Strength Characteristics and Impact Resistance of Fiber-Reinforced Geopolymer Concrete Elements

This chapter investigates the effects of fibers on the mechanical characteristics and impact resistance of GPC made using a blend of Class F fly ash (50%) and GGBS (50%) as binders. The alkaline initiator solution used to activate the GPC binder was a 12molar concentration NaOH solution mixed with liquid Na2SiO3. Mixes were made using a fly ash to alkaline liquid ratio of 2.0 and steel fibers were added in the quantities of 0.5%, 1%, 1.5%, and 2% by weight of the concrete. The mechanical properties of the material, namely its compressive strength, flexural strength, and split tensile strengths, were investigated. The impact resistance of plain and fiber-reinforced GPC was tested using 80 cm × 60 cm × 50 mm slab components. A drop hammer test was performed on the slabs. Experimental results showed that the compressive strength, split tensile strength, and flexural strengths of optimized 2% fibrous geopolymer concrete raised by 30.19%, 36.67%, and 75.87%, respectively, compared to plain GPC. In the GPC slabs with 0.5% to 2% steel fibers (GPCS0.5-GPCS2), the initial crack load increased 1.25–2.5 times more than in plain GPC slabs. The impact energy released by a 2% fiber-reinforced slab element was found to be higher when compared to other fiber-reinforced slabs. The analytical results from using Abaqus 2017 and the experimental results were highly comparable for crack patterns. Regression models were developed for plain and fiber-reinforced GPC components to predict impact energy at the initial crack and ultimate stages.