At what temperature can't concrete be poured?

When the average temperature of the day is higher than 35 degrees, measures should be taken to reduce the temperature of concrete entering the mold in summer construction, which should not be higher than 35 degrees.

The average daily outdoor temperature is below 5 degrees for five consecutive days. At the beginning of winter construction, measures should be taken to ensure that the temperature of concrete entering the mold is not lower than 5 degrees.

There is no clear stipulation that concrete should not be poured below the minimum temperature, but the minimum specification of antifreeze in Chinese specifications is-15℃, and its service limit temperature can reach -20℃. Judging from the pouring effect or concrete strength guarantee, it is not suitable for construction below-15℃.

Because the temperature is set according to what construction method you use, if the construction period is tight, you don't have to consider how low the temperature is when using the greenhouse method.

Extended data:

During winter construction, we should keep close contact with meteorological and hydrological departments, grasp the weather changes in time, and take corresponding preventive measures according to the weather changes in time to ensure the construction safety and smooth implementation of construction operations. In the process of construction, when the construction site changes, the construction plan and corresponding safety measures should be supplemented in time according to the changes.

Before winter comes, it is usually necessary to cover the construction operation surfaces such as formwork and steel bars with plastic film. For the processed steel bar, a wooden mat should be placed below to avoid the contact between the steel bar and frozen soil and clay, and to prevent the steel bar from rusting.

In case of rain and snow, the snow on the surface of the steel bar should be cleaned in time after snow, and the snow in the formwork (on the formwork) should also be cleaned up. However, if it is difficult to clean up sundries such as rain and snow, tools such as heaters, vacuum cleaners and gasoline blowtorches should be used for comprehensive cleaning.

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.

Baidu Encyclopedia-Winter Construction