2013 Session: 377

• Determining Impact of Degree of Blending Between Virgin and Reclaimed Asphalt Binder on Predicted Pavement Performance Using Mechanistic-Empirical Pavement Design Guide
  Abstract: Past studies have indicated binder from reclaimed asphalt pavement (RAP) aggregates do not fully blend within the hot mix asphalt (HMA), resulting in a partial degree of blending (DOB). The degree of blending is defined as the percentage of RAP binder that is effectively mobilized within the mix. This study will focus on determining the impact of DOB on predicted pavement performance using MEPDG level I analysis of 25% RAP mixes with three RAP sources. Dynamic complex modulus tests were conducted on each RAP source with two conditions: full blending and a calculated “Actual” DOB. Most state agencies assume full blending, which is an assumption that may lead to under asphalting or a relatively stiffer mix. However, it is unclear how this will affect the predicted pavement performance. For the full blending samples, it was assumed that all of the RAP binder was mobilized in the mix, and the virgin binder was offset accordingly. The “Actual” DOB samples were mixed after a DOB was determined. MEPDG level I analysis was conducted using typical structures, climate, and traffic conditions for the state of New Jersey. Also rutting and fatigue cracking performance between the two DOBs were compared for each of the RAP sources. The results indicate DOB has a negligible effect on fatigue and rutting performance for the three RAP sources tested, all of which had high actual DOB’s, greater than 85%. Therefore, for RAP with such high DOB values, full blending assumption would be cost effective and would not compromise the pavement performance. However, RAP variability will need to be controlled to ensure quality performance.
  Authors: Coffey, Sean; DuBois, Eric; Mehta, Yusuf A.; Purdy, Caitlin
  Authors: Coffey, Sean; DuBois, Eric; Mehta, Yusuf A.; Purdy, Caitlin
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-0571
• Effect of Asphalt Oxidation on Performance of LTPP SPS-9A Sections in Connecticut
  Abstract: Six asphalt pavement test sections were constructed in 1997 on Route 2 in Connecticut to conduct the Special Pavement Study (SPS-9A) experiment under the Long Term Pavement Performance (LTPP) program. The SPS-9A experiment lasted 12 years and targeted comparison of long-term performance of SuperPave and Marshall mixes modified with recycled asphalt pavement (RAP). This paper analyses differences in post-termination distresses and structural capacity in the LTPP SPS-9A sections as related to their asphalt oxidation level after 12 years of service. The distress data was retrieved from videologs collected by an Automated Road Analyzer, while structural capacity was evaluated by elastic moduli backcalculated from deflections measured by a Falling Weight Deflectometer. The oxidation levels were measured by a portable infrared spectrometer on the pre-stored original binders and those extracted from the cores. In addition, direct infrared measurements on asphalt mixtures from the top of the cores were conducted. On average, all RAP-modified mixes yielded lower elastic moduli than non-modified ones. In addition, RAP-modified SuperPave mixes shown higher severity of surface cracking and very high level of weathering. The difference in the effect of RAP on structural integrity and distress performance of Superpave and Marshal mixes was attributed to aging susceptibility of their binder components.
  Authors: Yut, Iliya; Zofka, Adam
  Authors: Yut, Iliya; Zofka, Adam
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-2032
• Investigation into Top-Down Cracking of Asphalt Pavements in North Carolina
  Abstract: Top-down cracking has become a commonly reported cracking mechanism in asphalt pavements worldwide. In top-down cracking a crack initiates at the surface of an asphalt concrete pavement and propagates to the bottom of the asphalt pavement layer. Because the location and governing state of stress for top-down cracking are different than for bottom-up cracking, pavement cracking performance analysis needs to be robust enough to account for the complex mechanisms that are involved in top-down cracking. This study applies the viscoelastic continuum damage finite element model to the evaluation of two pavement sections in North Carolina where top-down cracking has been identified. Small specimen geometries are used to perform simplified viscoelastic continuum damage (S-VECD) testing on individual asphalt layers obtained from field cores. The S-VECD model and the Fourier finite element program are used together (as the VECD-FFE model) for pavement cracking performance simulations and employ the structure and layer material properties obtained from the two study pavements. The simulation results clearly support the propensity of these pavements to exhibit top-down cracking. In addition to this laboratory testing and analysis, the deflection-based method suggested by Uhlmeyer et al. is applied to the data obtained from pavement sections with known crack initiation locations in order to investigate the method¡¯s validity. The Uhlmeyer method uses the AREA parameter that is determined from falling weight deflectometer deflections, and pavement thicknesses. The analysis results show a clear difference in the AREA versus pavement thickness relationship between the pavement sections with top-down cracking and those with full-depth cracking.
  Authors: Park, Hong Joon; Kim, Y. Richard
  Authors: Park, Hong Joon; Kim, Y. Richard
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-4141
• Effects of High-Modulus Asphalt Binders on Performance of Typical Asphalt Pavement Structures
  Abstract: High modulus asphalt binders (HMABs) have been widely studied in the last 10 years. One of the most significant advantages of HMABs is their rutting resistance. In this study other factors related to the performance of HMABs in pavement engineering were studied: stiffness, elastic recovery, asphalt layer thickness reduction, workability and thermal cracking resistance. One neat binder, one hard-grade paving asphalt binder, three high modulus modifiers, and linear styrene-butadiene-styrene were included. Rotational viscosity, frequency sweep, elastic recovery and bending beam rheometer tests were performed. MEPDG software (Mechanistic-Empirical Pavement Design Guide) was selected to analyze whether HMABs could reduce the thickness of wearing or binder course. Workability was evaluated by measuring the effect of mixing temperatures of HMABs using a newly proposed method for evaluating coating using coarse aggregate water absorption. Results showed that HMABs had higher stiffness and elasticity than neat binder (Performance Grade 64-22). Based on MEPDG analysis for the same total pavement permanent deformation, it was estimated that the asphalt layer thickness was reduced by 8.9 to 27.9% by replacing the neat binder with HMABs in the study. Pavements constructed with HMABs had slightly less bottom up cracking than pavements constructed with neat binders. The coarse aggregate absorption method provided evidence that acceptable coating could be achieved at reasonable mixing temperatures for HMABs. A drawback of HMABs was the slight decrease in the low temperature performance grade. The application of HMABs where the low design temperature of the pavement is lower than -16 ¡ãC should be with caution.
  Authors: Geng, Han; Clopotel, Cristian; Bahia, Hussain U.
  Authors: Geng, Han; Clopotel, Cristian; Bahia, Hussain U.
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-4423
• Determining Impact of Degree of Blending Between Virgin and Reclaimed Asphalt Binder on Predicted Pavement Performance Using Mechanistic-Empirical Pavement Design Guide
  Authors: Mehta, Yusuf
  Authors: Mehta, Yusuf
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-0571
• Effect of Asphalt Oxidation on Performance of LTPP SPS-9A Sections in Connecticut
  Authors: Yut, Iliya
  Authors: Yut, Iliya
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-2032
• Effects of High-Modulus Asphalt Binders on Performance of Typical Asphalt Pavement Structures
  Authors: Geng, Han
  Authors: Geng, Han
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-4423
• Investigation into Top-Down Cracking of Asphalt Pavements in North Carolina
  Authors: Park, Hong
  Authors: Park, Hong
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 377
  Paper Number: 13-4141