Performance of Hybrid Glass Fiber-Reinforced Slag-Fly ash Blended Geopolymer Concrete

This study evaluates the effect of different combinations and volume fractions of hybrid glass fibers (GF) addition on the properties of slag-fly ash blended geopolymer concrete. Two types of GF (A and B) with different lengths (24 and 43 mm) were considered. GF were incorporated solely or in a hybrid combination. Three combinations of hybrid GF were used with A:B ratios of 3:1, 1:1, and 1:3 at a fixed volume fraction of 1%. Three volume fractions (0.5, 1.0, and 1.5%) were utilized with a GF hybrid combination having A:B ratio of 1:1. The performance was characterized by the workability, 1-and 7-day compressive strength, and 7-day splitting tensile strength. The experimental test results showed that the addition of GF had an adverse effect on the geopolymer concrete workability. Yet, mixes with hybrid GF were more workable than counterparts made with a single type of GF. Furthermore, the addition of hybrid GF combinations increased the compressive and splitting tensile strength by up to 26 and 59%, respectively, compared to the plain control mix. Increasing the hybrid GF volume fractions up to 1% enhanced the strengths. Superlative strengths were noted upon incorporating more long GF in the hybrid GF combination, i.e., the mix having A:B ratio of 1:3. Findings highlight the ability to improve the hardened properties of slag-fly ash blended geopolymer concrete using hybrid GF while maintaining adequate workability.