Advanced Asphalt Technologies

State College, PA, United States

Advanced Asphalt Technologies

State College, PA, United States
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Christensen D.W.,Advanced Asphalt Technologies | Anderson D.A.,Pennsylvania State University | Rowe G.M.,Abatech Inc.
Asphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions | Year: 2016

The development of the well-known Christensen-Anderson (CA) rheological model grew out of attempts to model the relaxation spectra of asphalt binders using a skewed logistic distribution function. For this reason, there are very strong relationships between the CA model parameters and the characteristics of relaxation spectra for asphalt binders. This paper presents a recently developed equation that allows direct and accurate calculation of the relaxation spectra from CA model parameters, demonstrating the nature of this relationship. Of the CA model/spectrum parameters, the most important in terms of describing overall behavior and potential performance is the R-value, which describes the shape and skewness of the spectrum. This parameter and other similar rheological parameters have been linked to various important aspects of asphalt binder behavior, including fatigue resistance, chemical composition and degree of oxidative aging. This makes the parameter R a potentially useful parameter for inclusion in asphalt binder specifications; although care must be taken in how it is determined to ensure that it is accurate, repeatable and reflects the performance characteristics of interest. © 2016 Taylor & Francis.


Trewella J.C.,PetroTech Consultants LLC | Bonaquist R.,Advanced Asphalt Technologies | Sanchez V.,Kior
Asphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions | Year: 2012

The production of renewable liquid transportation fuels is growing rapidly, particularly in the United States and Europe. This paper examines the potential for using co-products from this rapidly growing manufacturing base as blending components in asphalt. Several blends of biofuel co-products in a paving grade asphalt binder were prepared and performance grading properties were measured. Asphalt concrete mixtures using the various blends and a somewhat moisture sensitive aggregate were tested in accordance with AASHTO T283 to evaluate resistance to moisture damage. Initial laboratory findings indicate that some of these materials may be useful as binder extenders, having minimal impact on the performance grade while imparting added benefits.


Mogawer W.,University of Massachusetts Dartmouth | Bennert T.,Rutgers University | Daniel J.S.,University of New Hampshire | Bonaquist R.,Advanced Asphalt Technologies | And 2 more authors.
Asphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions | Year: 2012

The main focus of this study was to obtain plant-produced Reclaimed Asphalt Pavement (RAP) mixtures, to document the mixtures production parameters and to evaluate the degree of blending between the virgin and RAP binders. The effect of mixture production parameters on the performance (in terms of stiffness, cracking, rutting and moisture susceptibility) and workability of the mixtures was evaluated. Eighteen plant-produced mixtures were obtained from three locations in the Northeast United State. RAP contents (0 to 40&) were varied and softer binders were used. The data and analysis illustrated that the degree of blending between RAP and virgin binders is a function of production parameters. The stiffness of the mixtures increased as the percent of RAP increased, but not when the discharge temperatures of the mixtures were inconsistent. The cracking resistance was reduced as the percent of RAP increased. The rutting and moisture damage resistance improved as the percent of RAP in the mixtures increased. Finally, reheating the mixtures in the laboratory caused a significant increase in the stiffness of the mixtures.


Mogawer W.,University of Massachusetts Dartmouth | Bennert T.,Rutgers University | Daniel J.S.,University of New Hampshire | Bonaquist R.,Advanced Asphalt Technologies | And 2 more authors.
Road Materials and Pavement Design | Year: 2012

The main focus of this study was to obtain plant produced Reclaimed Asphalt Pavement (RAP) mixtures, to document the mixture production parameters and to evaluate the degree of blending between the virgin and RAP binders. The effect of mixture production parameters on the performance (in terms of stiffness, cracking, rutting, and moisture susceptibility) and workability of the mixtures was evaluated. Eighteen plant produced mixtures were obtained fromthree locations in the Northeast United States. RAPcontents (zero to 40%) were varied and softer binders were used. The data and analysis illustrated that the degree of blending between RAP and virgin binders is a function of production parameters. The stiffness of the mixtures increased as the percentage of RAP increased, but not when the discharge temperatures of the mixtures were inconsistent. The cracking resistance was reduced as the percentage of RAP increased. The rutting and moisture damage resistance improved as the percentage of RAP in the mixtures increased. Finally, reheating the mixtures in the laboratory caused a significant increase in the stiffness of the mixtures. © 2012 Taylor & Francis.


