Feasibility Study on Using Coal Chemical Residue for Cement Road Construction

The waste residue produced by coal gasification is called coal gasification slag, and there is no effective use of this residue. In order to solve the problems of resource wastage and environmental pollution, we have analyzed the properties of coal gasification slag and found that its main components are similar to silicate cement and hence it can be used as an additive to replace a portion of aggregates and cement. In this paper, we analyzed the properties of coarse and fine slag and evaluated their compatibility with cement paste at different dosages. The main study includes characterization methods such as chemical elemental analysis, thermogravimetric analysis, XRD, stretching and SEM. The results showed that the coarse slag was flaky or granular with a smooth and dense surface, and some of the slag samples were completely melted and agglomerated into spheres, while the fine slag was flocculated with a honeycomb surface. In addition to carbon, the chemical compositions of coarse slag and fine slag are similar, mainly containing SiO2, silica-aluminate and Fe2O3. The mass loss of fine slag is 4.3 mg. Coal gasification fine slag has a high weight loss rate, and it has a certain ability for decomposition and oxidation reactions at high temperatures, but it is less stable. We added different dosages of fine slag to cement paste and evaluated the properties by assessing the expansion, hydration, density and fluidity of the paste.