The Research On Performance And Mechanism Of Modified Asphalt Of Waste Rubber Powder Activated By Coating

As a macromolecule solid waste,waste tires can lead to a great threat to human health and environment.The appication of crumb rubber into asphalt not only can make full use of waste tires,but also can improve the comprehensive temperature performance of the asphalt.But the problem of poor storage stability due to the poor compatibility restricted the application of crumb rubber modified asphalt in road engineering.Therefore,based on the principle of the dissolution in the similar material structure,polyamide possessing good compatibility with crumb rubber and matrix asphalt was used as the activator to modify crumb rubber through polymer surface coating.The compatibility of crumb rubber and matrix asphalt was improved by the uniform polyamide coating formed on the crumb rubber surface.Meanwhile the storage stability and the road performance of modified asphalt were thus improved.The physical properties and modification mechanism of modified asphalt based on activated crumb rubber were studied.The main content included the following three parts:(1)Based on the principle of similar compatibility,the coating material with good compatibility with asphalt was selected,and the crumb rubber was activated by solvent method.Furthermore the scanning electron microscopy and infrared spectroscopy were used to analyze the surface property of activated crumb rubber and the reaction during activation process.The research showd that polyamide 6 had been evenly coated on the surface of the crumb rubber after the coating activation process.There was no chemical change in the activation process of crumb rubber.(2)By orthogonal experiment,combined with range analysis and variance analysis,the effect of activated crumb rubber content and preparation process on high and low temperature performance,storage stability and other technical properties of crumb rubber modified asphalt were studied.Then the content of crumb rubber and the preparation process were optimized.The research showd that the content of activated crumb rubber had the most obvious influence on the performance of modified asphalt.With the increase of the content of activated crumb rubber,the high and low temperature performances of activated crumb rubber modified asphalt were improved,but the storage stability was greatly reduced;only parts of the performance were influenced by the shear time and shear temperature.With the increase of shear temperature and shear time,the technical performances were improved in a certain range.The optimum content of crumb rubber is 20%,the optimum shearing temperature is 180?,and the optimum shearing time is 60min.(3)The optimum preparation technology was used to prepare modified asphalt normal crumb rubber and activated crumb rubber modified asphalt.The effect of activation of crumb rubber on the technical performance of modified asphalt was studied through a series of experiments.The modified effect of ordinary crumb rubber was compared with that of activated crumb rubber.The results showd that the storage stability,the high temperature performance and the rheological property of the modified asphalt based on activated crumb rubber were significantly improved,but the elastic property and low temperature energy decreased slightly.(4)The microstructure and blending mechanism of the modified asphalt based on activated crumb rubber were analyzed by microcosmic means,and the modified mechanism model was obtained.The results showd that the interation activation of crumb rubber with asphalt was a physical swelling process.By the activation of polyamide coating,the swelling degree of the crumb rubber in the asphalt was increased and the dispersion of crumb rubber was more even in the asphalt.