Behavior of Sustainable Functionally Graded Beams Made of Hybrid Geopolymer Concrete

Functionally graded concrete (FGC) is an advanced building technique that allows structural components to satisfy diverse mechanical and durability specifications. In this study, hybrid geopolymer concrete (HGC) was used in constructing reinforced FGC beams to improve their flexural performance and sustainability. One HGC mix was used and compared with the corresponding control cement-based concrete mixture. The HGC mix was made of FA, slag, and dolomite powder (DP) binders. The structural performance of ten reinforced FGC beams, with different cross-sections and varying concrete layer configurations, was evaluated by four-point bending tests. The results indicated that beams utilizing HGC in the tensile zone showed improved ductility and load-carrying capacity relative to those constructed with the corresponding cement-based concrete. The functionally graded configuration, particularly when HGC is placed in the crucial tension zone, markedly enhanced both the ultimate deflection by 30% and ductility by 73%. These findings highlighted the advantages of using HGC in constructing FGC beams for sustainable, high-performance concrete structures, facilitating diminished cement usage, reduced carbon emissions, and enhanced structural resilience.