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A Phenomenological Fatigue Performance Model Of Asphalt Mixtures Based On Fracture Energy Density
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Book Synopsis A Phenomenological Fatigue Performance Model of Asphalt Mixtures Based on Fracture Energy Density by : A. M. Bahadori
Download or read book A Phenomenological Fatigue Performance Model of Asphalt Mixtures Based on Fracture Energy Density written by A. M. Bahadori and published by . This book was released on 2014 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study the fatigue performance of asphalt mixtures was interpreted based on fracture energy density. Recent studies indicate that the fracture energy from indirect tension tests correlates with the field performance of asphalt concrete. The fracture energy density was obtained from indirect tensile strength tests, and the fatigue performance of asphalt mixtures was evaluated with four-point bending beam fatigue tests implemented at three different strain levels. Two different asphalt mixtures with varying binder contents were tested during this study. Test results showed that the fracture energy density could be an appropriate material property in phenomenological fatigue models. Thus a phenomenological fatigue model based on fracture energy density is presented, and this approach could be advantageous because a simple fatigue model based on fracture energy density does not require time-consuming fatigue tests. For comparison purposes, the various types of fatigue models were evaluated, and fatigue models based on fracture energy density and dissipated energy showed rather high prediction accuracy. In general, fatigue models based on the energy concept have the least dependence on material properties and can predict the fatigue lives of asphalt mixtures without changing coefficients.
Book Synopsis Fatigue Analysis of Asphalt Concrete Under Indirect Tensile Mode of Loading Using Crack Images by : Manh Tuan Nguyen
Download or read book Fatigue Analysis of Asphalt Concrete Under Indirect Tensile Mode of Loading Using Crack Images written by Manh Tuan Nguyen and published by . This book was released on 2012 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, various fatigue criteria for indirect tensile (IDT) fatigue tests were evaluated and a new approach to identify the fatigue failure was proposed based on a crack-length criterion. The IDT fatigue tests were conducted to characterize the fatigue behavior of various asphalt mixtures, such as three warm mix asphalt mixtures and a polymer-modified asphalt mixture. During the IDT tests, digital cameras were mounted to monitor crack growth on the both faces of a specimen. Existing three fatigue failure criteria were evaluated regarding to fatigue-crack development. Then, a crack-length limit was proposed as a fatigue criterion. The IDT strength tests were also conducted to determine fracture energy of the mixtures. Based on the new fatigue criterion, a fatigue performance model was constituted with dissipated and fracture energy parameters. The fatigue model proposed in this study successfully predicted the fatigue lives of the mixtures with a high level of accuracy. The main advantage of this fatigue model is that it does not need a transfer function to convert the fatigue life to crack length or area, because fatigue-crack length is directly determined from the crack-length limit.
Book Synopsis Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields by : Inge Hoff
Download or read book Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields written by Inge Hoff and published by CRC Press. This book was released on 2022-07-07 with total page 673 pages. Available in PDF, EPUB and Kindle. Book excerpt: Innovations in Road, Railway and Airfield Bearing Capacity – Volume 3 comprises the third part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field.
Book Synopsis Understanding Mechanisms Leading to Asphalt Binder Fatigue by :
Download or read book Understanding Mechanisms Leading to Asphalt Binder Fatigue written by and published by . This book was released on 2012 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue cracking is one of the primary modes of failure in asphalt pavements. Cracking typically occurs within the asphalt binder phase of asphalt mixtures. Thus, asphalt binder fatigue resistance is critical in determining overall pavement fatigue performance. One procedure commonly used to characterize asphalt binder fatigue resistance is the time sweep test, which consists of repeated torsional loading of a cylindrical specimen in the Dynamic Shear Rheometer (DSR). Generally, apparent changes in material properties with respect to number of cycles of loading are used to define fatigue failure of the asphalt binder. Results of this test have been shown to correlate well with asphalt mixture fatigue performance. However, the mechanisms responsible for changes in material properties during fatigue testing in the DSR were previously not well understood. Results in this study demonstrate that fracture can account for changes in loading resistance of asphalt binders during time sweep testing. Under cyclic torsional loading of cylindrical specimens, macro fracture is shown to manifest in the form of edge fracture. Edge fracture is a circumferential crack starting at the periphery of a cylindrical sample that propagates inward as loading is applied, reducing the effective sample size. Digital visualization of the fractured specimens allowed for determination of the fractured and intact sample area. Predictions of fracture propagation based on measurements of loading resistance and fracture mechanics concepts agreed favorably with actual measurements based on visualization. Furthermore, the fracture morphology and progression of crack growth of asphalt binders matched those observed for other materials under similar loading conditions.Based on these results, fatigue damage characterization of asphalt binders can be improved by incorporating fracture mechanics into an analysis framework for DSR fatigue test results. An analysis framework based on fracture principles is presented. The proposed model allows predicting fatigue life at any loading amplitude using the results of a single fatigue test. Additionally, it is demonstrated that time-temperature superposition is applicable to fatigue crack propagation of asphalt binders, allowing for efficient prediction of fatigue performance at multiple temperatures. The model is validated using a comparison between asphalt mixture and binder fatigue test results.
