Research On The Frost Resistance And Chloride Penetration Resistance Properties Of Gangue Concrete

Coal gangue is an industrial waste product in the process of coal mining and coal extraction. Due to the long-term accumulation and year by year a large number of abandoning not only occupy the land resources, but also under certain conditions coal gangue will be self-ignition, the atmosphere and underground water were polluted seriously. At present, some coal gangue as raw material is used to prepare ceramic, refractory and cement, but the effective utilizated rate of coal gangue is still less than 70%.In this paper, the physical characteristics of coal gangue as coarse aggregate, which includes the gradation, apparent density, water absorption, crushing index, mud content and so on are studied in this paper, XRD is used to analyze the phase composition of coal gangue. Through the basis experimental research, respectively to study effects of water binder ratio, sand ratio, aggregate cement ratio and coarse aggregate level matching to frost resistance and resistance to chloride ion permeability of coal gangue concrete. And the orthogonal experiment is carried out. At last, the microstructure and morphology were observed by SEM.The experimental study shows that:(1)In a certain range, when the aggregate cement ratio raised from 3.9 to 5.1,the strength loss rate of coal gangue concrete after 200 freezing thawing cycles is bigger and bigger, and it shows that the bigger the aggregate cement ratio is, the worse the frost resistance of coal gangue concrete is;(2)When sand ratio is 42%, the strength loss ratio of coal gangue concrete is the lowest, and the frost resistance of coal gangue concrete is the best;(3)When the coal gangue aggregate gradation is in the range of 0.6~1.4(proportion of coarse coal gangue and fine coal gangue), the strength loss rate of coal gangue concrete changed from decreasing to increasing with the increase of aggregate gradation, and when the ratio of coal gangue and fine coal gangue is 1:1, the strength loss ratio of coal gangue concrete is the lowest, the frost resistance of coal gangue concrete is the best;(4)when the water binder ratio increased from 0.3 to 0.45, the strength loss ratio of coal gangue concrete increased as the ratio of water cement ratio increasing, which shows that the smaller the water cement ratio, the better the frost resistance of coal gangue concrete is;(5)The experimental research on the freezing resistance of coal gangue concrete by admixture type, the 28 d strength of the coal gangue concrete mixed with naphthalene series water reducer is the highest, the strength loss rate is the lowest, and the frost resistance performance is the best;(6)Through the experimental research on the freezing and thawing cycles of coal gangue concrete, we can know the influence factors of C40 coal gangue concrete properties are: water cement ratio, water cement ratio, aggregate ratio, aggregate gradation, water cement ratio is 0.3, the ratio of water to cement ratio is 3.9, sand ratio is 42%, and the aggregate gradation is 1:1, the frost resistance of coal gangue concrete is the most favorable. Effect of water binder ratio on coal gangue aggregate concrete resistance to chloride ion permeability was prepared by combination of coal gangue aggregate concrete has the best resistance to chloride ion penetration is A2B3C2D3, namely the water binder ratio is 0.39, sand rate was 43%, the ash collection ratio is 4.2, aggregate gradation is 1:1, this is 6h. The amount of coal gangue aggregate concrete is 985.36 C, with a strong ability to resist chloride ion penetration.By the SEM microscopic analysis shows that: the coal gangue concrete than low water gel, the gel pores and the pores are filled with water gel, blocking the pores of concrete, the concrete density is larger, the electric flux decreases and the resistance to chloride ion permeability enhancement. Coal gangue in transition zone between aggregate and cementitious materials, a transition zone to make coal gangue concrete more easily damaged, holes the flux increases, coal gangue concrete resistance to chloride ion permeability decreased.