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Description of ultra-low cement refractory castable
Low cement castable refers to new castable containing little binding dose. The key is to use ultrafine particles of no more than 1μm. Its thermal shock resistance, slag resistance and erosion resistance are significantly improved, surpassing similar firebrick. Further reduction of binder content can produce ultra-low cement refractory castable and cementless castable.
Physical and chemical index
| Low Cement Castable | Corundum | Alumina | Alumina | Alumina | Alumina | Clay | |
| KR-90 | KR-80 | KR-70 | KR-60 | KR-50 | KR-40 | ||
| Chemical composition, % | Al₂O₃ ≥ | 90 | 80 | 70 | 60 | 50 | 40 |
| CaO ≥ | 2.5 | 2.5 | 2.5 | 2.5 | 2.5 | 2.5 | |
| Bulk density, g/cm3 ≥ | 110℃×24h | 2.95 | 2.75 | 2.6 | 2.5 | 2.4 | 2.3 |
| 1500℃×3h | 2.9 | 2.7 | 2.6 | 2.4 | 2.4 | 2.3 | |
| Compressive strength, MPa ≥ | 110℃×24h | 60 | 45 | 45 | 40 | 40 | 40 |
| 1500℃×3h | 80 | 75 | 70 | 60 | 60 | 60 | |
| Breaking strength, MPa ≥ | 110℃×24h | 8 | 7 | 6 | 6 | 6 | 6 |
| 1500℃×3h | 10 | 10 | 10 | 8 | 8 | 8 | |
| Linear Change PLC, % ≤ | 110℃×24h | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 |
| 1500℃×3h | -0.5 | -0.5 | -0.5 | -0.5 | -0.5 | -0.2 | |
| Max. service temperature, ℃ | 1700 | 1600 | 1500 | 1450 | 1400 | 1350 |
Reasons for overall pouring of ultra-low cement refractory castable
Ultra-low cement refractory castable has the characteristics of low porosity, small pore size, high density, good volume stability, high strength, and low water addition. It overcomes the significant decrease in strength of ordinary castables at 800-1200 ℃ and increases with temperature, which can increase the thermal shock resistance of the furnace body by more than twice.