Experimental study and computational analysis of structural performance of reinforced geopolymer concrete beams

PurposeIn this study, the aim is to explore the effects of geopolymer concrete (GPC) strength and reinforcement ratio on the flexural performance of reinforced GPC beams. Furthermore, a calculation formula for the ultimate flexural bearing capacity, specifically tailored for reinforced GPC beams, has been established.Design/methodology/approachNine reinforced geopolymer concrete (RGPC) beams were designed with the reinforcement ratio and GPC strength as the primary parameters. These beams were subjected to four-point bending tests to investigate their failure modes, strain distribution, ultimate load-bearing capacity, load-deflection curves and ductility characteristics.FindingsThe results, which have direct implications for construction practices, showed that increasing the reinforcement ratio from 0.68 to 1.05% and 1.25% boosted the yield load by 34.6–42.7% and the ultimate load by 47.1–47.5% while reducing displacement ductility by 12.5–∼18.1% and crack width by 30–40%. Raising the GPC strength from C30 to C50 at the same reinforcement ratio reduced cracks 10–15% and increased the cracking moment 12.9–16.3%. However, the current concrete specifications underestimate the moment bearing capacity by more than 10%. A new analytical method based on equilibrium equations, deformation coordination, and GPC stress-strain relationships accurately predicted the load-bearing capacity, with an average error of 1.8%.Research limitations/implicationsThis study evaluates the durability of GPC by testing nine RGPC beams. Four-point bending tests were used to examine the impact of reinforcement ratio and GPC strength on the beams' flexural performance. The results, which have direct implications for construction practices, showed that increasing the reinforcement ratio from 0.68 to 1.05% and 1.25% boosted the yield load by 34.6–42.7% and the ultimate load by 47.1–47.5% while reducing displacement ductility by 12.5–18.1% and crack width by 30–40%. Raising the GPC strength from C30 to C50 at the same reinforcement ratio reduced cracks 10–15% and increased the cracking moment 12.9–16.3%. However, the current concrete specifications underestimate the moment bearing capacity by more than 10%.Practical implicationsMeanwhile, a calculation model for evaluating the structural performance of RGPC beams based on the equilibrium equation, the deformation coordination relationship and the GPC compressive stress-strain relationship is proposed. The proposed model and parameters reflect the structural performance of RGPC beams more accurately than the traditional concrete structural calculation equations and specialized parameters, and the prediction results of their structural performance are more reliable. In this paper, the flexural capacity of RGPC beams is investigated and analyzed, aiming to improve the design theory of the enhanced RGPC beam structure to provide references for further research and application of this new type of GPC material and to promote the application and development of RGPC beams in practical engineering. At the same time, it supports the promotion of green buildings and low-carbon economic growth. It has important scientific significance and practical value for developing green and sustainable civil engineering structures.Social implicationsMeanwhile, a calculation model for evaluating the structural performance of RGPC beams based on the equilibrium equation, the deformation coordination relationship and the GPC compressive stress-strain relationship is proposed. The proposed model and parameters reflect the structural performance of RGPC beams more accurately than the traditional concrete structural calculation equations and specialized parameters, and the prediction results of their structural performance are more reliable. In this paper, the flexural capacity of RGPC beams is investigated and analyzed, aiming to improve the design theory of the enhanced RGPC beam structure to provide references for further research and application of this new type of GPC material and to promote the application and development of RGPC beams in practical engineering. At the same time, it supports the promotion of green buildings and low-carbon economic growth. It has important scientific significance and practical value for developing green and sustainable civil engineering structures.Originality/valueThis research holds practical application value and supports the adoption of GPC technology in the fields of green building and low-carbon development.