The hydraulic binder in conventional and low-cement castables, made by fusing or sintering limestone and bauxite or alumina. It sets by forming calcium aluminate hydrates, which release their chemically bound water at roughly 200 to 350 C during dry-out. Higher-alumina grades give better refractoriness. Its lime reacts with silica and impurities at high temperature to form low-melting phases, which is why low- and no-cement castables exist.
Calcium aluminate cement in that castable is the 70 percent grade, so cure it a full day before you light anything.
Cement has a shelf life. Old or damp bags set slowly or not at all, so check the date code on castable pallets before the job.
Also heard as
- CAC
- high-alumina cement
- aluminous cement
Related terms
Castable
Dry refractory mix of aggregate, fines and binder that is mixed with water and poured or pumped like concrete.
Low-cement castable
Dense castable with 1 to 2.5 percent lime from cement, using micro-fines and dispersants for strength and low porosity.
Cure
To hold freshly placed castable moist and at moderate temperature so its cement can fully hydrate.
Dry-out
Controlled first heat-up of a new monolithic lining to drive off water without cracking or spalling.