Experimental study on the fatigue performance of emulsified asphalt cold recycled mixtures

Abstract

With advantages such as energy saving, environmentally friendliness, green, low carbon emission, and high economic efficiency, emulsified asphalt cold recycled mixtures (CRM) have been used increasingly extensively, and their range of application has also extended from the base layer to the lower surface layer. Thus, studying their fatigue performance is particularly important. The inevitable secondary compaction in the construction process significantly affects the fatigue performance of emulsified asphalt CRM. However, relevant studies concerning the effect of secondary compaction on the fatigue performance of emulsified asphalt CRM are still lacking, and the conclusions of existing studies investigating the effect of emulsified asphalt CRM composition on its fatigue performance are inconsistent. In this study, the effect of emulsified asphalt content, cement type, cement content, and reclaimed asphalt pavement (RAP) content on fatigue performance was investigated through controlled strain four-point bending fatigue tests, and the effect of secondary compaction on the fatigue performance of CRM was comparatively studied by simulating the secondary compaction with indoor wheel rolling tests. The results showed that the fatigue performance of CRM increased significantly with the increase of emulsified asphalt content. With the increase of ordinary Portland cement content, the fatigue performance improved and then degraded. The fatigue performance peaked at the cement content of 1.5% and then decreased sharply. Mixing with high early-strength cement resulted in little improvement in fatigue performance but reduced it at the content of 3%. The fatigue performance increased with the increase of RAP content. Secondary compaction substantially improved the fatigue performance of CRM, and the fatigue performance was underestimated by the existing evaluation methods. This study could provide guidance and reference for the composition design of CRM and the objective evaluation of its fatigue performance.