The role of adding high-alumina cement to refractory castables is mainly for binding. The higher the alumina content, the higher the refractoriness. The lower the alumina content, the higher the calcium oxide content. Add high-alumina cement as a binder to de-mould the refractory castable within 24 hours. High alumina cement will affect the fluidity of refractory castables, construction time, and de-molding time. If used improperly, it will have a great impact on the construction of refractory castables.
Introduction of High Alumina Cement
The content of aluminum and calcium in high-alumina cement is different, including CA-50, CA-70, and CA-80. CA-50 high alumina cement is yellow cement, and its raw materials are bauxite and limestone. CA-70 high-alumina cement has fewer impurities and has better setting characteristics and refractoriness than CA-50 refractory cement. It is a binder used in the preparation of low-cement refractory castables. The aluminum content of CA-80 high alumina cement is 80%, and it contains α-AL2O3 micro powder, which is used as a binder in high-grade refractory castables. Because CA-70 and CA-80 have high alumina content in cement, they can improve the weak links of the set speed and medium temperature strength of refractory castables. And because of the low calcium content, the later strength of the refractory castable has a longer service life.
Precautions for Adding High-Alumina Cement to Refractory Castables
CA-50 high alumina cement is generally used in medium and low-grade refractory castables. CA-50 cement has the weakest strength at 800℃. Therefore, if the temperature of the furnace lining is 800℃, it is also the most embarrassing temperature. The temperature is not high, instead of using general refractory castables, low cement castables must be used. Low-cement castables have low calcium content, good strength at mid-temperature, and good strength in later use.
CA-70 and CA-80 high-alumina cement have high aluminum content and low addition ratio, so they are used in low cement refractory castables. It not only enhances the strength of refractory castables but also reduces the calcium content of refractory castables. It can also improve the use of medium temperature strength.
Therefore, adding high alumina cement to refractory castables depends not only on the combination. It should also be noted that the CA-50 high-alumina cement or the high-alumina cement of CA-70 and CA-80 should be added according to the use temperature.
What is the Effect of Adding High Alumina Cement to the Preforms?
Some refractory manufacturers call preforms shaped refractories, while others call them unshaped refractories. The combination of high-alumina cement is inseparable in the production process of precast parts. High alumina cement has a high hydraulic active coagulation effect, and the hardening time usually does not exceed 1 day. High alumina cement is the main source of early strength of refractory preforms. High-alumina cement plays a role in hardening the cement as soon as possible, and in high-grade high-alumina cement, it also hardens, and it also plays a vital role in the later strength.
The high-alumina cement used to make the preform determines the initial setting and later strength of the preform. High alumina cement plays an important role in the production of precast parts.
For the production of precast parts, different grades of high alumina cement are added according to different grades of precast materials. It is necessary to consider both the early setting time and later strength.
In summary, high alumina cement is very important for refractory castables and precast materials. Regarding the setting time of refractory castable preforms, early setting time. The difference between silicate combined castable and aluminate combined castable. The early setting time of silicate combined castable shall not exceed 45 minutes, and the final setting time shall not exceed 360 minutes, which is 6 hours.
Rongsheng Monolithic Refractory Manufacturer
Rongsheng is an advanced, fully automatic, environmentally-friendly monolithic refractory Manufacturer, with a production line annual output of 80,000 tons. We mainly provide high-quality refractory lining materials for various thermal furnace equipment, including various types of refractory bricks and various proportions of refractory castables, refractory plastics, refractory ramming materials, etc. If you need to buy various refractory products such as refractory concrete, refractory mortar, refractory castable, refractory cement, etc., please contact us. We will provide you with services according to your specific requirements for the working conditions of the refractory lining of the thermal furnace.