老化对纳米膨润土改性沥青流变性能影响研究

Influence of Aging on Rheological Properties of Nano-Bentonite Modified Asphalt

为探究老化对纳米膨润土改性沥青流变性能影响,将3%纳米膨润土加入到基质沥青中以制备改性沥青,然后对改性沥青和未改性沥青进行旋转薄膜烘箱(RTFOT)和两个周期的压力加热老化试验(PAV),在每一次老化后,通过动态剪切流变仪(DSR)测试沥青的高温和中温流变性能,计算高温和中温连续分级温度;并且在每次PAV老化后对沥青进行弯曲梁流变仪(BBR)试验,计算沥青的低温连续分级温度;最后,在每次老化后对沥青进行FTIR试验,测试沥青中亚砜基和羰基的变化情况,建立亚砜基和羰基与复数剪切模量G*和相位角δ的关系。结果表明:纳米膨润土提高了基质沥青的高温连续分级温度,降低了中温和低温连续分级温度,沥青的高温性能、疲劳性能和低温抗开裂性能得到改善;log(G*)和δ与吸光度(亚砜基+羰基)的决定系数都大于0.9,表明它们之间具有很强的相关关系。

To investigate the effect of aging on the rheological properties of nanobentonite modified asphalt,3% nanobentonite was added to the asphalt to prepare modified asphalt,and then the modified asphalt and unmodified asphalt were subjected to rotating film oven(RTFOT)and two cycles of pressure heating aging test(PAV).After each aging,the asphalt was tested by dynamic shear rheometer(DSR)for high-temperature and medium-temperature rheological properties to calculate the high and medium temperature continuous grading temperatures.After each PAV aging,the asphalt was tested by bending beam rheometer(BBR)to calculate the low temperature continuous grading temperature.Finally,FTIR tests were performed on the asphalt after each aging to test the changes of sulfoxide group and carbonyl group in the asphalt,and to establish the relationship between sulfoxide group and carbonyl group with complex shear modulus G*and phase angle δ.The results show that nanobentonite increases the high-temperature continuous grading temperature and decreases the medium-and low-temperature continuous grading temperature of the asphalt,indicating that the high-temperature performance,fatigue performance and low-temperature anti-cracking performance of the asphalt are improved;the coefficients of determination of log(G*)and δ with absorbance(sulfoxide group + carbonyl group)are both greater than 0.9,indicating a strong correlation between them.