Refractory Bricks

What are the reasons for the low cement castables to be easy pulverization?

Jul 15,2019

After the construction of the low cement castable, the green body is prone to damage, and some of the surface is powdered and peeled off. If the time is long, the green body may lose the bonding strength and collapse. Henan Rebar New Materials Co., Ltd. summarized the following reasons:

After the production of low-cement refractory castables, the gas is naturally exhausted within 24 hours, and the surface is slowly hardened. After three to five days, the skin peeling phenomenon occurs, and the powder is peeled off by hand pressing.

First, caused by alkali reaction

The soluble alkali in the castable is hydrolyzed, reacts with carbon dioxide in the air to produce carbonate, and the cement hydrates, and the two will continue to react. Continuous decomposition of calcification. As long as there is cement hydration product, the above reaction will be cycled, the product will continue to decompose, and the castable body will be damaged from the inside and outside.

Second, the temperature and humidity are large

The higher the curing temperature, the easier it is to wet the pores in the castable body. Under wet conditions, the dissociation of soluble alkali in the castable is easier.

Third, the density of the blank is low

When the density of the green body is low, the porosity increases, and water and carbon dioxide in the air are more easily diffused into the green body to pulverize the green body.

Fourth, too much water

The amount of water added is good, but it has side effects on the initial strength and density of the green body, and it is easy to cause hydration reaction, and the surface of the green body is pulverized.

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