Effect of Hydration Process on Properties and Microstructure of Coal Gangue Admixture Concrete

다국어 초록 (Multilingual Abstract)

The mineral of coal gangue is mainly kaolinite, which can be used as mineral admixture after activation. In order to study the effect of coal gangue on the hydration process of concrete, 20% coal gangue powder was used to replace cement to prepare concrete. The phase composition, microstructure morphology and pore structure of concrete hydration products at different ages were observed by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR). At the same time, the experimental study on the compressive strength, splitting tensile strength and flexural strength of coal gangue admixture concrete with time and relationship was carried out. The results indicate that the addition of coal gangue powder significantly affected the hydration process of cement. In the cement-coal gangue powder-water system, coal gangue particles adsorbed a large amount of CH generated by cement hydration after curing for 14 d. The (AlO4)4− group in the coal gangue power replaced the (SiO4)4− on the calcium silicate hydrate (C-S-H) structure of the hydration product, thereby generating a new flocculated polymer calcium aluminosilicate hydrate (C-A-S-H). Until the curing age exceeded 56 d, the CH content in the slurry was less, and the hydration reaction rate of coal gangue became slowe. The unhydrated coal gangue particles played the “micro-aggregate effect”, filled in the pores and reduced the number of macropores and pores. The density of concrete microstructure increased, which promoted the continuous increase of concrete strength.

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