Performance,Economic,and Environmental Assessment of Steel Slag Aggregate in Roller Compacted Concrete Pavement

Utilization of steel slag aggregate (SSA) in roller compacted concrete pavement (RCCP) provides a promising approach to mitigate natural aggregate depletion and reduce the environmental footprint of pavement construction. This study systematically evaluates RCCP mixtures with SSA replacement levels from 0% to 100%, considering fresh state behavior, mechanical, durability and functional properties, economic and life cycle assessments (LCAs). The moisture density test revealed that an increase in SSA contents (0%–100%) increased the optimum moisture content (13%–35%) and improved the dry density by 1.2%–5.2%. Low and moderate inclusions of SSA (25%–50%) enhanced compressive and flexural strength (16%–21%) because of denser packing and better aggregate–mortar bonding. However, higher replacement levels (≥ 75%) of SSA reduced the mechanical performance because of excessive angularity and poor packing. Durability and functional assessments indicated that an increase in SSA content improved abrasion and skid resistance and increased water absorption because of its vesicular porous structure. Economic analysis showed that moderate SSA content (50%) reduced slab thickness and construction costs by up to 16%, while higher SSA content increased initial construction costs because of thicker slabs. The LCA revealed a decrease in 11% carbon dioxide emissions and 7% energy consumption at moderate SSA inclusion. To integrate the engineering, economic, and environmental performance outcomes, a hybrid entropy–analytic hierarchy process method was used to assign weights, and the Technique for Order Preference by Similarity to Ideal Solution was employed for ranking. The results indicate moderate SSA (50%) inclusion as the most balanced and sustainable mixture in RCCP.