Properties of UHPC products prepared by sawing mud and gold mine tailings via static pressure forming

This study investigated the feasibility of the synergistic replacement of two solid wastes in ultra-high-performance concrete (UHPC), where Sawing mud (SM) and Gold mine tailings (GT) were used to replace cement and Quartz Sand (QS), respectively. UHPC mix was designed based on the particle close packing model, and test specimens were prepared using a static pressure process. Mechanical properties, durability, and microstructural characteristics were systematically analyzed under varying SM replacement ratios and complete QS substitution with GT. Results indicated that optimal performance was achieved with a molding pressure of 22 MPa, water-binder ratio (w/b) of 0.17, superplasticizer dosage of 0.6 %, 30 % cement replacement by SM, and 100 % replacement of QS by GT. Under these conditions, the UHPC exhibited flexural strength and compressive strength of 15.7 MPa and 83.6 MPa, respectively, at 28 days. While maintaining good durability, it also demonstrated a freeze-thaw resistance grade of F300 and a chloride ion penetration resistance grade of "very low". Microstructural analysis revealed that GT incorporation had limited impact on hydration processes and hydration products, with reduced porosity. This research confirms the viability of SM and GT as sustainable alternatives for cement and QS in UHPC production. This study realizes the high-value synergistic utilization of dual solid wastes, namely SM and GT. It significantly reduces the pressure of solid waste stockpiling and lowers the consumption of resources such as cement and quartz sand, provides technical references for the research and development of low-carbon building materials in areas with concentrated mining and stone processing industries, promotes the development of UHPC toward ecological and low-cost directions, and possesses both environmental benefits and engineering application value.