Evaluation of Steel Fiber Reinforced Geopolymer Concrete Made of Recycled Materials

The experimental program of this study aims to investigate the tensile behaviour of geopolymer concrete reinforced with steel fiber and made of recycled materials. The primary ingredients of the steel fiber reinforced geopolymer concrete in this study were waste materials. The recycled steel fiber was extracted from tires and chopped into tiny fibers with an average length of 20 mm and an average diameter of 0.7 mm. The fly ash-based geopolymer concrete in this study consisted of coarse aggregate, which was crushed recycled concrete. Also, the fine aggregate was crushed waste glass. In addition to the compressive strength, tensile test procedures such as splitting tensile strength, double punch tensile strength, and flexural tensile strength were all investigated in this study. Recycled steel fiber was compared to a new and hybrid steel fiber (50% new + 50% recycled) with three different volumetric percentages of steel fiber (0.5%, 1.0%, and 1.5%). The new steel fiber geopolymer concrete mix with 1.5% of steel fiber showed the highest test results among other mixes. This conduct could be explained as the new steel fiber having a uniform, straight shape with hooked ends, increasing the anchorage between the fly ash binder and the steel fiber. In addition, the recycled steel fiber was contained some rubber crumbs that could be another reason that negatively affected the tensile properties of the geopolymer concrete.