Pft 2.docx

Contents 1. Abstract........................................................................................................................................................... 3 2. Crack............................................................................................................................................................... 3 3. Types of Cracks in Buildings ............................................................................................................................. 3 3.1 Shrinkage:................................................................................................................................................. 3 3.2 Hairline: ................................................................................................................................................... 4 3.3 Settlement: ................................................................................................................................................ 4 3.5 Vertical: .................................................................................................................................................... 5 3.6 Diagonal: .................................................................................................................................................. 6 3.7 Horizontal:................................................................................................................................................ 6 3.8 Structural:................................................................................................................................................. 6 3.9 Floor cracks: ............................................................................................................................................ 7 3.10 Cracks in Roof Slab: ............................................................................................................................... 7 3.11 Cracks in Brick Mortar Joints: ............................................................................................................... 7 3.12 Crack Formation below the Load Bearing Walls: .................................................................................. 8 3.13 Main Wall and Cross Walls Joint Cracks: ............................................................................................. 8 3.14 Cracks Found in R.C.C Columns and Masonry: .................................................................................... 9 3.15 The Horizontal cracks between R.C.C slab and the brick parapet: ........................................................ 9 3.16 Vertical Cracks at Junction of R.C.C. Column and Wall Masonry: ....................................................... 9 3.17 Horizontal Crack at the Junction of Roof Slab and Masonry Wall Support:.......................................... 9 3.18 Cracks in Foundation: .......................................................................................................................... 10 3.19 Extension of Existing Building: ............................................................................................................ 10 4. Major Causes of Cracks in Buildings:--........................................................................................................ 11 4.1 Initial Shrinkage: .................................................................................................................................... 11 4.2 Thermal Movement: ................................................................................................................................ 12 4.3 Elastic Deformation: .............................................................................................................................. 12 4.4 Creep Movement:.................................................................................................................................... 12 4.5 Chemical Reaction: ................................................................................................................................ 12 4.6 Foundation Movement and Settlement of Soil: ....................................................................................... 12 4.7 Cracking Due To Vegetation: ................................................................................................................. 13 4.8 Permeability of Concrete: ....................................................................................................................... 13 4.9 Structural Design: .................................................................................................................................. 13 4.10 Poor Workmanship: .............................................................................................................................. 13 4.11 Lack of Maintenance: ........................................................................................................................... 14 4.12 Natural Forces: .................................................................................................................................... 14 5-Repairing & Maintenance of Iqbal Hall:- ...................................................................................................... 15 5.1 Efflorescence:- ........................................................................................................................................ 15

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5.2-Horizontal and vertical cracks: - ........................................................................................................... 15 5.3 Penetration of Water due to unbound of foundation top:- ...................................................................... 16 5.4 Improper Disposal of 1st & 2nd Floor Sewerage. .................................................................................... 16 5.5 Wear & Tear :- ....................................................................................................................................... 17 5.5 Refurbishing Of Doors Wall joints:- ....................................................................................................... 17 5.6 Internet Box:-.......................................................................................................................................... 18 5.7 Electric socket:- ...................................................................................................................................... 18 Conclusion:- ..................................................................................................................................................... 19 Reference: ......................................................................................................................................................... 19

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1. Abstract Building cracks are most common problem found in any type of building. We all love to have a house which structurally safe and beautiful but it is not so easy, one has to overcome natural calamity, soil failure, construction faults, improper design, and inadequate joints causing to develop cracks on the building. Though the cracks in concrete cannot be prevented entirely but they can be controlled by using adequate material and technique of construction and specific design criteria. On timely identification of such cracks and adopting preventive measure are essential. Active cracks causes seriously problem and they need special attention as they are structurally hazardous. So, it is important to understand the types of cracks, crack patterns and their causes and the preventive measures to be taken to control the cracks. 2. Crack A crack is a complete or incomplete separation of concrete into two or more parts produced by breaking or fracturing. Cracks are one kind of universal problems of concrete construction as it affects the building artistic and it also destroys the wall’s integrity, affects the structure safety and even reduce the durability of structure. 3. Types of Cracks in Buildings The cracks appear in the structure, at a certain period of time. Most commonly caused cracks with their respective causes and precaution, are explained below The cracks appear in the structure, at a certain period of time. Most commonly caused cracks with their respective causes and precaution, are explained below 3.1 Shrinkage: Shrinkage cracks in a poured concrete foundation can be diagonal or vertical and are usually uniform in width. Sometimes these cracks have a V-shape (less frequent), with the top of the crack looking larger and the crack getting smaller as it travels towards to floor and diminishing or stopping before reaching the bottom of the foundation wall. If the crack reaches the bottom, the crack might damage the building's footings, and the crack might have a significant impact on the foundation structure.

