Used In cement and steel industries .Resistant to high temperatures above 80 Alumina, have a very high strength values. CEMENT and LIME rotary klin firing hoods, STEEL walking beam furnaces bottoms REFINERIES proses furnaces and heaters.

| Material | Percentage | Typical |
|---|---|---|
| Al2O3 | 80-85 % | 83 % |
| SiO2 | 3-5 % | 4 % |
| CaO | 1.5-2.5 % | 2 % |