The necessity of concrete antifreeze in winter construction

According to the practical work showed that low temperature and negative temperature environment on the cement concrete construction is very adverse. The environment temperature is low, may slow down of hydration reaction of cement, which affect the growth of cement concrete strength. According to the experiment it is concluded that: every 1 ℃ below the environment temperature, the hydration of cement to reduce about 5% ~ 7%, the hydration of cement within the range 1 to 0 ℃ activity dramatically reduced, hydration is slow. Generally when the environment temperature is less than. . . 3 ℃, the free water will begin to freeze, the temperature reached - Almost all around 10 ℃, the free water freeze into ice, causing the hydration and hardening of cement stop completely, which greatly influence the performance of the concrete. When the water is converted into solid ice, its volume increases about 9%, the internal stress of cement concrete, aggregate and the relative displacement of cement particles and water to the surface of the negative temperature internal migration, formation of ice in cement concrete polymers cause local structural damage. The density of water at 4 ℃ maximum, when the temperature dropped below 4 ℃, the actual volume of water has started to expand, for the new mix cement concrete cement hydrates formed by structure can cause damage. Experiments show that: the new pouring concrete early to suffer freezing will greatly reduce the ultimate strength, strength loss rate could reach 50% of the label design, even causes damage on the whole structure. But when suffering from frozen after cement concrete critical strength, ultimate strength of cement concrete loss is small, also the overall structural failure will not occur. In winter low temperature construction, therefore, can be a certain amount of cement concrete antifreeze added to concrete, cement to make concrete under negative temperature keep sufficient liquid, to continue the hydration of cement, when environment temperature into the right temperature, cement concrete strength can grow further, and reach or exceed the design label, to reasonably to improve the concrete performance. Therefore, cement concrete antifreeze in winter construction has played a very important role.