Research on the preparation and performance characteristics of activated copper tailings grouting material based on solid waste synergy

With China’s rapid economic and societal development, the increasing amount of industrial solid waste, among which tailings are predominant, is seriously threatening ecological and environmental safety. To address the dual objectives of developing grouting materials and disposing of copper tailings, this study develops a new grouting material using copper tailings (CT), ground granulated blast furnace slag (GGBFS), and metakaolin (MK) as raw materials. Copper tailings have been activated through different methods, including grinding, chemical additives, and calcination. The activation mechanisms are analyzed through X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Response surface methodology (RSM) was employed to examine the interactions among factors influencing the experimental response variables. The research results indicate that the optimal grinding time for copper tailings is 20 minutes, and the optimal calcination temperature for copper tailings is 800°C. The activity index of copper tailings under different activation methods is ranked from highest to lowest as follows: mechanical-chemical-thermal activation (81.4%), mechanical-chemical activation (79.6%), mechanical-thermal activation (75.7%), mechanical activation (74.5%), and thermal activation (71.8%). Considering both activation cost and efficiency, mechanical-chemical activation is identified as the optimal activation method. The optimal mix proportions of the grouting materials are 20.6% CT, 11.5% GGBFS, and 8.4% MK. This grouting material exhibits excellent resistance to corrosion in aqueous, saline, acidic, and alkaline environments. In the grouting model test, the average compressive strength of the reinforced body reaches 3.09 MPa. The grout uniformly fills and encapsulates both external surfaces and internal cracks in the geotechnical body, showcasing excellent diffusion and reinforcement performance. This study provides a high-performance, low-cost grouting material for engineering construction, and offers an innovative approach to the resource utilization of tailings and other solid wastes.