Green concrete alternatives: Utilizing industrial byproducts in geopolymer systems

The structural performance of Recycled Coarse Aggregate (RCA) concrete wrapped with Fiber-Reinforced Polymer (FRP) has received research attention; however, the confinement behavior of Red Mud-based Geopolymer Concrete (RMGC) incorporating RCA and strengthened with Carbon Fiber-Reinforced Polymer (CFRP) remains insufficiently addressed, particularly through advanced modeling. This study addresses this gap by experimentally and numerically evaluating the axial compressive behavior of CFRP-confined RMGC cylinders, where variations include concrete strength, number of CFRP layers, and confinement configuration. A validated Finite Element Modeling (FEM) model was employed to simulate key parameters, such as cylinder diameter, fiber thickness, modulus of elasticity, and orientation. Results revealed that confined strength f cc ′ improved by 125 % when the diameter and f co ′ increased, while a 7.47 % reduction occurred with increased modulus E f . Additionally, a novel regression-based model was developed, achieving a predictive accuracy of R 2 = 0.96 , outperforming prior models. This study presents a refined analytical tool and a validated parametric database for optimizing CFRP confinement in geopolymer RCA concrete, thereby supporting sustainable, efficient, and high-performance structural design.