1. When the average temperature of the day is lower than 5℃, the water spraying natural curing method shall not be adopted.

2. The strength of concrete before freezing should not be less than 5MPA.

3. When the concrete is cooled to 5℃, or when the temperature difference between the concrete surface and the outside is not more than 20℃, the formwork and insulation layer can be removed, and the formwork should be covered in time after formwork removal to make it cool slowly.