Mogawer W.S.,University of Massachusetts Dartmouth | Austerman A.J.,University of Massachusetts Dartmouth | Bonaquist R.,Advanced Asphalt Technologies
Transportation Research Record | Year: 2012

The purpose of this research study was to evaluate the effects of plant type and roduction parameters on the stiffness, performance, and degree of blending between the aged and virgin binders of plant-produced reclaimed asphalt pavement (RAP) mixtures. Mixtures from a batch and a drum plant and the corresponding production information were obtained. The stiffness of each mixture was evaluated by measuring the dynamic modulus. Moisture susceptibility and rutting potential were evaluated with the Hamburg wheel tracking device. Low-temperature cracking characteristics were evaluated with the asphalt concrete cracking device. Finally, the workability of the mixtures was evaluated with an asphalt workability device. Binder was extracted from each mixture to measure the degree of blending between the aged and virgin binder. The degree of blending between the aged RAP and virgin binder in each mixture was evaluated with an analysis approach that used the ratio of the mixture dynamic modulus to the recovered binder shear modulus. Batch and drum plants produced RAP mixtures that performed similarly to the control mixtures and exhibited good blending. None of the RAP mixture tested showed increased susceptibility to moisture damage, rutting, and low-temperature cracking susceptibility as the RAP content was increased. Workability testing identified a potential construction issue as the mixture workability decreased as the amount of RAP in the mixture increased. Finally, the performance data indicated the importance of the proper virgin binder grade selection for mixtures with higher amounts of RAP.


Christensen Jr. D.W.,Advanced Asphalt Technologies | Bonaquist R.,Advanced Asphalt Technologies
Road Materials and Pavement Design | Year: 2012

This paper presents a unique approach to analyzing surface cracking in HMA pavements, based upon the concept of reduced cycles. In the first half of the paper, empirical equations are presented for predicting damage curves for any HMA mixture under a wide range of loading conditions. These equations have been developed using a large database of fatigue test results, and confirmed with data from several independently gathered data sets. The equations use as predictors modulus and other parameters calculated from the change in modulus with time and/or temperature. The second half of the paper applies these equations to fatigue experiments carried out at the Federal Highway Administrations Automated Loading Facility (ALF) in MacLean, VA. This analysis involved estimating the reduced cycles at critical points in the surface of the test sections at the initial appearance of surface cracking. Statistical methods were then used to develop equations for predicting the onset of cracking. Although the approach is promising, some additional work is needed before the method should be applied to general problems in pavement design and analysis. © 2012 Taylor & Francis.


Mogawer W.S.,University of Massachusetts Dartmouth | Austerman A.J.,University of Massachusetts Dartmouth | Bonaquist R.,Advanced Asphalt Technologies | Roussel M.,University of Massachusetts Dartmouth
Transportation Research Record | Year: 2011

This study designed and evaluated the performance of thin-lift mixtures that incorporated a high reclaimed asphalt pavement (RAP) content, recycled asphalt shingles (RAS), and a warm-mix asphalt (WMA) technology, both individually and collectively. A Superpave® 9.5-mm mixture was designed with new materials and designated as the control mixture. The same control mixture was developed with 40% RAP, with 5% RAS, and with 35% RAP and 5% RAS. Each of the mixture designs was then repeated at a lower mixing and compaction temperature according to a wax-based WMA technology. The effect of the RAP, RAS, or both on the stiffness of each mixture was measured by using the dynamic modulus. The performance of each mixture was determined by measuring (a) its reflective cracking resistance with an overlay tester, (b) its lowtemperature cracking resistance with an asphalt concrete cracking device, and (c) its moisture susceptibility with a Hamburg wheel tracking device. In addition, binder was extracted from each mixture and the performance grade determined. The mixtures that incorporated high RAP content, RAS, or both exhibited higher stiffness, which was confirmed with the extracted binder grading results. The use of RAP, RAS, or both reduced the reflective cracking resistance but did not have a negative impact on the low-temperature cracking resistance of the mixtures. Moisture susceptibility test results indicated that the addition of RAP, RAS, or both improved the mixtures' resistance to moisture failure. The addition of WMA technology to the mixtures provided similar or improved performance in most of the mixture tests.


