Modeling and optimization for the combined valorization of calcined sediments and ground blast-furnace slag in eco-mortar formulations: Rheological, mechanical, microstructural, and environmental assessments

The need for sustainable alternatives to conventional cement has led to increased interest in incorporating mineral additions such as calcined dredged sediments (DS) and ground granulated blast-furnace slag (GBFS) in eco-mortar formulations. This study investigates the combined valorization of these materials as partial cement replacements (10–30 %) and their impact on rheological, mechanical, microstructural, and environmental properties using a Mix Design Model (MDM). The findings indicate that optimized formulations incorporating up to 30 % DS and GBFS achieve compressive strengths exceeding 50 MPa and flexural strengths up to 7 MPa at 90 days. Microstructural analysis confirms the formation of dense hydration phases, enhancing durability. Despite a slight reduction in workability due to increased viscosity, the environmental assessment reveals a substantial reduction in CO₂ emissions—up to 25 % (approximately 700 kgCO₂/ton of binder) compared to conventional mortars. These results highlight the potential of DS and GBFS as promising low-carbon alternatives in cementitious materials, with the statistical modeling approach enabling precise optimization of performance and environmental impact.