2013 Session: 656

• Reacted and Activated Rubber: Elastomeric Asphalt Extender
  Abstract: Asphalt rubber mixtures have traditionally been difficult to produce requiring specialized plant and equipment resulting in higher costs of manufacture. This in part is due to the need to produce asphalt rubber binder by blending at high temperatures for a significant time period (around 190C for typically 45 minutes to 1 hour). The complexities in the process have resulted in asphalt rubber mixes being significantly more expensive to produce than conventional paving mixtures. A new technology which produces a “Reacted and Activated Rubber” (RAR), which is an elastomeric asphalt extender, has been developed by hot blending and activation of a rubber granulate with a selected asphalt binder and activated mineral binder stabilizer (AMBS). RAR achieves similar results comparable to other types of polymer modified binders (PMB). However, a principle advantage with RAR is that it can be easily added to any HMA manufacturing facility using systems designed to feed particulate material into a batch plant (pug-mill) or drum mix plant. This paper describes how RAR is produced from raw constituent materials. Various tests on binder contrast the performance to typical paving grades and PMBs that are used in the USA. The implementation of RAR in various types of asphalt mixtures will be discussed and demonstrative examples of test results are provided. Tests on mixtures in wheel tracking and fatigue demonstrate how the binder performance tests translate into mixture performance. In all cases evaluated, the RAR mixtures out-perform non-modified and even conventional rubber modified equivalent materials.
  Authors: Sousa, Jorge B.; Rowe, Geoffrey M.; Vorobiev, Andrey; Ishai, Ilan
  Authors: Sousa, Jorge B.; Rowe, Geoffrey M.; Vorobiev, Andrey; Ishai, Ilan
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-2941
• Evaluating Effects of Ground Tire Rubber-Modified Asphalt and Dry Added Treated GTR on Performance Characteristics of RAP Mixtures
  Abstract: One approach to reduce the cost of asphalt mixtures and to produce environmentally friendly mixtures is to use more readily available recycled materials like Reclaimed Asphalt Pavements (RAP) and Ground Tire Rubber (GTR).In this study, GTR and Treated GTR were added to binder and to high RAP content mixtures. Rutting performance of the binders was evaluated by conducting the Multiple Stress Creep Recovery test, fatigue performance was evaluated by the Linear Amplitude Sweep test, and the degree of separation was measured by conducting the Cigar Tube Test . Also, the effect of a suspension agent on the degree of separation was determined. GTR and Treated GTR significantly improved the rutting and fatigue performance of the asphalt binders. The suspension agent successfully decreased the degree of separation between rubber particles and binder.GTR was introduced into the binder and the resulting rubberized binder was used to design a 9.5 mm Superpave mixture. The Treated GTR was directly added to the mixture. Treated GTR mixtures were mixed and compacted at lower temperatures compared to GTR mixtures. The dynamic modulus was determined using the Asphalt Mixture Performance Tester, reflective cracking performance was evaluated using the Texas Overlay Tester, low temperature cracking resistance was evaluated by the Thermal Stress Restrained Specimen Test, and rutting and moisture susceptibility was evaluated using the Hamburg Wheel Tracking Device.GTR and Treated GTR made the mixtures slightly more prone to reflective cracking, but improved their resistance to rutting, moisture susceptibility, and low temperature cracking.
