Characterizing and Predicting Dynamic Modulus of Hot-mix Asphalt for Mechanistic-empirical Design Guide PDF Download
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Author: Nam Hoai Tran
Publisher:
ISBN:
Category : Asphalt concrete
Languages : en
Pages : 768
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Author: Nam Hoai Tran
Publisher:
ISBN:
Category : Asphalt concrete
Languages : en
Pages : 768
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Book Description
Author:
Publisher:
ISBN:
Category : Pavements, Asphalt concrete
Languages : en
Pages : 45
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Book Description
The proposed Mechanistic-Empirical Pavement Design Guide (MEPDG) procedure is an improved methodology for pavement design and evaluation of paving materials. Since this new procedure depends heavily on the characterization of the fundamental engineering properties of paving materials, a thorough material characterization of mixes used in Virginia is needed to use the MEPDG to design new and rehabilitated flexible pavements. The primary objective of this project was to perform a full hot-mix asphalt (HMA) characterization in accordance with the procedure established by the proposed MEPDG to support its implementation in Virginia. This objective was achieved by testing a sample of surface, intermediate, and base mixes. The project examined the dynamic modulus, the main HMA material property required by the MEPDG, as well as creep compliance and tensile strength, which are needed to predict thermal cracking. In addition, resilient modulus tests, which are not required by the MEPDG, were also performed on the different mixes to investigate possible correlations between this test and the dynamic modulus. Loose samples for 11 mixes (4 base, 4 intermediate, and 3 surface mixes) were collected from different plants across Virginia. Representative samples underwent testing for maximum theoretical specific gravity, asphalt content using the ignition oven method, and gradation of the reclaimed aggregate. Specimens for the various tests were then prepared using the Superpave gyratory compactor with a target voids in total mix (VTM) of 7% ± 1% (after coring and/or cutting). The investigation confirmed that the dynamic modulus test is an effective test for determining the mechanical behavior of HMA at different temperatures and loading frequencies. The test results showed that the dynamic modulus is sensitive to the mix constituents (aggregate type, asphalt content, percentage of recycled asphalt pavement, etc.) and that even mixes of the same type (SM-9.5A, IM-19.0A, and BM 25.0) had different measured dynamic modulus values because they had different constituents. The level 2 dynamic modulus prediction equation reasonably estimated the measured dynamic modulus; however, it did not capture some of the differences between the mixes captured by the measured data. Unfortunately, the indirect tension strength and creep tests needed for the low-temperature cracking model did not produce very repeatable results; this could be due to the type of extensometers used for the test. Based on the results of the investigation, it is recommended that the Virginia Department of Transportation use level 1 input data to characterize the dynamic modulus of the HMA for projects of significant impact. The dynamic modulus test is easy to perform and gives a full characterization of the asphalt mixture. Level 2 data (based on the default prediction equation) could be used for smaller projects pending further investigation of the revised prediction equation incorporated in the new MEPDG software/guide. In addition, a sensitivity analysis is recommended to quantify the effect of changing the dynamic modulus on the asphalt pavement design. Since low-temperature cracking is not a widespread problem in Virginia, use of level 2 or 3 indirect tensile creep and strength data is recommended at this stage.
Author: Amara Loulizi
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 32
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This project evaluated the procedures proposed by the Mechanistic-Empirical Pavement Design Guide (MEPDG) to characterize existing hot-mix asphalt (HMA) layers for rehabilitation purposes. Thirty-three cores were extracted from nine sites in Virginia to measure their dynamic moduli in the lab. Falling-weight deflectometer (FWD) testing was performed at the sites because the backcalculated moduli are needed for the Level 1 procedure. The resilient modulus was also measured in the lab because it is needed for the Level 2 procedure. A visual pavement rating was performed based on pavement condition because it is needed for the Level 3 procedure. The selected cores were tested for their bulk densities (Gmb) using the AASHTO T166 procedure and then for their dynamic modulus in accordance with the AASHTO TP62-03 standard test method. Then the cores were broken down and tested for their maximum theoretical specific gravity (Gmm) using the AASHTO T-209 procedure. Finally an ignition test was performed to find the percentage of binder and to reclaim the aggregate for gradation analysis. Volumetric properties were then calculated and used as input for the Witczak dynamic modulus prediction equations to find what the MEPDG calls the undamaged master curve of the HMA layer. The FWD data, resilient modulus data, and pavement rating were used to find the damaged master curve of the HMA layer as suggested for input Levels 1, 2, and 3, respectively. It was found that the resilient modulus data needed for a Level 2 type of analysis do not represent the entire HMA layer thickness, and therefore it was recommended that this analysis should not be performed by VDOT when implementing the design guide. The use of Level 1 data is recommended because FWD testing appears to be the only procedure investigated that can measure the overall condition of the entire HMA layer.
