What is the effect of temperature on concrete pouring?

The temperature of concrete entering the formwork is 5-30℃, and the temperature of formwork is 5-35℃. Below or above this temperature range will be affected. Specifically, at low temperature, the fluidity of water slows down or even freezes, which will hinder the mixing process of concrete and even block it, which is not conducive to its pouring in the form of mud.

At high temperature, the evaporation rate of water is accelerated, which makes the concrete lose water faster and the dry board agglomerate, which is not conducive to watering.

With the increase of unit water consumption, due to high temperature and large evaporation, the water consumption for mixing concrete will inevitably increase, otherwise the quality of concrete will be affected. Machinability is reduced. Due to the large evaporation, the slump loss of concrete during transportation and pouring is large, which will reduce the workability of concrete. Due to the high temperature, the hydration of cement will be accelerated, and in severe cases, false coagulation will occur, which will affect pouring.

It will raise the temperature of concrete. Because of the high temperature, the internal hydration heat is not easy to dissipate, which will increase the internal temperature rise of concrete. If it is not properly maintained, it is easy to cause surface cracking due to evaporation and high temperature. Especially mass concrete, we must attach great importance to cooling.

Extended data

At low temperature, the slump of concrete generally does not exceed 100mm, so as to minimize bleeding and set as soon as possible. At low temperature, bleeding will stay on the surface of commercial concrete for a long time, which will affect the normal plastering process. The untreated surface of facing concrete is one of the main reasons for the surface defects of concrete.

If the surface exudation is forced into concrete during plastering, the surface water-cement ratio will increase, resulting in the decrease of strength, air content and surface impermeability. The design of concrete materials should minimize bleeding. If bleeding occurs during construction, it should be removed before plastering.