| As a main component of China’s high-grade highway pavement,SBS modified asphalt pavement has gradually approached its service life under the long-term effect of increasing traffic volume and environmental factors,which result in bulk of waste asphalt.Recycling these waste SBS modified asphalts will yield significant economic and environmental benefits.Ordinary asphalt recycling is the main point of domestic and international research,for instance,the extraction and recycling of ordinary asphalt,blending laws of new and aged asphalt,which are referred to “Technical Specifications for Highway Asphalt Pavement Recycling”.The aging and recycling mechanism of SBS-modified asphalt is more complicated than that of ordinary asphalt provided that the existence of SBS-modified polymer.Further research and demonstration should be conducted to analyze whether SBS-modified asphalt followed by recycling specifications of ordinary asphalt.Based on the technology and science project of Department of Transportation in Shan-Dong province “Research on Key Technology and Engineering Application of Green Circulating Thermal Regeneration of Modified Asphalt Mixture”,the study makes a deep research to investigate the extraction,recycling laws and performance of SBS-modified asphalt.Systematic,theoretical and experimental research was carried out deeply on Abson method and rotating evaporative reclaimer.Key experimental parameters of two methods for recycling SBS-modified asphalt was determined.Based on the aging degree of the waste modified asphalt extracted and recovered,three kinds of SBS modified asphalt with different degrees of aging,which blended with six new SBS modified asphalt for recovery with blending ration 15%,25%,35%,50%,were prepared by laboratory simulated aging method.It is investigated that the effect of new asphalt of different penetration on conventional physical indexes,rheological properties,microstructure and functional group changes of different grades of aged asphalt,on the basis,mixing design and road performance test of recycled SBS-modified asphalt mixtures was conducted.Firstly,it is tested that the basic performance index values such as viscosity and penetration of each kind of aged asphalt with different new asphalt added.The influences of new asphalt type,aged asphalt content on basic properties of recycled modified asphalt besides regeneration ratio relationship and predicting equation were obtained by regression analysis.Secondly,based on dynamic mechanical analysis method,temperature scanning,repeated shearing,multiple stress creep recovery test was conducted to investigate the influence of new asphalt on the complex modulus,rutting factor of recycled asphalt.Furthermore,the microstructure and chemical functional group composition of aged asphalt,new asphalt and recycled asphalt were analyzed by fluorescence microscopy and infrared spectroscopy.Recycling mechanism of SBS-modified asphalt was investigated in the perspective of microstructure.At last,Recycling laws of SBS-modified asphalt was used to guide the production of customized new asphalt,and then realize the regeneration of recycled SBSmodified asphalt mixtures of specific project.Experimental results of which high temperature stability,low temperature crack resistance and water stability of recycled asphalt mixtures were used to demonstrate the theoretical rationality and technical feasibility of the method in this study.In conclusion,Laboratory tests were conducted to determine the effect of blending ratio of different degreed of aged asphalt besides penetration of new asphalt on recycled asphalt.The feasibility and regularity of SBS-modified asphalt recycling have been proved that it can be used to guide SBS modified asphalt recycling engineering. |
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