Effect of ground granulated blast furnace slag and fly ash on mechanical properties and sulfate attack resistance of fine-grained concrete using sea sand

This paper presents study results on the effects of ground granulated blast furnace slag (GGBFS) and fly ash (FA) on the slump, mechanical properties, absorption, and sulfate resistance of fine-grained concrete using sea sand (FGCSS). Seven types of fine gained-concretes (FGC) with W/ B ratios of 0.38 were prepared including: FGC for reference that use cement and treated sea sand (FGCR), FGC for reference that use cement and sea sand (FGCR-SS), three types of FGCSS that use GGBFS as a substitution for cement and two type of FGCSS that use both GGBFS and FA. The aggregate used consists of river sand with a modulus of fineness 2.77 and sea sand (SS) with a modulus of fineness 1.05. The study results showed that FGCR-SS had an increase in strength compared to FGCR at 7, 28 days but had a lower decrease in strength compared to FGCR at 90 days. FGCSSs using GGBFS to replace cement by 30-50% showed an improvement in compressive strength and splitting tensile strength at all experimental ages. For FGCSSs using both GGBFS and FA, a replacement of 35%GGBFS and 15%FA also showed an improvement in the compressive strength and splitting tensile strength from 28 days later. FGCR-SS showed 3.15 times more expansion than FGCR at 180 days. The use of GGBFS and FA in FGCSS significantly reduced sulfate expansion compared with that of FGCR-SS; at 180 days, the sulfate expansion of both FGC using 70% GGBFS and FGC using a combination of 35% GGBFS and 15% FA was almost similar to that of FGCR.