Trb superpave Abstracts 2002
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- Bu səhifədəki naviqasiya:
- Rotary Loaded Wheel Testing For Hot Mix Asphalt Quality Control
- Target And Tolerance Study For The Angle Of Gyration Used In The Superpave Gyratory Compactor (Sgc)
- The Effect of Various Aging Techniques on Asphalt Low-Temperature Properties
- Dynamic Modulus of Asphalt Concrete Using a Hollow Cylinder Tensile Tester
- Determination of Moisture in HMA and Relationship with Tender Mix Behavior in the Laboratory
- Effect of Fine Aggregate Angularity (FAA) on Compaction and Shearing Resistance of Asphalt Mixtures
- A Standardized Procedure for Analysis of the Dynamic Modulus (| E *|) Data to Predict Asphalt Pavement Distresses
- Statistics for Superpave HMA Construction QC/QA Data
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TRB Superpave Abstracts 2002 81st Transportation Research Board Annual Meeting Washington D.C. January 13-17, 2002 Table of Contents
Statistics for Superpave HMA Construction QC/QA DataFrazier Parker, Jr. Director, Highway Research Center Auburn University, Auburn, AL 36849 Telephone No.: (334)-844-6284 Fax: (334)-844-6290 e-mail: fparker@eng.auburn.edu M. Shabbir Hossain Assistant Professor, Civil Engineering Department Texas Tech University, Lubbock, TX 79409-1023 Telephone No.: (806)-742-3471 ext. 340 Fax: (806)-742-3488 e-mail: shabbir.hossain@coe.ttu.edu ABSTRACT Asphalt content, air voids and mat density measurements for Superpave mixes were collected during 1997, 1998, 1999 and 2000 to develop statistics for a statistical quality control / quality assurance program for the Alabama Department of Transportation (ALDOT). Data were analyzed to determine if accuracy and variability improved and stabilized as contractors accumulated experience with Superpave mixes, to compare contractor and ALDOT measurements, and to assess the effects of maximum aggregate size and design ESAL range. Analyses indicated accuracy and variability of asphalt content measurements for Superpave mixes remained consistent and comparable to Marshall mixes. Variability of voids for Superpave mixes stabilized but remained higher than variability of voids for Marshall mixes. The accuracy in achieving target voids for Superpave mixes deteriorated and stabilized at values poorer than achieved for Marshall mixes. Variability of mat density measurements for Superpave mixes decreased and stabilized at values comparable to Marshall mixes. The accuracy of mat density measurements for Superpave mixes improved but stabilized at values poorer than achieved for Marshall Mixes. There are significant difference between the measurements of contractor and ALDOT measurements. Asphalt content decreases as design traffic level and maximum aggregate size increase. The level of mat density achieved increases as maximum aggregate size increases. KEY WORDS: Superpave, hot mix asphalt concrete, asphalt content, air voids, mat density,construction, quality control and quality assurance. Return to Table of Contents Coarse Versus Fine-Graded Superpave Mixtures: Comparativeevaluation Of Resistance To Rutting Prithvi S. Kandhal, Associate Director National Center for Asphalt Technology (NCAT) 277 Technology ParkwayAuburn, AL 36830 Phone: 334-844-6228 Fax: 334-844-6248 Email: pkandhal@eng.auburn.edu L. Allen Cooley, Jr., Research Engineer National Center for Asphalt Technology (NCAT) Email: coolela@eng.auburn.edu
Both coarse and fine-graded hot mix asphalt mixtures can be designed within the gradation control points recommended within the Superpave mix design system. However, some states have begun to specify only coarse-graded mixtures (below the restricted zone) and other states are specifying only fine-graded mixtures (above the restricted zone). This study was conducted to compare coarse-graded Superpave mixtures with fine-graded Superpave mixtures in terms of resistance to rutting so as to determine whether restrictions on gradations (either coarse- or finegraded mixtures) are justified. Fourteen mixtures comprising two nominal maximum aggregate sizes: 9.5 and 19.0 mm; two coarse aggregates: granite and crushed gravel; and four fine aggregates: sandstone, limestone, granite, and diabase, were tested. Resistance to rutting of both coarse- and fine-graded mixtures was evaluated using three test methods: Asphalt Pavement Analyzer, Superpave shear tester, and repeated