Effect of aggregate and powder content on the performance of refractory castable

Aug 14,2017
Refractory castables can be prepared with a variety of refractory powder and aggregate, but with neutral or acidic, weakly alkaline materials most appropriate. Refractory powder and aggregate is a refractory castable matrix material, its variety, dosage, fineness and particle size of the refractory castable properties have a greater impact, must be based on the requirements of a reasonable choice, to make the best use.
Refractory powder is the most important component of phosphoric acid refractory castable, and it reacts with the cementing agent to produce physical and chemical changes, which directly determine the performance of refractory castables. The compressive strength of the refractory castable increases with the increase of the aluminum content of the powder. However, when the temperature is about 1400 ℃, the grade is low, and the strength is high. What softening temperature increases slightly with the amount of aluminum in the powder. But the change in the post-burning line, the apparent porosity of the bulk density and the impact is not obvious.
In the phosphoric acid and refractory castables, there must be a sufficient amount of powder to wrap the surface of the particles, and react with the cement to form a strong combination of refractory castables have better performance. When ensuring a certain degree of ease under the premise of excessive powder, the amount of cement should also be a corresponding increase in the refractory castable
Performance is unfavorable; powder too little, although the amount of cement is reduced, but the surface of the refractory aggregate is not wrapped all the powder, cement is not strong, the structure of transport, so the strength decreased.

Powder fineness also has a direct impact on the performance of refractory castables. In general, the compressive strength increases as the specific surface area of the powder increases. Because the finer powder, the greater the surface area, the better the activity, so the more easily react with the cement. Therefore, for the phosphoric acid and refractory castable powder fineness requirements: less than 0.088mm should not be less than 85%. Generally do not use refractory mud for powder, but not in the powder mixed with other impurities. Refractory aggregate is also an important component of refractory castables, from the role of skeleton, accounting for about 70% of its total. The effect of refractory aggregate on the performance of refractory castable is different, and the grade of aggregate is different.