Mechanical Properties and Constitutive Relation of Waste Fiber Geopolymer Recycled Aggregate Concrete

To address the negative environmental impact of industrial and construction solid waste accumulation, a novel waste fiber geopolymer recycled aggregate concrete (WFGRAC) has been produced employing recycled coarse aggregates, geopolymers, and waste fibers. The mechanical properties and working mechanism of WFGRAC have been comprehensively analyzed through a combination of mechanical performance tests and mesoscopic finite element simulations. A constitutive model for WFGRAC under uniaxial compression was also established. The results demonstrated that WFGRAC exhibited a 5.71% increase in compressive strength compared to ordinary recycled concrete. However, when the waste fiber content exceeded 5%, the mechanical properties of WFGRAC declined as the fiber content increased. The interfacial transition zone (ITZ) in recycled concrete is identified as a weak area where damage initiates during compression. The constitutive model for WFGRAC under uniaxial compression was established through strain statistical analysis and was proven to effectively reflect the observed stress-strain relationship.