Carbonation resistance of mortar produced with alternative cements

Abstract

The use of alternative cements with lower CO₂ emissions during production compared to ordinary Portland cement (PC) is only sustainable, if the durability and with it the service life of components and structures produced with them are not compromised. In this project, the carbonation resistance of mortars produced with calcium sulfoaluminate cement (CSA) and three different slag-based cements is studied in accelerated conditions and natural exposure. Additionally, the diffusion coefficients of oxygen ($D_{{{\text{O}}_{2} }}$) and carbon dioxide ($D_{{{\text{CO}}_{2} }}$) are measured (the latter one only on carbonated mortars) and the change in mortar porosity due to carbonation is determined. Mortar PC used as reference and mortar CSA display the lowest carbonation coefficients, both in accelerated conditions and natural exposure. The three systems based on slag display higher carbonation coefficients. After carbonation, the diffusion coefficient $D_{{{\text{O}}_{2} }}$ is increased for all mortars except for mortar PC, whose total porosity is decreased as well, in contrast to all other mortars. The diffusion coefficients $D_{{{\text{O}}_{2} }}$ and $D_{{{\text{CO}}_{2} }}$ show a linear relationship in the carbonated mortars.