Shrinkage cracks should not be ongoing nor of structural significance, though they may invite water entry through the wall. In poured concrete foundations, shrinkage cracks are usually due to conditions at original construction: poor concrete mix, rapid curing or possibly other states. In any case, concrete shrinkage causes the concrete to develop internal stresses. Unless control joints were included in the wall or floor slab design, these stresses would cause the wall or floor is likely to crack in a classic "concrete shrinkage pattern" as the concrete cure.

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3.2 Hairline: Hairline cracks may develop in concrete foundations as the concrete cures. Hairline cracks do not cause problems with the stability of the foundation but do cause leakage problems. If the cracks appear shortly after pouring the concrete foundation, concrete may have been mixed poorly or poured too quickly. In poured concrete foundations, hairline crack frequently appear in the center of the walls because the wall corners have greater stability

3.3 Settlement: Settlement cracks may appear when the underlying ground has not been compacted or appropriately prepared or if the subsoil was not of the proper consistency. A settlement crack may also appear as a random crack above areas where the soil of the subgrade was uneven after the concrete was poured. Settlement cracks are usually more extensive at the top of the crack than the bottom as the foundation "bends" over a single point, allowing differential settlement. This type of crack is usually continuous and may occur multiple times in a wall.

3.4 Temperature & Shrinkage: Horizontal cracks found in the center of the wall are most likely caused by an applied load such as backfill around foundation compacted improperly or too soon, earth compacting as it

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settles, hydrostatic pressure against foundation due to high water table and poor drainage against the foundation wall, or heavy equipment operated too soon or too close to the foundation wall. Horizontal cracks found high up on the wall are most likely caused by frost damage. Sometimes these fine cracks are not noticed for years. In a case like this, a structural engineer should be consulted.

3.5 Vertical: Vertical cracks often appear in multiples (multiple cracks in one or more area). Vertical foundation cracks in poured concrete foundations that tend to appear nearly straight or wandering, generally even in width, intermittent, or more often straight is caused by shrinkage/thermal and are usually low risk. If there is significant vertical dislocation or signs of ongoing movement, you should consult a structural engineer. If the cause is shrinkage, it is probably less of a concern than if due to settlement.

A vertical foundation crack due to earth loading or frost would be unusual. A more massive vertical crack can occur when the construction contractors incorrectly prepare the concrete footings and when the wall had poor steel reinforcement as the workers poured the concrete for the wall. Cracks can also occur during the footing settlement.

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3.6 Diagonal: Settlement usually causes diagonal cracks that are almost the full height of the foundation wall. When there's a settlement problem with footing on one side of the wall, this settlement can also cause a diagonal crack. In a case like this, a structural engineer should be consulted. If the diagonal crack is wider at the top than at the bottom, then it may be caused by expansion clay soil or frost damage. If the crack is wider at the bottom than the top, there is likely a problem with the settlement beneath.

3.7 Horizontal: Horizontal cracks found in the center of the wall are most likely caused by an applied load such as backfill around foundation compacted improperly or too soon, earth compacting as it settles, hydrostatic pressure against foundation due to high water table and poor drainage against the foundation wall, or heavy equipment operated too soon or too close to the foundation wall. Horizontal cracks found high up on the wall are most likely caused by frost damage. Sometimes these fine cracks are not noticed for years. In a case like this, a structural engineer should be consulted.

