This paper portrays the first set of results of nanoscale viscoelastic (VE) properties of asphalt binders obtained using the recently developed Atomic Force Microscopy-Nanoscale Dynamic Mechanical Analysis (AFM-nDMA) testing mode. To this end, nanoscale frequency sweeps were carried out on eight different asphalt samples including an unmodified asphalt binder and seven Low-Density Polyethylene (LDPE) modified binders. The nDMA testing mode was successful in obtaining the nanoscale VE properties of asphalt binder and constructing nanoscale master curves. This method was also used successfully to distinguish among the different constituents of heterogeneous binder samples based on their dynamic viscoelastic properties. Furthermore, bulk-scale frequency sweeps tests were performed using a Dynamic Shear Rheometer (DSR) in order to compare the nanoscale properties with the bulk properties. There were major differences between the bulk and nanoscale test results. For example, nanoscale dynamic modulus values were higher than their bulk-scale counterparts and the difference increased with an increase in temperature and/or decrease in frequency. On the other hand, the nanoscale phase angle values were less than their bulk counterparts and the difference increased with an increase in frequency. These findings indicate that asphalt binders exhibit stiffer and more elastic behavior at the nanoscale than at the bulk scale. There are distinct differences in the shapes of the master modulus and phase angle curves obtained from the nano and bulk measurements. This paper includes testing guidelines and procedures that would be useful for future experimental investigations of nano VE properties.

中文翻译：

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使用 AFM-nDMA 测试对沥青结合料进行纳米级粘弹性表征

本文描述了使用最近开发的原子力显微镜-纳米级动态力学分析 (AFM-nDMA) 测试模式获得的沥青结合料的纳米级粘弹性 (VE) 特性的第一组结果。为此，对八种不同的沥青样品进行了纳米级频率扫描，包括一种未改性的沥青粘合剂和七种低密度聚乙烯 (LDPE) 改性的粘合剂。nDMA 测试模式成功获得了沥青结合料的纳米级 VE 特性并构建了纳米级主曲线。该方法还成功地用于根据其动态粘弹性特性区分异质粘合剂样品的不同成分。此外，使用动态剪切流变仪 (DSR) 进行体积尺度频率扫描测试，以比较纳米级特性与体积特性。体积和纳米级测试结果之间存在重大差异。例如，纳米尺度的动态模量值高于它们的体尺度对应物，并且差异随着温度的升高和/或频率的降低而增加。另一方面，纳米级相位角值小于它们的体相角值，并且差异随着频率的增加而增加。这些发现表明，沥青粘合剂在纳米尺度上比在体积尺度上表现出更硬和更具弹性的行为。从纳米和体测量获得的主模量和相角曲线的形状存在明显差异。