The effects of asphalt migration on the flow number of asphalt mixture

摘要

Asphalt migration is one of the significant detrimental effects on asphalt pavement performance. In order to simulate the post-migration state of asphalt amid asphalt pavement layers and further investigate the effects of asphalt migration on the flow number (FN) of asphalt mixture, the samples with different asphalt contents layers were firstly separated into the upper and lower half portions and then compacted together. By conducting the repeated load permanent deformation test with the Superpave Simple Performance Tester (SPT), the effects of asphalt migration on the flow number of asphalt mixture and the variation laws of the flow number at different testing temperatures and under different loads were analyzed in this paper. Results show that, after the asphalt migration, the flow numbers of asphalt mixtures decrease to different degrees with the increment of testing temperature or load and are more susceptible to temperature over the load. The flow numbers are the highest when asphalt mixtures have the optimum asphalt content layers and then decrease with the incremental difference of asphalt content in the upper and lower half portions, indicating that the asphalt migration has compromised mixture's rutting resistance. The more asphalt migrates, the worse rutting resistance will be found in asphalt mixture. It is deemed that the flow number of asphalt mixture is comprised of two parts, one is provided by asphalt mortar and the other by coarse aggregates (generally considered as a constant under the same load). Additionally, based on the repeated load permanent deformation test, the effects of asphalt migration on the flow number of asphalt mixture and the variation laws of the flow number of asphalt post-migration can be better construed at the quantitative level. (C) 2019 Elsevier Ltd. All rights reserved.