不同热氧强度作用下SBS改性沥青性能的演变规律

Evolution Rule of SBS Modified Asphalt Performance under Different Thermal-oxidative Intensities

为研究不同热氧老化时间和温度对3种SBS改性沥青物理和流变性能的影响,并探讨不同老化时间和温度作用下SBS改性沥青的老化动力学,采用物理指标试验和动态剪切流变试验进行了测试。综合分析了软化点增量、残留针入度比、延度保留率和黏度老化指数。发现相比于基质沥青,软化点不适于作为研究SBS改性沥青老化动力学的参数;170,180℃老化后,SBS改性沥青稠度明显增大,低温延展性明显下降;老化时间10~20 h范围内,沥青黏度显著增大,老化速率加快;SBS改性沥青老化程度受基质沥青和聚合物改性剂的共同影响。通过分析复数模量老化指数(CMAI),发现老化温度为150℃时,成品SBS改性沥青结果未表现出明显的老化前后变化;老化温度为163,170℃和180℃时,3种沥青样品的CMAI均随老化时长的延长而变大;相同老化温度的相位角老化指数(PAAI)随老化时间增长而减小;通过CMAI与PAAI表现出的老化性能差异在老化温度更高时更加显著。应用老化动力学模型,建立了基于SBS改性沥青表观黏度的老化动力学方程。由该动力学模型求得的老化后的计算值与实际老化后的黏度值接近。不同老化温度下,以-ln(Rt/R0)对t进行线性回归直线的斜率越大,SBS改性沥青的老化受温度和时间影响越明显。

In order to study the effects of different thermal oxygen aging time and temperatures on the physical and rheological properties of 3 kinds of SBS modified asphalt,and to discuss the aging kinetics of SBS modified asphalt under different aging time and temperatures,the physical indicator test and dynamic shear rheological test are carried out.Softening point increment(SPI),residual penetration ratio(RPA),ductility retention ratio(DRR)and viscosity aging index(VAI)are comprehensively analysed.It is found that(1)compared with base asphalt,the softening point is not suitable as a parameter for studying the aging kinetics of SBS modified asphalt;(2)after aging process at 170℃ and 180℃,the consistency of SBS modified asphalt increases obviously,and its low temperature ductility decreases obviously;(1)in the range of aging time from 10 h to 20 h,the viscosity of asphalt increases significantly and its aging rate accelerates;(4)the aging degree of SBS modified asphalt is affected by both base asphalt and polymer modifier.By analyzing the complex modulus aging index(CMAI),it is found that(1)there is no significant difference in the CMAI of commercial SBS modified asphalt at the aging temperature of 150℃;(2)the CMAI of the 3 asphalt samples all increase with the aging time at aging temperature of 163,170,180℃;(3)the phase angle aging index(PAAI)decreases with the increase of aging time at the same aging temperature;(4)the differences in aging performance observed by CMAI and PAAI are more significant at higher aging temperatures.With the application of aging kinetic models,the aging kinetic equation based on the apparent viscosity of SBS modified asphalt is established.The calculated values based on the aging kinetic model are close to the actual aged viscosity values.At different aging temperatures,the greater the slope of the linear regression line of-ln(Rt/R0)to time,the more obvious the aging of SBS modified asphalt affected by temperature and time.