Potential of Saturated Coal Gasification Slag as the Fine Aggregate of Cement‐Based Materials

This paper studied the feasibility of saturated coal gasification slag (SCGS) as the fine aggregate of cement‐based materials, and discussed the influence of SCGS on the fluidity and compressive strength of cement mortar as fine aggregate based on the study of physical and chemical properties of the particles. The analysis of the mechanism of SCGS on cement hydration was carried out through analysis of the mineral phase composition, pore size distribution and microstructure, as well as thermal analysis of the cement–coal gasification slag (CGS) mixture hydration product. The results indicate that SCGS as fine aggregate does not introduce significant expansion risk. When added to the mortar, SCGS exhibits better flowability and mechanical properties than dry CGS (DCGS). Furthermore, analysis of hydration products shows that SCGS could increase hydration degree of cement and facilitate the formation of calcium–silicate–hydrate (C–S–H gels, contributing to the improvement of the strength. SCGS effectively reduced both the proportion of harmful pores and the pore connectivity within the mortar. Additionally, C–S–H gel fills the microvoids present on the surface of the SCGS mortar, thereby enhancing the compactness of the mortar.