ABSTRACT

In this study, the mix design volumetrics and cracking potential of foamed Warm Mix Asphalt (WMA) containing various amounts of Reclaimed Asphalt Pavement (RAP) were evaluated. It was found that the increased coating ability of the foamed WMA binder counteracted the lowering of mixing and compaction temperatures for WMA. Therefore, both control HMA and foamed WMA exhibited similar mix design volumetrics up to certain lower temperatures. However, further reductions in the mixing and compaction temperatures for foamed WMA were found to exhibit improper mixing between aggregates and foamed binder. Despite foamed WMA exhibiting similar volumetric properties as HMA up to certain lower temperature, their fatigue cracking performance was found to be significantly different. The foamed WMA was found to exhibit higher cracking resistance compared to HMA in Louisiana Semi-Circular Bending (SCB) and Illinois Flexibility Index Test (I-FIT) tests. A similar trend in the cracking resistance was observed for coarser mixes in the Abrasion Loss Test (commonly known as Cantabro test). However, the Cantabro test could not screen finer mixes for their cracking resistance as it lacks a mechanistic basis. Finally, the foamed WMA technology was found to increase the cracking resistance of asphalt mixes. The higher RAP content in the foamed WMA, on the contrary was found to lower the cracking resistance of asphalt mixes due to incorporation of aged and stiffer binder from RAP.

摘要

在这项研究中，评估了含有不同数量的再生沥青路面 (RAP) 的泡沫温拌沥青 (WMA) 的混合设计体积和开裂潜力。发现发泡 WMA 粘合剂的涂层能力增加抵消了 WMA 混合和压实温度的降低。因此，对照 HMA 和发泡 WMA 在某些较低温度下都表现出相似的混合设计体积。然而，发现进一步降低泡沫 WMA 的混合和压实温度会导致骨料和泡沫粘合剂之间的混合不当。尽管泡沫 WMA 在某些较低温度下表现出与 HMA 相似的体积特性，但发现它们的疲劳开裂性能显着不同。在路易斯安那州半圆弯曲 (SCB) 和伊利诺伊州柔韧性指数测试 (I-FIT) 测试中，与 HMA 相比，发泡 WMA 表现出更高的抗裂性。在磨损损失测试（通常称为 Cantabro 测试）中，对于较粗的混合物，观察到类似的抗开裂趋势。然而，Cantabro 测试无法筛选更精细的混合物的抗裂性，因为它缺乏机械基础。最后，发现泡沫 WMA 技术可以提高沥青混合料的抗裂性。相反，发现泡沫 WMA 中较高的 RAP 含量会降低沥青混合料的抗裂性，这是因为加入了来自 RAP 的老化和更硬的粘合剂。在磨损损失测试（通常称为 Cantabro 测试）中，对于较粗的混合物，观察到类似的抗开裂趋势。然而，Cantabro 测试无法筛选更精细的混合物的抗裂性，因为它缺乏机械基础。最后，发现泡沫 WMA 技术可以提高沥青混合料的抗裂性。相反，发现泡沫 WMA 中较高的 RAP 含量会降低沥青混合料的抗裂性，这是因为加入了来自 RAP 的老化和更硬的粘合剂。在磨损损失测试（通常称为 Cantabro 测试）中，对于较粗的混合物，观察到类似的抗开裂趋势。然而，Cantabro 测试无法筛选更精细的混合物的抗裂性，因为它缺乏机械基础。最后，发现泡沫 WMA 技术可以提高沥青混合料的抗裂性。相反，发现泡沫 WMA 中较高的 RAP 含量会降低沥青混合料的抗裂性，这是因为加入了来自 RAP 的老化和更硬的粘合剂。