Cracks In Buildings - Thermal Crack

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Preetham Granite M.D addressed the gathering of engineers (Association of Madurai Civil Engineers) on Cracks in Buildings - Causes & Remedies at Hotel Weshtern Park ( 01.09.2016).

Principal Causes of cracks in buildings

* Thermal stresses

* Elastic deformation

* Chemical Reaction

* Foundation movement and settlement of soil

* Moisture movement

* Vegetation

THERMAL CRACK:

Materials expand on heating and contract on cooling. But magnitude of variation depends on materials.

When there is restraint to movement of structure, internal stresses develop, resulting in cracks due to tensile or shear stresses.

Extreme cases, thermal stresses may exceed those of loading.

Thus thermal movement is most potent cause of cracking in buildings and needs serious attention.

Thermal coefficent of concrete is twice that of brickwork.

Drying shrinkage of concrete is 3 to 4 times that of brick masonry.

Immediate construction of parapet wall Parapet wall does not have self weight to counter shear force by concrete,

Thermal movement depends on number of factors.

Temperature variation,

Dimensions,

coefficient of thermal expansion,

Thermal conductivity.

Coefficient of thermal expansion Colour of surface Dark colours and highly textured materials have lower reflectivity than light coloured and soft texture.