Mechanical performance and structural feasibility of recycled construction and demolition waste aggregates as bases for water-retentive pavements

To expand the application scope of recycled aggregates (RA) derived from construction and demolition waste, this study evaluated the technical feasibility of utilizing RA with high water absorption in the base layer of water-retentive pavements. Laboratory characterization—including the water-holding capacity (WHC), California Bearing Ratio (CBR), resilient modulus ( M r ), and freeze and thaw (F–T) resistance—was conducted on RA mixtures with varying recycled concrete aggregate (RCA) to recycled clay brick aggregate (RCB) ratios (0%–100%, denoted as 100RCA and 100RCB for pure RCA and RCB mixtures, respectively), with natural aggregates (NA) mixture as the control. Finite element structural verification was subsequently performed. As RCB content increased, WHC improved while CBR and M r showed an overall declining trend. RA mixtures exhibited two to three times higher WHC than NA (24.4%–36.9% vs. 12.4%). The soaked CBR value of 100RCB mixture (121.6%) remained above the regulatory limit ( ≥ 120%) for light-traffic applications specified in Chinese standards. M r of all mixtures exhibited clear stress-dependent behavior, well described by constitutive models( R 2 > 0.93 ), ranging from 260 MPa (NA) to 180 MPa (100RCA) to 120 MPa (100RCB) at a bulk stress of 208 kPa. F–T cycling (12 cycles) exerted negligible influence on M r . Structurally compliant pavement configurations were identified for all materials; notably, even 100RCB met all design criteria through moderate increases in surface and base layer thickness, confirming the structural feasibility of RA-based water-retentive pavements for light-traffic applications such as sidewalks, bicycle lanes, and parking areas.