Study On Basic Mechanical Properties And High-temperature Resistance Of Non-spontaneous Combustion Gangue Concrete

With the continuous development of my country’s economy and the rapid advancement of urbanization,the shortage of sand and gravel resources has become increasingly prominent.At the same time,the country has strengthened the construction of ecological civilization and paid more and more attention to environmental issues.In order to reduce the environmental pollution and resource waste caused by the accumulation of a large number of non-self-igniting coal gangues,this paper uses the non-self-igniting coal gangue produced in the coal washing plant as raw materials to prepare different non-self-igniting coal gangue replacement rates(0,30%,50%,70%,100%),water-cement ratio(0.35,0.4,0.45),additional water(75%,saturated surface dry)and aggregate gradation(5-25 mm,5-20 mm,10-25mm)non-automatic Research on the basic mechanical properties and high temperature resistance of coal-fired gangue coarse aggregate concrete at room temperature.The specific research content and results of this article are as follows:(1)The chemical composition,mineral composition and basic physical properties of non-spontaneous combustion coal gangue are detected and analyzed,and the physical performance indexes such as bulk density,apparent density,water absorption rate and crushing value of non-spontaneous combustion coal gangue are obtained.Compared with common gravel,non-spontaneous combustion coal gangue basically meets the requirements of concrete coarse aggregate.(2)The mix ratio of non-spontaneous combustion gangue concrete is designed,and the change law of non-spontaneous combustion gangue concrete slump with substitution ratio,water-cement ratio,additional water volume and aggregate grade is emphatically studied.The test results show that the water-cement ratio has the most obvious effect on the slump of non-spontaneous coal gangue concrete.The slump of non-spontaneous combustion gangue concrete decreases gradually due to the continuous increase of the replacement rate of non-spontaneous combustion gangue,and the replacement rate decreases by about 24% from100% to 0 slump.Through the study of spontaneous combustion gangue replacement ratio,water cement ratio,additional water consumption and aggregate level matching the basic mechanical properties and the effect of spontaneous combustion gangue concrete found that as the spontaneous combustion gangue replacement ratio and the increase of water cement ratio,the concrete compressive strength,splitting tensile strength and elastic modulus decreases on the whole,when replace rate of more than 50%,with three mechanics performance index decreased more obvious;Additional water quantity and aggregate grade have certain influence on non-spontaneous combustion gangue concrete.The saturated surface drying can effectively improve the compressive strength and elastic modulus of non-spontaneous combustion gangue concrete,but it is adverse to the splitting tensile strength.(3)The change rule of residual compressive strength of non-spontaneous coal gangue concrete with different non-spontaneous coal gangue substitution ratio and water-cement ratio at high temperatures of 100℃,300℃ and 600℃ was studied.The results show that high temperature has a great influence on the compressive strength of non-spontaneous combustion gangue concrete,and the residual compressive strength generally decreases with the increase of temperature,and the decline rate of the residual compressive strength of ordinary concrete is faster than that of non-spontaneous combustion gangue concrete,but at 300℃,the residual compressive strength increases.