Evaluation of asphalt properties in plant produced asphalt mixes

安大略省运输部（MTO）负责安大略省高速公路网的安全和质量。该网络的95%铺设的是热拌沥青（HMA）：一种由加热的石头、沙子或砾石与沥青水泥（原油的产物）结合而成的材料。**在安大略省，自2000年初采用Superpave技术以来，根据美国州和公路运输官员协会（AASHTO）标准的性能分级，沥青水泥的性能已被接受。然而，AASHTO标准中包含的老化方案，旨在模拟沥青水泥的短期（生产和放置）和长期（使用）氧化老化，已被证明与现场老化无关。** 2009年，安大略省交通部材料工程研究办公室（MERO）沥青部门增加了新的测试，以更好地表征沥青材料并预测安大略省沥青路面的性能。进行了一项研究来评估新测试以及它们与性能的相关性——该研究得出的结论是，如果能够在实验室中更好地复制田间老化，那么现有测试和新测试与田间的相关性都可以得到改善。尽管如此，新的测试方法已被MTO接受。对从HMA生产商沥青罐中采集的沥青水泥样品进行了测试。**此外，安大略省的一些市政当局进一步修改了本规范，将其应用于从HMA中回收的沥青水泥。即使用溶剂从HMA混合料中的集料中除去或提取沥青粘结剂，然后从溶液中回收沥青进行测试。由于研究表明，提取和回收过程会影响沥青水泥的性能，而且目前还不清楚回收沥青的性能与原始沥青的性能相比如何，因此人们对基于回收沥青水泥的验收标准的适当性表示担忧。**准确的材料特性对于工程师和业主预测性能非常重要。因此，本研究的总体目标是通过以下方式提供表征沥青水泥和HMA的框架：首先，比较目前的实验室老化方案和沥青水泥的现场老化；其次，沥青水泥和HMA的测量性能如何与性能相关联。**该研究还将包括对各个行业测试实验室报告的测试结果进行审查，以评估实验室之间测试结果的范围，以了解与回收沥青材料特性相关的测试可变性。****

The Ontario Ministry of Transportation (MTO) is responsible for the safety and quality of Ontario's highway network. 95% of this network is paved with hot mix asphalt (HMA): a material produced with heated stone, sand, or gravel bound together with asphalt cement, a product of crude oil. **In Ontario, asphalt cement properties have been accepted based on performance grading to the American Association of State and Highway Transportation Officials (AASHTO) standards since the adoption of the Superpave technology in early 2000's. However, the aging protocols included in the AASHTO standard, which are intended to simulate the short term (production and placement) and longer term (in service) oxidative aging of asphalt cement, have been shown to not correlate with field aging. **In 2009, the Bituminous Section of the Materials Engineering Research Office (MERO) of the MTO added new tests to provide better characterization of asphalt materials and prediction of asphalt pavement performance in Ontario. A study was conducted to evaluate the new tests and how well they correlate with performance - the study concluded that correlation to field for both the current and new tests could be improved, if field aging can be better replicated in the lab. Nonetheless, the new test methods have been adopted by MTO for acceptance. Testing is carried out on asphalt cement samples collected from HMA producers' asphalt tanks. **In addition, some municipalities in Ontario have further modified this specification, applying them to recovered asphalt cement from HMA. That is, the asphalt binder is removed or extracted from the aggregates in the HMA mix by using a solvent, then the asphalt is recovered from the solution for testing. There are concerns with the appropriateness of acceptance criteria based on recovered asphalt cement, because research has shown that the extraction and recovery process can impact the asphalt cement properties, and there is no understanding of how the recovered asphalt properties compare to the original virgin asphalt. **Accurate material characterization is important for engineers and owners to predict performance. Therefore, the overall objective of this research is to provide a framework for characterizing of asphalt cement and HMA by: firstly, comparing current laboratory aging protocols to field aging of asphalt cement; and second how the measured properties of the asphalt cement and HMA correlate to performance.**The study will also include a review of test results reported by various industry testing labs, to assess the range in test results between labs, to understand the testing variability associated with material characterization of recovered asphalt.****