Modified Phyllite Powder And Study On Road Performance Of Its Asphalt Mixture

Due to the huge reserves of waste rocks in major mining sites across the country,it occupies a large amount of land resources and affects the surrounding ecological environment.Therefore,this thesis takes the green mine as the background and chooses the waste rock-phyllite of Ansteel as the experimental research object,supplemented by silane coupling agent KH-550,to explore its feasibility as an asphalt mixture filler,to alleviate the hazards caused by waste rocks in mine dumps.Silane coupling agent can improve the wetting area and bonding strength between inorganic and organic substances.Utilizing this feature,it can be used to enhance the bonding between asphalt and acidic fillers.Due to the high content of SiO₂ in phyllite powder,it will affect the road performance of phyllite powder asphalt mortar and mixture.Attempt to add silane coupling agent to phyllite powder for modification,and explore its modification mechanism.To test the road performance of the modified phyllite powder asphalt mortar and mixture,and compare the road performance difference between it and limestone mineral powder asphalt mortar and mixture,and analyze the reasons.Preparing different dosages of silane coupling agent-modified phyllite powder and limestone mineral powder in advance,and according to different powder-to-asphalt ratios to make asphalt mortar.According to high and low temperature performance tests,Brookfield viscosity tests and adhesion tests,it was found that the high and low temperature performance,temperature sensitivity and adhesion of modified phyllite powder asphalt mortar are significantly improved.And when the dosages of silane coupling agent is 1.5%,the properties reach the best.According to the results of the double line model,the optimum powder-to-asphalt ratio range of limestone mineral powder asphalt mortar is 0.93～0.97,the optimum powder-to-asphalt ratios range of sandy phyllite powder asphalt mortar,chlorite phyllite powder asphalt mortar and carbonaceous phyllite powder asphalt mortar are 0.88～1.01,0.88～1.01 and 0.89～1.02,and the optimum powder-to-asphalt ratios range of modified sandy phyllite powder asphalt mortar,modified chlorite phyllite powder asphalt mortar,modified carbonaceous phyllite powder asphalt mortar are 0.95～1.02,0.95～1.02 and 0.95～1.03.According to the results of scanning electron microscope and infrared spectrum,the specific surface area of silane coupling agent-modified phyllite powder is larger than that of limestone mineral powder and unmodified phyllite powder.The surface of the modified phyllite powder also produced a large number of granular protrusion and clearance holes.phyllite powder will dehydration condensation reaction with the inorganic functional group in the silane coupling agent,thus forming a polysiloxane coupling layer on the surface of the modified phyllite powder.Meanwhile,the high polymer in asphalt will also entangle with the organic functional group in silane coupling agent to form a stable spatial structure.After the phyllite powder is modified by the silane coupling agent,the cohesiveness between it and the asphalt is improved,and the road performance of the asphalt mortar are also improved to varying degrees.In this study,the grading type of asphalt mixture used is AC-13,the optimum oil-stone ratio of limestone mineral powder asphalt mixture is 5.05%,the optimum oil-stone ratios of sandy phyllite powder,chlorite phyllite powder and carbonaceous phyllite powder asphalt mixtures are 5.12%,5.13%and 5.15%,the optimum oil-stone ratios of modified sandy phyllite powder,modified chlorite phyllite powder and modified carbonaceous phyllite powder asphalt mixture are 5.18%,5.19%and 5.20%.According to rutting test,low temperature bending test,immersion Marshall test,freeze-thaw split test,it was found that compared with the limestone mineral powder asphalt mixture,the three kinds of modified phyllite powder asphalt mixtures have their high temperature anti-rutting performance increased by 19.9%,15.2%and12.5%,the low temperature flexural strength increased by 12.7%,10.5%and 8.9%,the water stability increased by 8.3%,7.5%and 6.7%.According to the efficiency coefficient method to analyze the road performance and material cost of various types of asphalt mixtures,it can be concluded that the total cost of modified phyllite powder asphalt pavement is smaller than that of limestone mineral powder asphalt pavement.