Xing C, Liu L, Li M
The Key Laboratory of Road and Traffic Engineering, Ministry of Education, Tongji University, Shanghai, China.
J Microsc. 2020 Jun 4. doi: 10.1111/jmi.12931.
A peak force quantitative nanomechanical mode (PF-QNM) can be used to simultaneously measure the topographical and nanomechanical property maps of samples. Currently, few studies used this mode to investigate the phase characteristics of bitumen in mastics and mixtures. The present study adopted hot-bitumen-pouring methods to prepare base bitumen surface samples and further used frozen-storage and low-temperature-cutting methods to prepare the internal samples of base bitumen in mastics and mixtures. Then, the atomic force microscopy (AFM) PF-QNM mode was used to collect data on the topographical and nanomechanical properties of bitumen and bitumen in mastics and mixtures. The results indicated that a typical bee structure only appeared on the bitumen surface. In contrast to the bitumen surface, the bitumen interior showed two phases, A- and B-phase, which were close in some properties to the periphase and paraphase of the bitumen surface, respectively. Furthermore, the addition of mineral aggregates affected the phase characteristics of the free bitumen interior. With an increase in the mineral aggregate surface area, the proportion of A-phase decreased and that of B-phase increased in the free bitumen interior. LAY DESCRIPTION: Bitumen is a complex mixture of hydrocarbons primarily applied for pavement materials. In the pavement industry, the bituminous mixture is a multilevel system, in which bitumen acts as a binder binding the aggregates and fillers to form bituminous mixture. Currently, atomic force microscopy (AFM), which is an advanced microscopy technology, has been used to investigate bitumen surface phase characteristics at the nanoscale. However, few studies have directly explored the nanoscale phase characteristics of bitumen in mastics or mixtures. Recently, with the progress of technology, a peak-force-quantitative-nanomechanical mode (PF-QNM) can be used to simultaneously measure the topographical and nanomechanical property maps of samples. Relying on this advanced mode, this study analyzed the nanoscale phase characteristics of the bitumen surface and interior, and further explored the effect of mineral aggregates on bitumen interior phase characteristics. In detail, we used hot-bitumen-pouring methods to prepare bitumen surface samples and adopted frozen-storage and low-temperature-cutting methods to prepare the internal samples of bitumen in mastics and mixtures. Subsequently, AFM PF-QNM mode was used to collect topographical and nanomechanical property maps of bitumen and bitumen in mastics and mixtures. The results indicated that the bitumen interior only consisted of two phases, where the A-phase presented low adhesion, deformation, and dissipation, while the B-phase presented high adhesion, deformation, and dissipation. A-phase and B-phase of the bitumen interior were close to the periphase and paraphase of the bitumen surface, respectively. Furthermore, the addition of mineral aggregates significantly affected the bitumen interior phase characteristics.
峰值力定量纳米力学模式（PF-QNM）可用于同时测量样品的形貌和纳米力学性能图。目前，很少有研究使用这种模式来研究胶泥和混合物中沥青的相特征。本研究采用热沥青浇注法制备基础沥青表面样品，并进一步采用冷冻储存和低温切割法制备胶泥和混合物中基础沥青的内部样品。然后，使用原子力显微镜（AFM）的PF-QNM模式收集沥青以及胶泥和混合物中沥青的形貌和纳米力学性能数据。结果表明，典型的蜂巢结构仅出现在沥青表面。与沥青表面不同，沥青内部呈现出两相，即A相和B相，它们的某些性质分别与沥青表面的周相和次相相近。此外，矿物集料的添加影响了游离沥青内部的相特征。随着矿物集料表面积的增加，游离沥青内部A相的比例降低，B相的比例增加。铺设说明：沥青是一种主要用于路面材料的碳氢化合物复杂混合物。在路面行业中，沥青混合料是一个多级体系，其中沥青作为粘结剂将集料和填料粘结在一起形成沥青混合料。目前，原子力显微镜（AFM）作为一种先进的显微镜技术，已被用于研究纳米尺度下沥青的表面相特征。然而，很少有研究直接探索胶泥或混合物中沥青的纳米尺度相特征。最近，随着技术的进步，峰值力定量纳米力学模式（PF-QNM）可用于同时测量样品的形貌和纳米力学性能图。基于这种先进模式，本研究分析了沥青表面和内部的纳米尺度相特征，并进一步探讨了矿物集料对沥青内部相特征的影响。详细地说，我们使用热沥青浇注法制备沥青表面样品，并采用冷冻储存和低温切割法制备胶泥和混合物中沥青的内部样品。随后，使用AFM的PF-QNM模式收集沥青以及胶泥和混合物中沥青的形貌和纳米力学性能图。结果表明，沥青内部仅由两相组成，其中A相表现出低粘附性、低变形和低耗散性，而B相表现出高粘附性、高变形和高耗散性。沥青内部的A相和B相分别与沥青表面的周相和次相相近。此外，矿物集料的添加显著影响了沥青内部的相特征。
