Novel Asphalt Cement Test Methods and Compositions for Improved Flexible Pavement Performance

一个主要的研究目标将是开发简化的沥青性能分级测试和验收标准，使用户机构能够更好地控制路面裂缝。第二个目标是使用这些测试和标准来为加拿大工业设计更好的改性沥青。我们的工作将集中在如何缩短获取有关沥青水泥在冷处理过程中如何逐渐硬化的数据所需的时间，以解决目前测试耗时过长的问题。经验模型和基本模型将被用来从短期测试中预测长期属性。第二个目标将是调查改进的沥青成分。使用聚合物来增加沥青水泥满足最低性能要求的温度范围是众所周知的。最常用的是由苯乙烯和丁二烯制成的嵌段共聚物。然而，主链上含有二烯官能团的聚合物在使用过程中会发生快速氧化降解，从而导致所需性能的损失。因此，我们将研究如何利用二烯官能度较低的聚合物(高乙烯基牌号)或不含二烯的聚合物(苯乙烯-丙烯酸丁酯共聚物)。据推测，这种材料的性能优于目前行业中可用的材料，因为它们对聚合物链断裂的抵抗力要高得多。最后，我们将研究如何提高基质沥青的氧化稳定性。预计油砂沥青可以为沥青配方提供显著增强的起始原料。油砂沥青衍生的沥青水泥中易氧化的极性分子相对较少，因此在低温下应不会受到逐渐的可逆硬化的影响，或者通过与氧气反应而发生的不可逆硬化。然而，目前还没有关于这一主题的出版物。改进的规格测试和沥青组成将通过基础和应用跨学科研究来开发。本科生和研究生都将接受重要领域的培训，包括流变学、失效力学、材料科学和工程、聚合物、热分析等。这项研究将为加拿大的道路和知识基础带来重大好处。

A primary research objective will be to develop simplified performance grading tests and acceptance criteria for asphalt allowing user agencies to better control pavement cracking. A secondary objective is to use these tests and criteria to design better modified asphalt for Canadian industry. Our work will focus on ways to shorten the time it takes to obtain data on how asphalt cements gradually harden during cold conditioning, addressing a concern that current tests take too long. Empirical and fundamental models will be used to predict long-term properties from short-term tests. A secondary objective will be to investigate improved asphalt compositions. The use of polymers to increase the temperature range over which an asphalt cement meets minimum performance requirements is well established. The most commonly used are block copolymers made with styrene and butadiene. However, polymers that contain a diene functional group in their backbone suffer from rapid oxidative degradation in service and a consequent loss in desirable properties. Hence, we will investigate how polymers with less diene functionality (high vinyl grades) or no diene (styrene-butyl acrylate copolymers) can be utilized. It is hypothesized that such materials outperform those currently available in the industry because of their significantly higher resistance to polymer chain cleavage. Finally, we will investigate how the base asphalt's oxidative stability can be improved. It is expected that oil sand bitumen can provide significantly enhanced starting materials for asphalt formulation. Oil sand bitumen derived asphalt cements are relatively low in readily oxidized, polar molecules, and hence should suffer little from gradual, reversible hardening at cold temperatures, or irreversible hardening through reaction with oxygen. However, there are currently no publications on this topic. Improved specification tests and asphalt compositions will be developed through both basic and applied interdisciplinary research. Both undergraduate and graduate students will be trained in important areas including rheology, failure mechanics, materials science and engineering, polymers, thermal analysis, etc. The research will lead to significant benefits for Canada's roads and knowledge base.