The use of high percentages of reclaimed asphalt pavement (RAP) in asphalt mixtures offers economic and environmental advantages. However, state agencies place limits on RAP usage to avoid its indiscriminate use without a full understanding of its long-term performance implications. To achieve a more informed and rational use of higher RAP contents, it is essential to quantify recycled binder availability (RBA) and incorporate it into asphalt mixture design. The current design methods often assume complete RBA, leading to less durable mixtures. Standardized mixture design methods fail to rigorously account for the effects of RBA on the volumetric composition of asphalt mixture. Recently, the availability adjusted mixture design (AAMD) method was developed to address these issues by explicitly considering partial RBA in the interpretation of mixture volumetric properties and accounting for the role of RAP agglomerations on aggregate structure. This study tests the hypothesis that the AAMD method can mitigate the adverse performance consequences of RAP through the control of ‘available’ volumetric and effective binder properties. This was achieved by comparing virgin and RAP mixtures designed with similar ‘available’ volumetric properties according to the AAMD method. Additionally, control mixtures with RAP contents ranging from 20 to 35 percent were compared to AAMD mixtures with similar ‘available’ volumetric properties designed with the same RAP content and with 50 percent RAP. The collective results demonstrate that the AAMD method effectively mitigates negative performance consequences of RAP by controlling the ‘available’ volumetric and effective binder properties.

中文翻译：

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可用性调整配合比设计方法作为减轻 RAP 对沥青混合料性能不利影响的工具

在沥青混合料中使用高比例的再生沥青路面（RAP）具有经济和环境优势。然而，国家机构对 RAP 的使用进行了限制，以避免在没有充分了解其长期性能影响的情况下随意使用。为了更明智、更合理地使用较高的 RAP 含量，必须量化再生粘合剂的可用性 (RBA) 并将其纳入沥青混合料设计中。当前的设计方法通常假设完整的 RBA，导致混合物的耐用性较差。标准化混合料设计方法未能严格考虑 RBA 对沥青混合料体积组成的影响。最近，开发了可用性调整混合物设计 (AAMD) 方法来解决这些问题，该方法通过在混合物体积特性的解释中明确考虑部分 RBA 并考虑 RAP 团聚对聚集体结构的作用。本研究测试了以下假设：AAMD 方法可以通过控制“可用”体积和有效粘合剂特性来减轻 RAP 的不利性能后果。这是通过比较根据 AAMD 方法设计的具有相似“可用”体积特性的原始混合物和 RAP 混合物来实现的。此外，将 RAP 含量范围为 20% 至 35% 的对照混合物与具有相似“可用”体积特性的 AAMD 混合物进行了比较，该 AAMD 混合物设计为具有相同的 RAP 含量和 50% RAP。集体结果表明，AAMD 方法通过控制“可用”体积和有效粘合剂特性，有效减轻了 RAP 的负面性能影响。