DIFFERENT SOURCES OF CRACKS IN CONCRETE:
Cracking is one of the most common problems in concrete and it should be avoided seriously. Different causes of cracks in concrete are described below.
Shrinkage is one of the major causes of cracking in hardened concrete. In drying shrinkage, the volume of concrete is gradually decreased and if the component is restrained against free movement, tensile stresses are developed which causes cracks.
2. TEMPERATURE CHANGES:
The temperature variation in concrete results in the differential volume change. When the tensile strain capacity of concrete exceeds due to the differential volume change, it will crack.
3. CHEMICAL REACTION:
Due to the alkaline nature of cement, it reacts with the carbon dioxide (CO2) present in the atmosphere resulting in an appreciable increase in the volume of the materials which finally leads to cracking.
4. POOR CONSTRUCTION PRACTICES:
Poor construction practices such as adding excessive water to the mix, lack of curing, poor compaction, using low-grade materials, unreasonable placements of construction joints etc. are also responsible for cracking in concrete.
5. ERRORS IN DESIGN & DETAILING:
Errors in design and detailing such as an inadequate amount of reinforcement, improper design of foundation, precast members and slabs, improper selection of materials, lack of sufficient contraction joints etc may result in excessive cracking.
6. CONSTRUCTION OVERLOADS & EARLY FORMWORK REMOVAL:
The load induced in the structure during construction can also lead to cracking especially at the younger stage when the formwork is removed earlier.
7. ELASTIC DEFORMATION AND CREEP:
The different components of the building such as wall, column, beam. slab etc undergo elastic deformation when loaded. The deformation of concrete depends on the type of building materials used in the construction such as bricks, cement concrete blocks etc. This unusual deformation of concrete results in cracking.
8. CORROSION OF CONCRETE:
The corrosion of steel develops a huge amount of iron oxides and hydroxide that have a much greater volume than the volume of metallic iron. Hence the volume is increased and cracks.