Effects of Material Composition and Curing Parameters on Performance of Cold Central Plant Recycled Cement-Stabilized Gravel

To promote the large-scale recycling of reclaimed inorganic aggregates (RAI) generated from highway reconstruction projects, the effects of RAI content, reclaimed asphalt pavement (RAP) incorporation, RAI pretreatment, standing time, curing temperature, and curing mode on the performance of cold central plant recycled cement-stabilized gravel (CCSG) were investigated in this study. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize microstructural changes. Increasing RAI content from 0% to 90% increased the optimum moisture content but slightly reduced the maximum dry density. Without RAP incorporation, the 7-day unconfined compressive strength (UCS), elastic modulus, and splitting tensile strength (STS) decreased by 30.34%, 21.29%, and 25.46%, respectively. Abrasion pretreatment and pozzolanic slurry strengthening improved mechanical performance. Compared with untreated CCSG, the latter increased the 28-day UCS, elastic modulus, and STS by 63.67%, 37.27%, and 64.77%, respectively. A 4-h standing period reduced the 7-day UCS and elastic modulus by 15.8% and 13.9%, respectively, while lowering the curing temperature from 20 °C to 5 °C reduced them by 26.9% and 18.8%, respectively. Abrasion pretreatment modified the surface morphology of RAI, whereas pozzolanic slurry strengthening formed a more continuous surface strengthening layer and denser bonding zones. These findings clarify the effects of RAI content, pretreatment, and preparation and curing parameters on the mechanical performance of CCSG.