The surface of concrete after forming appears white gray, the phenomenon of large collapse is usually the result of a variety of factors. The following is an analysis of the possible causes of this problem:
Temperature influence. In winter, the temperature is low, especially when the temperature is below 5°C, the concrete surface is prone to white gray, mainly because the hardening reaction of the concrete at low temperatures is affected, resulting in abnormal color.
Fly ash content is too high. When the amount of fly ash added to the concrete is too much, the surface of the concrete may show a gray color, which is a reflection of the color of fly ash.
Too much calcium and limestone. When the content of calcium ions and limestone in concrete is too high, it will lead to white mud condensation on the surface of concrete. At the same time, this may also lead to the problem of increased slump loss, and too high alkali ions are also a reason for the surface whiteness.
The influence of heat of hydration and water demand. There is a close relationship between concrete slump and hydration heat and water requirement, and the interaction between the two may lead to the increase of concrete slump.
Influence of admixture composition. When the admixture contains more nano components, the concrete may appear white gray and collapse.
Influence of early strength agent. When early strength agent is added to the mixture of admixtures, abnormal color and collapse of concrete surface may also be caused.
The effect of antifreeze. When antifreeze is added to concrete, it is possible to cause a similar situation, resulting in abnormal color of the concrete surface and increased collapse.
The effect of expansion agent. When too much expansion agent is added to the admixture, the concrete may have similar problems, such as abnormal surface color and increased collapse.
