Which practice helps reduce moisture loss in hot weather concreting?

• A. Misting slab with water prior to casting
• B. Use sealed forms
• C. Do not cure
• D. Increase cement content

Answer: (A)

In hot weather concreting, controlling evaporation from the fresh concrete is crucial to prevent plastic shrinkage cracks and premature drying. Misting the slab with water before casting creates a damp substrate, which lowers the suction that the concrete would otherwise impose on the surface and reduces the rate at which moisture is lost once the concrete is placed. This helps keep more moisture in the mix during the early hydration period and promotes better curing conditions.

Sealed forms mainly affect moisture loss through the sides but don’t address the rapid evaporation from the exposed top surface after placement. Not curing allows moisture to escape unchecked, worsening drying and cracking, and increasing cement content raises heat and shrinkage risks rather than mitigating moisture loss.