热老化下纳米蒙脱土/SBS复合改性沥青愈合性能及微观机制分析

Analysis of Healing Properties and Microscopic Mechanism of Nano Montmorillonite/SBS Composite Modified Asphalt Under Heat Aging

为研究热氧老化对纳米蒙脱土(MMT)改性沥青多次损伤愈合性能的影响,基于动态剪切流变仪、扫描电镜、傅里叶变换红外光谱以及凝胶色谱试验,研究了沥青微观形貌、化学结构以及分子量分布对其愈合性能的影响,并探讨了纳米改性沥青在不同老化时间的多次损伤愈合规律。结果表明:随着老化时间的延长,苯乙烯-丁二烯-苯乙烯(SBS)改性沥青的愈合性能呈下降趋势,且随着损伤次数的增加,老化时间对SBS改性沥青愈合性能的影响逐渐加剧。而MMT可以增强沥青的抗老化能力,在短期老化阶段沥青的轻质组分变化受到抑制,沥青中的分子链数量、支链长度及小分子含量受老化时间的影响较小,从而减小了老化时间对沥青愈合性能的影响。但随着老化时间的继续延长,沥青中以片层状分布的MMT同沥青相分离,导致其抗老化性能减弱,因此长期老化对MMT改性沥青多次愈合性能的影响显著。

In order to study the effects of thermal oxidative aging on the multiple damage healing properties of nano montmorillonite(MMT)asphalt,based on dynamic shear rheometer,scanning electron microscope,fourier transform infrared spectroscopy and gel permeation chromatography,the effects of multiple damage healing methods on the nano modified asphalt at different aging time were discussed,while the effects of asphalt micro morphology,chemical structure and molecular weight distribution on the healing properties were also studied.Results showed that the healing index of styrene-butadiene-styrene(SBS)modified asphalt decreases with the extension of aging time,while the influence of aging time on the healing performance of SBS modified asphalt increased with the increase of damage times.MMT could enhance the aging resistance performance of asphalt.The volatilization of light components in asphalt was inhibited in short term aging,while the number of molecular chains,length of branched chains and content of small molecules in asphalt were less affected by aging,thus slowing down the effect of aging on the healing performance of asphalt.However,with the extension of aging time,the layered MMT in asphalt was separated from the asphalt phase,while the aging resistance performance of MMT was effected.At this stage,nano modified asphalt basically lost healing ability under multiple damage.