Research On The Preparation And Properties Of Modified Asphalt Based On Grafting Activation Of Waste Rubber Powder

Waste tire rubber powder that has the characteristics of heat-resistance,corrosion-resistance and low elastic modulus is one of the comparatively mature modifiers for modified asphalt,which can enhance the pavement performance of asphalt after blended with asphalt.However,the rubber powder has poor compatibility with asphalt and the modified asphalt has poor storage stability,which limits its application and promotion in road engineering.Based on the above-mentioned problems,as well as the molecular design principle,this paper selects the graft modifier-acrylamide,which can both react with the surface functional grous of rubber powder and interact with the functional groups in the asphalt.And the wet process was applied to rubber powder to prepare grafted rubber powder modified asphalt.Through orthogonal test,combined with range analysis and variance analysis,the influence of preparation process on the main technical properties of grafted rubber powder modified asphalt is studied,and the optimal preparation process is Preferred,The matrix asphalt,rubber powder modified asphalt and grafted rubber powder modified asphalt were prepared by the preparation process.The effects of rubber powder grafting on asphalt performance and mechanism were studied by comparing the macroscopic properties and microstructure of the three.The following were the main findings:(1)The microscopic characteristics and chemical structure of the grafted rubber powder were characterized by SEM and FT-IR micro-analysis.The results showed that the grafted rubber powder was more fluffy,larger than the surface area,and N-H,C=O,C-N-H containing acrylamide,which confirmed that acrylamide had been grafted onto the surface of the rubber powder.(2)Orthogonal test results showed that the effect of mixing amount of grafted rubber powder on the modified asphalt was the most obvious.With the increasing dosage,the high and low temperature properties and rheological properties of grafted rubber powder modified asphalt were improved.The shearing temperature had a significant effect on the penetration and softening point only at 25? and the effect would be improved with the increasing shear temperature.The technical performance was improved within a certain range,but the rubber powder degraded and the asphalt aging was aggravated in excess of a certain range;The cutting time didn't have significant effect on the technical performance.It was recommended that the optimum blending amount of the grafted rubber powder modified asphalt was 20%,the optimum shearing temperature was 180?,and the optimum shearing time was 60 min.(3)Comparing three major indicators of experimental results DSR,BBR and DSC showed that the grafted rubber powder modified asphalt had lower temperature sensitivity and plasticity;it had excellent high and low temperature properties and thermal stability.Segregation and fluorescence microscopy studies showed that the segregation phenomenon was improved as well as the thermal storage stability.The grafted rubber powder was evenly distributed in the asphalt to form a stable mixed structure.(4)The FT-IR study of matrix asphalt,rubber powder modified asphalt and grafted rubber powder modified asphalt showed that N-C=O characteristic peak appeared in the grafted rubber powder modified asphalt and the C-O-C characteristic peak disappeared,which indicated that graft rubber powder was both physically blended and chemically reacted with the asphalt.