load confined creep test. Statistical analyses of the test data obtained by the three performance tests indicate no significant difference between the rutting resistance of coarse- and fine-graded Superpave mixtures. It has been recommended that mix designs should not be limited to designing mixes on the coarse or fine side of the restricted zone. KEY WORDS: Superpave, asphalt mixtures, HMA, coarse-graded, fine-graded, gradation, rutresistance, permanent deformation, creep test, APA, SST Return to Table of Contents Prediction of the Viscoelastic Response and Crack Growth in Asphalt Mixtures using the Boundary Element Method Bjorn Birgisson, Assistant Professor Email: bbirg@ce.ufl.edu Boonchai Sangpetngam, Graduate Research Assistant Email: bsang@ufl.edu
Email: rroqu@ce.ufl.edu Dept of Civil Engineering, University of Florida 345 Weil Hall, P. O. Box 116580 Gainesville, FL 32611-6580 Tel: (352) 392-9537 ext. 1458 Fax: (352) 392-3394 ABSTRACT It has long been accepted that cracking of hot-mix asphalt (HMA) pavements is a major mode of premature failure. Many state agencies have verified that pavement cracking not only occurred in fatigue cracking in which a crack initiates from the bottom of the asphalt layer but also in other modes such as low temperature cracking, and the more recently identified top-down cracking. In order to improve current pavement designs and the cracking resistance of mixtures it is necessary to understand the mechanisms associated with crack initiation and crack growth in HMA mixtures. However, the complexity of the problem and the lack of simple-to-use analysis tools have been obstacles to a better understanding of hot-mix asphalt fracture mechanics and the development of better hotmix asphalt fracture models. Up until today, the well-known finite element method has been the primary tool used for modeling cracks and their effects in mixtures and pavements. Unfortunately, it is both complex and numerically intensive for fracture mechanics applications. This paper presents the displacement discontinuity boundary element method, which is a numerical method that has been very successful in many other engineering fields, as a potential method for modeling cracking in hot-mix asphalt mixtures and pavements. A series of examples are provided to illustrate the effectiveness of the method in dealing with cracks, crack propagation, and viscoelasticity in hot-mix asphalt. It was concluded that the method was easy-to-use, resulted in accurate solutions, required minimal computation time, and thus significantly simplified the modeling of crack-related problems. Keywords: pavement cracking, modeling, numerical method, displacement discontinuity Return to Table of Contents Rotary Loaded Wheel Testing Forhot-Mix Asphalt Quality Control Chris Edgar (Principal) for REGIS Engineering Solutions, Inc 3017-A Atlanta Highway Montgomery, AL 36109 Phone: (334) 272-0022 Fax: (334) 221-5204 RegisEng@aol.com ABSTRACT Loaded wheel testing (LWT) of hot-mix asphalt (HMA) is commonly utilized for design verification, but the practicality of conventional equipment has not been conducive to quality control (QC) testing during production. Recent advancements in load mechanism design have resulted in the development of a simpler rotary loaded wheel tester (RLWT) that may produce QC results during production comparable to those generated via LWT during design. The National Center for Asphalt Technology (NCAT) prepared dual sets of QC-type samples in the SUPERPAVE gyratory compactor that were subsequently used to compare rutting susceptibility results from four different types of HMA mixes. The Asphalt Pavement Analyzer (APA) was used as the LWT standard for the study. Tested specimens revealed a predictable relationship between measured rut depths in the two devices, which would enable users to interchangeably use the RLWT to generate APA data for either design verification or to monitor as-built quality during production. Having established a correlation between APA and RLWT results, subsequent research sought to simulate testing in the production environment by varying the asphalt content in each mix slightly from design values. Subsequent data revealed that the RLWT detected increased rutting susceptibilities with increased asphalt contents, as would be expected. Thus, the RLWT may have promise in obtaining meaningful QC results at a plant during mix production. Return to Table of Contents Effect of Aggregate Structure on Rutting Potential of Dense-Graded Asphalt Mixtures by Bensa Nukunya, Post-Doctoral Associate, E-mail: bensa123@ufl.edu Reynaldo Roque, Professor, E-mail: rroqu@ce.ufl.edu Mang Tia, Professor, E-mail: mtia@ce.ufl.edu Dept of Civil and Coastal Engineering University of Florida 124 Yon Hall P. O. Box 116580 Gainesville, FL 32611-6580 Tel: (352) 392-9537 Fax: (352) 392-3394
