Experimental Study On Mechanical Properties And Carbonation Resistance Of Coal Gangue Aggregate Concrete

Coal gangue is produced in the process of production and processing of solid wastes, emissions each year equivalent in 10~15% of coal production, stocks has accumulated more than 4.5 billion tons, is one of the largest solid waste emissions now in our country. As one of regeneration utilization way of coal gangue, coal gangue was broken, sorting and screening made from coal gangue aggregate thickness, added to replace some or all of the normal weight aggregate concrete, light-weight aggregate concrete production, is an effective measure to improve coal gangue utilization, can bring tremendous environmental benefit, economic benefit and social benefit. Based on the original state with different thermal activation activity of coal gangue aggregate thickness as the research object, by means of experimental study and theoretical analysis, to study the microstructure characteristics of coal gangue aggregate concrete, basic physical mechanical properties and carbonation resistance, and systematic analysis of the activity of coal gangue aggregate thermal activation, replacement ratio, water cement ratio on the microstructure of cement concrete, the influence of the macro mechanical properties and carbonation resistance, gangue aggregate concrete quality evaluation model. Thesis research results can be used as the selection of concrete aggregate for coal gangue principles and promote coal gangue aggregate concrete composite application in civil engineering, to provide scientific theoretical basis.In order to quantitatively evaluate the activity of coal gangue fine aggregate and coarse aggregate, the thermal activation of coal gangue activity are studied, by conducting XRD diffraction analysis test, the original state and calcined 500℃, 600℃, 700℃, 800℃ and 900℃ of gangue test analysis, explores the thermal activation active changing with the calcination temperature. Then by conducting ICP ion dissolution test, gangue fine aggregate of different calcination temperature and the activity of coarse aggregate to carry on the quantitative evaluation, combining previous research results, thus forming coal gangue powder, fine aggregate, the activity of the coarse aggregate unified evaluation system, and study the activity of different coal gangue fine aggregate the impact on the strength of hardened cement mortar.By conducting a series of microscopic test, such as XRD, SEM, EDXA activity of different thermal activation of coal gangue fine aggregate of hydration process of cement mortar was studied. The activity of coal gangue fine aggregate is different, can play the ash in cement mortar reaction degree is different, this will also affect the hydration degree of cement mortar, the hydration products of hardened cement mortar have great influence and microstructure. This article from different coal gangue fine aggregate activity of thermal activation, water cement ratio and curing age on the impact of the hydration process, comprehensive analysis of the hydration process of gangue fine aggregate mortar. And the combination of hardened cement mortar compressive strength and flexural strength test, from microscopic analysis on coal gangue fine aggregate active influence on strength of hardened cement mortar, to further explore coal gangue fine aggregate play a role of ash in cement mortar.Because of coal gangue fine aggregate thermal activation activity is different, its and the degree of cement hydration products secondary hydration reaction is different, and with the increase of coal gangue fine aggregate ash activity, to a greater impact on pore structure of hardened cement mortar, the total porosity of hardened cement mortar, total pore volume and specific surface area and pore structure parameters change, will affect the strength of hardened cement mortar. By the mercury intrusion method(MIP) and environmental scanning electron microscope(SEM) analysis method, and USES the fractal theory in the Menger sponge model, the box dimension of fractal dimension calculation method of the model, analyzes the pore structure of hardened cement mortar, explores the relationship between pore structure and strength of hardened cement mortar.For coal gangue- ordinary gravel mixture aggregate concrete, fine aggregate are all made of the highest thermal activation active fine aggregate, which can maximize the utilization of coal resources, and can give full play to the coal gangue fine aggregate ash activity, to the light-weight aggregate concrete microstructure and macro mechanical properties to produce beneficial effects. Coal gangue coarse aggregate using two cases of burning and burning, and then by 0%, 30%, 50%, 70% and 100% amount of regular gravel aggregate, the preparation of coal gangue aggregate concrete. Through the test of coal gangue, for ordinary gravel mixture aggregate concrete cube compressive strength, prism compressive strength, splitting tensile strength, bending strength, elastic modulus and so on basic mechanical properties, this paper expounds the water cement ratio, coal gangue after replacement and calcined coal gangue coarse aggregate characteristics influence on the mechanical properties. Test is studied based on the uniaxial compressive stress-strain full curve of the coal gangue-general constitutive relation model of the mixture of gravel aggregate.Fracture toughness of concrete is refers to the concrete to resist the ability of crack instability propagation, it is also a important index to measure the fracture characteristic of coal gangue aggregate concrete. In this article, through prefabrication incision of three point bending test, the specimens of the light-weight aggregate concrete fracture toughness(KIC) was measured and studied the different water cement ratio, coal gangue coarse aggregate replacement rate and calcined coal gangue coarse aggregate characteristics of gangue aggregate concrete after the effect of fracture toughness. Reveals the fracture mechanism of coal gangue aggregate concrete, and puts forward the main cause of coal gangue aggregate concrete crack extension.Test using thermal activation activity of coal gangue fine aggregate all regular river sand, then use calcined coal gangue coarse aggregate and calcination of two kinds of circumstances, and the coal gangue coarse aggregate according to the different proportion of 0%, 30%, 50%, 70% and 100% amount of regular gravel aggregate, the coal gangue concrete carbonation resistance performance. Established concrete carbonation model with multi-parameter water-cement ratio, carbonization time and gangue content of the coarse aggregate suitable for carbonation depth.