Download or read book Hot-mix Asphalt Mixtures written by and published by . This book was released on 1999 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Using Viscoelastic Continuum Damage Approach by : Y. Richard Kim
Download or read book Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Using Viscoelastic Continuum Damage Approach written by Y. Richard Kim and published by . This book was released on 2002 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction -- Objectives and summary -- Theoretical background -- Test methods -- Materials and specimen fabrication -- Uniaxial testing -- Determination of viscoelastic properties from IDT test -- Development of a simple performance test and validation -- Conclusions and recommendations -- Implementation and technology transfer plan -- References -- Appendices.
Book Synopsis Characterization of Fatigue Cracking and Healing of Asphalt Mixtures by : Xue Luo
Download or read book Characterization of Fatigue Cracking and Healing of Asphalt Mixtures written by Xue Luo and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing methods to characterize fatigue cracking and healing are generally empirical or phenomenological in nature, which does not satisfy the need to develop mechanistic-based pavement design methods. The objective of this study is to characterize fatigue cracking and healing of asphalt mixtures using an energy-based mechanistic approach. A controlled-strain repeated direct tension (RDT) test is selected to generate both fatigue cracking and permanent deformation in an asphalt mixture specimen. Fatigue cracking is separated from permanent deformation from a mechanical viewpoint. The development of fatigue cracking is described by the evolution of the damage density and the increase of the average crack size with the increase of loading cycles. A creep and step-loading recovery (CSR) test is designed to measure the internal stress in the recovery phase of an asphalt mixture specimen. The internal stress and the strain measured in the recovery phase are used to conduct the mechanistic analysis of recovery and healing of the asphalt mixture specimen. Then healing is described using the decrease of the damage density and average crack size with time. Different types of asphalt mixtures produce distinctly different fatigue cracking and healing characteristics. The effect of mixture composition, temperature, and aging are evaluated using the approach above. The entire series of tests for fatigue, permanent deformation and healing can be completed in one day, with the healing part requiring only a matter of minutes. The methods proposed in this study characterize fatigue cracking and healing of asphalt mixtures using its essential cause and effect relationship.
Book Synopsis Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Based on Viscoelastic Analysis of Indirect Tensile Test by :
Download or read book Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Based on Viscoelastic Analysis of Indirect Tensile Test written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the viscoelastic characterization of asphalt concrete in indirect tensile testing and the development of a simple performance test for fatigue cracking. The analytical solutions to calculate creep compliance and center strain from displacements measured on the specimen surface were developed based upon the theory of viscoelasticity. These developments were verified by 3-D finite element viscoelastic analysis and tests. A simple performance test was developed based on these solutions and work potential theory. To evaluate its validity, the indirect tensile tests were performed on WesTrack asphalt mixtures varying aggregate gradations, asphalt contents, and air void contents. Fracture energy obtained from indirect tensile strength testing and creep testing was highly correlated with field performance of these mixtures at WesTrack. A combination of indirect tensile creep and strength testing was proposed as a simple performance test for fatigue cracking. Recommendations for expanding the applicability of the simple performance test developed are provided.
