热氧老化作用对高黏改性沥青黏弹特性的影响

Thermal-oxygen aging effects on viscoelastic properties of high viscosity modified asphalt

为了研究热氧老化作用对高黏改性沥青黏弹特性的影响,选择2种高黏改性剂制备高黏改性沥青。首先,分别对其进行旋转薄膜加热试验和压力老化容器加速沥青老化试验,模拟短期老化和长期老化现象;然后,采用扫描电镜观察热氧老化作用对高黏改性沥青微观结构的影响;最后,采用温度扫描试验、弯曲蠕变劲度试验及线性振幅扫描试验,分别研究了热氧老化作用对高黏改性沥青高低温黏弹特性及中温疲劳特性的影响。结果表明:长期老化对高黏改性沥青性能的影响大于短期老化对其性能的影响;从微观结构来说,热氧老化作用主要从2个方面影响高黏改性沥青性能,即轻质组分的挥发和高黏改性剂的溶胀、降解;从宏观性能来看,高温状态下,热氧老化作用使高黏改性沥青的复数剪切模量增大,相位角减小,高温黏弹性指标Z减小,抗车辙能力增加;低温状态下,热氧老化作用导致高黏改性沥青的蠕变速率与蠕变劲度之比(m/S)降低,蠕变柔量导数减小,低温变形能力变差,且在低温状态下温度对高黏改性沥青变形能力的影响远大于老化程度的影响;中温状态下,热氧老化作用使高黏改性沥青的屈服应力增大,疲劳寿命减小。

To study the thermal-oxygen aging effects on viscoelastic properties of high viscosity modified asphalt, two high viscosity modifiers were selected to prepare high viscosity modified asphalt in the laboratory. The rolling thin film oven test and the pressurized aging vessel test were selected to simulate the short-and long-term aging of two kinds of high viscosity modified asphalt, respectively. Then, a scanning electron microscope was used to investigate the thermal-oxygen aging effects on the microstructure of high viscosity modified asphalt. Finally, the temperature sweep test, the flexural creep stiffness test, and the linear amplitude sweep test were used to study the effects of thermal-oxygen aging on the high-and low-temperature viscoelastic properties and the medium-temperature fatigue properties of the high viscosity modified asphalt. The results show that, the effects of long-term aging on the viscoelastic properties of high viscosity modified asphalt are greater than that of short-term aging. In terms of microstructure, thermal-oxygen aging mainly affects the properties of high viscosity modified asphalt from two aspects, the volatilization of light components, and the swelling and degradation of the high-viscosity modifier. From the perspective of macroscopic performance, under high-temperature conditions, thermal-oxygen aging will increase the complex shear modulus of high viscosity modified asphalt, decrease the phase angle and the high-temperature viscoelastic index Z, and increase the anti-rutting ability. Under low-temperature conditions, thermal oxidative aging reduce the ratio of creep stiffness to creep rate m/S and the creep compliance derivative of high viscosity modified asphalt, indicating that the low-temperature deformation ability of high viscosity modified asphalt become worse. At low-temperature, the effect of temperature on the deformation capacity of high viscosity modified asphalt is much greater than that of the aging degree. The effect of thermal oxidative aging increases the yield stress of high viscosity modified asphalt at medium-temperature, indicating that the fatigue life is reduced. 3 tabs, 7 figs, 28 refs.