Yusuf A. Mehta, Assistant Professor Department of Civil and Environmental Engineering Rowan University 201 Mullica Hill Road, 329 Rowan Hall Glassboro, NJ 08028 Tel: (856) 256-5327 Fax: (856) 256-5342 E-mail: mehta@rowan.edu
Zero Shear Viscosity of Asphalt Binders Dr. David A. Anderson, Professor Penn State University 201 Transportation Research Building, University Park, PA 16802 Telephone: (814) 863-1912, E-mail: daa@psu.edu Yann M. Le Hir, Formerly Visiting Researcher, Penn State Bitumen Development and Technical Assistance 51, Esplanade du Général de Gaulle 92907 Paris La Défense Cedex, FRANCE Telephone: +33 (0)1-41-35-99-60, E-mail: yann.le-hir@totalfinaelf.com
51, Esplanade du Général de Gaulle 92907 Paris La Défense Cedex, FRANCE E-mail: jean-pascal.planche@totalfinaelf.com Didier Martin, Research Study Leader on Asphalt, Elf Research Center, BP22, 69360 Solaize, FRANCE E-mail: didier.martin@totalfinaelf.com
Recently there has been considerable interest, especially in Europe, in the use of zero shear viscosity as a specification criterion for asphalt binders. This interest is precipitated by the apparent inability of the current Superpave criterion, G*/sinδ, to capture the contribution to rutting resistance afforded by polymer modification. Zero shear viscosity (ZSV) can be determined directly from long-term creep tests but such tests are time consuming and are often very difficult to perform. Several alternative methods for determining the ZSV have been proposed in the literature including extrapolation of the dynamic viscosity to zero frequency, applying the Cross model to dynamic data, and the superposition of multiple short-term, nonsteady state creep tests. In this paper a number of method for determining the ZSV from both creep and dynamic data are evaluated. Laboratory test data for ten different unmodified and modified binders was obtained through a series of creep and dynamic experiments. ZSV values obtained from two of the more promising methods are compared along with a comparison of the ZSV ranking with the Superpave grading temperature. The authors concluded that two of the methods provided very similar values for the ZSV when applied over a considerable range in test temperature and that the results from the two methods can be used interchangeably for the materials that were tested. The binders ranked quite differently when ranking according to their Superpave grading temperature or their ZSV. Keywords: Asphalt binder, Zero Shear Viscosity, Superpave grading, creep testing Return to Table of Contents Impact of Different Types of Modification on Low Temperature Tensile Strength and Tcritical of Asphalt Binders Susanna Man Sze Ho and Ludo Zanzotto University of Calgary 2500 University Drive NW Calgary, Alberta T2N 1N4 CANADA Phone: 403-220-8077 and 403-220-8918 Fax: 402-282-7026 e-mail: smsho@ucalgary.ca and lzanzott@ucalgary.ca Daryl MacLeod Husky Energy P.O. Box 6525, Station D Calgary, Alberta T2P 3G7 CANADA Phone: 403-298-6304 Fax: 403-298-6161 e-mail: Daryl.Macleod@huskyenergy. ABSTRACT Since the introduction of the Superpave asphalt binder specification, the asphalt industry has a useful guideline to choose appropriate materials to meet the requirements of a specific climatic locale. Acid, alkaline and polymer modification are just some of the ways to modify asphalt to meet the Superpave specification. The Direct Tension Test (DTT) technique was applied to study the low-temperature properties of modified asphalt in terms of DTT failure stress values and the critical cracking temperature (Tcritical). The Bending Beam Rheometer (BBR) usually failed to detect the improvement in low-temperature performance in polymer modified asphalt (PMA). The DTT results show that polymer modification with elastomeric type polymer improves the low-temperature performance of PMA. In some PMA, the failure stress value was higher than 9.5 MPa. The DTT technique for PMA is also discussed. The effect of acid or alkaline