Haggag M.M.,University of Massachusetts Dartmouth | Mogawer W.S.,University of Massachusetts Dartmouth | Bonaquist R.,Advanced Asphalt Technologies
Transportation Research Record | Year: 2011

Warm-mix asphalt (WMA) is the generic term used to refer to a group of technologies that are used to produce asphalt pavement mixtures at temperatures lower than those of traditional hot-mix asphalt (HMA). One of the potential benefits of WMA is that it provides better fatigue cracking characteristics than does HMA. The lower temperatures should reduce the aging of asphalt binders that occur during production. The reduced aging of asphalt binders should lead to improved fatigue characteristics of asphalt mixtures. The research reported here addressed two main objectives. The first was to study the impacts of three WMA technologies on the fatigue cracking resistance of HMA by using one asphalt binder and two aggregate sources. The fatigue characteristics were measured by using a uniaxial, cyclic, direct tension compression test. The second objective was to analyze the data produced by the test by using the simplified viscoelastic continuum damage approach proposed in the NCHRP 9-43 Phase I report. Three WMA technologies were used: Advera, Evotherm 3G, and Sasobit. All mixtures were produced by using a PG 64-22 virgin binder. Data showed no significant difference between HMA mixtures and WMA mixtures for each mix except for the Advera.


Booshehrian A.,University of Massachusetts Dartmouth | Mogawer W.S.,University of Massachusetts Dartmouth | Bonaquist R.,Advanced Asphalt Technologies
Journal of Materials in Civil Engineering | Year: 2013

The master curve of an asphalt binder provides a relationship between the binder stiffness and reduced frequency over a range of temperatures and frequencies. Accordingly, the master curve makes it possible to predict viscoelastic properties over a wide frequency range and also to predict viscoelastic properties at any temperature. To construct a master curve, the stiffness of an asphalt binder at multiple temperatures and frequencies is measured. The data are then fitted into a viscoelastic model applied to asphalt binders. Recently, a methodology has been developed that utilizes the measured dynamic modulus of a hot-mix asphalt (HMA) mixture and the master curves for the as-recovered binders to determine the degree of blending between aged and virgin binders in asphalt mixtures that incorporates recycled materials. This study presents the methodology for constructing asphalt binder master curves in a step-by-step format. The study also describes in a step-by-step format the methodology for evaluating the degree of blending between aged and virgin binder. Furthermore, to clarify the method and elaborate on the analysis of experimental results, plant-produced mixtures containing different percentages of recycled asphalt pavement (RAP) were obtained and tested. The test results were used to develop the master curves and examine the degree of blending by the aid of the methodology explained in the paper. © 2013 American Society of Civil Engineers.


Christensen D.W.,Advanced Asphalt Technologies | Bonaquist R.,Advanced Asphalt Technologies
Road Materials and Pavement Design | Year: 2015

This paper presents an improved version of the Hirsch model for estimating the modulus of hot-mix asphalt (HMA) from asphalt binder modulus and mixture composition. The original Hirsch model was developed in 2002 and has been shown by several independent researchers to be reasonably accurate. However, the authors believed that the model could be improved by addressing several issues: (1) simplifying the Hirsch equation mathematically; (2) including aggregate specific gravity as a predictor, which indirectly accounts for variations in aggregate modulus; (3) including strain level as a factor; (4) recalibrating the model using a data set gathered using the asphalt mixture performance tester following current standard protocols; and (5) addressing steric hardening during testing. These goals were achieved, although it appears that under normal testing conditions strain sensitivity and steric hardening are not significant factors affecting HMA dynamic modulus. Verification of the model using a limited amount of independently collected data suggests that the improved model eliminates or reduces a tendency of the original model to underestimate HMA dynamic modulus values. © 2015, Taylor & Francis. All rights reserved.

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