels into concrete components by drilling holes and grouting dowels in epoxy adhesive. Guidelines for the installation of the dowels and an evaluation of anchoring agents are contained in the Material Information Report, MI-120, "Evaluation of Pull-out Testing of Epoxy Coated Dowels in Concrete Using Grouts and Epoxies". The embedment lengths recommended in the report apply only to barrier walls and parapet walls that have a good quality concrete; the embedment length may have to be revised for other applications based on design load and pull-out test load of the dowels, and the manufacturer’s recommended bond strength. Only epoxy resins shall be used. 11.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Dowels into Concrete [0904-0165]

each

904

NSSP

Conditions For Use

The dowel bar material are usually with the reinforcing steel items. 11.3

Special Provisions

The drilling and grouting for dowels may be included with the concrete placement item by a nonstandard special provision when the quantity is small. A NSSP specifying a pull-out tests to be performed by the Contract Administrator is required; the designers should obtain the NSSP from the Concrete Section. 11.4

Calculating Quantities

The quantity is calculated from the drawings based on the number of dowels to be installed. 11.5

Contract Drawings

The diameter of the dowel bars, the type of anchoring agent, location, depth and diameter of holes required for the installation of dowels shall be shown on the Contract Drawings. The Designer is to ensure that the embedment length of dowels is adequate to sustain the design loads and dowel pull-test loads.

April, 2004

3A-42

A12

BARRIER WALL RAILING PARAPET WALL RAILING

12.1

General

This section applies to the metal railings that are used on barrier walls and parapet walls. 12.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Barrier Wall Railing [0908-0020]

m

908

Parapet Wall Railing [0908-0030]

m

908

12.3

Standard Special

Conditions For Use

Contract Drawings

The appropriate Standard Drawing contained in the Structural Manual should be completed and inserted in the Contract. Standard Drawing OPSD-4019.000 contained in the Ontario Provincial Standards Manual for Roads and Municipal Services, Volume 3 should be included with the list of standard drawings in the D4 Forms.

April, 2004

3A-43

A13

EMBEDDED WORK IN STRUCTURE

13.1

General

This section applies to the installation of ducts, junction boxes, anchorage assemblies and other similar materials that are embedded in the structure.

13.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Embedded Work in Structure - Ministry [0913-0010]

L.S.

913

Embedded Work in Structure - Bell Canada [0913-0020]

L.S.

913

Embedded Work in Structure - Utility [0913-0040]

L.S.

913

L.S.

913

Embedded Work in Structure- Utility-2 [0913-0050]

Standard Special

Conditions For Use

The Utility's name should be entered into the item description. The Highway Design Office should be requested to do this for each project as required. MTO lighting ducts, traffic signal ducts and FTMS ducts are included in one item. 13.3

Special Provisions

A non-standard special provision is required: • •

to include the installation of insert supports and associated hardware when ducts are suspended under the deck; to provide specific details for replacement of conduit expansion joints for existing ducts.

13.4 April, 2004

Contract Drawings 3A-44

13.4.1

General

Applicable details of the ducts, expansion joint treatment, etc, should be shown in the contract drawings. The details of the proposed work should be reviewed to ensure that the installation of the embedded work can be accommodated in the areas of congested reinforcing steel and at expansion joints. Appropriate OPSD and SS drawings should be included in the Contract. 13.4.2

Designer Action

The Designer is to consider the guidelines contained in the Appendix 913-A of OPSS 913 and provide information accordingly in the Contract Drawings. 13.4.3

Bell Canada

Material is supplied by Bell Canada and should be listed in the form, "Supplies by MTO to Contractor". Generally, MTO costs are recoverable from Bell. See Form - Recoverable. 13.4.4

Utility

The Contractor is responsible for the supply of materials. Generally, MTO costs are recoverable from the Utility. See Form - Recoverable.

April, 2004

3A-45

A14

EXPANSION JOINTS

14.1

General

This section is divided into two subsections to differentiate the requirements for installing Deck Joint Assemblies and repairs to existing deck joints.