modifiers on asphalt materials was also studied. It was found that acid or alkaline modification of asphalt is only temporary and can be reversed. Acid modification of asphalt can be reversed by reaction with alkaline materials such as lime or antistripping agents. Alkaline modification of asphalt can be reversed by reaction with acidic materials such as carbon dioxide. Alkaline can also be washed away by water. Even though BBR suggested a slight improvement in the low-temperature performance in acid or alkaline modified asphalt, the DTT failure stress values and Tcritical did not confirm this improvement. A relatively simple procedure allowing detection of acid or alkaline modification of asphalt materials is described. Return to Table of Contents Target And Tolerance Study For The Angle Of Gyration Used In The Superpave Gyratory Compactor (Sgc) Ghazi Al-Khateeb Asphalt Pavement Team Federal Highway Administration Turner-Fairbank Highway Research Center 6300 Georgetown Pike, HRDI-11 McLean, Virginia 22101 Ghazi.Al-Khateeb@fhwa.dot.gov
Asphalt Pavements Group Federal Highway Administration Office of Engineering, HIPT-10 400 Seventh Street Washington, D.C. 20590 Chuck.Paugh@fhwa.dot.gov
Asphalt Pavement Team Federal Highway Administration Kevin.Stuart@fhwa.dot.gov Thomas Harman Asphalt Pavement Team Leader Tom.Harman@fhwa.dot.gov
Senior Research Engineer Federal Highway Administration Office of Engineering, HIPT-10 400 Seventh Street Washington, D.C. 20590 John.D’Angelo@fhwa.dot.gov
ABSTRACT The Superpave gyratory compactor (SGC) is used to compact asphalt specimens for mixture testing in the Superpave system. Five companies currently manufacture SGCs for use in the United States, offering a total of eight different models. Each model employs a unique method of setting, inducing, and maintaining the specified angle of gyration. Calibration systems are required for each device for the angle of gyration. All angle measurements are made externally relative to the mold and none of the calibration systems can be universally used on all of the models. The specified external angle of gyration under load () is 1.25 degrees, with a tolerance of ± 0.02 degrees. The Federal Highway Administration (FHWA), in partnership with the TestQuip Corporation (New Brighton, MN), developed an angle validation kit (AVK) that measures the dynamic internal angle (DIA) of gyration. The DIA accounts for equipment compliance issues, which are not apparent in measuring the external angle. Bending in the upper and lower mold platens during compact reduces the compactive effort imparted to a specimen. Differences in specimen bulk specific gravities produced by different compactors have been attributed to differences in compliance between SGCs measured with the AVK. This necessitates a revision of American Association of State Highway and Transportation Officials (AASHTO) standard method 312-01(1) to ensure uniformity in compaction effort in the Superpave system. However, it would be inappropriate to assign the external angle target and tolerance to the DIA; compliance issues have existed throughout the development and implementation of the Superpave system. Assignment of the external specifications to the DIA would result in an increase in the compactive effort of all SGCs and in turn would invalidate the Ndesign table. The Transportation Research Board (TRB) Superpave Mixture/Aggregate expert task group (ETG) (the TRB Superpave Mixture/Aggregate ETG replaced the FHWA Superpave Mixture in 1999) directed FHWA to investigate the DIAs of the original pooled fund SGCs: Pine Instrument Company SGC model AFGC125X and the Troxler Electronic Company SGC model 4140 (figure 1). These models were developed in response to a national pooled fund equipment purchase conducted by the FHWA and were integral in the experiments that refined the Ndesign table that is used today. FHWA conducted a comprehensive testing program to establish recommendations for the DIA target and tolerance. The DIAs for the Pine and the Troxler SGCs were determined to be 1.176° and 1.140°, respectively, resulting in a proposed target of 1.16°. The sensitivity of the DIA on bulk specific gravity was also investigated, resulting in a proposed tolerance of ± 0.03°. Return to Table of Contents Online Tools for Hot-Mix Asphalt Monitoring Yüklə 294,36 Kb. Dostları ilə paylaş:
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