Safe and environmentally friendly use of coal gangue in C30 concrete

Abstract

Industrial solid waste coal gangue (CG) is used as the research object, and the mechanical activation-water washing pretreatment method was used to explore the feasibility of carbon removal by water washing and the improvement and microscopic mechanism of the treatment process on the cementitious activity of CG. The mechanism and effect of mechanical activation + water washing carbon removal were analyzed by loss on ignition, TG-DSC and heat release of floats. The calorific value of floats was 17.58 MJ/kg (5 min) and 11.18 MJ/kg (20 min), which could be used as coal products. It was found that the compressive and flexural strength of 5 min mechanical activation-water washing cementitious materials reached 30.3 MPa and 4.97 MPa. The concrete was prepared and the mechanical properties test and SEM, XRD, FTIR were carried out to study the microscopic hydration mechanism of the cementitious system. It was found that the replacement rate of CG was inversely proportional to the mechanical properties of concrete, and was proportional to the durability of concrete first and then inversely proportional, mainly because the incorporation of CG reduced the alkalinity of the system and affected the hydration reaction. Using the life cycle method, it is found that the carbon emissions of CG-based cementitious system are significantly lower than those of cement cementitious materials, which proves that the use of CG in the construction industry is a feasible way of low-carbon energy conservation and emission reduction.