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 accelerating 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.