Hu Chichun, Mai Yucan, Cannone Falchetto Augusto, Tartari Edith
School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510006, China.
Department of Civil & Environmental Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
Materials (Basel). 2021 Feb 21;14(4):1023. doi: 10.3390/ma14041023.
As a good asphalt modifier, natural asphalt has been the focus of more attention because of its low price and ability to improve the performance of modified asphalt. In this paper, the incorporation of a natural asphalt binder in the production of bituminous materials for pavement application in China was experimentally investigated to evaluate the feasibility of such a process and its potential benefits in terms of performance. For this purpose, an asphalt binder conventionally used in the south of China was blended with various percentages of a hard natural binder obtained from the region of Selenice in Albania. The content of Selenice natural bitumen (SNB) was 80.5%, having high molecular weight and the advantages of good stability and compatibility with virgin asphalt. The physical, rheological, and mechanical properties, as well as the modification mechanism of the binder and corresponding asphalt mixture, were evaluated in the laboratory. It was observed that the hard binder improved the response of the binder blend at high and intermediate temperature; this reflected a better stability, improved moisture susceptibility, and enhanced rutting resistance of the mixture. Fluorescence microscopy showed that after dissolving, the size of the SNB modifier became smaller and its distribution was uneven, presenting three forms, granular, agglomerated, and flocculent properties. Chemical test results showed that the modification mechanism of SNB was mainly related to the enhancement of hydrogen bonds and Van der Waals forces caused by sulfoxide and carbonyl along with the stress concentration caused by silica particles. Molecular composition revealed that the proportion of middle molecules has reduced while the proportion of large molecules has increased. It is considered that SNB is a promising low-priced natural modifier with excellent rutting resistance properties. Future research will be focused on the economic analysis, pavement life cycle assessment of SNB modified asphalt, and its application in perpetual pavements.
作为一种优良的沥青改性剂，天然沥青因其价格低廉且能够改善改性沥青性能而备受关注。本文通过实验研究了在中国道路工程中使用天然沥青作为粘结剂生产沥青材料的可行性及其在性能方面的潜在优势。为此，将中国南方常用的一种沥青粘结剂与不同比例的从阿尔巴尼亚塞莱尼采地区获得的硬质天然粘结剂进行混合。塞莱尼采天然沥青（SNB）的含量为80.5%，具有高分子量，与原生沥青具有良好的稳定性和相容性。在实验室中对粘结剂及相应沥青混合料的物理、流变和力学性能以及改性机理进行了评估。结果表明，硬质粘结剂改善了粘结剂混合物在高温和中温下的响应；这反映出混合物具有更好的稳定性、改善的抗水损害性和增强的抗车辙性能。荧光显微镜观察显示，溶解后SNB改性剂的尺寸变小且分布不均匀，呈现出颗粒状、团聚状和絮凝状三种形态。化学测试结果表明，SNB的改性机理主要与亚砜基和羰基引起的氢键和范德华力增强以及二氧化硅颗粒引起的应力集中有关。分子组成分析表明，中分子比例降低而大分子比例增加。认为SNB是一种具有良好抗车辙性能的、有前景的低价天然改性剂。未来的研究将集中在经济分析、SNB改性沥青的路面生命周期评估及其在长寿命路面中的应用。
