WHY CRACKS OCCURRED IN SLAB.

CAUSES OF CRACKS IN SLAB


1. Cracks due to Plastic shrinkage of concrete : When water dries up rapidly from the surface, plastic shrinkage occurs. As a result, the top surface of the slab dries more quickly than the bottom one that leads to its pulling apart. Weather conditions like wind and low humidity accelerate this process. The shrinkage can be avoided by keeping the surface moist.

2. Cracks due to sulfate attack : When the concrete is permeable and its comes in contact with water contains sulfate then it develops crack in slab. 

3. Cracks due to alkaline aggregates : When the aggregates and cement present in the concrete are not harmonious with each other, it causes some chemical reactions that leads to cracks.

4. Cracks due to steel corrosion : This cracks are acting at a slab parallel to reinforcement. The steel mesh inside the concrete catches rust on getting moist and coming in contact with air. This happens due to any of the above mentioned reasons when a crack on the slab surface develops and air and water seeps in.

5. Cracks due to Overloads : Concrete is designed to withstand only a limited amount of load like dead load, live load etc.. If it exceeds that limit, cracks are developed in slab.

Other reasons for behind cracks occurring in slab.

  • Crack formed due to compromises in concrete quality.

  • The mixture of  concrete was not mixed well.

  • The water and cement ratio in concrete was not as per design.

  • The Spacing between main and distribution bars are more.

  • Concrete cover was not sufficient according to given standards.


  • Insufficient amount of steel reinforcement.


  • Less curing provided.


  • When formwork of the concrete was not fully tight.
  • Improper proportion of concrete.


  • Settlement of soil if slab laid directly on ground.


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