14.2

Deck Joint Assemblies

14.2.1

General

This subsection applies to the installation of new deck joint assemblies anchored in concrete or elastomeric concrete and joint armouring welded to existing armouring. 14.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Deck Joint Assemblies, Installation [0920-0010]

L.S.

920

920S01 920S05 109S47 112S05

Used when expansion joints are installed on new structures.

Deck Joint Assemblies, Modification [0920-0020]

L.S.

920

920S01 920S05 929S01 109S47 112S05

Used when existing expansion joints are replaced for structure rehabilitation

The items include the preparation of the blockout and installation of the deck joint assembly. The placement of the concrete in the joint and modification or welding of reinforcing steel is also included in the work. When the removal of concrete for the joint involves quantities of less than 1 m3, the removal may be included with the deck joint assemblies - modification item. The removal of the existing deck joint assembly including the removal of concrete and reinforcing steel is usually included with concrete removal – deck joint assemblies tender item. 14.2.3

Special Provisions

A non-standard special provision is required to detail: • •

installation details for deck joint assemblies anchored in elastomeric concrete; refer to OPSS 928 for concrete removal if the minor removals are included with deck joint assemblies- modification item.

April, 2004

3A-46

•

deck joint assembly installation where the block-out method in OPSS 920 would not be used.

14.2.4

Contract Drawings

14.2.4.1

General

The following standard drawings along with the joint selection criteria for joints Type A, B and C are contained in the Structural Manual: The Standard Drawings with barrier walls: • SS113-10, SS113-12 and SS113-13 without drainage system and, • SS113-11, SS113-12, SS113-13 and SS113-14 with drainage system. The Standard Drawings with parapet walls: • SS113-15 without drainage system and, • SS113-16 with drainage system. The standard drawings SS113-20, SS113-21 and SS113-22 used for modular joint are also contained in the Structural Manual. The standard drawings require job specific information to be added by the Designer. The Contract Drawings should show the following when applicable: • • • • • • • • •

existing conditions; location of sawcuts; extent of concrete removal; reinforcing steel to be removed; modification to existing reinforcing steel; additional reinforcing steel and dowels; location of the ducts in curb areas and modifications required to accommodate the ducts; method of attachment to existing armouring; detail of EVA foam to seal parapet wall joint gap and longitudinal joint between decks, [EVA foam must be 25% wider than the joint gap].

For stage construction, the location of the splice in the expansion joint armouring should be 100 mm beyond the construction joint in the concrete. This provides sufficient clearance to properly carry out the splice. When the joint is to be welded to existing armouring and the wearing surface is a latex modified overlay, the drawing should specify a 40 mm maximum height for the preformed retainer. Where the joint is to be anchored in elastomeric concrete, the minimum dimensions of the blockout shall be as follows:

April, 2004

3A-47

• •

horizontal width shall be 150 mm from the back of the armouring on the deck side and full width of ballast wall on the abutment side; vertical clear cover shall be 25 mm under the armouring.

Elastomeric concrete must extend 150 mm up the curb face. The construction notes should specify that elastomeric concrete should be placed against asphalt and concrete, not the reverse. 14.2.4.2

Skewed Decks

On structures with a skew between 15º and 45º, the expansion joint anchorages should be welded to the armouring at a 30º skew on the deck side. For skews less than 15º or greater than 45º on the deck side, the expansion joint anchorages should be welded at right angles to the armouring. The joint anchorages should always be placed at right angles to the joint armouring on the abutment side. No adjustment is required to the longitudinal reinforcement of the deck for all structures with skews up to and including 45º. For structures with a skew greater than 45º, short bent bars shall be lapped with the deck reinforcing bars. 14.2.4.3

Narrow Ballast Walls

If the width of the existing ballast wall is at least 250 mm but less than 300 mm, the joint anchorage shown on the standard drawings should be modified to provide 50 mm concrete cover. If the width of the ballast wall is less then 250 mm and cannot be widened, the steel nosing that is used to protect the edge of the concrete end dam should be deleted to allow sufficient room to place the concrete. Alternatively, a joint anchored in elastomeric concrete should be considered. 14.2.4.4

Installing Deck Joint Assemblies After Paving

As a guideline, deck joints assemblies should not be installed after paving in the following cases: • • • •

when new joint extrusions will be welded to existing armouring; existing structures that will not be resurfaced; early completion time is required in the Contract; new structures with paving to be carried out in a future Contract.

