The influence of lithium slag and steel fiber on the stress–strain behavior of recycled aggregate concrete materials under axial tension

With the development of the construction industry, the treatment of construction waste has become an environmental problem that needs to be solved urgently, and lithium slag (LS), as a by-product of calcined spodumene, has a large environmental pollution and a low utilization rate. In order to improve the recycling rate of LS and explore its application in building materials, the effects of steel fiber (SF) and LS on the stress–strain behavior of RAC composites under axial tensile action were systematically studied by preparing RAC test blocks with different steel fiber volume fractions (V<inf>f</inf>) and lithium slag substitution ratios (LSR) using recycled aggregate concrete (RAC) as the matrix. The results show that when the LSR is 5% and the V<inf>f</inf> is 1.2%, the lithium-slag-reinforced and steel-fiber-reinforced RAC (LS-SF-RAC) exhibit the highest toughness among all test blocks, indicating that there is a significant synergistic effect between LS and SF, and the appropriate increase of V<inf>f</inf> under low LSR conditions can significantly improve the tensile performance of LS-SF-RAC. This finding not only provides an effective way to improve the recycling rate of LS, but also provides a theoretical basis for the performance optimization of RAC, which has important engineering application significance for promoting the resource utilization of construction waste and the research and development of green building materials.