What Is the Difference Between Calcium Silicate Board and Cement Board?
Calcium silicate board and cement board are often confused because both are rigid, inorganic, non-combustible building boards. However, they are fundamentally different materials with different manufacturing processes, chemistry, and applications.
Comparison at a Glance
| Property | Calcium Silicate Board | Cement Board |
|---|---|---|
| Manufacturing | Autoclave curing (190-220°C, 12-18 bar) | Cold pressing, ambient curing |
| Crystal Phase | Xonotlite (6CaO·6SiO&sub2;·H&sub2;O) | Cement hydrate (Portland cement matrix) |
| Color | White to off-white | Gray |
| Density (g/cm³) | 0.17 - 0.90 (170-900 kg/m³) | 1.0 - 1.5 (1000-1500 kg/m³) |
| Thermal Conductivity | 0.056 + 0.00011t W/m·K (insulating) | 0.3 - 0.5 W/m·K (non-insulating) |
| Max Service Temp | 650°C to 1100°C | Up to 200°C (dehydrates and cracks above) |
| Primary Use | High-temperature industrial insulation | Tile backer board, construction sheathing |
Manufacturing Process Difference
The fundamental difference is in how the two materials are made. Calcium silicate board is produced by reacting lime and silica in a high-pressure steam autoclave at 190-220°C. This hydrothermal reaction forms xonotlite crystals that interlock into a rigid, microporous structure with inherent thermal insulation properties. Cement board is produced by cold-pressing a mixture of Portland cement, sand or silica flour, and reinforcing fibers into a flat sheet, then allowing it to cure at ambient temperature. No autoclave step is involved in standard cement board production.
Application Difference
Calcium silicate board is an industrial thermal insulation material. It is used to insulate pipes, vessels, furnaces, and kilns operating at temperatures up to 1100°C. Cement board is a construction material used as tile backer board in bathrooms and kitchens, or as exterior wall sheathing. Cement board has no meaningful thermal insulation value and cannot withstand temperatures above approximately 200°C before the cement hydrate decomposes.
Why the Confusion Exists
In some markets, the term "calcium silicate board" is used loosely for low-density cement-based building boards that contain silica. These products are not true xonotlite calcium silicate insulation. True calcium silicate insulation board, as manufactured by Mingfa, is an autoclaved product with distinct thermal and mechanical properties designed for industrial high-temperature service.