Study On Aging Mechanism Of Functionalized SBS Modified Asphalt

The rapid developments of traffic costruction raised a higher claim for pavement perfornances.The application of modified asphalt has become the main means to enhance the performance of use.Styrene-Butadiene-styrene block copolymer(SBS)modified asphalt has been widely used because of its excellent performance.The unsaturated carbon-carbon double bond in SBS is easy to aging,which affects the pavement performance.At the same time,SBS modified asphalt is prone to segregation due to the difference between SBS and asphalt,which has a negative impact on the performance of modified asphalt.The compatibility of SBS with asphalt and the aging degree of SBS can be improved by reducing the content of carbon-carbon double bond in SBS,and the compatibility of SBS with asphalt can be increased by adding carboxyl group to the main chain of SBS.It is of great significance to study the aging mechanism of functionalized SBS modified asphalt by optimizing the chemical structure of SBS itself.In view of the two main problems of aging and compatibility of SBS modified asphalt,three kinds of modified asphalt with different functional treatment are selected for aging mechanism,including partial hydrogenated SBS(SEBS),chemically grafted maleic acid and partial hydrogenated SBS(MAH)and nanocomposite SBS(OSBS)modified asphalt.The test results based on rheological properties,compatibility properties,and microstructure are discussed by thermal oxidative aging and ultraviolet aging.The storage stability test and fluorescence microscopy test results show that the storage stability of SEBS and MAH modified asphalt is significantly improved compared with SBS modified asphalt.The high and low temperature rheological parameters show that the high temperature stability of OSBS and SEBS modified asphalt is further improved compared with SBS modified asphalt.The low-temperature performance of MAH modified asphalt is improved compared with SBS modified asphalt.The aging parameters based on performance changes show that OSBS modified asphalt has better anti-aging ability under three kinds of aging conditions,followed by SEBS modified asphalt,and MAH modified asphalt has relatively weak anti-aging performance.Infrared spectroscopy analysis showed that OSBS and SEBS modified asphalt had lower CI and SI values.In addition,the BI of SEBS and MAH modified asphalt is significantly lower than that of SBS modified asphalt,while OSBS modified asphalt BI is close to SBS modified asphalt.The content of unsaturated double bond in SBS,SEBS,MAH and OSBS modified asphalt is quantitatively analyzed by electrochemical test.The difference of molecular structure is verified.There is a relationship between the different molecular structures and the properties.Reasonable control of the content of unsaturated double bonds can improve the comprehensive properties of modified asphalt.SBS modified asphalt obtained by different reinforcement methods shows that the high temperature and anti-aging performance of SEBS and OSBS modified asphalt are improved,while the low-temperature performance has a slight influence.SEBS and MAH modified asphalt have better dispersibility and compatibility,and the low temperature performance of MAH modified asphalt is enhanced.