Author: M. Emin Kutay
Publisher:
ISBN:
Category : Asphalt emulsion mixtures
Languages : en
Pages : 120
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This is the final report of the Part 1 (HMA Mixture Characterization) of the "Preparation for Implementation of the Mechanistic-Empirical Pavement Design Guide in Michigan" project. The main objectives of the Part 1 were (i) to conduct a literature search to determine the existing and past research on HMA mixture characterization for M-E PDG, (ii) review MDOT's HMA testing program, and (iii) laboratory testing of samples collected. Scope of the literature review included the past and on-going research on HMA characterization as a preparation for the M-E PDG (or DARWin-ME) as well as predictive models for some of the key inputs such as the Complex (Dynamic) Modulus (/E*/) mastercurve. Several regression-based /E*/ models were evaluated and calibrated for local asphalt mixtures in Michigan. In addition, an Artificial Neural Network (ANN) model has been developed for better prediction of /E*/ from asphalt volumetrics. The research team reviewed the current HMA test data available as part of the MDOT testing program and compared it with the test data required by the M-E PDG. In addition, an extensive laboratory testing program was conducted to characterize asphalt mixtures commonly used in Michigan for the Complex (Dynamic) Modulus /E*/, Complex Shear Modulus (/G*/) of binders and Indirect Tension Strength (IDT) at low temperatures. A standalone software, called DYNAMOD, was developed to serve as a database for all the material testing performed in this project. The DYNAMOD will allow engineers to easily reach the material testing data and generate input files that can directly be imported by the M-E PDG (or DARWin-ME).
Author: American Association of State Highway and Transportation Officials
Publisher: AASHTO
ISBN: 156051423X
Category : Pavements
Languages : en
Pages : 218
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Author: Erfan Hajibandeh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Measuring the quality of as-built Asphalt Concrete (AC) mixtures provide useful information about the current and long-term performance of pavements. By the advent of the mechanistic-empirical pavement design method, the dynamic modulus has become one of the primary performance indicators required for characterizing the performance of AC mixtures. The dynamic modulus is commonly measured using cylindrical specimens having a 100 mm diameter and a 150 mm height (full-size specimens). Testing as-built AC mixtures using this geometry is rarely possible because the required specimen height is greater than the typical AC lift thickness. In this study, the feasibility of using small-scale cylindrical specimens to measure the dynamic modulus of AC mixtures was investigated. Initially, the specimens were prepared in the laboratory using loose mixtures obtained from the field. Dynamic modulus test was conducted on full-size and two small-scale (common height of 110 mm and two diameters of 38 and 50 mm) geometries extracted from gyratory compacted samples. A uniaxial hydraulic loading frame was used to test specimens at the standard temperatures and frequencies. Both small geometries showed similar performances to full-size specimens except at high temperature of 37.8°C, where they resulted in greater dynamic modulus values compared to full-size geometry. The coefficient of variation for 38mm-diameter specimens was found to be higher than two other geometries. Secondly, field cores were collected from highways to characterize as-built AC mixtures using three tests, including dynamic modulus, Hamburg Wheel-Tracking (HWT), and ignition oven. Ignition oven test was performed on field cores to mainly control the aggregate gradation of mixtures. For the dynamic modulus test, small-scale specimens were extracted from field cores, and stiffness values at 37.8°C were corrected using calibration factors obtained from the initial phase. For the HWT test, the heights of field cores were adjusted, and the test output parameters were correlated with the calibrated dynamic modulus values at 37.8°C. The results showed that small-scale specimens are capable of measuring the as-built dynamic modulus of AC mixtures and predicting their rutting performance in the laboratory.
