ASPECTS OF THE PORE SOLUTION CHEMISTRY OF HYDRATED CEMENT PASTES CONTAINING METAKAOLIN

The hydroxide ion concentrations of expressed pore solutions of Ordina ry Portland cement pastes containing 0, 10 and 20% of metakaolin by we ight of cement were determined at various stages of hydration. Effects produced by two types of metakaolin, differing in degree of purity, w ere compared and, in each case, incorporation of metakaolin into the p astes was found to cause a long-term reduction in pore solution hydrox ide ion concentration. The presence of metakaolin was also found to re sult in an increase in the extent to which chloride ions, introduced v ia the mix water, were excluded from the pore solution phase. The sign ificance of these results in relation to the ability of hydrated cemen t matrices containing metakaolin to provide corrosion protection to em bedded steel is considered. Copyright (C) 1997 Elsevier Science Ltd.