Study On Degradation Of Polymer Modified Asphalt Binders During Thermal Storage And Transportation

In asphalt pavement engineering,polymer modified asphalt binders are widely used by pavement builders due to its excellent high and low temperature performance.However,when the modified asphalt binders are tested according to the existing evaluation indicators,the test results can meet indicators requirements.However,there are many phenomena that test results cannot meet indicators when the asphalt binders are tested at the construction site,which seriously affects the construction of polymer modified asphalt binders pavement and service use.It is difficult to find the source of problem,which has caused confusion for production staff.Therefore,this paper simulates the thermal degradation process of modified asphalt binders during transportation and storage,and analyzes the factors affecting the degradation of modified asphalt binders,which will help improve the quality of modified asphalt binders during storage and transportation.In this paper,the conventional properties,viscosity,fourier transform infrared spectroscopy,and low temperature properties of two asphalt binders(SK70 and ZH90)and four polymer modified asphalt binders(SBSMA,CRMA,CR/SBSMA,and SBRMA)were studied.The influences of different factors(such as time,temperature and oxygen concentration)on macroscopic properties changes of polymer modified asphalt binders during thermal storage are analyzed.The influences of different factors on the crack resistance under low temperature environment of polymer modified asphalt binders are evaluated.The effects of different factors on microstructure and molecular weight change of four polymer modified asphalt binders during thermal storage were studied.The micro morphology changes of polymer modified asphalt binders under different time,temperature and oxygen concentration were also analyzed.These tests can comprehensively understand and evaluate the macroscopic properties and microstructure of polymer modified asphalt binders during thermal storage and transportation.The main conclusions can be drawn as following: For thermal degradation test in thin air(TDTTA),when the temperature is same,the softening point,ductility and penetration of polymer modified asphalt binders show a decreasing trend with the time increasing.The effects of temperature on penetration,softening point,and ductility of polymer modified asphalt binders can be ranked as: 163 °C>150 °C>130 °C.The higher the oxygen concentration,the worse the performance of polymer modified asphalt binders during storage or transportation.For TDTTA,the performance at low temperature of polymer modified asphalt binders are decreased with time increasing.The effects of different temperatures on the low temperature performance of polymer modified asphalt binders can be ranked as: 163 °C>150 °C>130 °C.It is found that the effects of TDTTA on the low-temperature performance of asphalt binders are greater than that of asphalt binders at lower oxygen concentrations.For the thermal degradation test in thin air or anaerobic environment,the changes of CI values and SI values of polymer modified asphalt binders are not significant.In addition,comparing with the effects of TDTTA on the chemical structure of polymer modified asphalt binders,the polymer modified asphalt binders after TFOT has a higher CI value and a lower BI value.For TDTTA,when the temperature is the same,the distribution uniformity of polymer modifiers in asphalt binders gradually worsens with time increasing,and the particle size of polymer modifiers gradually changes.The higher the temperature,the more obvious the particle size difference of polymer modifier(or the more uneven the dispersion of polymer modifier particles).In addition,the higher the oxygen concentration,the dispersion of polymer modifier particles in asphalt binders gradually becomes uneven.The test results show that the effects of time,temperature and air concentration on the performance of polymer modified asphalt need to be fully considered during the storage and transportation of modified asphalt binders...