The Designer should review the reinforcing details in the blockout areas to make sure that the reinforcing steel in the blockout does not interfere with the paving operation. The reinforcing steel in the blockout should be designed to allow for the placement of the steel in conjunction with the deck joint assembly. The number of epoxy coated bars or stainless steel bars placed prior to the installation of deck joint assembly should be minimized in blockout areas for new deck designs.

April, 2004

3A-48

14.3

Repairs to Existing Deck Joints

14.3.1

General

The replacement of existing preformed seals for armoured joints and installation of ethyl vinyl acetate (EVA) seals in longitudinal joints on existing bridges is covered in this subsection for repairs to existing deck joints.

14.3.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Repair of Existing Deck Joints [0920-0030]

L.S.

920

NSSP

Use for repair of existing armoured expansion joints including replacement of preformed seals and installation of EVA seals in longitudinal joints.

The removal of the existing preformed seal and any sawcutting and removal of concrete to create a recess to accommodate a new EVA seal for longitudinal joints is included with the item. The installation of EVA seals on new structures is included with the appropriate concrete placement item.

14.3.3

Special Provisions

A non-standard special provision is required to describe: • •

removal of the existing seal and describe any special preparation of the joint gap; any other repairs required for existing deck joint assemblies not covered by specifications.

14.3.4

Calculating Quantities

The length of the seal should be determined from contract drawings to the nearest metre. 14.3.5

Contract Drawings

The dimensions of the joint recess, the type of seal and the location of the field splices should be shown on the Contract Drawings. EVA foam must be 25% wider than the joint gap; the depth of the recess should allow for an increase in seal depth when it is compressed to fit the joint gap. If the EVA foam is expected to undergo April, 2004

3A-49

movement, adhesives should not be placed at the bottom of the recess to allow the seal to accommodate the movement of the joint; otherwise, the seal may crack due to stress concentrations.

April, 2004

3A-50

A15

BEARINGS

15.1

General

This section applies to replacement or repairs of existing bearings. Guidelines for bearing design and the requirements for welding shoe plates to steel girders are given in the Structural Manual. 15.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Bearings [0922-0010]

L.S.

922

922F01

Conditions For Use Used for replacement of existing bearings or installation on new structures.

The removal of existing bearings and minor concrete removal to predetermined dimensions can be included with the bearing item if there are no other removal items for the structure. Jacking, temporary supports and any strengthening of structural steel at bearing locations should usually be specified under separate tender items. (Refer to A18). 15.3

Special Provisions

Although OPSS 922 covers the requirements for bearing installation, a non-standard special provision may be required when replacing the bearings to include removals and other details not covered by the specifications. A non-standard special provision is required for bearing repairs to address the following when applicable: • • • • • • • • •

disassembly and modifications to existing bearings; fabricating new components and reassembly; preparation of existing surfaces; drilling and filling of holes for anchors; resetting of bearings; coating of bearing components; cleaning and greasing of existing roller bearings; other work as appropriate; basis of payment clause.

15.4 April, 2004

Contract Drawings 3A-51

The Contract Drawings should show the following when applicable: • • • • • • • •

existing conditions and new bearings; components to be replaced; surface preparation requirements; location of jacking points and jacking forces; sequence of construction; setting and levelling procedures; anchorage details; welding requirements.

When replacing existing bearings with elastomeric bearings, the bearing seats should be recast if necessary. Grout levelling pad is not permitted. If a grout levelling pad is required for mechanical bearings, the thickness of the grout shall be 12 ± 3 mm. If the depth of pad is greater than 15 mm, the bearing seats should always be recast with new concrete. The addresses and phone numbers of the Manufacturers of the non-shrink grout are as listed in the Designated Sources Manual.

