Traditional Culture Encyclopedia - Weather forecast - How many degrees below zero will cement fail when it is used?

How many degrees below zero will cement fail when it is used?

About zero will be unfavorable to cement hardening, but it is not absolute. It should be noted that to prevent freezing and keep warm, it should be possible to build a house in a particularly cold area.

The powder exterior wall can be used as the ground in a few days at high temperature, that is, 3 or 5 days. The interior wall will not be affected.

Stop working below zero as much as possible. When the temperature is above-10℃, cement antifreeze is added to the concrete, and 3% ~ 8% of the cement mass is added according to different temperatures. The temperature is below minus 10 degrees. Don't say that.

Portland cement production technology shows that limestone and clay are the main raw materials in cement production. The raw materials are crushed and ground into raw materials, and then sent to a cement kiln to be calcined into mature materials, and then ground together with a proper amount of clinker gypsum (sometimes additives or additives).

Extended data:

The drying method usually adopts a closed-circuit operation system, that is, the raw materials undergo fine grinding, separator, coarse grinding and grinding, and the equipment used in the drying and grinding process is carried out simultaneously with most materials, such as barrel grinding, unloading grinding and roller grinding. Wet process usually adopts open-circuit systems such as tube mill and rod ball mill, and there is no backflow through the mill, but there are also closed-circuit systems with classifier or arc screen.

High temperature dehydrates the crystal water in gypsum and turns it into slurry, losing the ability to adjust the setting time. Pseudocoagulation is related to many factors. It is generally believed that the main reason is that the internal temperature of the mill is high during cement grinding, so that gypsum dihydrate is dehydrated into gypsum hemihydrate. When cement is mixed with water, gypsum hemihydrate quickly reacts with water to form gypsum dihydrate, forming a needle-like crystal network structure, which makes the cement slurry solidify.

In addition, the rapid growth of gypsum potassium produced by adding high alkali to some cement and potassium sulfate and gypsum dihydrate will also cause false solidification. False coagulation is different from rapid coagulation, and its heat release is small. After strong stirring, the plasticity of the slurry recovered and reached normal coagulation, and the strength was not affected.

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