A.Don Marsh responds: Concrete cracking is caused by stresses due to drying shrinkage, temperature change, or applied loads.

Drying shrinkage. Drying shrinkage is an inherent and unavoidable property of concrete. During the setting and hardening stages, excess mixing water in the concrete evaporates, causing the concrete to dry from the surface inwards. Shrinkage begins near the surface, pulling at the moist inner portions of the concrete, which are restrained by...

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