The Relationship between the Strength of Refractory Castables and Refractory Cement

Refractory castable is an essential unshaped refractory material among refractory materials. It is widely used for advantages such as convenient construction and saving manpower. To ensure that the refractory castable is more suitable for kiln smelting during actual use, its Hardness and refractory resistance are both important parameters of refractory materials. If the hardness does not meet the requirements, it will be difficult to provide a good working environment for the kiln. The proportion of cement in the refractory castable is the key to the hardness of the refractory castable. Although refractory cement affects the hardness of refractory castables, it does not mean that the greater the proportion of refractory cement, the better the strength! This understanding shows that there is insufficient understanding of refractory castables. Next, let’s take a closer look.

Introduction to the strength-hardenability of refractory castables:

Refractory cement is also called aluminate cement. When it is mixed with refractory aggregate, powder, and water, under the action of the cementing agent, it does not need to be calcined at high temperatures. It can achieve chemical or physical results if it meets its specific requirements. The combination results in the hardening of the refractory material and its high strength. This process is called hardening. There are three main types of hardening, which are introduced in detail below.

1. Water glass is an air-hardening binder. Realizing its hardening strength requires a dry air environment, but its refractoriness and load softening point are low. It is suitable for applications below 1000°C that require relatively high strength, good wear resistance, and resistance to acid erosion parts, but cannot be used in locations where water or steam is often affected.

2. Phosphate is a thermosetting bonding agent. Its hardening strength can only be achieved after being treated at a certain temperature. Its characteristic is that it does not harden and consolidate at room temperature. To solidify and have a certain strength, a coagulant needs to be added. It hardens and consolidates at 500°C, and the strength also increases. However, at about 800°C, low strength at medium temperatures is its disadvantage, and then the strength increases with temperature. This kind of castable has good high-temperature performance, wear resistance, slag resistance, and rapid cooling and heating resistance, and can be used at temperatures of 1400-1600°C.

3. If the refractory cement content in the refractory castable is too high, it will cause a certain proportion of water to be added to react after the binder is added to harden. Only in this way can the castable form a certain strength during condensation and hardening, we can this kind of refractory castable is called hydraulic.

Refractory cement is the main factor affecting the strength of refractory castables. If the amount of cement is not added correctly or the amount of cement is too small, the strength of the castables will be less than ideal. Therefore, the refractory cement content in the castables must be proportioned through reasonable machine mixing and cannot be added casually.