Experimental Study on the Performance of Copper Tailings as the Subbase of Expressway Pavement and Its Engineering Application

This paper aims to explore the high-performance and high-value application of copper tailings in the base course of pavement, while reducing the utilization of natural aggregates and other resources. Through the study of the mix proportion design of copper tailings base course, the variation law of material strength of copper tailings base course under different copper tailings blending ratios was studied, and the suitable copper tailings blending ratio for the base course of pavement under heavy traffic and above grades of expressways was determined. Through the comparative study of the bonding effect of different binding materials on the copper tailings base course, the advantages of low hydration heat and high specific surface area steel slag composite materials as binding materials were clarified. Finally, combined with the implementation of the engineering entity, a complete set of construction technology for copper tailings base course was formed. The research found that when the blending ratio of copper tailings in the base course of pavement is too high, the performance will decline significantly under the same amount of binding materials. Considering the economy and road performance, the blending ratio should be controlled within 30%. The use of steel slag composite materials can improve the strength and reduce the risk of cracking in the base course of pavement. In the implementation of the engineering entity, copper tailings were successfully applied to the base course of expressway pavement, verifying its high-value and high-performance application effect.