Investigation into the Role of Recycled Coarse Aggregate Quality in the Behavior of Geopolymer Recycled Pervious Concrete

Geopolymer recycled pervious concrete (GRPC) provides a promising solution for low-carbon construction through the utilization of industrial by-products and recycled coarse aggregates (RCA). However, the influence of RCA quality on the durability performance of GRPC remains insufficiently understood. In this study, GRPC was prepared using RCA of high, medium, and low quality, denoted as H-GRPC, M-GRPC, and L-GRPC, respectively. The mechanical properties, permeability, fatigue resistance, freeze-thaw resistance, and microstructural characteristics were systematically investigated. The results showed that RCA quality had a limited effect on permeability, whereas the mechanical performance and durability of GRPC were strongly dependent on RCA quality. The initial compressive strengths of H-GRPC, M-GRPC, and L-GRPC were 79.2, 75.3, and 60.0 MPa, respectively, with corresponding flexural strengths of 7.3, 6.7, and 6.2 MPa. After 100,000 fatigue cycles, compressive strength increased by 3.7%, 4.4%, and 3.0%, respectively. After 200 freeze-thaw cycles, the overall freeze-thaw durability followed the order H-GRPC > M-GRPC > L-GRPC. Microstructural analysis revealed that higher RCA quality promoted a denser matrix, a more intact interfacial transition zone, and a higher degree of geopolymerization. These findings provide guidance on selecting appropriate RCA quality for durable GRPC design.