Evaluation of the pore solution of concretes with mineral additions subjected to 14 years of natural carbonation

Abstract This work aims to evaluate the pore solution using the ex situ leaching method of a wide variety of modified concretes with mineral additions, and submitted to a natural carbonation for 14 years of exposure in a typical urban environment. The results of chemical analyses of pH, electrical conductivity, and ionic strength are thus presented, considering the carbonated and non-carbonated concrete layers. Mixtures with silica fume, metakaolin, rice husk ash, fly ash and blast furnace slag were produced, aiming to generate different chemical parameters related to the pore solution. The results showed that the decrease in ionic strength, altered mainly by the reduction in the concentration of OH−, explains the significant drops in pH and conductivity in carbonated concrete. In the same way, a significantly lower conductivity was observed for the concretes with mineral additions, which partially explains why these concretes have so much stronger resistivity (bulk or surface resistivity) compared to plain concretes.