Mechanical and thermal properties of steel slag/stone-wood plastic composites reinforced with calcium sulfate whisker

• Incorporation of calcium sulfate whisker (CSW) into steel slag/stone-wood plastic composites increased tensile, flexural, and impact strengths by 28.13%, 25.02%, and 45.55%, respectively, outperforming pure talc powder (TP)-based composites. • Steel slag powder (SSP) combined with CSW can effectively replace part of the talc powder filler, reducing raw material costs and promoting sustainable utilization of industrial waste. • CSW reinforcement is achieved through bridging, micro-filling, and synergistic interactions with SSP, while SSP’s metal oxides (MgO, Al2O3, Fe2O3) crosslink with the carbonaceous skeleton to form a stable protective layer, improving thermal stability. • The findings provide a low-cost, high-performance alternative for the stone-wood plastic industry, mitigating environmental issues associated with steel slag stockpiling and talc mining.