Structural performance of reinforced geopolymer concrete beams incorporating construction and demolition waste-based recycled precursors and aggregates

The rising demand for sustainable construction materials has led to the extensive exploration of geopolymer concretes utilizing construction and demolition waste (CDW) as recycled precursors and aggregates, providing a feasible alternative to traditional concrete. However, there has been limited research on the potential of CDW-based reinforced geopolymer concrete (RGPC) as viable structural components, particularly when high amounts of CDW powders and aggregates are included. This study comprehensively investigates the effects of various CDW-based coarse and fine aggregates, including recycled concrete aggregate (RCA), recycled brick aggregate (RBA), and recycled tile aggregate (RTA) on the structural performance of RGPC beams prepared with CDW-binder. The structural performance of RGPC beams was evaluated through flexural bending, load-deflection, shear resistance, crack pattern analysis, post-cracking residual load-carrying capacity tests and compared to conventional concrete beams. The impact of two varying shear-span-to-depth (a/d) ratios ranging from 1.0 to 2.0 was also evaluated. The results demonstrated that all CDW-RGPCs exhibited structural properties comparable to conventional reinforced concrete beams, though RCA showed comparatively higher structural performance than their RTA and RBA counterparts, especially in terms of bending and load-carrying capacities. These experimental results were also confirmed through finite element modeling using ABAQUS, which accurately predicted the stress distribution and failure patterns of RGPC. The findings highlight the feasibility of CDW-based RGPC beams as sustainable alternatives to conventional reinforced beams for high-performance structural applications, offering substantial potential to reduce the environmental footprint of the construction industry.