April, 2004

3A-52

A16

CATHODIC PROTECTION

16.1

General

This section applies to the installation of the anodes and associated instrumentation for impressed current cathodic protection of bridge decks and substructure components. The more common tender items associated with the electrical work required for cathodic protection installations are also covered by this section. The Designer should refer to the Electrical Design Manual for the tender items that are associated with the installation of the AC power supply to the cathodic protection equipment cabinet. The design of cathodic protection system is described in the Cathodic Protection Manual for Concrete Bridges (Reference 1). OPSS 935 has never been implemented for Ministry’s Contracts; but in the past, the Ministry has used several special provisions to administer cathodic protection work. In year 2004, a standard special provision 999S27 has been developed to cover the items that previously were administered by individual special provisions for cathodic protection on bridge decks. 16.2

Tender Items

16.2.1

Conductive Bituminous Overlay System

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Anodes, Pancake Type [0999-9035]

each

999S19

Applies to bridge deck applications only.

Voltage Probes [0999-9036]

each

999S24

Applies to the conductive bituminous overlay system only.

The conductive bituminous overlay system is no longer used for new installations, however these tender items may be kept in Contract Preparation System (CPS) in case existing system is to be repaired. However, when this system is used for repairs in future, a non-standard special provision would be required to cover requirements for the items listed under sub-section 16.2.4. The placement of the conductive bituminous overlay is a Planning and Design tender item and is carried out under the tender item, "Electrically Conductive Mix”.

16.2.2 April, 2004

Continuous Anode Mesh System 3A-53

Item Description [CPS Code]

Unit

Anode Mesh [0999-9044]

OPSS

Standard Special

Conditions For Use

m2

999S27

This SP applies to bridge decks only. A NSSP is required for cathodic protection of substructure.

Anode Overcoat [9999- 0995]

m2

NSSP

Applies to substructure applications only.

Anode Overcoat Test Panels [9999- 0996]

L.S.

NSSP

Applies to substructure applications only.

For bridge deck installations, the anode mesh is embedded in a normal concrete overlay administered by OPSS 930 tender items.

16.2.3

Arc Sprayed Zinc System Item Description [CPS Code]

Unit

Anodes, ARC- sprayed Zinc Type [9999-9113]

m2

16.2.4

OPSS

Standard Special NSSP

Conditions For Use Applies to substructure applications only.

All Systems

Item Description [CPS Code]

Unit

OPSS

Standard Special

Cathode Connections [0999-9042]

each

999S27*

Reference Cells [0999-9043}

each

999S27*

L.S.

999S27*

Rigid Ducts and April, 2004

3A-54

Conditions For Use * This SP applies to bridge decks only. A NSSP is required for cathodic protection of substructure.

Used when conduits and junction boxes are either

Item Description [CPS Code] Junction Boxes for Cathodic Protection [0999-9030]

Unit

Extra Low Voltage Cables for Cathodic Protection [0999-9028]

L.S.

999S27*

Cathodic Protection Rectifiers [0999-9045]

L.S.

999S27*

Cathodic Protection Cabinets [0999-9037]

OPSS

Standard Special

Conditions For Use mounted on the surface of the structure and/or embedded in concrete in abutment, sidewalks and barrier walls.

999S27*

each

Concrtete Pads for Cathodic Protection [0999-9038]

each

999S27*

Cathodic Protection Remote Monitoring and Control Units [0999-9039]

L.S.

999S27*

Acceptance Testing for Cathodic Protection [0999-9040]

L.S.

999S27*

* For these items, the special provision 999S27 applies to bridge decks only. When substructure is cathodically protected, a NSSP is required to administer these items.

16.3

April, 2004

Contract Drawings

3A-55

The Contract Drawings should contain the following details: • • • • • • •

layout of zones and sub-zones; layout and details of installation of all hardware including routing for lead wires; treatment required at deck drains and joints; location of cathodic protection equipment cabinet; layout of rectifier and control panel in cathodic protection equipment cabinet; routing and size of conduit; location of power supply including size of hardware, ducts and wire.

Examples of the details required in Contract Drawings are contained in the Cathodic Protection Manual for Concrete Bridges, [Reference 1].

April, 2004

3A-56

A17

ACCESS TO WORK AREA

17.1

General

This section applies to access required to rehabilitate components of a structure.

