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

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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.