Chloride-bearing characteristics of alkali-activated slag mixed with seawater: Effect of different salinity levels

Abstract

This paper presents the microstructural properties of KOH-activated slag pastes produced with natural seawater under different salinity levels. The seawater-mixed samples exhibit higher 91-day strength compared to the control sample produced with deionized water. Their reduced total porosity and decrease in average pore size are closely related to the strength improvement. The dense microstructure is composed of reaction products resulting from the inclusion of seawater; these include Cl-hydrocalumite, Cl-hydrotalcite, AlClO, K2SO4, CaCO3, calcium aluminum iron oxide carbonate hydroxide hydrate, and aluminum chloride hydrate. In addition, CO32- in the CO3-hydrotalcite and CO3-hydrocalumite is replaced by chloride ions, and then a Cl-bearing phase is formed, leading to a higher bound chloride content. Lastly, in the single ocean current investigated in this study, the strength of seawater-mixed samples is weakly vulnerable to salinity variation.