Use of Calcium Aluminate Cement in High Strength Concrete for Fast Repair of Old Concrete Slabs

The oxides present in the chemical compositioii of calcium aluminate cement, especially monocalciiim aluminates. is what gives the concrete manufactured with this type of cement its slow setting, quick hardening properties. The products generated during hydration of anhydrous phases in calcium aluminate cement. will depend on ambient conditions at the moment of hydration. Broadly speaking. at temperatures below 25°C the hydrates fonned are hexagonal (metastable), whilst above 40°C they are cubic (stable). Metastable products naturally. thennodynarnically, permanently and irreversibly tend to stabilise. This process is called conversion. This is an intrinsic characteristic of concretes made with calcium aluminate cement and must be taken into account in the mix design. In Spain several experiments have been canied out with calcium aluminate cement on airports and roads. The repaired surface on the Madrid-Barajas Airport apron, has been in service since December 1996 and has so far delivered excellent performance.