Behavior of High-performance Geopolymer Concrete Beams with Substitution of Silica Fume and GGBS/Fly Ash

The flexural behaviour of high-performance geopolymer concrete (HPGPC) beams with partially substituted ground granulated blast furnace slag (GGBS)/fly ash and silica fume (SF) is examined in this experimental investigation. An alkaline activator solution consisting of sodium hydroxide and sodium silicate in a 1:1.5 ratio at 8M concentration was used to create geopolymer concrete in place of traditional cement. Seven distinct mix proportions (M1–M7) were made with variable amounts of SF replacement (0%, 5%, 7.5%, and 10%), and in certain mixes, a continuous 0.2% glass fibre reinforcement was added. The concrete mix was intended to reach a goal mean strength of 80 MPa. Mechanical attributes such as modulus of elasticity, water absorption, flexural strength, split tensile strength, and compressive strength were assessed. According to the findings, 7.5% silica fume replacement is ideal for increasing compressive strength, and 0.2% glass fibre addition further boosts tensile and flexural performance. Seven 100 × 200 × 2000 mm geopolymer concrete beams were also cast, allowed to cure for 28 days, and then tested under two-point loading in a loading frame with a 1000 kN capacity. Important flexural parameters were examined, including moment-curvature, moment-rotation characteristics, deflection, ultimate load, and first fracture load. Evaluations comparing high-performance geopolymer concrete beams to control specimens showed improved ductility and load-bearing capability, demonstrating the efficiency of glass fibre and silica fume in maximizing flexural behaviour.