Environmental and mechanical performance of molybdenum tailings concrete columns using LCA

This study evaluates the environmental–mechanical performance of three types of molybdenum tailings concrete columns, where molybdenum tailings were used as a substitute for fine aggregate. The columns investigated were reinforced (RMoTC), concrete-filled steel tube, and steel tube-confined, using a life cycle assessment framework. A cradle-to-grave system boundary was established, covering the raw material production, transportation, construction, maintenance, and demolition stages. Environmental impacts were monetised using the willingness-to-pay (WTP) method, while mechanical capacity was assessed through standard axial load-bearing equations. To couple environmental and mechanical performance, an integrated environmental–mechanical performance factor (γint) was proposed, defined as the ratio of axial capacity to total life-cycle WTP, to evaluate overall sustainability efficiency. The results reveal that steel tubular columns exhibit significantly lower environmental impacts than RMoTCs, mainly due to reduced formwork use and maintenance requirements. Increasing the molybdenum tailings replacement ratio decreases total WTP by approximately 7.1%–8.7% for 30 MPa concrete with full substitution. Enhancing material strength markedly improves γint and increasing the steel ratio slightly lowers γint (5.9%–8.7%) due to the larger environmental cost, while variations in cross-sectional diameter have negligible effects. These findings support sustainable design optimisation for molybdenum tailings concrete structures.