Design Data New 1

Light Weight Concrete Decorative Products Technical Data

CONTENTS 1.

INTRODUCTION

2.

RAW MATERIALS 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10

3.

4.

MANUFACTURING 3.1

MIXING 3.1.1 3.1.2 3.1.3

3.2

MOULDS 3.2.1 FIBRE GLASS MOULDS 3.2.2 POLYSTYRENE MOULDS 3.2.3 MOULD OILS 3.2.4 OTHER MOULDING TECHNIQUES

3.3

MOULD COATING 3.3.1 MOULD COATING TECHNIQUE 3.3.2 APPLICATION

GENERAL DENSITY SELECTION OF DENSITY AND CEMENT CONTENT TYPICAL MIXED DESIGNS

ADHESIVE CEMENT 5.1 5.2 5.3

6.

AND DISTRIBUTION BATCHING DRY MATERIALS AND WATER AIR ENTRAINING AGENT TO PRE FOAM MIXING AND DISCHARGE

MIXED DESIGN 4.1 4.2 4.3 4.4

5.

CEMENT CONTENT E.P.S. AIR ENTRAINING AGENT CALCIUM SULPHATE (GYPSUM) FIBRES ALUMINIUM POWDER CEMENT ADDITIVE PIGMENTS SAND WATER

PREMIXED ADHESIVE CEMENT CONCENTRATES ADHESIVE MIXES ADHESIVE CEMENT

TYPICAL DESIGN OF INDIVIDUAL ITEM

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Light Weight Concrete Decorative Products Technical Data

7.

6.1 6.2

BALUSTRADES COLUMNS

6.3

CORNICES 6.3.1 SOLID AND HOLLOW 6.3.2 SMALL CORNICES 6.3.3 BIG CORNICES 6.3.4 SEGMENTED CORNICES 6.3.5 PUSHED SECTION CORNICES

6.4 6.5

ARCHITRAVE AND SMALL ITEMS WINDOW HOODS AND SILLS

QUALITY CONTROL 7.1 7.2 7.3

8.

CONCRETE DENSITY SURFACE COMPRESSION TEST QUALITY OF FIXING OPERATION 7.3.1 WELDING (IF REQUIRED) 7.3.2 MASONRY ANCHOR AND EPOXY ANCHORS 7.3.3 ADHESIVE 7.3.4 CONCRETE COVER TO STEEL 7.3.5 QUALITY OF FINISH

STANDARD OF SPECIFICATION 8.1

INCLUSION IN CONTRACT DOCUMENTS

8.2

STANDARD SPECIFICATION 8.2.1 CONCRETE DENSITY 8.2.2 SURFACE COMPRESSION STRENGTH

8.3 8.4 8.5 8.6

CONCRETE COVER TO STEEL FIXING AND INSTALLATION SHOP DRAWING TOLERANCE

1. INTRODUCTION

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Light Weight Concrete Decorative Products Technical Data

Light Weight Concrete (LWC) is a composite material consisting of a mortar of hydraulic cement, fine aggregate, polystyrene bead, airentraining agent and reinforced with synthetic fibre or alkali resistant glass fibres. The LWC may contain Calcium Sulphate (Gypsum), aluminium powder and admixtures. LWC products are safe, have good chemical resistance and will not rot or corrode. LWC is made of inorganic materials and will not burn, has negligible smoke emission and offer good fire resistance. LIGHT WEIGHT Concrete Decorative products have been widely used for many years and ideally suited to the architectural decoration to buildings, ornament and civil structures, due to the versatility durability and much lighter than the conventional one. In order to maximise the potential of the system both in terms of architectural expression and in relation to construction economics it is important to understand the full range of design possibilities. This manual has been prepared to document many of these possibilities. It is not intended to be exhaustive and each new project will bring with it new challenges and solutions.

2.

