Pore solution chemistry of alkali-activated ground granulated blast-furnace slag

The chemical composition and pH of the pore solution extracted from six dif ferent ground granulated blast-furnace slag (GGBFS) pastes were determined. The concentrations of Si, Ca, Al, and Mg are functions of the pH of the aq ueous phase, with high pH associated with the higher concentrations of Si a nd Al and the lower concentrations of Ca and Mg. When GGBFS is mixed with a n aqueous phase with pH higher than 11.5, the reaction is activated or acce lerated. The main hydration product was identified as C-S-H, and hydrotalci te, at later stages of hydration, was observed in the pastes with an aqueou s phase of a high pH. The effect of pore solution on the alkali activation of GGBFS is discussed with reference to the hydration products. (C) 1999 El sevier Science Ltd. All rights reserved.