Book Synopsis Simple Indexes to Identify Fatigue Performance of Asphalt Concrete by : Xuan Chen
Download or read book Simple Indexes to Identify Fatigue Performance of Asphalt Concrete written by Xuan Chen and published by . This book was released on 2020 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using indexes based on engineering properties is among the ways to evaluate the quality of an asphalt concrete mix in terms of its resistance to fatigue cracking. These indexes typically are developed based on measuring asphalt concrete or asphalt binder properties in a laboratory test. Among such tests, the semicircular bend (SCB) test has shown potential as a promising test to determine fatigue resistance of asphalt mixtures. In the work presented, this test was explored extensively to determine proper fatigue performance identifiers from the test. Numerous tests were conducted to determine the effect of asphalt mix composition on the SCB fatigue test results. A major index considered from this test for evaluation is the flexibility index (FI), which is defined as the ratio of fracture energy and the post peak slope at inflection point derived from a typical load-deformation or stress-strain monotonic test. This index has been proposed based on extensive research at the University of Illinois. In the work presented in this study, tests were conducted on both short- and long-term aged asphalt mixes to evaluate FI and its reliability as a fatigue resistance indicator. The mix components considered as test variables included binder content, air void, and binder stiffness. The results showed a significant reduction in FI fatigue resistance after long term aging. Reduced FI is believed to associate with reduced fatigue life. The sensitivity of FI and other engineering properties to mix parameters were investigated in this research. It was found that FI could not be used alone and as a sole indicator of fatigue performance. It was determined that two indexes are needed for this purpose the first presents the mix toughness and ductility, and the second is a strength- or stiffness-based index.
Book Synopsis Development of a New Fatigue Performance Test Using the Hamburg Wheel Tracking Device by : Ali Sahraei Joubani
Download or read book Development of a New Fatigue Performance Test Using the Hamburg Wheel Tracking Device written by Ali Sahraei Joubani and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this study was to develop a new test that would be simple to conduct and analyze for evaluating resistance of asphalt mixtures to fatigue cracking. For this purpose, a piece of equipment known as the Hamburg Wheel Tracking Test (HWTT) was used. HWTT has been widely accepted as a reasonable and reliable test to evaluate the rutting and moisture damage performance of asphalt mixtures but its use for evaluating fatigue resistance of asphalt mixtures is relatively a new concept. Its use as a fatigue test is advantages over current laboratory fatigue tests because of the possibility of considering various underlying support layers when the specimen is subjected to repeated loading. Ability to assess the asphalt mixture fatigue resistance in a layered system under repeated loading and in a laboratory environment provides the opportunity to integrate material design and pavement structural design for optimum performance. In addition, this test is practically feasible as a routine test method in terms of reliability, equipment availability, and data processing efficiency. The tests were conducted on a two-layer structure with the asphalt concrete slab as the top layer and the neoprene or an unbound aggregate base as the underlying layer. Based on the numerical analysis, a width of 6 inches was selected as the optimum width for this study. However, the experiment also included the 4-inch width for comparison. The thickness of the slab was selected at three levels: 1.0, 1.5, and 2.0 inches, with the 1.5-inch thickness being the main thickness applied to most of the slabs. In an asphalt pavement structure, the surface layer is often designed at a thickness of 1.5 to 2.0 inches. These tests were based on strain amplitude growth corresponding to three defined stages during the test (Early, Middle, Late). The impact of several factors on the test results was investigated. Those factors included the slab width and thickness, the underlying support type and condition, temperature of the test, the speed of tracking, and the type of asphalt mixture. The experiment showed that as the slab thickness become smaller, the strain amplitude and its corresponding growth rate become larger, exhibiting a relatively higher rate of fatigue damage. Using the unbound aggregate base proved to be challenging because of difficulty in achieving a smooth, even surface. A smooth surface was required to ensure proper bond of the gauges and collection of the data. Using synthetic rubber neoprene provided a smooth base and delivered a more reliable dataset compared to the aggregate base in this study. As expected, temperature played a significant role in the experiment, as a higher initial strain amplitude was observed at elevated temperatures. A higher strain and increased strain growth rate were observed at lower loading speeds. After determining the appropriate dimensions, temperature, and underlying support, tests were conducted on six different asphalt mixes. Strain development was monitored at the bottom of the slab for each mix. From the data collected, a new fatigue life model was developed to evaluate the fatigue performance of asphalt pavements when tested under the conditions explored in this research. The fatigue life in this model is defined as the number of HWTT load cycles at which the strain amplitude doubles, or equivalently, when the stiffness is reduced to half. This determination is made under the premise that the test operates in stress control mode. It was found that the rate of growth in strain amplitude during the test increased considerably when the binder content in the mix was decreased, validating the importance of ensuring adequate binder content in the asphalt mix. The SMA mixture demonstrated a higher rate of strain amplitude increase compared to the dense-graded mixtures. The mix with 35% RAP content and a PG 64-22 binder delivered lower growth in strain amplitude compared with other mixes. The IDEAL-CT test was also performed to draw comparisons. However, based on the outcomes, it showed no correlation with the results of the newly developed fatigue test. Based on the growth of strain amplitude throughout the test, a fatigue life model was developed. The fatigue life can be determined using this model, based on the number of cycles, with a criterion of either a 50% reduction in stiffness or a doubling of the strain amplitude. Finally, a numerical model was developed, and the observed strain response demonstrated that this model is capable of predicting both the type of response and the magnitude of strain amplitude with relative accuracy.
