On the Structural Performance of Recycled Aggregate Concrete Columns with Glass Fiber-Reinforced Composite Bars and Hoops

TLDR

Structural members comprising geopolymer recycled aggregate concrete reinforced with glass fiber‑reinforced polymer bars have not been adequately investigated for axial compressive loading. The present study evaluates the structural efficiency of GFRP‑reinforced geopolymer recycled aggregate concrete members under axial compression. Nine 250 mm × 1150 mm compressive members were fabricated to study how the number of longitudinal GFRP bars and the spacing of transverse GFRP hoops/ties affect performance, and an empirical model was developed to predict axial load‑carrying capacity from the experimental data. The results show that reducing the pitch of GFRP hoops increases ductility, increasing the number of longitudinal bars up to eight raises axial load‑carrying capacity (reaching a 2.11 % reinforcement ratio), while ten bars reduce capacity; the empirical model accurately predicts these outcomes, confirming the column’s feasibility and environmental sustainability.

Abstract

Structural members comprising geopolymer recycled aggregate concrete (RAC) reinforced with glass fiber-reinforced polymer (GFRP) bars have not been investigated appropriately for axial compressive loading cases. The present study addresses this knowledge gap by evaluating the structural efficiency of GFRP-reinforced geopolymer recycled aggregate concrete (GGRAC)-based members subjected to axial compressive loading. A total of nine compressive members (250 mm in cross-section and 1150 mm in height) were constructed to examine the effect of the number of longitudinal GFRP bars and the vertical spacing of transverse GFRP hoops/ties. The experimental results portrayed that the ductility of GGRAC compressive members improved with the reduction in the pitch of GFRP hoops. The axial load-carrying capacity (LCC) of GGRAC compressive members increased by increasing the number of GFRP bars up to eight (corresponding to a reinforcement ratio of 2.11%) while it decreased by using ten longitudinal GFRP bars (corresponding to a reinforcement ratio of 2.65%). Additionally, an empirical model was suggested to predict the axial LCC of GGRAC compressive members based on a large amount of experimental data of similar members. The experimental results and related theoretical predictions substantially prove the applicability and accuracy of the proposed model. The proposed column represents a feasible structural member in terms of material availability and environmental sustainability.