17.2

Tender Item

Item Description [CPS Code]

Unit

OPSS

Standard Special

Access to Work Area, Work Platform and Scaffolding [0928-0055]

L.S.

928

SP

Conditions For Use

This item should be used when the access to work on the deck soffit or substructure involves a significant cost and the requirements for access are independent of the tender quantities involved. ie. if tender quantities increase or decrease, the requirements for access should still be the same. Conversely, if the cost of access is expected to fluctuate in direct proportion to the tender quantities of the various items involved, the cost of access should be included with those items.

17.3

Special Provisions

OPSS 928 is replaced in its entirety by a special provision in 2004. This special provision requires the Contractor to submit detailed working drawings for debris platforms, work platforms and access to work areas. 17.4

Contract Drawings

The general location of the work should be shown on the drawings so that the Contractor can estimate the cost of access requirements. When it is expected that the working platform will be supported from the structure, the contract drawings should indicate the maximum construction loads that may be imposed on the structure. It is normal practice not to show access details as the Contractor usually has his own approach based on his equipment and method of operation.

April, 2004

3A-57

A18

TEMPORARY SUPPORT AND JACKING

18.1

General

This section is divided into the following subsections: 18.2 Temporary Support 18.3 Jacking 18.2

Temporary Support

18.2.1

General

This subsection applies to the construction of temporary support systems required for: • • •

rehabilitation of the substructure when concrete removal could lead to overloading of the structure; replacement of bearings; replacement of a bridge deck in stages when the structure evaluation report indicates that temporary supports are required during deck removal.

18.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Temporary Support [0919-0010]

L.S.

919

109S46

Conditions For Use

When the superstructure is supported by temporary blocking at the supports and no major construction of a support system is involved, this blocking should be included with the jacking item. 18.2.3

Special Provisions

Since the OPSS 919 does not adequately cover temporary supports for rehabilitation, a NSSP may be required to specify the project specific requirements for the design, submission of working drawings and construction of the temporary supports. 18.2.4

Contract Drawings

The location and loads imposed on the temporary support system shall be shown on the contract drawings.

April, 2004

3A-58

When a complex system is required, all the details should be shown on the contract drawings. The design of the support system should allow enough room for workers and equipment to place concrete after the formwork and falsework are erected.

18.3

Jacking

18.3.1

General

This subsection applies to the jacking of the superstructure during rehabilitation.

18.3.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Jacking [0999-9220]

L.S.

N/A

NSSP

Conditions For Use

The strengthening of diaphragms at the jacking location when required should be carried out under the tender items for structural steel. Jacking may be included with the bearing item when minor repairs to bearings are required or when the jacking is required to adjust the bearings.

18.3.3

Special Provisions

A non-standard special provision is required to: • • • • •

• •

describe the details of the jacking operation including the maximum lift required and the maximum allowable differences in lift between jacking points; specify blocking at bearing seats; specify time limitation imposed by traffic requirements; include provisions for ramping the ends of the raised deck with asphalt when the structure is to remain open to traffic while in the jacked position on temporary blocking; inform the Contractor that he has to hire an Engineer to prepare the Working Drawings. The Working Drawings then shall be submitted to QVE for stamping. The stamped copy then shall be submitted to the Contract Administrator for information purpose only prior to commencement of the jacking; specify the experience requirements of QVE; include temporary support with the item when there is no separate item for temporary support;

April, 2004

3A-59

• • •

instruct the Contractor to notify Bell Canada's free Locate Service prior to carrying out the jacking operation; include the basis of payment clause. inform the Contractor that he shall determine the type, number and capacity of the jacks and the methods to be used; and all shall be shown on the Working Drawings.

18.3.4

Contract Drawings

The Contract Drawings should specify the location of the jacking points and jacking forces. The suggested sequence of construction on the Contract Drawings should be reviewed to determine if any design details of the existing structure and the proposed rehabilitation may hinder the jacking operation. If possible, the structure should be jacked after the concrete for expansion joint blockout has been removed and prior to increased dead weight of the structure due to the rehabilitation.

