Evaluating the Low-temperature Properties of Asphalt Binders Extracted from Mixtures Containing Recycled Materials

Abstract

The use of recycled materials − such as reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) − in asphalt mixtures reduces natural resources demands and decreases materials dumped in landfills. The aged binders included in the recycled materials alter binders’ low-temperature properties included in asphalt mixtures. Therefore, asphalt binders were extracted from asphalt mixtures collected from the field as cores. Due to the limited amount of extracted asphalt binders (EABs), a dynamic shear rheometer was used to examine the low-temperature properties [e.g., true temperature (Tt), continuous temperature (Tc), and delta continuous temperature (ΔTc)]. Using recycled materials in asphalt mixtures increased EABs’ low temperatures, Tt and Tc , and decreased EABs’ ΔTc values when compared to EABs from mixtures without recycled materials. Using RAS in asphalt mixtures degraded the low-temperature properties of EABs, Tt and Tc increased and ΔTc decreased, when compared to EABs from mixtures containing RAP. Increasing the asphalt binder replacement (ABR) percentages by recycled materials increased Tc and decreased ΔTc . The flow activation energy (Ea) was related to the Tc and ΔTc values, and very strong relationships were observed between Ea and Tc and Ea and ΔTc . The researchers modelled two low-temperature prediction models to predict Tc and ΔTc depending on the grade of the virgin asphalt binder, ABR types and percentages, and asphalt mixtures ages.

Performance Evaluation of Extracted Asphalt Binders from Field Cores Containing Recycled Components: Load- and Non-Load-Associated Cracking Resistance

“…The Superpave fatigue cracking parameter (|G*|.sinδ) values, on the other hand, increased, indicating lower resistance to fatigue cracking [25]. Furthermore, increasing the RAP percentage in binders and mixtures resulted in a decrease in load-and non-load-associated cracking resistance [26][27][28][29]. The authors explained this reduction in the cracking resistance by relating it to the stiff nature of the aged asphalt binders included in the RAP [26][27][28][29].…”

Enhancing the Contribution of Recycled Asphalt Shingles to Asphalt Binders Using Rejuvenators

“…RAS contains oxidized air-blown asphalt binders, polymers, granules, mineral fillers, and fibers [2][3][4]. Utilizing RAS in asphalt mixes modifies the performance of the total binders in these mixes due to interactions between RAS and the virgin binders [4][5][6]. In asphalt mixtures, two types of shingles are permitted: Manufactured waste and tear-off (post-consumer) shingles [7,8].…”

“…Because the oxidized and aged binders in RAS enhanced the stiffness and elasticities of the binder, utilizing RAS in asphalt mixes increased the rutting resistance of the mixes and extracted asphalt binders as compared to virgin mixes and binders [4,5]. However, increasing the stiffness of the asphalt binder lessened its ductility, and relaxation potential, and increased its cracking capability [6,17,18].…”

“…This was due to the polymeric components included in shingles [5] that enhance the fatigue cracking resistance. Using RAS as a modifier with the neat binder influences the lowtemperature performance of the modified asphalt binder [6,23]. When the RAS binder was blended with neat binder, the low temperature increased by 0.4°C for every 1% of asphalt binder replaced by RAS [23].…”

“…When the RAS binder was blended with neat binder, the low temperature increased by 0.4°C for every 1% of asphalt binder replaced by RAS [23]. When compared to binders extracted from RAP-containing mixes, the use of RAS exacerbated the low-temperature characteristics of extracted binders [6].…”