Understanding and Preventing Concrete Plastic Shrinkage Cracks
Ever noticed those random cracks that appear on a concrete surface? What causes them? How do you minimize those cracks? Get the answer to all these questions right here.
What are those cracks called and how do they form?
Those cracks are called Concrete Plastic Shrinkage Cracks and they may be parallel or appear randomly on a concrete surface when it is in the plastic state i.e. before concrete sets.
What causes Plastic Shrinkage cracks?
When water evaporates from the concrete surface, concrete tends to shrink and generate tensile stress. But being in the plastic state, concrete does not gain enough strength to resist this and hence it cracks. This generally occurs when the evaporation rate is more than 1 kg/m2/hr.
How to minimize the Plastic Shrinkage Cracking?
The best way is to minimize the evaporation rate just after finishing by spraying curing compound or water mist on the concrete surface
Remember, water ponding on the surface after the concrete is set will not help to prevent plastic shrinkage cracks
Using fibre or fibre cement like Duraguard Microfiber help to minimize the crack
Slower screeding rate and delayed trowelling can reduce the extent of plastic cracks