RAW MATERIALS 2.1

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CEMENT CONTENT

Light Weight Concrete Decorative Products Technical Data

The most widely used cement in LWC products is Ordinary Portland Cement. It is advisable to keep cement content of all the lightweight decorative concrete above 600kg/m³. If the density below 700kg/m³ is being used, then pure cement will be used. 2.2

E.P.S.

E.P.S. beads can be added to the concrete mix to reduce density but the quantity must be correct to maintain a stiff mix. This is particularly suitable for hand packing thin shell products where it is necessary to “plaster” the material on to chicken wire. E.P.S. has a draw back that it becomes visible when those chips sometimes causing customer complaint. 2.3

Air Entraining Agent

A.E.A. can be added either directly to the mix or volume batched using a large container for hand addition to the mixer. It can produce air entrained concrete for increased durability, resistant to damage by frost and de-icing salts, and to improve the cohesion and workability of concrete mixes where poorly graded aggregates must be used. Concrete mix design with A.E.A. can be developed to eliminate the need of E.P.S. and ideally suited for the production of balustrades, columns, solid cornices etc. 2.4

CALCIUM SULPHATE (GYPSUM)

Calcium sulphates should be added to all mixes to reduce long term drying shrinkage. The addition of 0.5% to 2%(by weight) of Calcium Sulphate to cement is recommended. 2.5

FIBRES

The synthetic and alkali resistance fibres made from nylon will improve the strengths characteristics of all lightweight concrete mixes. Although reasonably expensive, the addition of up to 0.6kg of fibres per cubic meter is advisable for all concrete being used as the finished surface of any items. The main application for synthetic fibres is to eliminate early age cracking and any resultant long-term problems. It also increased impact resistance and reduce the problem of chipping or corner damage. 2.6

ALUMINIUM POWDER

Aluminium powder can be added to mixes to produce a percentage of expansion during the first 30 minutes to one hour after placing. This will assist in moulding filling and reduce slumping sometimes WSCSB

Light Weight Concrete Decorative Products Technical Data

experienced with tall items like columns. Aluminium powder also reduces long-term shrinkage. 2.7

CEMENT ADDITIVE

Cement additives like calcium chloride can be added and used for speeding up the setting of concrete. It is advisable not to use it in items containing non-galvanised steel as it has a corrosive effect on those non-protected steel. Recommended quantities are from 1kg/m³ to 5kg/m³. 1kg/m³ should reduce initial set about 6 to 8 hours while 5kg/m³ could reduce it to 2 to 3 hours. Other forms of accelerator that do not contain chlorides are available and could be used in items containing steel reinforcement. 2.8

PIGMENTS

Pigments may be used to colour LWC decorative products. Special care is required to achieve uniformity of colour and the strong colours are not usually achievable without significant variation. 2.9

SAND

Various types of sand can be used for the production of LWC decorative products but it should be washed and clean type. However, for mix designs not using any E.P.S. and of densities below 1,200kg/m³ the sand should be fine and clean. For the density above 1,200kg/m³, the particle size should not be greater than 6mm. And for the densities range from 800kg/m³ to 1200kg/m³, the particle size should be below 1mm. For any mix that below 800kg/m³, it should be pure cement. It is important to carry out a series of trials on available sands to ascertain which one or ones give best results. 2.10

WATER

Water should be clean and free from deleterious matter and should meet relevant standards for used to make ordinary concrete.

3.

MANUFACTURING 3.1

MIXING AND DISTRIBUTION

3.1.1 BATCHING DRY MATERIALS AND WATER

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Light Weight Concrete Decorative Products Technical Data

