Effects of cold storage temperature on thermoreversible aging in heavily oxidized asphalt binders

In order to better understand the thermoreversible aging characteristics of asphalt after heavy oxidation, six selected heavily oxidized asphalt containing different proportions of C20H42 are subjected to extended bending beam rheometer (ExBBR) tests, while modulated differential scanning calorimetry (MDSC) and atomic force microscope (AFM) are also performed on the asphalt. The results indicate that the introduction of heavy oxidation will not only affect the low temperature properties of the asphalt but also its thermoreversible aging characteristics, but this effect will receive an influence of the storage temperature. This is due to the increase in viscosity of the asphalt after heavy oxidation, which makes it difficult for C20H42 to migrate, while the increase in storage temperature can release the potential of the degree of thermoreversible aging of the asphalt by accel-erating the movement of wax molecules. And like C20H42, the grade loss of asphalt blended with C30H62 is different at different storage temperatures and oxidation levels, which proves that for heavily oxidized asphalt, multiple storage temperatures should be selected for testing its grade loss. Combined with thermal and morphological analysis, the introduction of heavy oxidation not only increases the amount of wax precipitation, but also significantly increases the thermoreversible aging of the asphalt by lowering the Tg of the asphalt and forming more perfect crystals during low temperature storage. Finally, by comparing the grade loss due to cold storage and extended oxidation, it can be found that the incorporation of C20H42 will make the asphalt more influenced to physical hardening. Therefore, it is necessary to study the effect of asphalt wax content on the degree of thermoreversible aging of heavily oxidized asphalt.

Automated summary

To better understand the thermoreversible aging of heavily oxidized asphalt, experiments on six different asphalt samples with various C20H42 proportions were conducted, including extended bending beam rheometer (ExBBR) tests, modulated differential scanning calorimetry (MDSC) tests, and atomic force microscope (AFM) observations. The results demonstrate that heavy oxidation affects both the low temperature properties and thermoreversible aging characteristics of asphalt, with the former being influenced by storage temperature. The increased viscosity due to heavy oxidation hinders C20H42 migration, but higher storage temperature promotes thermoreversible aging by facilitating wax molecule movement. Furthermore, analysis reveals that the grade loss of asphalt blended with C30H62 varies at different storage temperatures and oxidation levels, indicating the importance of selecting multiple storage temperatures for testing heavily oxidized asphalt. Combined with thermal and morphological analysis, heavy oxidation increases wax precipitation, lowers the Tg of asphalt, and forms more perfect crystals during low temperature storage, thereby significantly enhancing thermoreversible aging. Finally, the incorporation of C20H42 intensifies physical hardening of asphalt, highlighting the need to study the effect of asphalt wax content on the degree of thermoreversible aging in heavily oxidized asphalt.