Examination of Mixing Proportion in Self-Compacting Gangue-Based Pavement Concrete

In recent years, with the rapid development of the coal-mining industry, the output of gangue has increased at a faster pace, while its utilization remains relatively low. The accumulation of a large amount of gangue has brought about a large environmental problem. In order to improve the utilization rate of waste gangue, and to solve the secondary environmental problems caused by gangue pollution, this paper conducted research on an economic and environmentally friendly gangue-based self-compacting concrete. This study designed aggregate industrial-analysis experiments to analyze the moisture content of the gangue and limestone, finding that the moisture content of gangue is 39% higher than that of limestone. By orthogonal experimental methods, the study investigated the fluidity, compressive strength, splitting strength and abrasion resistance of self-compacting gangue concrete. It was concluded that the optimal replacement rate of gangue for coarse aggregate is around 30%, the optimal replacement rate of fly ash for cement is around 30%, the optimal addition of polycarboxylate superplasticizer is 0.5% of the mass of cementitious materials, and the optimal rate of shear steel fibers is around 1% of the concrete capacity. In addition, this paper investigated the interfacial transition zone (ITZ) of the aggregate–cement slurry and found that the ITZ of gangue aggregate and cement mortar is more likely to generate AFT crystals, which will contribute more to the improvement of the strength of concrete in the early stage. In addition, a field-effect analysis was carried out in this study, and it found that gangue-based self-compacting concrete, as an environmentally friendly material, can basically meet the design requirements of C30 paving concrete.

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