All premix processes involve the blending together of the cement, sand, water, and fibre in a mixer prior to being formed. It is generally advisable to add the required water to the mixer before dry materials. Add dry materials by weight or volume in correct quantities and allow it blend for about 30 seconds. 3.1.2 AIR ENTRAINING AGENT TO PRE FOAM Foam may be added directly to mix with quantity controlled by the amount of A.E.A. added. After naturally foam can be generated into a container of known volume and added to the mix by hand. This method is more accurate when batching small quantity of mix. See Operator Manual for lightweight concrete low pre-foam. 3.1.3 MIXING AND DISCHARGE The duration of concrete mixing or blending should be sufficient to “stir in” all pre foam material. Usually, 30 seconds to one minute after the addition of pre foam. Check density by weighing a known volume of mixed wet concrete and control the density by adjust the volume of pre foam added. Add more pre foam if density is too high and reduce the pre foam if density is too low. The discharge of LWC concrete from mixer is same as normal concrete with hopper or directly into moulds. Concrete containing E.P.S. will hold for 1-2 hours. Concrete not containing E.P.S. should be used within 30-60 minutes after being batched. 3.2

MOULDS

3.2.1 FIBRE GLASS MOULDS Conventional fibreglass moulds are suitable and widely used for casting LWC decorative products. It is sometimes advisable to fill moulds up-side down to ensure air not trapped under the overhang.

3.2.2 POLYSTYRENE MOULDS Polystyrene moulds can be made for many cornices profiles by using CNC machine to cut profiles with a controlled hot and fast wire-cutter. This type of moulding is particularly suitable for projects needing rapid delivery of a large quantity of one particular

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Light Weight Concrete Decorative Products Technical Data

profile. Moulding can be made very quickly and put into service immediately. 3.2.3 MOULD OIL Normal used or recycled motor oil can be used for fibreglass or steel moulds. It is advisable to wipe off excess oil so that none is “pooling” low spots within the mould as this will damage the concrete in that region and cause surface cracks. Polystyrene moulds will deteriorate much more rapidly if mineral based oils are used. Vegetable base oils (cooking oil or palm oil) are more suitable to preserve the mould. 3.2.4 OTHER MOULDING TECHNIQUES All other techniques used to mould dense weight concrete, can be used for lightweight concrete such as silicon rubber, steel, wood or concrete moulds. LWC have available some special techniques of moulding directly with wet sand or with granulated recycle rubber and polyurethane. These methods are complex and require specialist instruction. 3.3

MOULD COATING

3.3.1 MOULD COATING TECHNIQUE LWC have developed techniques for coating the inside surface of moulds with polystyrene modified cement slurries or grouts, 1mm to 2mm thick so that the surface of the final product is hard and perfect. Slurry or grout can be made with the mixing of Skim Coat Powder with cement. This should be mixed using a power mixer as for “normal” skim coats. 3.3.2 APPLICATION The slurry can be simply painted onto mould surface using a “dabbing” technique, or using a hopper spray gun or pump spray. Even large vertical surfaces can be treated this way such as columns and balustrades producing the need for a final finish of the cost product. Almost any products will benefit from the use of this technique, as the surface will be smooth and hard. The backup concrete can be mostly lighter because it is already be protected by the coating. Dependant on the coatings thickness the density could be as low as 400kg/m³.

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Light Weight Concrete Decorative Products Technical Data

4.

MIXED DESIGN

4.1

GENERAL

For the most decorative items, the cost of the concrete mix is not usually a large factor in the project or overall cost. Consequently it is advisable to use relatively high cement contents to produce strong and reliable concrete. For repetitive items or ‘retail’ sales such as balustrades, columns etc. may not necessarily follow the designed mix, and each user can tailor make a mix design to suit his particular market. 4.2

DENSITY

Many different densities will be of use in creating decorative concrete solutions, ranging from as low as 300kg/m³ to 1,500kg/m³. Where the concrete is to be the finished surface, such as columns, balustrades, cornices etc. it is not advisable to use below 800kg/m³ if it contains E.P.S. Density can be reduced by add more E.P.S. or A.E.A. as stated in work methodology. 4.3

SELECTION OF DENSITY AND CEMENT CONTENT

The correct selection of density and cement content is related to practical experiences and should be sought from Weng Sum Construction Sdn. Bhd. personnel when assessing a new project. Generally if the item is accessible to the public it should be above 1000 density. If it is not assessable it could be 600 density or below.

