Hydration Behavior, Mechanical Performance, and Sustainability of Ground Mine Waste Rock Blended Cement

Supplementary cementitious materials such as fly ash and blast furnace slag are widely used to reduce emissions associated with Ordinary Portland Cement (OPC); however, their availability is declining due to the transition towards renewable energy. In contrast, mine waste rock (MWR) is generated in large quantities and requires urgent recycling to support sustainable mining practices. This study investigates ground recycled mine waste rock blended cement (GRMBC) as a circular-economy-based alternative to conventional SCMs. Mine waste rock was mechanically ground to a median particle size of 40 µm. GRMBC containing up to 50 wt.% MWR was evaluated for hydration behaviour, microstructure, porosity, and mechanical performance. Enhanced late-age hydration, increased C–S–H formation, and compressive strengths comparable to OPC were achieved at 10–20% replacement levels. Sustainability assessment indicated a 20–30% reduction in CO₂ emissions and material cost per MPa, demonstrating the potential of GRMBC as a low-carbon cementitious binder.