Shear behavior of glass fiber-reinforced slag-fly ash blended geopolymer concrete beams

Geopolymer composites are considered eco-friendly materials for the development of low-carbon concrete structures. The shear behavior of slag/fly ash blended geopolymer concrete beams reinforced with glass fibers (GF) was investigated in this research and compared to that of similar beams with and without conventional steel stirrups. Test parameters included the stirrup spacing (50 and 100 mm), length of GF (24 and 43 mm), GF volume fraction (v_f = 0.5, 1.0, and 1.5 %), and GF combination (single type and hybridized). Test results confirmed the viability of GF in controlling the development and growth of shear cracks and improving the shear resistance of reinforced geopolymer concrete (RGC) beams. The shear strength gain caused by conventional steel stirrups was in the range of 46–95 %, whereas that caused by GF ranged from 20 % to 46 %. Increasing the GF volume fraction to values greater than 1 % did not result in a significant additional improvement in the shear behavior of the tested beams. The shear performance of the RGC beams reinforced with hybrid GF was superior to that of their counterparts reinforced with a single type of GF. Test results demonstrated the potential use of a hybrid combination of GF as a substitution for the minimum amount of conventional steel stirrups in RGC beams. Refined analytical models capable of providing a consistent and conservative prediction for the shear strength of RGC beams reinforced with GF were introduced and verified against test results.