Study on preparation and performance of cement-stabilized macadam containing ground sludge gasification slag (GSGS)

Traditional cement-based road materials face problems of high energy consumption and carbon emissions, and the use of activated solid waste as a substitute for cementitious materials has been applied in road engineering. Sludge gasification slag (SGS), a product obtained from the pyrolysis and gasification of sludge, is a typical silicon–aluminum-rich solid waste that exhibits good compatibility with alkaline activation systems due to its potential activity. This study focuses on the component reconstruction mechanism of SGS in alkali-activated materials, employing cement (P) and carbide slag (CS) for synergistic modification, exploring the mechanism for enhancing the cementitious properties of sludge gasification slag under multi-component mixing conditions, and verifying its feasibility for use in cement-stabilized macadam. The results show that GSGS and GCS have a synergistic activation effect in the cement hydration system, promoting the formation of C–(A)–S–H gel and AFt. When both are incorporated in a mass ratio of 6 : 4 and account for 70% of the composite system, the compressive strength is increased by 53.19% compared to alone. When the composite material is used in cement-stabilized macadam with a 40% replacement ratio of cement, there is no significant decrease in strength, verifying the feasibility of using cement-composite sludge gasification slag in cement-stabilized macadam.