Castable Refractories

A castable refractory is mixed with water, cast or vibrated into place and forms a monolithic structure after drying. It is used where the shape is complex or frequent repair is needed, such as ladles, launders, furnace spouts, tundishes and covers.

Low-cement and ultra-low-cement types provide low porosity and high strength. The composition is alumina-based; grades with silicon carbide or other additives are available depending on the metal and slag type. Maximum service temperature, slag attack and thermal shock govern the selection.

Mixing water amount, casting, curing and the first dry-out schedule are critical steps. Excess water increases porosity and reduces strength, and fast heating can cause explosive spalling from steam pressure.