Effects of Size and Flexural Reinforcement Ratio on Ambient-Cured Geopolymer Slag Concrete Beams under Four-Point Bending

With the rise in cement production required by conventional concrete, CO2 emissions increase, causing pollution to the atmosphere. Geopolymer concrete (GPC) is investigated in the literature as an eco-efficient alternative to conventional concrete (CC). However, most geopolymer studies focus on studying the mechanical properties of GPC, with only limited investigations on the structural performances of structural elements using GPC. The structural behaviors of GPC elements are yet to be completely understood, and there are no current studies on investigating the structural behaviors of geopolymer slag concrete. Thus, this paper investigates the flexural performances of reinforced geopolymer slag concrete beams, focusing on the effects of different beam depths and reinforcement ratios. Five full-scale ambient-cured reinforced geopolymer slag concrete beams were tested under four-point flexure, in addition to one control conventional concrete (CC) beam. The structural performances are evaluated, including the cracking moment, flexural capacity, load-deflection relationship, and crack distribution. The results indicate that the flexural behaviors of GPC beams are comparable to that of the CC beams. Compared to the CC beams, the GPC beams have 7.4% higher flexural moment capacity, 60% lower stiffness, 28% lower ductility, and 18.3% higher toughness. Finally, the Egyptian code of practice ECP 203 and ACI 318 are found to be applicable to safely design under-reinforced GPC flexural beam elements.