Repair of Cracks in Brickwork in Building
Cracks occur in walls due to differential movements caused by temperature, settlement of foundation,shrinkage.,etc.From the nature of the cracks,we can infer the seat of movement.A line drawn normal to the cracked line will intersect the seat of settlement as shown below.
Any leakage od drains and consequent softening of soil or other types of settlement or movements can be the cause of these cracks.
Cracks in Masonry due to various causes
1 = Crack due to settlement of corner
2 = Crack under RC Slab due to lifting up of corners in two way slabs
3 = Cracks due to settlement of column C
4 = Cracks below slab as a result of the movement due to temperature effect
5 = Crack with larger width at top due to heaving of centre as occurs in Black Cotton Soil
The first step before repair of cracks is to find the cause of the cracks and try to remedy the cause.For example,if the cause is due to foundation movement,it is worthwhile to proceed as follows.
- If there is any leakage of drain,gulleys,manholes,it can soften the foundation soil and cause differential settlement.Such leakage should stopped.
- In clayed soils,the foundation can be strengthened (for example, by plastering the brickwork below the ground level which might not have plastered).In more serious cause,the foundation soil can be improved by lime injection or some other means.Otherwise, the foundation itself can be strengthened by underpinning.
The cracks in brick walls can be repaired by the following methods:
1. If the cracks are less than 1.5 mm in width,they are generally filled up with putty (made at site or commercially avalible) and painted.
2. Cracks which are wider than 1.5 mm but are not very serious are repaired by rakin them out to about 25 mm and refilling with 1 cement, 2 lime, 9 sand mortar or preferably with other patented crack-filling compounds available in the market.Separate types of elastic crack-filling compounds one suitable for small cracks in the form of paint and another suitable for large cracks (in the form of a semi-soild paste) – are available for filling the cracks,These are superior to Portland cement mixes.
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