Research On Application Of Compound Activated Coal Gangue In Pavement Engineering

Coal gangue is a kind of solid waste produced in the process of coal mining and coal washing.As the amount of coal mining increases year by year,the discharge of coal gangue has also increased sharply,and it has become one of the largest solid wastes in my country by volume and discharge.The disposal method of coal gangue is generally to form coal gangue hills by naturally loose stacking nearby,which not only takes up a large amount of land,but also presents dangers such as spontaneous combustion and explosion,weathering,environmental pollution,landslides,and collapse,which pose certain threats to the local ecological environment and safety.Therefore,the research of coal gangue resource utilization technology has become a research hotspot at home and abroad.Based on previous research and related results of the research group,this project uses the high alumina and silica properties of coal gangue in the Ordos Plateau arsenic area to propose a technology that uses coal gangue instead of clay to improve the composition of traditional sandstone materials.A systematic study Its compressive strength,tensile strength,dry shrinkage,freeze-thaw resistance,water stability and other properties are used in field construction based on indoor tests.The specific research content and main conclusions of this topic are as follows:（1）In this paper,a composite activation method combining mechanical activation and thermal activation is used to improve the pozzolanic activity of coal gangue.X-ray diffractometer,scanning electron microscope and other equipment are used to analyze the changes in mineral composition,chemical composition and microstructure before and after composite activation.Using Ca（OH）₂ consumption and bound water content as indicators to explore the pozzolanic activity of coal gangue after complex activation.The results show that the combined activation method of mechanical activation and thermal activation can significantly improve the activity of coal gangue;when the holding time is the same,the higher the calcination temperature,the lower the content of kaolinite,and the consumption and binding of Ca（OH）₂ The higher the water content,the higher the activity of the coal gangue,but when the temperature is higher than 700℃,the activity increase is less;when the calcination temperature is 700℃,the longer the holding time,the lower the kaolinite content,and the consumption of Ca（OH）₂ The higher the combined water content,the higher the activity of coal gangue,but when the holding time is longer than 2h,the increase in activity of coal gangue is less.（2）Using composite activated coal gangue instead of clay to improve the composition of traditional sandstone materials,and explore the impact of different composite activated coal gangue replacement amounts（0%,10%,30%and 50%）on the road performance of modified coal gangue sandstone The research and systematic analysis of the influence of the substitution amount of composite activated coal gangue on its compression resistance,flexural resistance,shrinkage resistance,freeze-thaw resistance,and water seepage resistance performance.The test results show that composite activated coal gangue can significantly improve the road performance of coal gangue.With the increase of coal gangue substitution,the compressive,flexural,freeze-thaw resistance and water seepage resistance properties of the gangue-modified sandstone are gradually improved;The 3d compressive strength value of the 50%coal gangue content group is 1.09MPa,which is 1.09 times the 28d strength of the control group without coal gangue.The 30%coal gangue content group has the best freeze-thaw resistance,and the strength loss rate of 40 freeze-thaw cycles is 20.52%,but its anti-stretch performance is the worst.The shrinkage coefficient is 163.5×10^-6,which is about not mixed with coal gangue.6.74times the group.（3）This subject is based on the indoor road performance test research of the gangue modified triad material,and carried out practical road engineering application research in the Changxu Coal Mine Reclamation Area of Ordos,Inner Mongolia.The solidity and the 7d unconfined compressive strength and deflection value of the pavement and subgrade after maintenance are tested,and the road application effect and construction precautions of the coal gangue modified triad material are comprehensively analyzed.The results show that the moisture content and compaction are not easy to control in the field construction.The unconfined compressive strength of the pavement base after 7 days of curing is lower than that of the laboratory specimens,and its deflection value meets the requirements of the pavement base.In the on-site construction,attention should be paid to the control of the moisture content of the mixture,the degree of compaction,and the maintenance of the completed pavement base.