Chloride-ion activities in simplified synthetic concrete pore solutions: The effect of the accompanying ions

Concrete pore solutions are concentrated electrolytes in which the activity of the chemical species must be calculated properly to determine the equil ibrium state of such solutions. In this work, the chloride-ion activity coe fficients in synthetic con crete pore solutions have been obtained potentio metrically, using different calibrated Cl- ion-selective electrodes (ISEs); also, a discussion about the performance of the different Cl- ISEs in alka line media is presented. Experimental results are compared with the calcula ted results, using Fitter's specific ionic-interaction model, and good agre ement is observed between them.