A new progressed mastic aging method and effect of fillers on SBS modified bitumen aging

• Published in: Construction & building materials Vol. 238; p. 117732
• Main Authors: Xing, Chengwei, Liu, Liping, Sheng, Jianwei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30-03-2020
• Subjects: Aging method; Mastic; Molecular size distribution; Rheological property; SBS modified bitumen; Rheological property; Aging method; Molecular size distribution; Mastic; SBS modified bitumen
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.117732

•A new progressed method is proposed for mastic aging.•MSCR results imply that fillers adopted in this manuscript alter the relative aging rate of SBS modifiers and base bitumen.•GPC results indicate that fillers adopted in this manuscript appear to accelerate the degradation rate of SBS modifiers.
Fillers are thought to affect bitumen aging properties in mastics. However, current laboratory standard bitumen aging methods are not suitable for mastics. In addition, the role of fillers on SBS modified bitumen aging is poorly documented. In this study, a modified mastic aging strategy is disclosed to ensure the consistency of filler/bitumen ratio before and after aging. This study shows that the modified aging method can avoid the change of filler/bitumen ratio, caused by separation of mastics from aging pans after aging. Based on the proposed aging method, the modified SBS bitumen and the corresponding mastics including limestone and ash are aged for different time intervals. Then, master curves and multiple stress creep recovery (MSCR) analyses are performed to explore the rheological properties of mastics. In addition, this investigation uses gel permeation chromatography (GPC) to monitor molecular size distribution of SBS modifiers in mastics during aging. Master curves indicate that fillers can decline the aging rate of the base bitumen in SBS modified bitumen, because of the lower reduction rate of fP in master curves of mastics by aging. With respect to MSCR tests, Jnr3.2 of mastics initially increases and, then, decreases with aging; while, that of SBS modified bitumen diminishes continuously. These observations strongly suggest that fillers can alter the relative aging rate of SBS modifiers and base bitumen. GPC results also support the mentioned explanations by rheological tests such that the fillers seem to accelerate degradation rate of polymers in mastics.