The Influence of CO2 Curing on the Properties of Coal Gangue Non-Fired Blocks

Coal gangue is a solid waste, which can cause serious pollution of the atmosphere and water sources due to its long-term accumulation. In this article, the influence of CO2-cured coal gangue on the slump flow, the mechanical strengths, the thermal conductivity coefficient, the chloride ion permeability, the water resistance coefficient and the leached Pb of the coal-gangue-block masonry are determined. Moreover, the temperature distributions at different measuring points of a coal-gangue-block cabin model are obtained. The results exhibit that CO2-cured gangue demonstrates positive effects on the slump flow, the mechanical strengths and the thermal conductivity coefficient, with the slump flow rates increasing by 0%~23.6%, the mechanical strength rates increasing by 0%~222.7% and the thermal conductivity coefficient rates increasing by 0%~73.2%. Straw fibers increase mechanical strengths and decrease thermal conductivity at rates of 0%~222.7% and 0%~32.6%. Foam decreases the mechanical strengths and the thermal conductivity coefficient by 0%~71.2% and 0%~87.1%. The chloride ion migration coefficients are decreased by 0%~42.1% and 0%~43.7% with the added CO2-cured coal gangue and the straw fibers. The added foam leads to an increase in the chloride ion migration coefficient of 0%~73.2%. The foam and the straw fibers show delaying temperature changes in a coal-gangue-block cabin model, while when CO2-cured coal gangue is added, the effect is the opposite. The CO2-cured coal gangue and the straw fibers lead to decreases in the leached Pb and Zn, while when the foam’s mass ratio increases, the result is the contrary.

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