CASE STUDY ON BUILDING CRACKS AND ITS REMEDIAL MEASURES UBMITTED BY .SADHAM HUSSAIN 11117203 .RUPA MANIKANDA PRABU 11117202 .SANKAR 11117205 .ASHIK ELAHI 11117168 .SASI KUMAR 11117206 .ASIP ALI 11117170 NDER THE GUIDANCE OF
INTRODUCTIONCracks in the building are of comman occurrence in a buldingIt is due to exceeding stress in a building componentsCauses of the cracks are mainly by increase in live load and dead load, seismic load etc.,
CLASSIFICATION OF CRACKSracks can be classified into two categories viz.,tructural crackson-structural cracks
STRUCTURAL CRACKSt arises due to incorrect designs, overloading of structuralcomponentsxpenses cracking of foundation walls, beams and columns orslab etc.,
NON STRUCTURAL CRACKShey are due to internal forces developed in materials due to moisturevariations, temperature variation, crazing, effects of gases ,liquids etc.,hey can be broadly classified into vertical, horizontal, diagonal,smoothened cracks
MAJOR CAUSES OF CRACKS Movements of the ground Over loading Effect of gases, liquids and solids Effect of changes of temperature General causes such as vibrations
ovements of grounds verloadingue to mining subsidence, land verloading of the buildingslips, earthquakes, moisturechanges due to shrinkable soils. verloading of the building parts results in cracks
OVERLOADING FORCED MAY BE DUE TO External ( excessive wind/snow loads) Internal ( from heavy machinery etc.,)
EFFECTS OF GASES, LIQUIDS AND SOLIDSasesnly gases like Co2 ( carbon di oxide ) is likely to produce cracks.t causes Carbonation of porous cement productseads into an overall shrinkage crazing cracks
iquidsater is the most commonly used liquid when not taken care it can behazardousonstruction water i.e., that in the utilization of water during theconstruction process
EFFECTS OF WATERhysical(i.e. due to change in water content)hemical ( directly or indirectly affecting other materials)
GENERAL VIBRATIONSibrations can cause cracks in buildings only when their amplitudeof vibrations are high.part from vibrations caused due to earthquakes, the vibrationscaused due to heavy machinery, traffic, sonic booms are alsoresponsible for the occurrence of cracks in buildings.
THERMAL MOVEMENTll materials expand on heat and contract on cool.hermal movement in components of structure creates cracks dueto tensile of shear stressesne of the most potent causes of cracking in buildings and need
GENERAL PRECAUTION TO AVOIDING CRACKSefore laying up foundation, the type of foundation to be usedshould be decided based on the safe bearing capacity of soil.roviding R.C deep beam or an involved T-beam with adequatereinforcements to withstand the stress due to differential groundmovements. This method is expensive
onstruction operations such as cutting for roads drainages etc., closeto the structures should be avoided this will results in reduction ofsoil moisture with consequent shrinkage of soil beneath thefoundation of the structure.n buildings close to the water courses are noticed in many places
PLACING OF CONCRETEoncrete should not be placed in heavy rains unless suitable shelteris provided.o avoid segregation, concrete should not be dropped from aheight of more than 1m.
hile placing the concrete in R.C.C members the alignment of formworkshould not be disturbed.oncrete should be laid continuously to avoid irregular and unsightly lines.nternal surface of the forms either steel or wood should have evensurfaces and should be oiled so that the concrete may not stick to it
MATERIAL QUALITYggregate should be hard, sound, durable, non-absorbent andcapable of of developing good bond with mortar.ater shall be clean and free from alkaline and acid materials andsuitable for drinking purposes.
TEST TO BE CARRIED OUTlump test to be carried out for the control of addition of waterand workability.onsistency of concrete should also be tested.
LAYING TECHNIQUE AND CURING METHODoncrete should be laid in layers and should be compacted whilelaying with wooden tamping rods or with mechanical vibrators untila dense concrete is obtainedfter two hours of laying concrete, when the concrete has begun toharden, it shall be kept damp by covering with wet gunny bags orwet sand for 24 hours
EVALUATION OF CRACKSo determine the effects of cracks in the building.irst the cracks location and extent should be noted down for theadopting suitable methods of repair and the future problems dueto that cracks.
rack widths should be measured to the accuracy of 0.001 in(0.025mm) using a crack comparator.ovements should be recorded with movement sensors.ased on the reports from the location and width the suitablemethods is adopted
rack as narrow as 0.002 in can be bonded by the injection ofepoxy.poxy injection can alone be used to restore the flexural stiffness.or water retaining structure cracks it can be repaired by theautogenous healing.
REPAIRING OF CRACKSouting and sealing.titching.dditional reinforcement.ravity fillingrouting
ROUTING AND SEALINGouting and sealing of cracks can be used in conditions requiringremedial repair and where structural repair is not necessary.outing and sealing is used to treat both fill pattern cracks andlarger, isolated cracks.he sealants may be any of several materials, including epoxies,urethanes, silicones, polysulfide, asphaltic materials, or polymermortars
STITCHINGtitching involves drilling holes on both sides of the crack andgrouting in U-shaped metal units with short legs (staples orstitching dogs) that span the crack.titching a crack tends to stiffen the structure, and the stiffeningmay increase the overall structural restraint.
he stitching procedure consists of drilling holes on both sides ofthe crack, cleaning the holes, and anchoring the legs of the staplesin the holes, with either a non shrink grout or an epoxy resin-based bonding system
ADDITIONAL REINFORCEMENTS Conventional reinforcement-Cracked reinforced concrete bridge girders have been successfully repaired by inserting reinforcing bars and bonding them in place with epoxy . This technique consists of sealing the crack, drilling holes that intersect the crack plane at approximately 90º ,filling the hole and crack with injected epoxy and placing a reinforcing bar into the drilled hole
restressing steel-Post-tensioning is often the desirable solutionwhen a major portion of a member must be strengthened orwhen the cracks that have formed must be closed.dequate anchorage must be provided for the prestressing steel,and care is needed so that the problem will not merely migrate toanother part of the structure
GROUTINGortland cement grouting-Wide cracks, particularly in gravity damsand thick concrete walls, may be repaired by filling with portlandcement grout.his method is effective in stopping water leaks, but it will notstructurally bond cracked sections.
GRAVITY FILLINGow viscosity monomers and resins can be used to seal cracks withsurface widths of 0.001 to 0.08 in. (0.03 to 2 mm) by gravityfilling.igh-molecular-weight methacrylates, urethanes, and some lowviscosity epoxies have been used successfully.he lower the viscosity, the finer the cracks that can be filled.
DRY PACKINGrypacking is the hand placement of a low water content mortarfollowed by tamping or ramming of the mortar into place,producing intimate contact between the mortar and the existingconcrete.
POLYMER IMPREGNATIONonomer systems can be used for effective repair of some cracks.A monomer system is a liquid consisting of monomers which willpolymerize into a solid.he most common monomer used for this purpose is methylmethacrylate.
he procedure consists of drying the fracture, temporarily encasingit in a watertight (monomer proof) band of sheet metal, soakingthe fractures with monomer, and polymerizing the monomer
CONCLUSIONhe discussion on our project mainly focused on the cracks deals withfailure due to improper settlement of foundation and poorconstruction.y the following discussed remedies and instruction what we haveconcentrated helps to reducing the cracks and move on to the next levelin the construction.