Refractory castable structure

Refractory castables are composed of three parts: binder, aggregate, and admixture, sometimes with the addition of coagulants.
Refractory aggregate is the main body of refractory concrete, and various refractory materials (such as clay, high alumina, silicon, magnesium, etc.), calcined clinker, or various waste bricks can be used as refractory aggregates to a certain extent. The particle size of aggregates has a significant impact on the quality of products, so in addition to certain limitations on the size of aggregate particles, there are also certain proportion requirements in terms of quantity. Refractory aggregates are equivalent to crushed stones and sand of ordinary building concrete. In the ingredients of refractory concrete, aggregates generally account for 70% to 80%. Among them, coarse aggregate (5-20mm) accounts for 35-45% of the ingredients; Fine aggregate (0.15-5mm) accounts for 30-35%.
The adhesive material plays a role in bonding and hardening, giving the product a certain strength. The types of binders that can be used include ordinary Portland cement, bauxite cement (high sales cement), magnesium cement, water glass, phosphoric acid, etc. To ensure that the concrete has sufficient fire resistance (the binder is a flux at high temperatures, and the more it is used, the lower the fire resistance of the concrete), and to reduce volume shrinkage during use, the amount of binder should be as small as possible, usually 10% to 25%, and it is hoped that the binder and bone materials cannot generate too many low melting substances.
Some refractory concrete (such as phosphate refractory concrete) must also add a small amount of coagulant in the ingredients to accelerate the hardening and consolidation of the concrete.
In order to improve the performance of refractory concrete, such as increasing its strength during the heating process and reducing volume shrinkage, a 10% to 25% admixture is often added. The raw material of the admixture is the same as the aggregate, and it is a finely ground refractory clinker powder, with a fineness of 70% to 80% below 0.088mm.