  Authors: Vahidi, Siavash; Mogawer, Walaa S.; Booshehrian, Abbas
  Authors: Vahidi, Siavash; Mogawer, Walaa S.; Booshehrian, Abbas
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4248
• Effects of Changing Virgin Binder Grade and Content on RAP Mixture Properties
  Abstract: Most highway agencies have decades of experience with HMA containing low to moderate percentages of reclaimed asphalt pavement (RAP) because the general perception that RAP mixtures may be more susceptible to various modes of cracking. As the RAP proportion increases there is the potential for an increase in mixture stiffness and decrease in resistance to cracking. Two options for increasing the durability of RAP mixtures proposed have been increasing the amount of virgin binder in the asphalt mixture or decrease the performance grade of the virgin binder. To assess these options, 0, 25 and 50 percent RAP mixtures at optimum asphalt content were designed using a standard PG 67-22 virgin asphalt binder. These mixtures were tested to evaluate the surface cracking, reflection cracking, and rutting using the energy ratio (ER), overlay tester (OT), and asphalt pavement analyzer (APA), respectively. These tests were also conducted on the RAP mixtures with 0.25% and 0.50% higher asphalt contents and at the optimum asphalt content using a softer virgin binder. Additionally, the linear amplitude sweep (LAS) methodology was used to assess the fatigue properties of the blended binders. The results show to improve cracking resistance increase the amount of virgin asphalt by 0.1 percent for every 10 percent of RAP binder in the mixture for up to 30 percent RAP binder. When the RAP binder exceeds 30 percent, a softer grade of asphalt should be used to increase the mixture’s resistance to cracking. All mixtures should be assessed for rutting susceptibility.
  Authors: Willis, James Richard; Turner, Pamela; Padula, Flávio Renato de Góes; Tran, Nam; Julian, Grant
  Authors: Willis, James Richard; Turner, Pamela; Padula, Flávio Renato de Góes; Tran, Nam; Julian, Grant
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4256
• Low-Temperature Performance Characterization of Biomodified Asphalt Mixtures Containing Reclaimed Asphalt Pavement
  Abstract: The sustainability movement in paving materials has led to the increased use of reclaimed asphalt pavement (RAP) in recent years. New developments in the area of pavement sustainability include the use of bio-modified asphalt binders (BMB) such as those containing bio-oils derived from swine manure. The current study examines the low temperature properties of RAP and virgin BMB mixtures to determine if these mixtures exhibit improved low temperature performance as compared to conventional hot mix asphalt (HMA).Disk-Shaped Compact Tension (DC(T)), Superpave Indirect Tension, and Acoustic Emission tests were employed to characterize low temperature properties of the asphalt mixtures. BMB mixtures exhibited higher DC(T) fracture energies as compared to HMA at all RAP levels. In addition, BMB mixture fracture energy displayed a reduced dependence on RAP content, as the difference in average fracture energy between BMB and HMA mixtures increased with higher RAP contents. Furthermore, BMB mixtures displayed consistently higher creep compliance which indicates that these mixtures can alleviate thermal stresses more easily than HMA.A recently developed acoustic emission testing procedure clearly indicated the effects of BMB as well as RAP in the mixture. The overall trends identified through AE testing were consistent with the findings from the DC(T) and ID(T) tests. In addition, AE results suggested a fundamental change in the behavior of the BMB RAP mixture relative to the HMA RAP mixture, e.g., a rejuvenating effect. In general, it was observed that BMB RAP mixtures exhibited superior low temperature cracking behavior as compared to HMA mixtures.
  Authors: Hill, Brian; Oldham, Daniel Joshua; Behnia, Behzad; Fini, Elham H.; Buttlar, William G.; Reis, Henrique
  Authors: Hill, Brian; Oldham, Daniel Joshua; Behnia, Behzad; Fini, Elham H.; Buttlar, William G.; Reis, Henrique
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-3773
• Enhancing Performance of Crumb Rubber-Modified Asphalts Through Controlling Internal Network Structure
  Abstract: In the current research, the effect of controlling the internal network structure of Crumb Rubber Modified Asphalts (CRMA) on property development was investigated. The investigation included evaluation by rheological and interrupted shear tests. Rheological testing involved monitoring the changes of the produced complex modulus (G*) and phase angle (ä) for the CRMA. In the interrupted shear tests, the shear stress profile for the produced CRMA was investigated. It was found that triggering critical conditions of combined interaction speed, temperature and time is essential to induce the formation of 3D network structure within the CRMA. Such triggering conditions play an important role in swelling, dissolution and release of Crumb Rubber Modifier (CRM) components into the asphalt liquid phase. Gel Permeation Chromatography (GPC) was utilized to characterize the nature of modifications that lead to the occurrence of 3D network structure within the produced CRMA. Formation of 3D network structure for the CRMA plays a major role in the enhancement of its rheological properties in terms of its stiffness and elasticity. Superior improvements in the stiffness and elasticity indicate improved rutting resistance as well as alleviated permanent deformation problems.
