Effect of K/Na on the alkali silica reaction of seawater and sea sand concrete

Abstract In recent years, research into the properties of seawater and sea sand concrete (SWSSC) has emerged as a prominent area of investigation, and the alkali silica reaction (ASR) of SWSSC is an urgent issue to be solved. However, little attention has been paid to the effect of K/Na on the ASR of SWSSC. In order to fill this gap, the effects of different K/Na on ASR products, pore structure, pH and alkali ion content, and expansion of SWSSC were measured. The findings demonstrated that the composition of the amorphous product ASR-P1 (K0.52Ca1.16Si4O8(OH)2.84-1.5H2O) of SWSSC exhibited an inverse relationship with K/Na, whereas the crystalline product K-shlykovite (NaCaSi4O8(OH)3-2.3H2O) displayed a direct correlation with K/Na. The increase of K+ concentration leads to the decrease of silica dissolution, which is the main reason for the lowest ASR degree in the high K/Na group. The transformation of ASR-P1 to K-shlykovite also resulted in different main ASR products in different K/Na groups. The findings of this study provide a foundation for the theoretical application of SWSSC in the field of ocean engineering.