Why should concrete not be poured on frozen ground?

Concrete should not be poured on frozen ground primarily because it will not cure properly. When concrete is placed in low temperatures, particularly on frozen ground, the water in the mix can freeze before the hydration process fully occurs. Hydration is the chemical reaction between water and cement that forms the strength and stability of the concrete. If the concrete freezes before it has properly set and cured, it can compromise the integrity and durability of the final product, leading to issues such as low strength and reduced resistance to environmental stresses.

Additionally, improper curing can also result in a higher susceptibility to cracking and other structural failures over time. Thus, pouring concrete on frozen ground is a critical concern and is generally avoided to ensure the longevity and quality of the concrete work.