Flexural and shear performance of geopolymer concrete reinforced with hybrid glass fibers

This study evaluates the flexural and shear performance of slag-fly ash blended geopolymer concrete reinforced with glass fibers (GF). Two types of GF, with different lengths (24 and 43 mm), were used either individually or as a hybrid combination. Each type of GF was incorporated singularly at 0.5, 1.0, and 1.5%, by volume. Three hybrid GF combinations were added to the geopolymer concrete at a fixed volume fraction of 1.0%, with short-to-long fiber ratios of 3:1, 1:1, and 1:3. The flexural performance was evaluated through load-deflection curves, flexural strength, deflection at peak, flexural residual strengths, flexural toughness, and flexural equivalent strength ratio. The shear performance was investigated using the shear load-deflection response, shear strength, shear toughness, and shear indices. Experimental results showed the flexural and shear performance improved upon the addition of GF. In fact, an enhancement in these properties was noted with GF length and volume fraction. However, mixes reinforced with hybrid GF combinations at a volume fraction of 1.0% outperformed those reinforced with a single type of GF, even at a higher volume fraction of 1.5%. Of the various mixes under investigation, the hybrid mix reinforced with a long-to-short fiber ratio of 3:1 exhibited superior performance. While the addition of GF improved the flexural and shear behavior, its effect was more apparent on the latter than on the former. Such findings provide experimental evidence of the improve the flexural and shear properties of geopolymer concrete using single and hybrid combinations of glass fibers.