Low Cement And Ultra Low Cement Refractory Castable Description
Low cement castable is a kind of calcium aluminate cement bonded castable, which’s CaO content is lower than 2.5%, i.e., the content of calcium aluminate cement is about half or one-third of ordinary calcium aluminate cement bonded castable. According to American ASTM standards, CaO content between 1.0%~2.5% is called low cement castable, CaO content less than 1.0% is called ultra-low cement castable. Be different from traditional refractory castable, low cement, and ultra-low cement castable adopt super fine powder( granularity less than 10μm) as main coagulation agent which’s chemical composition is the same or similar to the castable main material. So this kind of castable is hydration binding and coagulation binding coexisted castable.
Low Cement and Ultra Low Cement Refractory Castable Properties
- Low CaO content, can reduce the amount of middle and low temperature eutectic and thus enhance refractoriness, high temperature strength and slag corrosion resistance.
- Only need half or one third of water compared with ordinary castable, so the porosity is lower and have higher bulk density.
- When casted into formation, there is few cement hydrates and will not have hydration bond disintegration during heating, so the middle temperature strength will not decrease, with the raising of heat treatment temperature, the strength is gradually increased.
- When the granularity composition is properly adjusted, it can be used to prepare self flow castable and pump grouting castable.
Low cement and ultra low cement castable can be divided into low cement clay castable, low cement high alumina castable, low cement mullite castable, low cement corundum castable, low cement chrome corundum castable, low cement zircon mullite castable, low cement zircon mullite castable, low cement alumina sipnel castable, low cement carbon and silicon carbide castable, etc. By workability, low cement castable and ultra low cement castable can be divided into vibration low and ultra low cement castable and self flow low cement and ultra low cement castable.
Vibration Low Cement Castable Physiochemical Index
| Item | Clay Low Cement Castable | High Alumina Low Cement Castable | Corundum Low Cement Castable |
| Al2O3 % | 45 | 75 | 92 |
| SiO2 % | 50 | 12 | 5 |
| CaO % | <1.8 | <1.5 | <1.5 |
| Bulk Density(110℃, 24h) g/cm3 | 2.3 | 2.6 | 3.0 |
| Cold compression strength(110℃, 24h) Mpa | 72 | 75 | 85 |
| Linear change rate(1350℃, 3h) % | ±0.3 | ±0.5 | ±0.5 |
| Max working temperature ℃ | 1450 | 1600 | 1700 |
| Water needed % | 6.0~6.5 | 6.0~6.5 | 4~5 |
Low Cement Castable and Ultra Low Cement Castable Applications
Low cement and ultra low cement refractory castable are comprehensively used in various kinds of industrial furnaces and kilns covering metallurgy, petrochemical industry, machinery manufacturing, power plant, building material and so on. Low cement castable and ultra low cement castable has replaced traditional refractory products to build linings. Vibration type low cement and ultra low cement castable are mainly used to make thick linings, such as the inner lining of heating furnaces, heat treatment furnaces, electric furnace lids, vertical kilns, rotary kilns, blast furnaces tapping spout, steel ladle, iron ladle, etc. Self flow low cement castable and ultra low cement castable are mainly used as thin linings and the linings of high temperature refractory components with metal anchoring parts. For example, water cooling pipe outer lining of heating furnaces, linings of integral gunning machine used for gunning metallurgy, linings of RH and DH vacuum degassing equipment dip pipe, ladle gas supplying elements( permeation bricks) and high temperature abrasion resistant linings of petrochemical industry catalytic cracking reactors.
