Storage Stability Evabluation Of Rubber Powder Modified Asphalt

During the storage of crumb rubber modified asphalt,crumb rubber and asphalt are prone to segregation,which leads to poor stability of modified asphalt.Therefore,this paper takes rubber powder modified asphalt as the research object,explores the performance changes of the top and bottom samples of rubber powder modified asphalt under different storage time,and finds out an appropriate evaluation method for the stability of rubber powder modified asphalt during storage.The main findings are as follows:(1)The segregation test of crumb rubber modified asphalt was carried out,and the changes of softening point difference and density difference between the top and bottom samples of crumb rubber modified asphalt under different storage time were analyzed.The results show that the crumb rubber and asphalt have obvious segregation phenomenon after12 h storage,and the density difference between the upper and lower samples is also large.(2)The DSR test is used to analyze the difference of shear resistance between top and bottom samples of crumb rubber modified asphalt under different storage time.The test results show that there is no obvious difference in shear resistance between top and bottom samples after 0-8h storage,indicating that there is no obvious delamination and segregation between crumb rubber and asphalt,At this time,the crumb rubber modified asphalt is a homogeneous.After storage for more than 8h,the shear resistance of the top and bottom samples began to have a significant difference.(3)Then,the mechanism of the top and bottom samples was analyzed by means of infrared spectroscopy,thermogravimetry differential scanning calorimetry and scanning electron microscopy.The mechanism analysis shows that the rubber powder and asphalt are a physical blending reaction process,and also accompanied by the oxidation reaction of a small number of sub bonds.With the increase of storage time,the content of rubber powder in the bottom sample is more,and it is densely distributed,forming a compact structure grid,which makes the thermal stability of the bottom sample better than that of the top sample.(4)Finally,by comparing six methods to judge the storage stability of crumb rubber modified asphalt,it is found that softening point method,DSR,SEM,FTIR and TG-DSC are used to judge the storage stability of crumb rubber modified asphalt in terms of high temperature resistance,shear resistance,distribution state of internal substances,functional groups and thermal stability.However,the data difference between the upper and lower samples of density method is small,which can only be used as an auxiliary means for judgment.