  Authors: Ragab, Mohyeldin Safwat; Abdelrahman, Magdy; Ghavibazoo, Amir
  Authors: Ragab, Mohyeldin Safwat; Abdelrahman, Magdy; Ghavibazoo, Amir
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4363
• Modeling the Resilient Modulus for RAP Applications in Base Course Layers
  Abstract: The resilient modulus (MR) is an important parameter for base course layer. Utilizing RAP for 2 this layer must take into consideration the effect of various factors that may occur in the field on 3 the resilient modulus. Previous numerical models used for granular base layer could be utilized 4 for the RAP. Therefore, this research studies the suitability of using RAP procedures under the 5 effect of different factors such as water content, dry density, freezing-thawing cycles. Various 6 percentages of RAP (50%, 75% and 100% by weight) are employed in this research. All the 7 models included in the study take directly the effect of state of stresses but they consider the 8 other mentioned factors and their interactions on the resilient modulus indirectly. Results of this 9 study will determine the adequacy of the employed models in using RAP procedure in the base 10 course layer and which model best fits for RAP behavior under the effect of tested factors. Based 11 on the literature review, nine prediction models were chosen in this study to deal with the 12 granular base course layers so as to predict MR for RAP. A pilot analysis was made on these 13 models to compare between the measured and predicted values on MR under the tested factors. 14 Three models showed a good prediction for MR. These three models were assessed again in a 15 sensitivity analysis on regression parameters to choose the best-fit model for the RAP 16 applications.
  Authors: Noureldin, Ehab Magdy; Abdelrahman, Magdy
  Authors: Noureldin, Ehab Magdy; Abdelrahman, Magdy
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4627
• Evaluation of Dynamic Modulus Predictive Models for Asphalt Mixtures Containing Recycled Asphalt Shingles
  Abstract: Transportation agencies are increasingly using recycled asphalt shingles (RAS) in asphalt pavements for economic and environmental benefits. The primary components of RAS are asphalt, mineral filler, aggregate granules, and either organic or fiberglass fibers. The effect of these components on the dynamic modulus of an asphalt mixture, which is a key input in the Mechanistic-Empirical Pavement Design Guide (MEPDG) and a critical property of asphalt mixtures related to its performance, are still uncertain. As part of National Pooled Fund Study TPF-5(213), a series of experimental plans was conducted utilizing demonstration based paving projects to investigate various factors related to RAS utilization. Thirteen mix designs with RAS contents ranging from zero to six percent were developed and constructed in Indiana, Iowa, Minnesota, and Missouri. Field produced mixtures were procured and sent to Iowa State University¡¯s Asphalt Lab for laboratory dynamic modulus testing. The test results are used in this study to evaluate two commonly used dynamic modulus predictive models, the Witczak and Hirsch models. Two versions of the Witczak models, which were developed in 1999 and 2006, are evaluated in this research. It was found that the Witczak models were not very effective in estimating the modulus values of RAS mixtures. This study concludes that commonly used dosages of RAS in asphalt mixtures affects the prediction accuracies of the Witczak and Hirsch models due to biases of the E* predictive models in terms of input parameters, inaccuracies of input parameter measurements, effects of blend efficiency, and influences of the RAS fibers.