4.4

TYPICAL MIX DESIGNS

In any production facility, it is important to keep the number of standard mix designs to a minimum to avoid confusion. In highly competitive project it may be necessary to re-access these standards to save material cost, but it is unlikely that the effect will be great unless the volume is very large and the items are very simple. WSCSB

Light Weight Concrete Decorative Products Technical Data

Diagram below are designs for 5 basic densities 1500, 1200, 800, 600, 400. These designs are both given with and without E.P.S.

5.

MIX DENSITY

COMPRESSIVE REINFORCEMENT STRENGTH

1500

(MPA) 12 to 20

1200

Below 10

Steel bar or G.I. BRC mesh

800

N/a

G.I. BRC mesh only

600

N/a

G.I. BRC mesh only

400

N/a

N/a

Simulated to the design of structural concrete

TYPICAL USES

Column, thin section profile, perforated friezes, shell structure cornices, window hoods and sill, small decorations such as architrave etc. Balustrade, column shell, cornice, column base shell, corbel, diamond, keystone etc. Balustrade, window hood and sill, corbel, column shell, capital etc. Infill only

Infill only

REMARKS

It can be considered as semi-structural capable of supporting more than its self-load.

It can’t be used to support any other structure although it can support its own. It should not be expected to support much more than its own dead weight. This mix can generally only be used in applications where they are inaccessible to the public or where they are coated with denser material or skim-coat. This is light and soft & can only be used as infill to heavier material of reasonably thick skim coat.

ADHESIVES CEMENT 5.1

PREMIXED ADHESIVE CEMENT

Use only good premixed adhesive cement for the installation of LWC decorative products, as the expansion agent will help reduce shrinkage cracks and fill voids. WSCSB

Light Weight Concrete Decorative Products Technical Data

Sample data of premixed adhesive cement: Dry Condition (kN)

Wet Condition (kN)

Tensile Adhesion Typical value BS 5980 Min.

1.77 0.95

1.23 0.56

Shear Adhesion Typical value BS 5980 Min.

20.0 8.90

17.9 4.50

5.2

CONCENTRATES ADHESIVE

Concentrates Adhesive like MULTIPUR Bond Powder should be used for all patching and bedding of lightweight concrete products. Its excellent workability and bonding strength is very much suitable for the installation as well as patch up work for LWC decorative products. Sample data of concentrates adhesive: Pot life Coverage with 6 mm notch trowel Fungi resistance Bonding strength (DIN 18156) Testing Required Open time as evaluated by bonding 1346) Testing bedding after 5 minutes 10 minutes 20 minutes 30 minutes Required 20 minutes

5.3

Approx. 4 hours Approx. 10-12m² /25kg cement Excellent 1.3 N/mm² ≥ 0.5 N/mm² strength by European Standard (prEN 1.3 N/mm² 0.7 N/mm² 0.5 N/mm² 0.2 N/mm² > 0.5 N/mm²

MIXES OF ADHESIVE CEMENT USES

CEMENT (KG)

WATER (Ltr)

ADHESIVE 25 10 PATCHING 25 10 ∗PAINT COAT FOR TOUCH UP 25 30 ∗This coating will “stick” better than neat cement cracks.

6.

TYPICAL DESIGN OF INDIVIDUAL ITEMS

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FINE ADHESIVE SAND POWDER (KG) (g) 25 100 0 100 0 30 and not develop hairless

Light Weight Concrete Decorative Products Technical Data

6.1

BALUSTRADES

Use LWC for the replacement of dense weight concrete with the range of density from 1500kg/m³ to 1000kg/m³ for solid or hollow balustrades. Smaller size of balustrade usually cast in solid and most suitable for the normal reinforcement bar. It is also possible to produce hollow balustrades for those bigger size one, and cast in a similar technique to column design with the reinforcement G.I. BRC mesh. Unless the mould coating technique is being used it is advisable to use concrete not containing E.P.S. to reduce surface imperfection. (SEE FIGURE 1) 6.2

