For how long must concrete be protected from freezing after placement?

Concrete must be protected from freezing for at least 12 hours after placement. During this period, the hydration process is critical for the strength development of the concrete. If the concrete temperature falls below freezing, it can impede the hydration reaction and lead to incomplete cement hydration, which ultimately compromises the strength and durability of the concrete. The first 12 hours are particularly crucial because this is when the concrete is still in a plastic state and highly vulnerable to temperature fluctuations. Ensuring proper temperature control and protection from freezing during this timeframe is essential to maintain the integrity of the concrete mix. This understanding of concrete's behavior under cold conditions is vital for inspectors and workers involved in concrete construction to ensure long-lasting results.