Effects of desalinated sea sand on the alkali-silica reaction of seawater and sea sand concrete

Abstract

The application of seawater and sea sand concrete (SWSSC) can reduce the construction period and cost of island infrastructure, but it may also bring the risk of alkali-silica reaction (ASR) due to the presence of alkali ions in seawater and sea sand. To compare the characteristics of ASR between SWSSC and seawater and desalinated sea sand (DSS) concrete and investigate the effects of desalinated sea sand on the ASR of SWSSC, the properties and the ASR products of mortar-bars with different desalinated sea sand content were investigated. When the DSS proportion increased from 0% to 100%, the Na+, K+, and Ca+ concentration contents and pH of the specimens decreased by 22.6, 2.0, 45.1 mg·L+ and 0.05, and the expansion of mortar bars reduced by 0.16%. Desalination of sea sand could not eliminate the risk of ASR of SWSSC completely. The 14 days expansion of mortar bars with 100% DSS was 0.13%, and the precursors of ASR-P1 were observed by SEM. The experimental results of XRD, FTIR, Raman spectrometer, DTA, SEM, and EDX all showed that with the increase of DSS proportion, the content of Na-shlykovite and ASR-P1 were gradually reduced. A small amount of Mg element in both Na-shlykovite and ASR-P1 was detected by EDX, but the mechanism of Mg element in ASR of SWSSC needs further study. This study can provide a basis for the application of SWSSC in island infrastructure.