3.8 Structural: Structural cracks in residential foundations usually result from horizontal loading or settlement. Most (but not all) structural cracks resulting from an applied load (hydrostatic pressure or heavy equipment around foundation wall) are nearly horizontal and appear 16" to 48" from the top of the wall. They are more common in block foundation walls.

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3.9 Floor cracks: Floor cracks in concrete slabs are relatively common and usually not worrisome on a structural level. They should be repaired to prevent common issues like moisture, insects, and damage from seeping through. When floor cracks leak, it is usually caused by hydrostatic pressure or a high water table. Therefore, sealing the crack will redirect those issues elsewhere, so fixing the source of those problems beforehand is recommended.

3.10 Cracks in Roof Slab: The exposure of roof slab to higher temperature variation cause cracks numerously. This can be reduced by providing a weather proof course. New treatment methods and compounds are available as weather course that is applied over the terrace. 3.11 Cracks in Brick Mortar Joints: Vertical or horizontal cracks are seen at the brick mortar joints. One of the main reason is the sulfate attack that weakens the mortar. These cracks mainly appear after 2 to 3 years of construction. These cracks can be avoided by: 1-Checking the sulfate content of bricks used in construction. 2-The damping of brick wall has to avoided, as these are more prone to sulfate attack when it is damp.

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3.12 Crack Formation below the Load Bearing Walls: Cracks are observed below the load bearing walls, mainly those that supports R.C.C slabs. Now the temperature variation makes the reinforced concrete slab to expand or contract, but both in the horizontal direction. These are observed in the Top most story that is more exposed to the temperature changes. There no smooth contact between the wall and the slab. Hence the frictional forces are developed at the contact place of the wall and the slab. This creates cracking in the walls. The precaution that can be suggested is to provide a bearing plaster over the brick wall, which helps in having a smooth contact with the floor over it. If required a bituminous coating can be applied over the plaster applied

3.13 Main Wall and Cross Walls Joint Cracks: Improper bonding between the cross wall and the main wall creates cracks between the joints. This suggests us to have proper and quality bonding between the two walls. These are properly done by tooting.

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3.14 Cracks Found in R.C.C Columns and Masonry: One of the main reason behind this is the differential movement of the columns and the masonry because of temperature variation. This variation can be either expansion or contraction depending upon the temperature. These cracks can be hidden by making a groove in the reinforced concrete column and masonry junction. The provision of chicken wire alternatively at the plaster between the junction of columns and masonry can also help in this variation. 3.15 The Horizontal cracks between R.C.C slab and the brick parapet: The non-projecting slab is mainly subjected to such cracks. This too is due to the temperature variation and the drying shrinkage. Small micro cracks formed he propagated with the increase in expansion or contraction. These cracks can be hidden by making a groove at the masonry junction will help in hiding the cracks. The provision of chicken wire alternatively at the plaster junction can also help. 3.16 Vertical Cracks at Junction of R.C.C. Column and Wall Masonry: The cracks occur a few months after construction not only due to differential strain between R.C.C. and masonry because of elastic deformation, shrinkage and creep in R.C.C. column also act upon. As a preventive measure butterfly ties may be provided at the junctions. 3.17 Horizontal Crack at the Junction of Roof Slab and Masonry Wall Support: In case of framed structure roof slab, beams, and columns move jointly, causing diagonal cracks in walls which are generally parallel to the movement and horizontal cracks are located below the beams. Extent of movement in a framed structure is comparatively less as columns on account of their stiffness and ability to withstand bending stresses are able to resist and contain the movement to some extent. Both in load-bearing and framed structures, provision of adequate or protective cover on the roof is very important in order to avoid cracks in walls.

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3.18 Cracks in Foundation: Plinth protection around the building helps in preventing seepage of rain and surface water into the foundation; possibility of settlement cracks may thus be avoided. 3.19 Extension of Existing Building: When extension of existing building is desired, new construction should not be bonded with the old. Two parts should be separated by a step or expansion joint right from the foundation to top. Care should be taken while excavating below the foundation of existing building. When the existing structure is 20 – 25 m long, the old and the new work should be separated by an expansion joint with a gap of about 25 to 40 mm to allow room for unhindered expansion of the two portions.

