Effect of Alkaline-Earth Metal Oxide on Compressive Strength and Flexural Strength of Alkali-Activated Slag Cement Mortar

Abstract The effect of CaO and MgO content on the compressive strength (CS) and flexural strength (FS) of alkali-activated slag mortar (ASM), which was activated by NaOH (Na 2 O% = 4%), was investigated. The pore structure of alkali-activated slag paste was investigated via mercury intrusion porosimetry (MIP). The morphology of ASM was observed by field emission scanning electron microscope (FSEM). The study shows that the CS and FS of ASM, which was activated by NaOH, increase first and then decrease with the improvement of CaO and MgO content. The optimal CaO and MgO content for CS are both 9% of the slag mass. The CS of ASM with optimal CaO and MgO content can achieve 46.54MPa and 47.79MPa, respectively. The optimal CaO and MgO content for FS are 6% and 3% of the slag mass, respectively. The FS of ASM with optimal CaO and MgO content can achieve 11.23MPa and 11.11MPa, respectively. The comprehensive mechanics performance of ASM are the best, when the CaO content is 6%.