COLUMNS

For precast columns, direct replacement of dense weight concrete with the density from 1500kg/m³ to 1000kg/m³ concrete is most suitable. However, columns should be reinforced with a single layer of heavy-duty square galvanised mild steel fabric (BRC) or double layers of chicken wire mesh. This wire can be wrapped directly around the removable P.V.C. tube usually associated with precast columns. It is generally not advisable to use conventional reinforcement bar in lightweight concrete with the density below 1200kg/m³. At this density the concrete is too “soft” to effectively “hold” the large bars. Wire must be used, even in multiple layers will be much more effective. (SEE FIGURE 2) 6.3 6.3.1

CORNICES SOLID AND HOLLOW CORNICES

It is advised to produce solid or hollow cornices in section weighing below 50kg for most applications. For large cornices the length of each section may reduce to 600mm or below if the entire section is being cast.

6.3.2 SMALL CORNICES WSCSB

Light Weight Concrete Decorative Products Technical Data

For small cornices with the overall sectional size smaller than 300mm x 300mm, it usually cast in solid with the density range from 1200kg/m³ to 800kg/m³. The installation of this small cornice is simple, just fixed with adhesive cement, and secured with steel bend brackets at 600mm to 1000mm c/c with masonry anchor. (SEE FIGURE 3) 6.3.3 BIG CORNICES For those cornices with the overall sectional size bigger than 300mm x 300mm, hollow cornices have the advantage of being able to be used. Insert P.V.C. pipes or polystyrene block to the internal of cornice when it cast. (SEE FIGURE 4 & 6) It usually reinforced with G.I. BRC mesh and produced in smaller length. To install this cornice, the application of adhesive cement, and secured it by fixing with mild steel brackets and masonry anchor bolt at 300mm to 900mm c/c. (SEE FIGURE 4) 6.3.4 SEGMENTED CORNICES If the size of cornice is very large, it may be desirable to cut it horizontally so that there are more horizontal joints and fewer verticals. This will help with alignment in the horizontal directions and give cleaner lines. It is also possible to produce Hollow Cornices in this way to reducing both the weight and material usage. (SEE FIGURE 5) 6.3.5 PUSHED SECTION CORNICES It is possible to use the traditional method of pushing a profiled blade to produce shell and solid section and to cut into short section after setting. Two profile boxes are needed, one to cut the light weight and one to place or form the normal sand cement topping. A concrete mix containing a large quantity of E.P.S. is advisable so that it can form the profile or shape easily after pushing. This technique is complicated and it is advised to use it for very short runs and for curved items only. 6.4 WSCSB

ARCHITRAVE & SMALL ITEMS

Light Weight Concrete Decorative Products Technical Data

Due to most the architraves are small, the advantages of lightweight concrete is not so great in so far as weight in concerned. The ability to cut the lightweight is maintained however. It is therefore, advisable to produce in reasonably dense mix of pure pre-foam concrete containing extra fibre. Produce relatively short sections with the reinforcement (1.2m long) being typical. 6.5

WINDOW HOODS AND SILLS

Basically for the smaller profile type of hoods and sills are same as small cornices above. For some larger profiles, and if the item required to behave in a structural or semi structural manner, it is usually necessary to held conventional reinforcing being used, it is advisable to use 1500kg/m³ - 1000kg/m³ density concrete cast in solid or hollow. The additional of corbels or brackets to support items like this is advisable and these corbels can be used for architectural effect.

7.

