Design and Research on the Preparation of Pervious Concrete Using Carbonized Steel Slag as a Full Component

To address the environmental pressures and resource waste caused by massive stockpiling of steel slag, this study developed a carbonated steel slag pervious concrete binder using 40% steel slag powder as the primary cementitious component combined with CaO and MgO. The mechanical performance evolution was investigated, while XRD, SEM, and TG-DTG microcharacterization techniques were employed to reveal the carbonation mechanism and strength formation principles. The results demonstrate that when CaO and MgO contents reached 5% and 15%, respectively, the 28d compressive strength of mortar increased by 134.49% compared to the reference group. Microstructural analysis confirmed that CaO reacted to form CaCO3 crystals, while MgO enhanced strength by regulating CaCO3 crystal morphology to optimize product structure. Using steel slag as an aggregate, carbonated steel slag pervious concrete was prepared to investigate the influence mechanisms of B/A ratio and W/B ratio on compressive strength, permeability coefficient, and carbonation effects. The post-carbonation strength increase was adopted to evaluate carbonation efficiency. Increasing B/A ratio enhanced paste filling in aggregate voids, raising 28d compressive strength to 24.76 MPa, but thickened paste coating layers reduced permeability coefficient to 0.33 mm/s while impeding CO2 diffusion, decreasing carbonation strength growth rate by 22.76%. Initial W/B ratio elevation improved workability to increase strength to 23.76 MPa, whereas excessive water caused paste sedimentation and strength reduction. As W/B ratio rose, permeability coefficient decreased by 65.6%, while carbonation strength growth rate increased. The carbonated steel slag pervious concrete contained approximately 82% steel slag, demonstrating high resource utilization efficiency of steel slag and significant potential for carbon emission reduction.