Sustainable magnesium oxysulfate cementitious composites from agricultural and industrial wastes: performance and optimization

This study successfully developed a novel multi-source solid waste composite based on magnesium oxysulfate cement (MOSC). It significantly enhanced mechanical properties through optimized locust wood powder particle size, component dosage regulation, and the incorporation of fly ash (FA), ground slag (GS), and sodium silicate (SS). Optimizing wood powder size to 0.160–0.315 mm boosted flexural and compressive strengths. The synergistic incorporation of FA and GS yielded mechanical properties comparable to or superior to MOSC, with 28-day flexural and compressive strengths of 11 MPa and 80 MPa, respectively. Sodium silicate further enhanced properties, particularly fracture absorption energy under flexural loading. The ordered arrangement and tight network structure of the 5·1·7 phase promoted adequate hydration, improving overall performance. The optimized composites exhibited peak mechanical properties at 60d, with flexural and compressive strengths of 12.8 MPa and 79 MPa, respectively, and achieved a 65% multi-source solid waste consumption rate, offering significant economic and environmental benefits.