Effect of Tidal Zone and Seawater Attack on Alkali Activated Blended Slag Pastes

The marine environment has a significant deterioration effect on building materials. Among the different zones of the marine environment, the tidal zone has the highest deterioration. The current paper is the first attempt to study the effect of different treatment conditions-water curing, air curing, seawater curing, and simulated tidal zone-on the compressive strength and microstructure properties of alkali-activated slag (AAS) pastes without or with different mineral admixtures over different periods. Slag was partially replaced with 5 and 10% of different mineral admixtures-fly ash (FA), silica fume (SF), and quartz powder (Q)-by weight. After initial curing, the specimens were subjected to altered treatment conditions for 3, 6, and 12 months (M). The crystalline phases, microstructure analysis, and energy-dispersive X-ray spectra (EDS) of the selected samples were analyzed. The results indicated that the tidal zone has the highest aggressive deterioration on the specimens, followed by those exposed to seawater attack (submerged in seawater). The specimens cured in water exhibited the highest compressive strength, followed by those cured in air. The specimens containing Q showed the best performance, followed by those containing SF and FA, respectively, while the plain AAS pastes came in last place.