Generally, the ambient temperature is required to be not lower than 5 degrees Celsius, but this refers to the short-term temperature, which generally refers to 1-2 days. 1-2 days, 0 degrees can also be used for construction. As long as it is not lower than 0 degrees, but once it is lower than 0 degrees, construction cannot be carried out. Because there is water in cement, once the temperature is below 0 degrees Celsius, liquid water will solidify into solid ice.
Because winter construction needs thermal insulation covering, which consumes a lot of heat energy and increases the project cost, we should try to avoid site leveling, foundation treatment, outdoor decoration, roof waterproofing, high-altitude pouring concrete and other projects. For projects that have to be constructed in winter, winter construction measures should be formulated according to local conditions to keep abreast of temperature changes.
Extended data:
If the concrete is attacked by negative temperature during the setting process, the hydration of cement is hindered, and the free water in it begins to freeze, and the volume increases by 9%, which is in danger of freezing and cracking concrete, seriously affecting the quality of concrete. After the concrete is first frozen and then cured at room temperature, its strength can still be increased, but it cannot be restored to the unfrozen level; And the earlier it is frozen, the more difficult it is to recover the later strength.
In order to prevent early frost damage, it is usually required that the temperature of concrete at the beginning of curing should not be lower than 5℃. Because the heat storage method relies on the hydration heat of cement and the heat of concrete mixture itself to reach the predetermined temperature under the condition of heat preservation, its curing temperature needs to be raised above 10℃. Therefore, measures must be taken to prevent the heat from emitting too quickly during the mixing, transportation, pouring and tamping of concrete.
Baidu Encyclopedia-Winter Construction