High-early strength concrete must be maintained at a minimum temperature of what in moist conditions?

High-early strength concrete is designed to achieve significant strength within a short period, and proper curing at adequate temperatures is critical to ensuring this strength development. In moist conditions, maintaining a minimum temperature of 50 degrees Fahrenheit for 3 days allows the hydration process to proceed effectively, helping the concrete to attain its desired early strength without the risk of freezing or other adverse conditions that could impair its development.

This specific temperature and duration help to minimize issues such as cracking or delayed setting times, which can occur if the concrete is not kept at an adequate temperature. This practice aligns with guidelines from industry standards and codes that aim to ensure the durability and integrity of the concrete structure being built.