Utilization of coal gasification slag produced in the process of converting coal into combustible gas in cement: Multiscale evaluation, mechanistic analysis, and environmental impacts

• 0.09% DEIPA enhanced the reactivity of CGS. • The activation mechanism of DEIPA was attributed to complexation. • More C-(A)-S-H from synergistic reaction of DEIPA, CGS, cement. • Life cycles assessment shows sustainability of CGS-composite cements. This study investigated the sustainable utilization of coal gasification slag (CGS) in cement composites, with a focus on the activation and modification mechanisms of diethanol isopropanolamine (DEIPA) and its synergistic role in cement systems. The results indicated that DEIPA significantly promoted the dissolution of Al, Si, and Ca through complexation, thereby enhancing the reactivity of CGS. Moreover, DEIPA and CGS exhibited synergistic effects during cement hydration, markedly improving both compressive strength and workability. At a DEIPA dosage of 0.09 %, the 28-day compressive strength reached 43.6 MPa, representing a 9.8 % increase over the control group (39.7 MPa). Compared with OPC, the DEIPA-0.09 CGS composite reduced EE by 17.93 %, GWP by 26.54 %, and cost by 25.21 %. These findings demonstrated that DEIPA-modified CGS composite cement could serve as an effective alternative to traditional cement, mitigating climate impacts while reducing reliance on non-renewable resources. Overall, the study provided a promising strategy for the sustainable valorization of CGS and contributed to the development of low-carbon, resource-efficient construction materials.