  Authors: Yu, Jianhua; Williams, Ronald Christopher; Cascione, Andrew
  Authors: Yu, Jianhua; Williams, Ronald Christopher; Cascione, Andrew
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4489
• Analysis of RAP with Known Source History and Influence on Fatigue Performance
  Abstract: This study characterized RAP materials milled from the upper layer of three accelerated pavement test lanes that were exposed to climatic conditions over a number of years where the original binder and aggregate properties are known from the time of construction. The aggregates and binder in the RAP were extracted using the both solvents and ignition oven and compared to the construction data to quantify the changes in measured properties. Three mixes containing 0%, 20% and 40% RAP taken from one lane were then designed using virgin asphalt and aggregate materials from the same original source. The three mixes were tested for the dynamic modulus and cyclic direct tension fatigue to investigate the effect of RAP content on the mixture performance with a higher degree of control over the volumetric characteristics of the mix designs.Both solvent and ignition oven extraction resulted in a decrease in the aggregate specific gravity and increase in the absorption compared to original values known during construction. Binder content and gradation from solvent and ignition oven extraction were similar for the two unmodified asphalt RAP sources, but the RAP SBS modified asphalt exhibited closer values to the other two RAP materials using the ignition oven and did not with solvent. Mixes with 20% and 40% RAP could be satisfactorily designed to match the 0% RAP volumetrics. The dynamic modulus fatigue tests showed increasing stiffness, decreasing phase angle and decreasing fatigue resistance with increasing RAP.
  Authors: Li, Xinjun; Gibson, Nelson Harold
  Authors: Li, Xinjun; Gibson, Nelson Harold
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4901
• Long-Term Performance of High-RAP Pavements: Case Studies
  Abstract: This paper presents the summary of findings of several case studies on the long term performance of high recycled asphalt pavement (RAP) sections. The goal of this study was to provide the paving community with documentation on the long term performance of high RAP roadway sections compared to that of virgin sections using available information. Roadway sections which contained more than 20% RAP and that had been in place for at least 10 years were identified from across the United States with the help of the local agencies. The long term performances of these various recycled sections were compared directly to mixtures made with similar virgin materials via measurements of distress criteria. These distress criteria included rutting, cracking, ride quality, and any overall performance rating that the local agencies used in evaluating their pavement sections. The virgin sections were placed in the same general location and time frame as the recycled sections. The high RAP sections on average tend to exhibit a lower ride quality, more cracking, and better rutting resistance than the virgin sections but the differences are not always statistically significant. The differences between the performance ratings for RAP and virgin pavements were within 5-10 percent. Overall, pavement sections utilizing high RAP perform at a level comparable to that of virgin sections in these case studies.
  Authors: Anderson, Evan; Daniel, Jo Sias
  Authors: Anderson, Evan; Daniel, Jo Sias
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-1264
  Practice-Ready: Yes
• Performance Characterization of High Binder Replacement with Recycled Asphalt Shingles for Low N-design Mixture
  Abstract: ABSTRACTRecycled materials can be used effectively in asphalt mixtures to replace virgin asphalt binder or virgin aggregates. Virgin material (asphalt binder or aggregate) can be replaced utilizing reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in asphalt mixtures. In this paper, the effect of high asphalt binder replacement for a low N-design asphalt mixture including RAP and RAS on performance indicators such as permanent deformation, fracture, and fatigue potentials, and stiffness, was studied. A developed experimental program included complex modulus, fracture, overlay reflective cracking resistance, wheel track permanent deformations, and push-pull fatigue tests. The asphalt binder replacement, combinations of RAS and RAP asphalt binder, levels in the mix were in a range of 43 to 64%. Permanent deformation resistance of the mixtures was improved in the presence of RAS. Fracture tests at low temperature did not reveal any significant difference between the specimens prepared at varying percentages of asphalt binder replacement. Fatigue potential of mixtures increased with increasing RAS content and asphalt binder replacement. The specimens prepared with 2.5% RAS and PG 46-34 showed the best fatigue performance. The impact of asphalt binder bumping was highlighted by the results of all tests. The improvement in fatigue life and fracture energy was noticeable when the asphalt binder type was changed from PG 58-28 to PG 46-34 at the highest asphalt binder replacement level. The results showed that complex modulus test results can provide crucial information about the mix viscoelastic properties such as relaxation potential and long-term stiffness that can be used, along with fracture tests, to evaluate mix brittleness at relatively high asphalt binder replacement levels.