April, 2004

3A-60

A19

DECK DRAINAGE

19.1

General

This section is divided into the following subsections based on the type of drainage involved. Subsection

Application

19.2 Deck Drains and Drainage Tubes

Applies to the installation of new deck drains and, drainage tubes in existing decks, and void drains.

19.3 Modification of Deck Drains

Applies to the modification required to match new pavement profile.

19.4 Deck Drain and Drainage Tube Extension

Used when existing deck drains and drainage tubes require extensions downward beneath the deck.

19.2

Deck Drains and Drainage Tubes

19.2.1

General

This subsection applies to the installation of new deck drains, drainage tubes in deck and void drains into existing deck sections. 19.2.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Conditions For Use

Deck Drains [0999-9310]

each

N/A

NSSP

Drainage Tubes in Deck [0930-0175]

each

930

109S50

Use when installing drainage tubes to drain moisture under the asphalt at concrete end dams or depressions in the deck.

Void Drains [0999-9312]

each

N/A

NSSP

Used when installing void drains in voided thick deck slabs.

Use when installing new deck drains in existing decks.

When deck drains are installed in new deck sections, the drainage items are usually included with the appropriate concrete placement item. 19.2.3 April, 2004

Special Provisions 3A-61

A non-standard special provision is required for deck drains and void drains to: • • •

refer to Contract Drawings for installation details; include requirements for removal and disposal; include measurement for payment and basis of payment clauses.

19.2.4

Calculating Quantities

The number of deck drains, drainage tubes in deck and void drains shall be determined from the Contract Drawings.

19.2.5

Contract Drawings

19.2.5.1

All Items

The location of deck drains, drainage tubes in deck and void drains shall be shown on the Contract Drawings.

19.2.5.2

Deck Drains

Standard drawings OPSD-3902.01 to 3902.06 for deck drains are in the Ontario Provincial Standards Manual for Roads and Municipal Services, Volume 3. The drawings apply to new construction. Appropriate site-specific modifications may be required for rehabilitations.

19.2.5.3

Drainage Tubes in Deck

Standard drawing OPSD-3950 and OPSD 3951 for drainage tubes in deck are contained in the Ontario Provincial Standards Manual for Roads and Municipal Services, Volume 3. OPSD-3950 applies to deck replacements while OPSD-3951 applies to installation of drainage tubes into existing decks by core drilling.

19.2.5.4

Void Drains

Standard drawing OPSD-3921 for draining void tubes is contained in the Ontario Provincial Standards Manual for Roads and Municipal Services, Volume 3. As the detail applies to new deck construction, the standard drawing should be modified to suit installation into existing decks and the modified drawing shall be included in the Contract.

19.3

April, 2004

Modification of Deck Drains

3A-62

19.3.1

General

This section applies to modifications required to existing deck drains to match the new profile of the pavement and to drain moisture beneath the asphalt.

19.3.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Modification of Deck Drains [0930-0165] [0914-0021]

each

930 914

109S50

19.3.3

Conditions For Use

Calculating Quantities

The number of drains requiring modifications should be calculated from the Contract Drawings.

19.3.4

Contract Drawings

The location of the deck drains requiring modification should be shown on the Contract Drawings. Standard drawings OPSD-3901.01 to 3901.03, for adjusting deck drains upward to match the new pavement profile, are contained in the Ontario Provincial Standards Manual for Roads and Municipal Services, Volume 3. When adjusting drains downward to match a lower profile, the above drawings should be modified as appropriate and inserted in the Contract. When the drains do not require adjustment and presently do not have provision for drainage, a detail similar to the one shown in the OPSD Standards is required for drilling or burning slots into existing deck drains to drain water beneath the asphalt.

19.4

Deck Drain and Drainage Tube Extensions

19.4.1

General

This subsection applies to the extension of the existing deck drains and drainage tubes downward to prevent discharge of water onto other components of the structure. 19.4.2

April, 2004

Tender Items

3A-63

Item Description [CPS Code]

Unit

OPSS

Standard Special

Deck Drain Extension [0999-9311]

L.S.

N/A

NSSP

Drainage Tube Extension [0999-9321]

L.S.

