The Early Hydration of a Refractory Calcium Aluminate Cement in the Presence of Sodium Carbonate

摘要

The early hydration of a commercial refractory calcium aluminate cement, Secar 71, with and without Na_2CO_3 additions was followed by continuously monitoring the variations in conductivity, pH and temperature of a hydrating suspension of the cement. Samples were periodically withdrawn from the suspension and filtered and the resulting filtrate was then analysed. Results obtained on hydration without addition of the admixture yielded data similar to those already reported in the literature. When small amounts of Na_2CO_3 were dry mixed with the cement the hydration process was significantly modified. Hydration mechanisms that attempt to explain the observed results are proposed.