  Authors: Ozer, Hasan; Al-Qadi, Imad L.; Kanaan, Ahmad; Lippert, David Leslie
  Authors: Ozer, Hasan; Al-Qadi, Imad L.; Kanaan, Ahmad; Lippert, David Leslie
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4500
  Practice-Ready: Yes
• Forensic Study on Cracking Distress of New Jersey’s LTPP SPS-5 Sections: 30% RAP Versus Virgin Hot-Mix Asphalt
  Abstract: In 2010, New Jersey’s Long Term Pavement Performance (LTPP) SPS-5 sections closed out. Prior to the rehabilitation of these pavement sections, an extensive coring and forensic study was conducted to characterize the material properties of the Virgin and 30% RAP asphalt mixtures utilized on the project. Along with field cores, raw materials (i.e. – aggregates, binder, loose mix) was procured from FHWA-LTPP Materials Reference Library. Visual distress surveys from the LTPP database were collected and utilized to compare the mixture performance to the general field performance. Overall, the field performance indicated that both the virgin and 30% RAP sections initiated cracking within 1 to 3 years of each other, depending on the section evaluated. However, once cracking had been initiated, the 30% RAP sections cracked at a faster rate than the Virgin sections resulting in higher crack counts, even though the 30% RAP section was using a softer binder than the virgin section (i.e. – AC-10 vs AC-20). The Overlay Tester, Disk Shaped Compact Tension (DC(T)), and Low Temperature IDT and Creep Compliance were used to characterize intermediate and low temperature cracking properties of the mixtures. Asphalt binder characterization included PG grading, master stiffness curves, and Linear Amplitude Sweep (LAS) testing to characterize the stiffness and fatigue properties of the asphalt binders. The material testing program showed that the mixture test results matched the observed field cracking performance better than the asphalt binder testing conducted on the extracted and recovered asphalt binders. The Overlay Tester and DC(T) tests appeared to be the most sensitive to the cracking performance differences between the Virgin and 30% RAP mixtures, while the LAS test appeared to rank the fatigue performance of the 30% RAP mixture better than the Virgin mixture, which contradicted the observed field performance.
  Authors: Bennert, Thomas A.; Maher, Ali
  Authors: Bennert, Thomas A.; Maher, Ali
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 656
  Paper Number: 13-4289
  Practice-Ready: Yes
• Low-Temperature Performance Characterization of Biomodified Asphalt Mixtures Containing Reclaimed Asphalt Pavement
  Authors: Hill, Brian
  Authors: Hill, Brian
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-3773
• Low-Temperature Performance Characterization of Biomodified Asphalt Mixtures Containing Reclaimed Asphalt Pavement
  Authors: Oldham, Daniel
  Authors: Oldham, Daniel
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-3773
• Forensic Study on Cracking Distress of New Jersey's LTPP SPS-5 Sections: 30% RAP Versus Virgin Hot-Mix Asphalt
  Authors: Bennert, Thomas
  Authors: Bennert, Thomas
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-4289
• Enhancing Performance of Crumb Rubber-Modified Asphalts Through Controlling Internal Network Structure
  Authors: Abdelrahman, Magdy
  Authors: Abdelrahman, Magdy
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-4363
• Evaluation of Dynamic Modulus Predictive Models for Asphalt Mixtures Containing Recycled Asphalt Shingles
  Authors: Yu, Jianhua
  Authors: Yu, Jianhua
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-4489
• Modeling the Resilient Modulus for RAP Applications in Base Course Layers
  Authors: Abdelrahman, Magdy
  Authors: Abdelrahman, Magdy
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-4627
• Analysis of RAP with Known Source History and Influence on Fatigue Performance
  Authors: Gibson, Nelson
  Authors: Gibson, Nelson
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 656
  Paper Number: 13-4901