LAUSR

Abstract This paper studied the feasibility of the decarbonized coal gasification waste residues as the admixture of cement-based materials, and discussed the influence of coal gasification coarse slag (CGS) and fine ash (CGA) on the fluidity and compressive strength of cement mortar as the admixture based on the study of physical and chemical properties of the two types of particles. The analysis of the mechanism of coal gasification waste residue on cement hydration was carried out through analysis of the phase characteristics and microstructure, as well as thermal analysis of the cement-coal gasification waste residue mixture hydration product. The results showed that CGA had a negative influence on the fluidity of cement mortar although its particle morphology was mostly spherical, while CGS was conducive to the fluidity. Also, with a strength activity index of 100.9%, CGA had better pozzolanic reactivity than CGS whose strength activity index was 82.7%. XRD experimental results showed that the adding of CGA and CGS greatly reduced the content of calcium hydroxide in the cement hydration products. The fact was that there was no obvious calcium hydroxide in the hydration product when the amount of replacement cement was 30% after 28 days of hydration. Moreover, SEM results showed that the original morphologies of CGA and CGS were severely damaged in the later period of hydration. Therefore, the synergistic use of CGA and CGS may have a good effect on the fluidity and strength of cement-based materials.