Whereas the potential risk of alkali-silica reaction (ASR) in high-calcium alkali-activated materials (AAMs) system and doubts on the applicability of accelerated test methods for AAMs system, this study attempted to investigate the effect of alkali cations from activator and accelerated test conditions on the ASR in alkali-activated slag (AAS) mortars. The results indicate that the accelerated test conditions have noticeable influence on the ASR behavior in potassium silicate activated slag (PS-AAS) mortars. The mechanical properties of PS-AAS mortars are comparable to that of sodium silicate activated slag (SS-AAS) mortars, while the ASR-induced expansion of PS-AAS mortars was much lower than SS-AAS mortars under both 40℃, 95 %RH and 80℃, 1 mol/L NaOH conditions. Although the high temperature and extra alkalis increased the onset of expansion, the expansion rate in the early stage as well as final expansion value of PS-AAS mortars, the expansion value of PS-AAS mortars were below the threshold in the corresponding standards. The SEM/EDS analysis also revealed that the K/Si ratio of ASR products in PS-AAS mortars was higher than in SS-AAS mortars. The crystalline ASR products in SS-AAS mortars is a typical for Na-shlykovite, while it is K-shlykovite in PS-AAS mortars regardless of exposure conditions.

W. Wang, T. Noguchi, I. Maruyama, Effects of alkali cations from silicate activators and exposure conditions on the alkali-silica reaction in alkali-activated slag mortars, Constr. Build. Mater. 451 (2024) 138929.