Carbonation and Shrinkage Behavior of Alkali-Activated GGBS Mortar Incorporated with Supplementary Precursors

By increasing the investigations and applications of alkali-activated concrete, improvement of its behavior is a promising idea by using different materials and specifically secondary raw materials. In this study, an alkali-activated GGBS (AAG) mortar mixture having a ternary activator system including NaOH, Na2O.nSiO2, and K2O.nSiO2 was considered. The effect of the substitution of fly ash, metakaolin, calcined clay, and calcium alumina cement (CAC) by ground granulated blast furnace slag (GGBS) on carbonation resistance, as well as shrinkage behavior was investigated. It was observed that the replacement of GGBS with CAC reduced the total volume of pores, and their sizes. By the way, the shrinkage behavior of that showed about four times higher strain than the mixtures without CAC. On the other hand, the replacement of CAC with GGBS in AAG slightly improves the carbonation resistance, as well as capillary porosity. However, the substitution of GGBS with fly ash, metakaolin, and calcined clay resulted in a reduction of the carbonation resistance, as well as an increase of porosity.