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

一项主要研究目标将是制定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开裂。第二个目标是利用这些测试和标准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沥青水泥在冷调节过程中如何逐渐变硬数据所需的时间，以解决目前测试时间过长的问题。经验和基本模型将用于从短期测试中预测长期特性。第二个目标将是研究改进的沥青成分。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很好的。最常用的是由苯乙烯和丁二烯制成的嵌段共聚物。然而，在其主链中含有二烯官能团的聚合物在使用过程中会遭受快速的氧化降解，从而导致理想性能的丧失。因此，我们将研究如何利用具有较少二烯功能的聚合物（高乙烯基等级）或无二烯（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工业上可用的材料，因为它们具有明显更高的抗聚合物链裂解能力。最后，我们将探讨如何提高基础沥青的氧化稳定性。油砂沥青有望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的易氧化极性分子含量相对较低，因此在低温下逐渐可逆硬化或与氧反应不可逆硬化的影响较小。然而，目前还没有关于这一主题的出版物。改进的规格试验和沥青成分将通过基础和应用跨学科研究来发展。本科生和研究生将在流变学、失效力学、材料科学与工程、聚合物、热分析等重要领域接受培训。这项研究将为加拿大的道路和知识基础带来重大利益。

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.