Author: Y. Richard Kim
Publisher: CRC Press
ISBN: 1315736756
Category : Technology & Engineering
Languages : en
Pages : 1966
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Book Description
Asphalt Pavements contains the proceedings of the International Conference on Asphalt Pavements (Raleigh, North Carolina, USA, 1-5 June 2014), and discusses recent advances in theory and practice in asphalt materials and pavements. The contributions cover a wide range of topics:- Environmental protection and socio-economic impacts- Additives and mo
Author: Mir Shahnewaz Arefin
Publisher:
ISBN:
Category : Asphalt
Languages : en
Pages : 129
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This study evaluated the aging characteristic of foamed warm mix asphalt (WMA) produced by water injection in comparison to traditional hot mix asphalt (HMA). Four types of asphalt binders (PG 64-22, PG 64-28, PG 70-22, PG 76-22) were used in the preparation of the foamed WMA and HMA mixtures. All mixtures were prepared using limestone aggregates with a nominal maximum aggregate size (NMAS) of 12.5 mm that met the Ohio Department of Transportation (ODOT) Construction and Material Specifications (C&MS) for Item 442 (Superpave Asphalt Concrete).The short-term and long-term aging of the asphalt binders were simulated using the rolling thin film oven (RTFO) and the pressure aging vessel (PAV), respectively, while the short-term and long-term aging of the laboratory-prepared asphalt mixtures were simulated according to AASHTO R 30 (Mixture Conditioning of Hot Mix Asphalt).The dynamic shear rheometer (DSR) was used to characterize the viscoelastic behavior of the unaged, RTFO-aged, and PAV-aged asphalt binders, while the dynamic modulus (lE*l) test was used to characterize the viscoelastic behavior of the short-term and long-term aged foamed WMA and HMA mixtures.In addition, the mechanistic-empirical pavement design guide (MEPDG) global aging model was used to predict the effect of aging on the dynamic modulus (lE*l) of foamed WMA and HMA mixtures, and the MEPDG global aging model predictions were compared to dynamic modulus (lE*l) test results obtained in the laboratory for both asphalt mixtures. By comparing the DSR test results following RTFO and PAV to those obtained for the unaged asphalt binders, it was observed that PG 64-22 was the least susceptible to aging followed by PG 70-22, PG 76-22, and PG 64-28. Similar trends were also observed from the dynamic modulus test, where little difference was noticed between the short-term and long-term aged specimens prepared using PG 64-22 for both foamed WMA and HMA mixtures.The dynamic modulus test results also revealed slightly lower lE*l values for foamed WMA mixtures in comparison to traditional HMA mixtures. This indicates that foamed WMA mixtures are slightly more susceptible to rutting than HMA mixtures. However, by comparing the dynamic modulus of the long-term aged specimens to the short-term aged specimens, it was observed that the increase in stiffness for the foamed WMA mixtures was less than that for the traditional HMA mixtures. This indicates that foamed WMA mixtures are less susceptible to aging and subsequently fatigue cracking than HMA mixtures.Finally, by the comparing the MEPDG global aging model predictions to the dynamic modulus test results for both foamed WMA and HMA mixtures, it was observed that the MEPDG global aging model provided more reasonable predictions, especially at higher frequencies, but overestimated or underestimated the dynamic modulus at lower frequencies. This was observed for both foamed WMA and HMA mixtures, which suggests that this model can be used for both types of mixtures.
Author: Alex K. Apeagyei
Publisher:
ISBN:
Category : Binders (Materials)
Languages : en
Pages : 79
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The Guide for the Mechanistic-Empirical Design of New & Rehabilitated Pavement Structures (MEPDG), developed under NCHRP Project 1-37A and recently adopted by the American Association of State Highway and Transportation Officials (AASHTO), offers an improved methodology for pavement design and evaluation. To achieve this improved prediction capability, the MEPDG procedure requires fundamental material properties in addition to certain empirically determined binder and mixture properties as design inputs. One of the key tasks identified by the Virginia Department of Transportation's (VDOT) Asphalt Concrete MEPDG Committee was the laboratory characterization of asphalt mixtures commonly used in Virginia to generate a catalog of the MEPDG-required design inputs. The purpose of this study was to evaluate, compile, and present asphalt material properties in a format that could be readily used in the MEPDG software and to develop a comprehensive catalog of MEPDG design input parameters for pavement design in Virginia. To achieve this objective, 18 asphalt concrete mixtures, sampled from seven of the nine VDOT districts, were tested using a battery of MEPDG-required tests including dynamic modulus (E*), flow number (FN), creep compliance, tensile strength, and beam fatigue tests. Testing involving binder and volumetric properties of the mixtures was also conducted. Finally, rut tests using the asphalt pavement analyzer (APA), a standard VDOT test protocol, were conducted to enable a direct comparison of the APA and FN test results. On the basis of these tests, suggestions for additional studies were made. The results of the study were presented in a form matching the MEPDG input format, and a catalog of design input parameters was developed for the 18 asphalt concrete mixtures. Included in the catalog were binder stiffness, mixture E*, mixture gradation, and mixture volumetric properties that would enable a designer the flexibility to select the desired input level (1, 2, or 3) depending on the pavement type. An illustrative example of how the developed inputs could be implemented using the MEPDG software was also provided. The results showed that E* master curves of asphalt mixtures obtained using the five standard testing temperatures described in AASHTO TP 62 could be obtained by testing at only three temperatures, which could result in a substantial reduction of testing time. The results also showed that the FN test was a sensitive test for evaluating rutting susceptibility of asphalt mixtures in the laboratory. The FN test was found to be sensitive to binder stiffness, mixture stiffness, mixture volumetric properties, aggregate gradation, and amount of recycled asphalt pavement (RAP) for the mixtures considered in this study. The study recommends that the catalog of input data for typical asphalt mixtures developed in this study be considered for pavement design in Virginia. The data followed expected trends and compared quite well with those reported in previous studies. Further studies should be conducted to evaluate the FN test as an additional tool for evaluating rutting in asphalt mixtures. Mixtures containing higher amounts of RAP (>20%) exhibited comparatively lower rutting resistance than those with 20% or less RAP. This phenomenon was unexpected since it is generally believed that adding more RAP should result in stiffer and hence more rut-resistant mixtures. Additional research should be conducted to investigate this phenomenon further.
Author: Rafiqul Alam Tarefder
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages :
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