QUALITY CONTROL 7.1

CONCRETE DENSITY

Always check the wet density of concrete (for every four batches) by the workers of mixing concrete. This is best to carry out the weighing with a 5 Litre container of mixed concrete by using a simple balance hanging type weigh near the discharge of concrete mixer. The concrete should be taken from any part of the discharged concrete during the placing process. If irregularities are encounter then the subsequent mixes should be adjusted. A tolerance of ±100kg/m³ is acceptable. 7.2

SURFACE COMPRESSION TESTS

Regular check of surface compression strength should be carried out on items taken out of stock. These items can be sent to any testing lab and a report will issue. It is not necessary or advisable to make test cubes tests. Test on product taken from stock are more reliable and appropriate. 7.3

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QUALITY OF FIXING AND INSTALLATION

Light Weight Concrete Decorative Products Technical Data

Spot check should be carried on for the following items at the proposed materials. 7.3.1 Welding (if required) Check length of weld (minimum 3 x bar diameters) Sound of weld (free of putting) Carry out on every 200th weld. 7.3.2 Masonry Anchors and Epoxy Anchors Check the depth and diameter of holes as recommended by supplier. Check and make sure that chemical has fully filled the cleaned hole (free of dust) with evidence of excess at the face of wall. Carry out on every 50th Anchor for critical items. 7.3.3 Adhesive Check the mixing procedures are being followed. Check that adhesive is being applied in sufficient quantity to fulfil (SEE FIGURE 3) both sides of joints and adhered faces. Ensure that calking gun is being used for the difficult to fill joints.

7.3.4 Concrete Cover To Steel Check that correct concrete cover is being given to starter bars and imbedded bars. Check 1 bar in every 50 bars. 7.3.5 Quality Of Finish Check surface quality to ensure patching and skimming is carried out correctly. Check alignment of items for straightness, verticality and horizontality, and follow the guide specification agreed for the project.

8.

STANDARD OF SPECIFICATION

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Light Weight Concrete Decorative Products Technical Data

8.1

INCLUSION IN CONTRACT DOCUMENTS

If LWC is being specified for a particular project, or if the consultants or contractor wish to include a specification in the contract, we suggest the following as a guide. This specification should be included in Design And Construct tender submissions. 8.2

STANDARD SPECIFICATION

LWC decorative items shall be manufactured accordance with this recommendation.

and

fixed

in

8.2.1 CONCRETE DENSITY Concrete density will vary dependant on the construction of structural requirements of each item between 1500kg/m³ and 400 kg/m³. 8.2.2 SURFACE COMPRESSION STRENGTH The surface compression strength of items shall be in accordance with the following schedule: ITEMS DESIGNED TO CARRY APPLIED LOADS Balustrades, Columns, etc. Compression: 8 Mpa / Flexural: 1 MPa. ITEMS CARRYING SELF-WEIGHT BUT IN CONTACT WITH PEOPLE. Compression: 6 MPa / Flexural: 0.6 MPa. ITEMS NOT CARRYING APPLIED LOADS AND NOT IN CONTACT WITH PEOPLE Compression: 2 MPa / Flexural: 0.4 MPa.

8.3

CONCRETE COVER TO STEEL

The following concrete covers shall be maintained: WSCSB

Light Weight Concrete Decorative Products Technical Data

8.4

Cover to galvanised mesh

6 mm

Cover to reinforcement bar In concrete above 1200kg/m³ In concrete below 1200kg/m³

25 mm 30 mm

Cover to steel encased in Adhesive

10 mm

FIXING AND INSTALLATION

Fixing shall be carried out in accordance with LWC recommendations and shall be ensured that regular quality checks are made of welding and adhesive application. 8.5

SHOP DRAWING

Shop drawings of each item or groups of items to be manufactured and fixed shall be prepared and submitted for approval. These shop drawing shall show clearly concrete density and method of fixing. These drawings shall be submitted and approved by person in charge prior production or fixing. 8.6

TOLERANCE

The following tolerances shall be adhered to: Standard tolerances: Concrete strength ± 10% Concrete density ± 100kg/m³ Verticality 3 mm in 1m Horizontality 8 mm in 6m Surface smoothness 1 mm in 600 mm Where surfaces are to be fixed to substrates supplied by others, they shall generally be provided to the following tolerances: Verticality 6 mm in 1 m Horizontality 15 mm in 6 m If substrate is not within these tolerances it shall be plastered out or hacked by the main contractor.

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