基于纳米力学和官能团的沥青老化微观机理

Micro Mechanism of Asphalt Aging Based on Nano-mechanics and Functional Groups

采用原子力显微镜(Atomic Force Microscopy,AFM)技术来探索沥青老化规律,同时与传统的研究沥青老化方法傅里叶变换红外光谱(Fourier Transform infrared spectroscopy,FTIR)的研究结果进行比较。分别测试了基质沥青和SBS改性沥青在原状(未老化)、RTFO老化后和PAV老化后的微观力学特性及其官能团化学特性。结果表明,沥青的老化程度越高,"蜂状结构"发育越好,平均面积和最大面积越大。沥青试样内至少存在3个不同的微区具有不同的黏附力,其中"蜂状结构"相黏附力最低。老化影响沥青的纳米力学性能,提高沥青黏附力大小分布的均匀性,不同老化程度的SBS改性沥青的黏附力均大于基质沥青。老化引起沥青羰基和亚砜基等含氧官能团含量增加,丁二烯基含量减小。沥青老化后微观力学的变化与官能团的变化有良好关系。

The asphalt aging regularity is investigated by applying AFM technology, and compared with the result from FTIR （Fourier Transform infrared spectroscopy） in traditional method of studying asphalt aging. The micro mechanical properties and the chemical properties of functional groups of the base asphalt and the SBS modified asphalt in the states of original, RTFO aging and PAV aging are tested. The result shows that （ l ） the higher the aging degree of asphalt, the better the ＂bee-structure＂, and the larger the average area and the maximum area; （2） there are at least 3 different micro zones with different adhesion forces in the asphalt samples, where the ＂bee-structure＂ phase has the lowest adhesion force; （3） aging affected the nano-mechanical property and improved the distribution uniformity of asphalt adhesion magnitude, the adhesions of SBS modified asphalt with different aging degrees are larger than that of the base asphal aging caused the content of oxygen-containing functional groups such as carbonyl and sulfoxide groups increase and the content of butadienyl groups decrease; （5） the micro mechanical change of the aged asphalt has a good relationship with the change of functional groups.