Sulfate resistance of carbonated ternary mortar blends: Portland cement, reactive MgO and supplementary cementitious materials

Reactive MgO (rMgO) and supplementary cementitious materials are promising to formulate sustainable construction binders. This study compares the effect of GGBFS and FA on the properties of mortar systems containing both r-MgO and Portland cement (rMgO-PC) as binder. The experimental results reveal that the incorporation of 10% GGBFS or 10% FA increases the carbonation degree of the rMgO-PC system at rMgO replacement levels of 0%, 30%, 50% and 70%. The incorporation of 10% GGBFS or 10% FA reduces the expansion of mortars with the 0% and 30% rMgO replacement levels during the sulfate exposure. Sulfate exposure not only leads to the formation of ettringite and gypsum in the mortars with the 0% and 30% rMgO replacement levels, but also accelerates the formation of protodolomite in the 50% and 70% rMgO replacement levels. However, only the ettringite and gypsum were found to jeopardize the volume stability of carbonated mortars. (C) 2019 Elsevier Ltd. All rights reserved.