Selection of modified mining waste materials for sustainable open-pit haul roads: a fuzzy AHP-TOPSIS framework incorporating extreme climate and life-cycle perspectives

Open-pit haul roads are increasingly exposed to extreme climate conditions, while life-cycle carbon emissions are rarely incorporated into material selection in engineering practice. This study presents a fuzzy AHP-TOPSIS-based evaluation approach for mine-derived materials, in which extreme climate factors are integrated into the hierarchical weighting process and life-cycle carbon emissions are incorporated into the ranking procedure. The approach was applied to an open-pit haul road project at the Zijinshan Gold-Copper Mine in China to identify suitable pavement materials. Results under the SSP5-8.5 scenario indicated that mechanical strength and heavy metal control dominated decision priorities, while climate-related performance criteria, particularly stability and durability, also exhibit considerable importance. Life-cycle assessment results shown that polyvinyl alcohol-granulated blast-furnace slag stabilized blasting slag powder (PGBP) achieved the lowest carbon emissions due to reduced maintenance demand. The ranking consistently identified PGBP as the optimal alternative, and sensitivity analysis confirmed the robustness of the decision results under varying climate and carbon-weight scenarios. The proposed approach provided a practical and transferable decision-support tool for material selection in open-pit haul roads under complex environmental conditions.