Influence of decarburized coal gasification slag on the strength of concrete
In order to solve the problems of land and water pollution and great waste of resources caused by high carbon content gasification slag produced by coal gasification,this paper takes decar-bonized coal gasification slag as admixture,and conducts scanning electron microscopy and fourier transform infrared spectroscopy to analyze the microstructure and the characteristics of the functional groups on its surface.4-factor 5-level orthogonal test was designed,the specimens of decarbonized coal gasification slag concrete was prepared,the effects of decarbonized coal gasification slag on compressive strength of concrete at different ages was explored,and the hydration mechanism of hardened products was examined under the optimum proportion of decarbonized coal gasification slag.A detailed analysis was made of the effect of decarbonized coal gasification slag admixture on the compressive strength of concrete at different ages,with the hydration mechanism of hardening products explored under the opti-mal ratio of concrete mixed with decarbonized coal gasification slag.The results show that:the mixing ratio of water-cement ratio of the decarbonized coal gasification slag concrete is 0.18,silica fume mix-ing for 20％,fly ash mixing for 10％,decarbonized coal gasification slag mixing for 5％,and the con-crete has a better performance.10％or less mixing on the strength of the concrete has a more obvious enhancement,which can be used as an admixture for the preparation of high-strength concrete.At the early stage of hydration,grinding decarbonized coal gasification slag amorphous minerals and cement hydration produced by the reaction of calcium hydroxide to generate a large number of low-crystalline hydrated calcium silicate gel.The decarbonized coal gasification slag surface contains more oxygen-con-taining functional groups,with strong hydrophilicity,to a certain extent,accelerating the hydration reac-tion process.At the late stage of hydration,the highly crystalline calcium alunite and other needle and rod crystals were generated,so that its strength could be enhanced.
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