What happens to concrete when it is subjected to freeze-thaw cycles without proper protection?

When concrete is exposed to freeze-thaw cycles without adequate protection, it can crack and deteriorate. This phenomenon occurs because water contained within the concrete expands when it freezes. If the concrete does not have sufficient air-entrainment or other protective measures, the expansion can exert significant internal pressure, leading to cracks and spalling as the surface of the concrete breaks away.

Additionally, repeated freeze-thaw cycles can exacerbate this deterioration, with the cracks allowing more water to enter the concrete matrix. As this water freezes and thaws, more damage can occur, compounding the initial deterioration. This understanding is critical for ensuring the longevity and durability of concrete structures, especially in climates that experience significant temperature fluctuations. The appropriate use of additives, such as air-entraining agents, and ensuring proper curing and sealing practices can help mitigate the effects of freeze-thaw cycling on concrete.