Performance of Fe-Rich Alkali-Activated Materials in Na2SO4 Solution: Role of MgO/(MgO + CaO) in the Slag

To enable the usage of non-ferrous metallurgy slags in alkali-activated materials (AAMs), the influence of the chemical composition of slags on durability must be better understood. In this work, two slags were synthesized with different MgO/(MgO + CaO) weight ratios to investigate the effect on the sulfate resistance (Na2SO4) of AAMs. Experimental results suggested that a higher MgO/(MgO + CaO) ratio does not lead to higher strength, but the trend of the mass change and compressive strength change of two AAMs is quite similar upon Na2SO4 exposure for 24 weeks. The leaching of elements (Na, Al, and Si) during Na2SO4 exposure is more significant in the early stage, while Ca leaching is more pronounced in the late stage.