Enhancing Ultra-High-Performance Concrete with High-Titanium Slag Sand: A Sustainable Approach to Low Carbon Emissions

This study aims to explore the feasibility of utilizing high-titanium slag sand (HTSS) as a sustainable alternative to quartz sand in ultra-high-performance concrete (UHPC). The results indicated that incorporating HTSS accelerated cement hydration, enhancing 7-d and 28-d compressive strengths by up to 42.1% and 33.1%, respectively. Notably, at a 100% replacement ratio, the mixture exhibits distinct strain-hardening behavior with uniaxial tensile strength exceeding 6 MPa. Concurrently, autogenous shrinkage is reduced by 32% at 5 h and 68% at 7 d, while CO2 emissions and energy consumption are lowered by 53 kg/m3 and 826 kJ/m3, respectively. Despite its rough and porous morphology, HTSS only marginally affects rheological properties. These findings provide theoretical insights into the development of low-carbon, low-shrinkage UHPC through the strategic valorization of industrial solid waste.