In refractory castables, porosity can affect all performance indicators. Because the apparent porosity and bulk density are important quality criteria for controlling castables.

The effect of apparent porosity on the thermal expansion performance of castable largely depends on the distribution of porosity in the castable, and is not closely related to the size of apparent porosity.

After heat treatment, refractory castables are combined with ceramics. Thermal expansion is the change in the length and volume of the product that increases with temperature. The thermal expansion of castables is directly related to thermal shock resistance and volume stability, and thermal expansion directly affects thermal shock performance.

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The thermal expansion coefficient of refractory castable is close to that of the castable matrix, and there are many factors related to the strength of the bonding between the thermal expansion coefficient and particle size. The factors that affect the thermal expansion coefficient of castable include chemical composition, mineral composition, and the porosity of the product. The porosity has a significant impact on the thermal expansion performance of the castable. Pores are dispersed in a continuous solid matrix, and the castable is a composite material of pores and solid phases.

Thermal shock resistance is the ability of castables to resist rapid temperature changes without being damaged. Resistance and stability to temperature changes during rapid cooling and heating. During the use of refractory castables, they are often affected by rapid changes in environmental temperature, and frequent temperature changes can cause cracks and peeling of the refractory castables.

The higher the thermal expansion rate, the worse the thermal shock resistance; The higher the thermal conductivity, the better the thermal shock resistance. However, the particle size synthesis, density, size and distribution of pores, and resistance to thermal shock in refractory castable raw materials have a significant impact, and thermal shock stability cannot be determined solely by porosity.