Which condition is favorable for reducing shrinkage cracks during concrete curing?

High humidity is favorable for reducing shrinkage cracks during concrete curing because it helps to maintain moisture levels in the air and conversely in the concrete mix. When humidity is high, the evaporation rate of water from the surface of the curing concrete is reduced. This is crucial because excessive evaporation can lead to rapid drying of the concrete, which contributes to the formation of shrinkage cracks as the material shrinks while curing.

In contrast, lower humidity or conditions with high wind lowers the amount of moisture in the air, leading to faster evaporation from the concrete surface. High temperatures can exacerbate this effect further, increasing the likelihood of rapid drying and the potential for shrinkage cracks. Therefore, maintaining a damp environment through high humidity is a key factor in successfully curing concrete and minimizing shrinkage-related issues.