Will the temperature drop below zero and freeze after 24 hours of concrete pouring on the ground?

It will freeze. When the daily average outdoor temperature is lower than 5℃ for five consecutive days, the construction process is called winter construction. In winter, the temperature drops. In many areas, the temperature is below 0℃ (negative temperature), and the moisture contained in soil, concrete, mortar, etc. Building materials are brittle due to freezing, which brings many difficulties to building construction.

When the average temperature is lower than 5℃ or the daily minimum temperature is lower than -3℃ for five consecutive days, winter construction measures should be taken to ensure the engineering quality. 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.

When backfilling temporarily unused pipelines and their sites during the freezing period, the content and particle size of frozen soil blocks are not limited, but they should be properly handled after melting.

Earthwork backfilled under indoor ground cushion shall not contain frozen soil, and shall be compacted (compacted) in time and verified by tests. After the completion of filling and before the ground construction, anti-freezing measures should be taken.

Extended data:

Under the condition of negative temperature, stress control method or cold drawing rate control method can usually be used for cold drawing of steel bars. The stress control method should be adopted when the prestressed tendons of prestressed concrete structures are cold drawn. However, the method of controlling the cold drawing rate is not suitable for the cold drawing of hot rolled steel bars that cannot be divided into batches.

The minimum temperature of steel bar welding should not be lower than -20℃. At the same time, in snowy days or when the wind speed at the welding site exceeds level 3, the welded steel bar joints should have snow-proof and windproof measures, and it is forbidden to contact with snow and ice, resulting in excessive cooling.

The negative temperature arc welding of steel bars should adopt the method of layered temperature control. The covered electrode and welding current should be selected according to the brand, diameter, joint form and welding position of steel bars, and the interlayer temperature of hot rolled steel bars should be controlled between 150~350℃.

Air entraining agent can be mixed into concrete in winter, the purpose of which is to use a large number of evenly distributed micropores in concrete to slow down the destruction of capillary structure in concrete by freezing pressure of free water and improve its frost resistance, but the increase of air content will affect the compactness and strength of concrete and should be controlled.

Baidu Encyclopedia-Winter Construction