Equilibria of the chemical composition of the pore concrete solution Part II: Calculation of the equilibria constants of the synthetic solutions

Abstract

The chemical composition of synthetic solutions used to simulate the pore concrete solution was analyzed in Part I. It was not possible to match the experimental results obtained from concentration measurements of the ions present in the solutions with the results obtained from calculations based on the values of pK of $Ca(OH)_{2}$ and $CaSO_{4}$. The inconsistency between the experimental values and the theoretical calculations was attributed to the elevated concentrations that exist, and, therefore, the elevated ionic strength.

The errors that are committed when applying the Debye-Huckel theory make it imprecise for proper calculations at such high concentrations. As an alternative the use of “apparent constants” is proposed. These are calculated from the values of the concentrations directly measured in the solutions.