Effect of Fine Aggregate Blending on Short-term Mechanical Properties of Geopolymer Concrete

The present investigation is mainly focused on finding the mechanical properties of geopolymer concrete (GPC) mixes with different fine aggregate blending. Sand and granite slurry (GS) are blended in different proportions (100:0, 80:20, 60:40 and 40:60). Coarse aggregates of size 20 mm and 10 mm are blended in 60:40 proportions by percentage of weight of total coarse aggregate. Fly ash (class F) and ground granulated blast furnace slag (GGBS) were used at 50:50 ratio as geopolymer binders. Combination of sodium hydroxide (8M) and sodium silicate solution was used as an alkaline activator. Compressive strength, splitting tensile strength (STS) and flexural strength (FS) were studied after 7, 28 and 90 days of curing at ambient room temperature. From the results, it is revealed that the mechanical properties were increased till fine aggregate blending of 60:40 and decreasing trend has been observed at 40:60 fine aggregate blending. It is concluded that optimum fine aggregate blending was 60:40. The measured STS and FS of all mixes were compared with ACI 363R, CEB-FIP and ACI 318R predicted equations.