In case of extension of framed structure, twin columns should be provided with combined footing. Combined footing shall be provided during original construction.

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4. Major Causes of Cracks in Buildings:-Aging and natural deterioration of the building can result in many types of defects. While most of the defects are localized and non-structural in nature, there are few which are severe and can affect the structural safety of the buildings. Home or building owners should always be aware of the condition of their buildings. One of the best ways to avoid unnecessary panic is by identifying the defects early on and carry out timely repair and maintenance works to keep the building in sound structural condition. One of the most important defects to monitor are the cracks in buildings. Cracks can occur due to various reasons chemical reactions in construction materials, foundation movements and settling of buildings, changes in temperature and climate, environmental stresses like the nearby movement of trains, earthquakes etc. Faulty and defective design, poor quality materials, incorrect methods of construction, weather, and loads of wear and tear can create cracks. Most of the buildings develop cracks at some point in time during their lifetime, following are the top reasons that cause them. 4.1 Initial Shrinkage: Building materials like brickwork, concrete, etc. shrink in the beginning. This shrinkage is partially irretrievable. Shrinkage cracks in buildings wall can be reduced by using less rich cement mortar in the masonry and by suspending application of plaster on the brickwork surface, basically when the masonry has experienced most of its early shrinkage and has dried well after proper curing. Shrinkage cracks in rendering/plastering can be minimized by using mortar for the plaster which is less rich and perfect for providing resistance to durability and abrasion.

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4.2 Thermal Movement: All building materials expand on heat and contract on cooling. Thermal movement in the components of building structure creates cracks owing to tensile of shear stresses. But again, the scale of movement depends on their molecular structure and other properties. Thermal changes are one of the strongest causes of cracks in buildings and demand attention. Daily changes in temperature are more rapid and have a higher damaging effect than the seasonal changes, which are regular. On the other hand, in seasonal changes, the pressure gets relieved to a large extent on account of creep. 4.3 Elastic Deformation: Unevenly loaded walls suffer huge variation in stress in different parts which causes cracks in walls. When two construction materials (masonry, concrete, steel, etc) with wide different elastic properties under the effect of load are built together, different shear stresses in these materials result in cracks at the junction. Dead and live loads cause elastic deformation in structural components of a building. The amount of deformation is dependent hugely upon the elastic modulus of the material, the magnitude of loading and dimension of the components. 4.4 Creep Movement: Gradual and slow time-dependent distortion of the concrete structure under constant loads is known as creep. It can generate extreme stress and lead to the development of cracks. Additionally, creep increases with increase in cement and water content, water-cement ratio and temperature. Added to that, pozzolans and admixtures tend to increase the creep. Also, the increase of temperature in the steel bars surges creep as well. It decreases with a rise in the humidity of neighboring atmosphere and age of building material at the time of loading. The mechanism of creep is still vague and not visibly understood. At low-stress levels, it is believed to be due to seepage and viscous flow and at high-stress levels, it can be due to micro cracking and inter-crystalline slip. 4.5 Chemical Reaction: Chemical reactions in building materials increase their overall volume and internal stress which results in cracks. The materials involved weaken due to chemical reactions. Carbonation in cement-based materials, sulphate attack on cement products, alkali-aggregate reaction, and corrosion of reinforcement in concrete are few of the most common types of chemical actions on building materials. 4.6 Foundation Movement and Settlement of Soil: Shear cracks happen due to huge differential settlement in the foundation. Structures constructed on expansive soils which are vulnerable to swelling on absorbing moisture and shrink on drying due to change in moisture content of the soil are highly prone to cracking.