N/A

NSSP

19.4.3

Conditions For Use

Special Provisions

A non-standard special provision is required to: • •

refer to Contract Drawings for installation details; include measurement for payment and basis of payment clauses.

19.4.4

Contract Drawings

The location and details of deck drain and drainage tube extensions shall be shown on the Contract Drawings. The details for extending existing drain tubes can be addressed by making the appropriate modifications to Standard drawing OPSD 3950 contained in the Ontario Provincial Standards Manual for Roads and Municipal Services, Volume 3.

April, 2004

3A-64

A20

STRUCTURAL STEEL

20.1

General

This section applies to the strengthening and replacement of existing structural steel. Design requirements for structural steel are described in the Structural Manual and the Canadian Highway Bridge Design Code. 20.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Fabrication of Structural Steel [0906- 0011]

L.S.

906

906S01 906S02 109S43

Delivery of Structural Steel [0906-0020]

L.S.

906

109S43 109F16

Erection of Structural Steel [0906-0030]

L.S.

906

906S01 109S43

Shear Connectors [0999-9192]

each

N/A

NSSP

Conditions For Use

Used when shear connectors are to be added to existing structural steel.

Shear connectors required for new structural steel should be included with the structural steel item. The removal of existing structural steel should be included with the concrete removal lump sum items by NSSP. When minor quantities are involved, the tender items for the delivery and erection of structural steel may be included with the item, "Fabrication of Structural Steel". 20.3

Special Provisions

a) Structural Steel Special Provision 906S01 should be included in the Contract when the work does not involve welding of main members and/or critical members.

April, 2004

3A-65

The Designer has to fill in proper load and size restrictions of structural components required in Special Provision SP109F16. A non-standard special provision is required to: • • • •

cover the minor application of coating where there is no separate coating item; combine the work into one item for minor work; amend subsection 906.10.01 of OPSS 906 when delivery and erection of structural steel is included with the item "Fabrication of Structural Steel"; cover the repair of structural steel components and a non-standard tender item has to be created.

b) Shear Connectors A non-standard special provision is required to address the following: • • •

surface preparation of areas to be welded by wire brushing, scaling and/or grinding; refer to OPSS 906 for construction requirements; measurement for payment and basis of payment clauses.

20.4

Calculating Quantities

a) Structural Steel The quantity of shear connectors is calculated from the Contract Drawings.

20.5

Contract Drawings

All details of the structural steel and shear connectors shall be shown on the Contract Drawings.

April, 2004

3A-66

A21

BRIDGE DECK WATERPROOFING

21.1

General

This section applies to the waterproofing of bridge decks, the forming of grooves and filling with hot poured rubberized joint sealing compound, and the surface preparation required for wire broom textured and/or lightly scaled surfaces and rough areas to provide a surface acceptable for waterproofing. 21.2

Tender Items

Item Description [CPS Code]

Unit

OPSS

Standard Special

Bridge Deck Waterproofing [0914-0011]

m2/ L.S.

914

914S05 109F40

m

914

Membrane Reinforcement [0914-0040]

m

914

Deck Surface Preparation [0914-0050]

m2

914

Form and Fill Grooves [0914-0031]

21.3 April, 2004

Conditions For Use

Use as membrane reinforcement over cracks, construction joints and joints in deck. Placed directly over the asphalt membrane waterproofing and pressed in while waterproofing is still tacky. 109F40

Calculating Quantities 3A-67

Use with patch, waterproof and pave treatment when existing deck is wire broom textured or contains sawcut grooves. The surface preparation for light scaling and rough surfaces shall be administered as extra work.

When tender items are required for bridge deck waterproofing and deck surface preparation, the quantities are to be calculated to the nearest 0.1 m2 and then shown on the quantity sheet to the nearest m2. When tender items are required for form and fill grooves or membrane reinforcement, the quantities are to be calculated to the nearest 0.1 m and then shown on the quantity sheet to the nearest m. 21.4

Contract Drawings

Ontario Provincial Standard drawings OPSD-3906.02 and OPSD-3906.03 should be referenced in the Contract. The extent of the waterproofing and the location of the membrane reinforcement and form and fill grooves shall be shown on the Contract Drawings, if other than as shown on the standard drawings. The location of the construction joints in the deck should also be shown so bidders can determine the quantities for the membrane reinforcement. The Contract Drawings shall indicate whether the existing deck has wire broom texturing and/or rough areas. When requirements of OPSD 914 cannot be met due to restricted widths for stage construction, the Contract Drawings should show a minimum overlap of 50 mm for waterproofing between stages.

