Hydration of high alumina cement in the presence of alkalis

Some degradation processes in aluminous cement concretes are related to the presence of alkalis contained in aggregates or other external sources. Carbonation of aluminous cement in the presence of alkalis is sometimes called ‘alkaline hydrolysis’ and has been described by some authors as a catalytic-like process which leads to the total destruction of the affected element (concrete). The minimum parameters required for this hypothetical alkaline hydrolysis to occur have been established. However, despite several attempts made in specialized laboratories, the process has not yet been proven. The role played by K⁺, in particular, is still unknown. This paper attempts to investigate the hydration process of aluminous cement in the presence of high concentrations of K⁺ (1 and 3M). The influence of reaction temperature in the evolution of phases and the resistant development is also investigated.