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Shear cracks occur due to any of the following causes.  Unequal bearing pressure under different parts of the structure.  A low factor of safety in the design of foundations.  Bearing pressure being in excess of the safe bearing strength of the soil.  Local distinction in the nature of supporting soil.  These are serious cracks as they occur due to foundation movement of the corner and end of the building structure, hence demand special measures to prevent such cracks. 4.7 Cracking Due To Vegetation: The existence of any form of vegetation can be a reason of cracks in the walls of a building. This is mainly due to the expansive action of roots growing in the brick masonry or under the foundation. Simply put, the roots of trees set in the vicinity of a wall can create cracks in walls due to the growth of roots under foundation. The cracks occur in clay soil due to moisture contained by roots. 4.8 Permeability of Concrete: The deterioration process in concrete starts with the penetration of several aggressive agents and is a major cause of cracks on walls. Essentially, it dictates the capacity of concrete to survive weathering action, chemical attack, or any other process of deterioration. Hence, low permeability is the main factor to concrete resilience. There are several factors which control concrete permeability, water-cement ratio, curing, air voids due to deficient compaction, use of admixtures, micro-cracks due to loading, cyclic exposure to thermal differences, and oldness of the concrete. The permeability of cement mixture is a function of water-cement ratio given great quality materials, suitable proportioning and good construction practice. The permeability of the concrete is a straight function of the interconnection and porosity of pores of the cement paste. 4.9 Structural Design: Poor or bad structural design and specifications are another striking cause of the cracks in concrete works. The designer needs to consider all the environmental aspects which include soil investigations; this will enable the designer to come up with a proper robust design of the foundation. 4.10 Poor Workmanship: Inferior mixing of construction materials, like sand, cement, and aggregate cause cracks on the walls, slabs, beams, etc. Poor workmanship is normally a result of a lack of proper supervision, ignorance, negligence, carelessness, negligence, and many others or a combination of all these.

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4.11 Lack of Maintenance: It is crucial to always take good care of your house, and this can be done by doing regular maintenance works. This ensures the building structure is intact and it also adds to its lifespan. 4.12 Natural Forces: Earthquakes, tremors, winds, rains, flooding like the Kerala Havoc and many others can cause cracks in the buildings.

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5-Repairing & Maintenance of Iqbal Hall:After surveying the Iqbal Hall of NFC. Following repair and maintenance required to rehab the building. Pictures are attached for clear perspective. 2D perspective is attached with the report. 5.1 Efflorescence:In different parts of the building especially Washrooms area and surroundings, need repair of water bound treatment

5.2-Horizontal and vertical cracks: There is lot of horizontal and vertical cracks in Hall which is showing that structure plaster is not much viable.

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5.3 Penetration of Water due to unbound of foundation top:Rainy and overflow water of tank are continuous penetrating in the wall due to not taking of measures to stop. Construction of slab near foundation up to 3ft may stop this unsafe and harmful action.

5.4 Improper Disposal of 1st & 2nd Floor Sewerage. Disposal Of sewerage is major problem of building which is causing the damage to building aesthetics as well as causing efflorescence in building walls; the smell is also spreading nearby areas of the hall. Removal of extensive amounts of debris, garbage, waste, and unusable construction materials; sorting and reorganization of equipment.

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5.5 Wear & Tear :The whole building is required distempering as well as distemper base for its smoothness. The Aesthetics of building is old government building type. The outerside of building is Having Red Color. Previous color application may maintain its look as government which is quite positive for it.

5.5 Refurbishing Of Doors Wall joints:All doors are repaired but there post maintenance can’t be completed. Oiling and mechanism repair of doors, Creation of proper master key, creating new keys with duplicates for all missing keys for various locks in the building, installation of new key safes or The doors do not function well and are expensive to repair. They should one day be replaced by steel doors without the extensive glass component.

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5.6 Internet Box:Internet box in Iqbal Hall is totally destroyed due to improper maintenance. It required new boxes for better services. Replace these boxes with new one.

5.7 Electric socket:Electric socket in rooms as well as in washroom are totally damaged due to efflorescence which may cause a serious damaged for livelihood. Replace these sockets as soon as possible.

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Conclusion:Although we’ve heard it many times, nothing could be truer “an ounce of prevention is worth a pound of cure.” Preventative maintenance is the best way to keep your property in great shape. It also reduces the risk of unexpected repairs and improves it.

Reference: https://www.slideshare.net/muhammadsultanpervez7/types-of-cracks-in-building?qid=06194f9d-385d-4cf9-906db68b15ac8dde&v=&b=&from_search=1

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