Structural behavior of geopolymer concrete beams

In this study, the effects of steel fiber and polypropylene fiber on the flexural performance of fiber-reinforced geopolymer were investigated. Fiber reinforcement has emerged as a way to improve the brittleness of geopolymer. This study aims to examine the performance of fly ash/slag-based geopolymer concrete (FA/GGBFS) with different concentration of sodium hydroxide (NaOH) and different types of fibers (steel and polypropylene fibers). Alkaline liquid consists of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. The ratio of sodium silicate solution to sodium hydroxide was fixed to 2.50. The main factors studied were the evaluation of workability, compressive strength, split tensile strength, critical stress intensity factor, and fracture toughness. The study results showed that the incorporation of steel and polypropylene fibers into fly ash/slag based geopolymer concrete resulted in superior enhancement in the splitting tensile strength, flexural strength, area under the load-deflection curve and in the degree of fracture energy however the using of the different molar concentration of sodium hydroxide observed to be less important in the behavior of fiber reinforced geopolymer concrete. Keywords: Geopolymer concrete , fly ash, slag, steel fiber, polypropylene fiber and fracture toughness.