Castable refractory concretes

Castable refractories containing calcium aluminate cement (CAC) are used ubiquitously in a range of furnace lining applications in the iron and steel, cement, glass, ceramic, and petrochemical industries. This review outlines their development from conventional high cement materials, through low cement and ultra-low cement castables to the present materials which may be entirely free of CAC. Castables are defined in terms of both CaO content and installation procedure. Production routes, compositions, and microstructural evolution on hydration, setting, dehydration, and firing are described for pure CACs and castable refractories. The development of the low cement systems is discussed in terms of particle packing, dispersion, and rheology highlighting the influence of colloidal matrix additions of silica and alumina. Recent developments including cement free, self-flowing, shotcreting, and basic castables are described and the potential for carbon-containing systems evaluated.