2013 Session: 307

• Nanoscale Evaluation of Effect of RAP on Virgin Asphalt Binder Properties
  Abstract: In this paper, various nano and macro-mechanical techniques were used to study the effect of Reclaimed Asphalt Pavement (RAP) binder on the micro-structure and properties of a virgin asphalt binder and to evaluate the degree of blending that occurs between those binders. To this end, different atomic force microscopy (AFM) experiments (i.e. AFM tapping mode imaging, AFM nano-indentation, AFM force spectroscopy experiments) were conducted on a virgin asphalt binder, recovered RAP binder, and their composite. In addition, the dynamic shear rhoemeter (DSR) tests were conducted on the evaluated binders, and the dynamic modulus tests (E*) were performed on mixtures prepared using those binders to evaluate the degree of RAP blending and compare it with those obtained using the AFM test results. The results of the AFM images indicated that blending between the RAP and virgin binders occurs at the nano/micro-scale level in the composite binder at a fairly uniform manner. Furthermore, the nano-indentation test results indicated that the composite asphalt binder had significantly lower modulus than the RAP binder and closer to the virgin binder; however, the virgin binder modulus was still significantly lower than that of the composite. The force spectroscopy results indicated that the RAP had adverse effects on the adhesion properties of the composite binder. The results of DSR tests showed similar trends to that observed using the AFM nano-indentation results; however, the DSR was found to underestimate the effect of the RAP on the mechanical properties of the composite. Finally, the AFM test results suggested that about 85% of RAP was effective in the composite.
  Authors: Nazzal, Munir D.; Mogawer, Walaa S.; Kaya, Savas; Bennert, Thomas A.
  Authors: Nazzal, Munir D.; Mogawer, Walaa S.; Kaya, Savas; Bennert, Thomas A.
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-0153
• First Observation of Blending-Zone Morphology at Interface of Reclaimed Asphalt Binder and Virgin Bitumen
  Abstract: The challenge in designing recycled asphalt mixtures with a high amount of RAP is to estimate the blending degree between RAP binder and the added virgin bitumen. The extent of blending is crucial in this case as asphalt concrete response is influenced by the final binder properties. This paper focuses on the evaluation of interaction and extent of blending between RAP-binder and virgin bitumen by studying the microstructures of the ‘blending zone’ with atomic force microscopy (AFM). AFM is used to probe the change of microstructural properties from a RAP-binder and virgin bitumen to the blending zone of these two. Averaged microstructural properties have been observed in thin film blends of RAP-binder and pure bitumen. The morphology of the blending zone (spatial extent of about 50 µm) exhibits domains of a wide range of microstructure sizes from 160 nm to 2.07 µm and can be considered to be a completely blended ‘new material’ which has been observed directly for the first time. The fully blended binder properties are found to be in between those of the two individual binders, as could be inferred from the averaged microstructural properties imaged by AFM. This is also consistent with the results of mechanical tests (dynamic shear rheometer) on the same materials. Finally a design formula is proposed that relates the blending zone dimension to temperature and mixing time. This relation would bring the results of this study from small length scales up to the engineering level.
  Authors: Nahar, Sayeda Nowrozon; Mohajeri, Mohamad; Schmets, Alexander J. M.; Scarpas, Athanasios; van de Ven, Martin F. C.; Schitter, Georg
  Authors: Nahar, Sayeda Nowrozon; Mohajeri, Mohamad; Schmets, Alexander J. M.; Scarpas, Athanasios; van de Ven, Martin F. C.; Schitter, Georg
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-0763
• Evaluation of Rejuvenator's Effectiveness with Conventional Mix Testing for 100% RAP Mixtures
  Abstract: This paper presents research evaluating effectiveness of rejuvenators for production of very high (40-100%) Reclaimed Asphalt pavement (RAP) content mixtures. Nine differently originated softening agents were tested, including plant oils, waste derived oils, engineered products, as well as traditional and non-traditional refinery base oils. Two different dosages of the agents were added to binder extracted from RAP to evaluate their softening potential through testing of kinematic viscosity and penetration at two different temperatures. At 25°C the softening efficiency varied by a factor of twelve between the most and least effective rejuvenators. Consistency results at different temperatures were used to express temperature susceptibility by means of Penetration Index (PI), Penetration-Viscosity Number (PVN) and Bitumen Test Data Chart (BTDC) of the softened binders. The PI results varied measurably depending on the rejuvenator and supported the low temperature mixture test results, showing that PI may be a good and simple measure of rejuvenation effectiveness. Low temperature mixture embrittlement was evaluated at -10°C through determination of the indirect tensile strength and creep compliance for rejuvenated 100% RAP mixture samples. It can be concluded that four of the nine tested rejuvenators reduced extracted binder consistency to the necessary level and reduced susceptibility of RAP mixtures to low temperature embrittlement. Of the four, two engineered products tested had notably different performance but neither was superior to similar generic oils.
  Authors: Zaumanis, Martins; Mallick, Rajib B.; Frank, Robert
  Authors: Zaumanis, Martins; Mallick, Rajib B.; Frank, Robert
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-1447
• Aging Characteristics of RAP-Modified Binders: Rheological Properties
  Abstract: A study involving two RTFO-aged asphalts and their blends with 15 and 50 percent of extracted RAP binders was conducted to investigate the effect of RAP content and properties on the long-term aging characteristics of asphalt binders. This paper presents the influence of RAP binders on the rheological properties of fresh binders in terms of their aging characteristics. The results from rheological analyses of aged blended binders indicate that the aging characteristics of blended binders are dependent on fresh asphalt binders. The results show the crossover frequency decreases as RAP concentrations increase and the rheological index increases as RAP concentration increases. The pattern for stiffness increase as a function of aging times for RAP blended binders is similar to that of typical chemical aging kinetic model, where the stiffness increases substantially initially and then levels off at longer aging times. The results demonstrate that there is a linear relationship between the logarithm of G* and phase angle for RAP blended binders at all aging times and RAP contents, regardless of asphalt and RAP sources.
  Authors: Huang, Shin-Che; Turner, Thomas F
  Authors: Huang, Shin-Che; Turner, Thomas F
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-4226
• Evaluation of Rejuvenator's Effectiveness with Conventional Mix Testing for 100% RAP Mixtures
  Authors: Zaumanis, Martins
  Authors: Zaumanis, Martins
  Year: 2013
  Document Type: Presentation
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-1447
• Nanoscale Evaluation of Effect of RAP on Virgin Asphalt Binder Properties
  Authors: Nazzal, Munir
  Authors: Nazzal, Munir
  Year: 2013
  Document Type: Presentation
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-0153
• First Observation of Blending-Zone Morphology at Interface of Reclaimed Asphalt Binder and Virgin Bitumen
  Authors: Nahar, Sayeda
  Authors: Nahar, Sayeda
  Year: 2013
  Document Type: Presentation
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-0763
• Aging Characteristics of RAP-Modified Binders: Rheological Properties
  Authors: Huang, Shin-Che
  Authors: Huang, Shin-Che
  Year: 2013
  Document Type: Presentation
  Subject: Materials; Pavements
  Session: 307
  Paper Number: 13-4226