A22

April, 2004

PLANNING AND DESIGN ITEMS

3A-68

22.1

General

The tender items in this section will normally be prepared by the Planning Design Section. The scope of this section is limited to details that are not covered in Chapter B of the Contract Design Estimating and Documentation Manual, [CDED Manual, Volume 1]. 22.2

Hot Mix

The requirements for preparing Contract Documents for the various hot mix tender items are described in Section B313 of the CDED Manual. The Contract Drawings should show the following details: • • •

the total depth of asphalt including waterproofing; the lapping requirements for each course of asphalt and waterproofing when the lapping requirements of OPSS 313 cannot be met due to restricted area for stage construction; sawcutting of the longitudinal construction joint in asphalt to remove uncompacted asphalt roll over when the longitudinal construction joint in asphalt cannot be properly lapped.

A non-standard special provision may be required with the appropriate asphalt item to address the quality of the longitudinal construction joint and the payment for special treatment if required. The Structural Designer should coordinate with Planning and Design Section for such NSSP. Planning and Design Section should be made aware of any changes to the existing profile of the pavement. 22.3

Removal of Asphalt Pavement from Concrete Surfaces

The requirements for preparing Contract Documents for removal of asphalt pavement from concrete surfaces are described in Section B510 of the CDED Manual. The Structural Design Engineer is responsible for confirming whether the weight limitations to milling equipment according to OPSS 510 are acceptable. If impact and vibration damage is anticipated, the weight of the equipment should be reduced by NSSP. The depth of removal should be shown on the structural drawings. A note on the drawing should indicate whether the deck is waterproofed. 22.4

Roadway and Track Protection

OPSS 539 covers the requirements for roadway and track protection. A separate tender item is not required for minor protection, i.e. sandbagging. The Contract Drawings should show a line diagram for the areas requiring protection. A detailed scheme should be given in the Contract for major work. 22.5 April, 2004

Temporary Concrete Barrier 3A-69

The requirements for preparing Contract Documents for temporary concrete barriers are described in Section B553 of the CDED Manual. The location of the concrete barrier for each stage should be shown on the cross section and on the plan view of the deck. When the bridge deck is to be removed in stages, the Contract Drawings should show a detail for anchoring the concrete barriers to prevent lateral displacement on impact. A non-standard special provision will be required to address payment for this work. All the above details should be shown on structural drawings when it is requested by Planning and Design Section. 22.6

Traffic Control

OPSS 543 covers the requirements for traffic control. Planning and Design Section or the Consultant would prepare the drawings showing the requirements for traffic control. 22.7

Earth Excavation for Structure

The requirements for preparing Contract Documents for earth excavation for structures are described in Section B902 of the CDED Manual. The extent of the excavation should be shown on the structural drawings when it is requested by Planning and Design Section. When small quantities of excavation are involved, the work can be included with one of the lump sum items for concrete removal described in Appendix A1. An item for installing new subdrains may be required when excavation for abutment wall replacement is required.

A23

DEVELOPMENTAL REHABILITATION METHODS

The following rehabilitation treatments are in developemental stage: • •

Electrochemical Chloride Extraction FRP wrapping for columns

April, 2004

3A-70

•

Galvanic/Passive Cathodic Protection Systems such as: 1. Zink-Hydrogel Anode by 3M. 2. Al-Zn-Indium Arc Spray by Corrpro.

•

Hydrodemolition

NSSP and non-standard tender items would be required for the above rehabilitation methods on project specific bases until they are standardized, the regional Structural Sections should consult with Bridge Office and Concrete Section for the feasibility of using such methods on a project specific bases and obtain the appropriate specification.

April, 2004

3A-71