Analysis of rheological properties and micro-mechanism of aged and reclaimed asphalt based on multi-scales

2022 ◽  
Vol 321 ◽  
pp. 126290
Author(s):  
Mei Lin ◽  
Jun Shuai ◽  
Ping Li ◽  
Xiao Kang ◽  
Yu Lei
2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Weiying Wang ◽  
Songchang Huang ◽  
Yongchun Qin ◽  
Yiren Sun ◽  
Rui Dong ◽  
...  

With the development of pavement recycling technology, the requirement of reclaimed asphalt pavement (RAP) is substantially increasing. Warm-mix recycled asphalt (WMRA) technology has made great progress, which can effectively decrease the working temperature and improve the RAP content. In this study, the rheological properties of recycled binders with incorporation of high-percentage artificial RAP binder (30–70%) were evaluated using two types of warm-mix asphalt (WMA) additives, i.e., polyethylene wax R and surfactant M. The dynamic shear rheometer (DSR) and beam bending rheometer (BBR) tests were conducted on the recycled binders. The results showed that the temperature and frequency played an important role in determining the complex shear modulus of the high-percentage WMRA binders. The dependency of phase angle on frequency increased after the long-term aging. The WMA additive R had a relatively huge impact on the rheological properties of asphalt, which mainly occurred before the PAV aging of recycled asphalt binder; the WMA additive M had no significant impact on the rheological properties of recycled asphalt binder. The WMA additive R enhanced the low-temperature rheology of recycled asphalt binder, while the WMA additive M enhanced the high-temperature rheology of recycled asphalt binder. Both of these types of WMA additives improved the antifatigue performance of recycled asphalt binder. The increased content of RAP binder improved the high-temperature performance and reduced the low-temperature performance of the recycled asphalt binder. However, it had no obvious impact on the fatigue performance. In addition, there was a good linear relation between the RAP binder content and the two indexes of the multiple stress creep recovery (MSCR) test.


2022 ◽  
Vol 13 (1) ◽  
pp. 140-152
Author(s):  
Eslam Deef-Allah ◽  
Magdy Abdelrahman

The use of reclaimed asphalt pavement (RAP) and/or recycled asphalt shingles (RAS) in the asphalt mixtures is a common practice in the U.S.A. However, there is a controversy to date on how RAP/RAS interact with virgin asphalt binders (VABs) in asphalt mixtures. For mixtures containing RAP/RAS, the aged asphalt binders in RAP and air-blown asphalt binders in RAS alter the performances of the extracted asphalt binders (EABs). Thus, the rheological properties of EABs from these mixtures require more investigation. The focus of this paper was relating the high-temperature properties of EABs from field cores to the corresponding rolling thin film oven aged virgin asphalt binders (RTFO AVABs). Furthermore, a comparison of the effect of RAP and RAS on the high-temperature rheological properties of EABs was another objective. Different asphalt cores were collected from the field within two weeks after the pavement construction process in 2016. These cores represented eight asphalt mixtures with different asphalt binder replacement percentages by RAP, RAS, or both. The asphalt binders were extracted from these mixtures and considered as RTFO AVABs. The high-temperature rheological properties included the temperature sweep and frequency sweep testing and the multiple stress creep recovery testing. The EABs had higher stiffnesses and elasticates than the corresponding RTFO AVABs because of the aged binders in RAP/RAS. The binders in RAP interacted more readily with VABs than RAS binders.


Author(s):  
Yang Liu ◽  
Hainian Wang ◽  
Susan Tighe ◽  
Guangyuan Zhao ◽  
Zhanping You

Hot in-place recycling (HIR) is a process that reuses reclaimed asphalt materials to benefit the environment and conserve natural resources. HIR has not yet been widely applied in China because of technical drawbacks such as reclaimed materials’ fatigue properties and poor cracking resistance. Preheating is the first procedure in HIR and significantly affects the diffusion of rejuvenators within the aged asphalt and the remixing of virgin and aged mixtures. This study focuses on the effects of preheating on the rheological properties of rejuvenated asphalt binder using dynamic shear rheometer (DSR) testing. Three types of rejuvenators (Reju-A, Reju-B and Reju-C), three types of base asphalt binder (#50, #70, and #90), recovered asphalt from recycled asphalt pavement, and laboratory-aged asphalt were investigated to analyze the rheological properties under different heating conditions. The results show that (1) rejuvenators contain little in the way of viscous characteristics and have a viscosity-reducing effect on aged asphalt; (2) field-aged asphalt loses cohesion and gains rutting resistance during aging; and (3) preheating has a significant effect on diffusion of rejuvenators within aged asphalt as well as on rheological properties. In short, a good controlled preheating operation is critical to the quality of the asphalt rejuvenation process.


2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Rosa Veropalumbo ◽  
Francesca Russo ◽  
Nunzio Viscione ◽  
Salvatore A. Biancardo

The use of reclaimed asphalt pavement is a practice that is adding significant environmental value to road technologies, not only due to the reduction of materials sent to landfill but also because of the mechanical properties of the reclaimed asphalt (RA) that can be reused. This research focuses on the rheological properties of hot and cold bituminous mastics made up as follows: (1) hot mastics mixed with limestone filler (LF) and bitumen, (2) hot mastics, made from bitumen mixed with jet grouting waste (JW), a mixture of water, cement, and soil derived from land consolidation work in underground tunnels, and (3) hot mastics mixed with LF and JW as filler and bitumen. Three different ratios (0.3, 0.4, and 0.5) of filler per unit of neat bitumen (B50/70) were studied. The same number was used for mixing cold mastics, by using an appropriate laboratory protocol designed since the adoption of a cationic bituminous emulsion. A total of 18 mastics were prepared and investigated. The comparison was carried out using the frequency sweep (FS) test, analysing shear modulus G∗, applying the multistress creep and recovery (MSCR) test (40°C and 60°C) as well as the delta ring and ball (ΔR&B) test, focusing on two main issues: (1) the stiffening effect caused by the filler type used for mixing each mastic, and (2) a comparison, in terms of stiffening effects and nonrecoverable creep compliance (Jnr) of hot and cold mastic performance to highlight JW reuse in mastics. The results showed that the best G∗ performance at test temperatures higher than 30°C is given by cold mastic after 28 days of curing time when JW is added to LF and bitumen. The lowest Jnr value was 40°C and 60°C for the same mastic.


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