Utilization of marble, granite, and travertine sludge as sand replacements in self-compacting concrete with low-carbon binder: Rheological, mechanical, and environmental evaluation

This study presents a sustainable method for producing self-compacting concrete (SCC) by partially replacing natural sand with stone-cutting sludge (marble, granite, and travertine) at 10 %, 15 %, and 20 % levels. A low-carbon ternary binder system consisting of 85 % ground granulated blast furnace slag (GGBFS), 10 % ordinary Portland cement (OPC), and 5 % hydrated lime significantly reduces CO₂ emissions. Results indicate that a 10 % sand replacement with any sludge type, especially marble, improves flowability, viscosity, and segregation resistance without increasing admixture dosage. Moreover, replacement with 15 % and 20 % marble and travertine sludge maintains favorable rheological and mechanical properties. In contrast, granite sludge enhances fresh performance at 10 % but reduces workability and strength at higher replacement levels. Compressive strength increases by up to 5.9 % at optimal dosages, and Life Cycle Assessment (LCA) demonstrates a reduction of up to a 71.9 % in Global Warming Potential compared to conventional OPC-based SCC. A cost analysis confirms the economic benefits of reduced sand usage. This approach demonstrates that combining sand substitution with a low-cement binder system enables eco-efficient concrete production while promoting the utilization of industrial waste and achieving circular economy goals. • Producing SCC by partially replacing natural sand with different stone-cutting sludge. • A low-carbon ternary binder system consisting of 85 % GGBFS, 10 % OPC, and 5 % hydrated lime. • Improvement in concrete rheology by replacing 10 % of sand with different types of stone sludge. • Improvement of compressive strength by replacing 10 % and 15 % of sand with stone sludge. • 71.9 % lower Global Warming Potential compared to conventional OPC-based SCC.