Conventional Castables (Fireclay-Based)

A conventional castable is a fireclay or low-purity high alumina aggregate bonded with 15–25% calcium aluminate cement, the original castable formulation that has been used in industrial linings for over 50 years. It is roughly half the price of an equivalent low cement castable (LCC at 3–5% cement) and one-third the price of ULCC. The trade-off: lower hot strength, higher porosity, and lower slag resistance. Right product for backup linings and low-wear zones; wrong product for steel ladle hot face.

Use conventional castable for backup safety linings behind a working LCC or brick lining, boiler walls and roofs (non-hot-face zones), industrial waste incinerator general body, cement preheater meal chutes, foundry trough backup, and any minor repair work where the new material does not need premium hot-strength. Total cost of ownership is lower because the cheaper material is replaced more often but each replacement is cheap.

We supply Conventional 40 (38–42% Al₂O₃, rated to 1300°C) for boiler back walls, Conventional 50 (48–52% Al₂O₃, 1400°C) for general furnace linings, Conventional 60 (58–62% Al₂O₃, 1500°C) for higher duty backup, and Conventional 70 (68–72% Al₂O₃, 1550°C) for moderate hot-face zones in incinerators and small foundry furnaces. Insulating LD-1.5 (1.50 g/cc bulk density) for backup insulation behind dense linings.

More cement means more water needed to wet the cement particles for hydration, typically 8–12% water by weight versus 4.5–5.5% for LCC. The trade-off is higher porosity in the cured castable (cement hydration leaves micro-pores). For non-critical applications this porosity is acceptable; for slag-line and impact zones it is not, which is why LCC dominates those zones.

Conventional castables tolerate faster installation than LCC. Cast in 200–250 mm layers, vibrate for 20–30 seconds per layer, demould after 12–18 hours, and dry out at 25°C/hour to 110°C with an 8-hour soak, versus the 24-hour cure and 12-hour soak typical for LCC. A mid-size boiler sidewall job that takes 5 days with LCC can be done in 3 days with conventional castable.

Mahakoshal Refractories conventional grades 40 to 70, Calderys India conventional and budget castables, CUMI Super Refractories range, and Crown Ceramics for acid-proof variants. Stocked at our Delhi warehouse with pan-India dispatch and full export documentation for GCC and ASEAN customers.