Refractory castables are usually classified according to the size of the porosity, the selected bonding agent or bonding method, the type of aggregate and the construction method.
According to the porosity, it can be divided into dense refractory castables and insulated refractory castables.
Classified by bonding method, refractory castables can be divided into hydration combined refractory castables, chemically combined (including polymerization combined) refractory castables, hydration and polymerization combined refractory castables (typically represented by low cement combined refractory castables) and agglomeration Combine four types of refractory castables.
According to the special effects of binding agents and certain materials, they can be classified into the following 7 categories:
(1) Clay combined with refractory castable;
(2) Ultrafine powder (such as silica fume, etc.) combined with refractory castable;
(3) Cement bonded refractory castable;
(4) Chemically bonded refractory castables;
(5) ρ-Al₂O₃ (hydrated Al₂O₃) combined with refractory castable;
(6) Low cement combined refractory castable;
(7) Silicon and aluminum sol (sol-gel) combined with refractory castables.
According to the combination of raw materials, refractory castables can be divided into oxide refractory castables, non-oxide refractory castables and composite refractory castables. Oxide refractory castables can be subdivided into non-alkaline refractory castables and alkaline refractory castables.
According to the construction method, refractory castables (body) can be divided into vibration construction type refractory castables and self-flowing refractory castables.
According to whether the refractory castable contains cement content or CaO content, it can be simply divided into four categories: ordinary refractory castable, low cement refractory castable, ultra-low cement refractory castable and cement-free refractory castable.
Refractory aggregate is the part of +0.88mm or +0.1mm in the refractory castable. It is the main material in the structure of the refractory castable and acts as a skeleton. Refractory powder is the matrix part of the castable. After high temperature, it connects or cements the refractory aggregate to fill the pores, achieve close packing, ensure the fluidity and volume stability of the mixture, and promote sintering, and finally improve Density, strength and high temperature performance of refractory castables.
Therefore, the performance of refractory castables mainly depends on the raw materials used in the formulation. In order to improve the performance of refractory castables, most manufacturers have used high-purity raw materials, homogeneous materials, fused materials, synthetic materials, transformation materials and Superfine powder.