基于三维荧光光谱的沥青老化行为研究

沥青在服役过程中暴露在自然环境里,受到光、热、氧等的作用,易出现老化从而引起的多种病害,如裂缝、龟裂和坑槽等,严重影响沥青混凝土路面的服役寿命。为了提高沥青混凝土路面的耐久性能,揭示沥青在老化过程中的成分与结构的变化规律,基于荧光光谱技术,从沥青的荧光猝灭现象出发,利用实验室内的紫外老化与热氧老化,针对两种不同沥青进行了老化实验,并研究了沥青在老化前后的性能和组分变化;借助荧光分光光度计采集了沥青的三维荧光光谱,并分析了沥青荧光光谱谱图的特征,获取了沥青荧光光谱的峰值强度坐标,计算了老化前后峰值坐标的偏移向量。实验结果表明,沥青避免出现荧光猝灭的理想浓度是0.1 g·L-1;沥青老化后其软化点增加,针入度与延度减小;其四组分中饱和分基本不变,芳香分减小,胶质与沥青质增加。结合三维荧光光谱发现,沥青的荧光强度峰值坐标出现了“蓝移”,且沥青组成中的芳香分的含量决定了荧光光谱峰值的偏移程度;通过向量计算表明,峰值坐标偏移的向量的模大于36时,沥青已经严重老化。通过对沥青三维荧光光谱特征值的分析,可以有效评价沥青的老化过程,对提高沥青的耐久性具有重要意义。

Aging Behavior of Bitumen Based on Three-Dimensional Fluorescence Spectroscopy

Bitumen is easy to age under the natural environment of light, heat and oxygen. A good deal of damages of pavement caused by bitumen aging such as crack, chap and trenches, as well as the service life of asphalt pavement are shortened. In order to improve the durability of asphalt pavement and reveal the change rule of components and structure during the bitumen aging process, the fluorescence spectroscopy technique was carried out from the phenomenon of fluorescence quenching of bitumen in this paper. There are two bitumen that were carried out by ultraviolet aging (UV) and thin-film oven test (TFOT). The properties and components of bitumen were studied before and after aging. Furthermore, fluorescence spectrogram of bitumen was obtained by fluorescence spectrophotometer, and the characteristic of spectrogram was analyzed. In addition, the coordinates of fluorescence peak were found from the spectrogram, and the shifted vector was calculated at last. The results showed that optimum concentration is 0.1 g·L-1 to avoid fluorescence quenching. After aging, softening point of bitumen increases, penetration and ductility decreases. Furthermore, its saturate is unchanged, aromatics decrease, resins and asphaltenes increase. According to the three-dimensional fluorescence spectrum, the coordinates of fluorescence peak of bitumen appear "blue shift" after aging, and the content of aromatics in the bitumen defines the shift distance of fluorescence peak. In addition, bitumen has aged badly when the norm of shift vector is higher than 36. As characteristic parameter of three-dimensional fluorescence spectra was analyzed, it is possible to evaluate the aging process of asphalt effectively, which is of great significance to improve the durability of bitumen.