Effect of supplementary cementitious materials on the resistance of mortar to physical sulfate salt attack

Physical sulfate salt attack is one of the most rapid and severe deterioration mechanisms in concrete structures. One of the most common approaches to improve resistance of concrcte to sulfate attack is to use supplementary cementitious materials However, physical salt attack may still cause damage to concrete with supplementary cementitious materials. Moreover, according to some literature sources, some supplementary cementitious materials may even reduce resistance to physical salt attack. The current research investigates the effect of supplementary cementitious materials on the ability of mortars to resist physical sulfate salt attack and its relationship with pore structure and transport properties. Mortar specimens with 45 and 65% replacement of cement by ground-granulated blast-furnace slag and with 20 and 40% replacement of cement by fly ash were exposed to physical sulfate attack. The results show a good correlation between the pore microstructure and transport properties to the resistance to physical salt attack. Ground-granulated blast-fiirnace slag was found to improve the resistance to physical salt attack, while fly ash demonstrated a negative effect.