| In the current research,coal gangue powder was added as filler to asphalt and asphalt mixture to significantly improved the high temperature performance of asphalt mortar and asphalt mixture,its low temperature performance was reduced.According to the research results of the predecessors,the gangue powder was modified by silane coupling agent,and the road performance of silane coupling agent modified gangue powder asphalt mortar and asphalt mixture was studied.Compared with limestone ore and unmodified coal gangue powder asphalt mortar and asphalt mixture,and in-depth study of the silane coupling agent modified gangue powder asphalt mortar and its mixture road performance and modification mechanism.The coal gangue powder was modified with five dosages(0%,0.5%,1.0%,1.5%,2.0%)of silane coupling agent,and seven filler to bituminous ratio were made into asphalt mortar with limestone ore and unmodified coal gangue powder.Three kinds of asphalt mortar were tested for softening point,cone penetration,force ductility,dynamic shear rheology(DSR),bending beam rheological(BBR),Brookfield viscosity and asphalt adhesion.The results showed that compared with limestone ore and gangue powder,modified gangue powder can significantly improved the high temperature stability and low temperature performance of asphalt mortar,and can improved the adhesion between asphalt and filler.And the modification effect is best when the silane coupling agent is 1.5%.Secondly,considering the high and low temperature performance of asphalt mortar,the optimum filler to bituminous ratio of ore powder,coal gangue powder and modified coal gangue powder asphalt mortar is determined to be 0.97-1.15,0.93-1.07 and 0.95-1.11.Three kinds of fillers and asphalt mortar were subjected to X-ray diffraction(XRD),scanning electron microscopy(SEM),laser particle size analysis,infrared spectroscopy and low temperature nitrogen adsorption test.The results showed that the gangue powder,especially the modified gangue powder,has a larger specific surface area than the limestone ore powder,and the surface of the modified gangue powder has rich interstitial pore structure.The infrared spectroscopy test results showed that the hydrophilic functional group of the silane coupling agent dehydrates and condenses with the coal gangue powder to form a polysiloxane coupling layer,and the hydrophilic organic functional group is entangled with the high molecular polymer in the asphalt.A stable spatial structure improved the adhesion to the asphalt,thereby significantly improved the road performance of the asphalt mortar.The mix ratio of AC-13 asphalt mixture was designed for three kinds of fillers.The optimum oil-stone ratio of limestone ore powder,coal gangue powder and modified coal gangue powder asphalt mixture was determined by Marshall test,and the optimum filler to bituminous ratio was calculated.The results showed that the optimum oil-stone ratios of the three asphalt mixtures are 5.09%,5.17%and 5.24%,respectively.The optimum filler to bituminous ratio of powder is 1.11,1.07 and 1.06.Then rutting test,bending test,splitting test,immersion Marshall test and freeze-thaw split test were then carried out for the three mixtures.The results showed that the modified gangue powder can significantly improved the high temperature stability,low temperature crack resistance and water stability of the asphalt mixture compared with limestone ore and gangue powder. |
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