Chrome waste utilization in base layers: Mechanical strength and environmental risk assessment

This study investigates the partial substitution of natural aggregate (Na) with chrome mine waste (Cr w ) in highway base layers, focusing on mechanical performance and environmental safety. Cr w -Na mixtures with contents from 0% to 100% were tested using CBR, cyclic plate loading, chemical, and leachate tests. The 15% Cr w -85% Na mixture achieved the highest CBR (287.4%) with limited deformation (37 mm). Although the 60% Cr w blend also met the required strength level (156.6%), it showed higher settlement (50 mm) and three times greater vertical strain. SEM-EDX and chemical results indicated increased magnesium content and mineral changes at higher Cr w ratios. Leachate tests confirmed compliance with TS266 and international water standards; all samples were categorized as neutral drainage with low metal risk. The findings show that Cr w improves strength without causing environmental risk. Among tested mixtures, 15% Cr w offered the most balanced outcome in terms of field stability and performance.