Book Synopsis Development and Verification of the Overlay Tester Based Fatigue Cracking Prediction Approach by : Fujie Zhou
Download or read book Development and Verification of the Overlay Tester Based Fatigue Cracking Prediction Approach written by Fujie Zhou and published by . This book was released on 2007 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this project was to develop and verify the overlay tester (OT) based fatigue cracking prediction approach in which the OT is used to determine fracture properties (A and n) of hot-mix asphalt (HMA) mixtures. This approach was developed based on fracture mechanics. However, not only was the fatigue crack propagation characterized by Paris' law fracture concepts, but the crack initiation described by traditional fatigue model was also included in this approach. In this approach, the fundamental HMA fracture properties (A and n) were used to estimate fatigue life of asphalt pavements including crack initiation and crack propagation.
Book Synopsis Fatigue-fracture Relation on Asphalt Concrete Mixtures by : Chaiwat Na Chiangmai
Download or read book Fatigue-fracture Relation on Asphalt Concrete Mixtures written by Chaiwat Na Chiangmai and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is to examine potential relationships between fatigue and fracture parameters obtained from standardized laboratory tests. A flexural bending beam test was used to obtain two fatigue parameters, which include a traditional fatigue criterion based on stress or strain to find number of cycles to failure and a new fatigue criterion based on an energy approach known as the plateau value (PV). Similarly, a disk-shaped compact tension DC(T) fracture test was used to obtain fracture energy parameters, including: fracture strength, pre-peak fracture energy, post-peak fracture energy, and total fracture energy. A factorial of the eight possible correlations was computed to determine the strongest association between the fatigue and fracture parameters for the asphalt mixtures investigated. The study was motivated by the desire to investigate the feasibility of predicting time-consuming fatigue test results with fracture test results, which can be obtained much more rapidly. Based on the results obtained in this study, it was shown that a potentially strong correlation exists between fatigue and fracture mechanisms in asphalt concrete, as characterized by parameters associated with dissipated or consumed energy. As presented through the statistical analysis, the plateau value (PV) and the pre-peak fracture energy (Gf-pre) are the most highly correlated parameters from the fatigue and fracture tests, respectively. This study is based upon limited experimental data and is explored an initial starting point to find relationships between fatigue and fracture mechanisms. Much more experimented and analytical work will be needed to fully understand these relationships and to develop a standardized interconversion scheme.
Book Synopsis Development of an Image-based Multi-scale Finite Element Approach to Predict Fatigue Damage in Asphalt Mixtures by :
Download or read book Development of an Image-based Multi-scale Finite Element Approach to Predict Fatigue Damage in Asphalt Mixtures written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Image-based simulation of complex materials is a very important tool for understanding their mechanical behavior and an effective tool for successful design of composite materials. In this thesis an image-based multi-scale finite element approach is developed to predict the mechanical properties of asphalt mixtures. In this approach the "up-scaling" and homogenization of each scale to the next is critically designed to improve accuracy. In addition to this multi-scale efficiency, this study introduces an approach for consideration of particle contacts at each of the scales in which mineral particles exist. One of the most important pavement distresses which seriously affects the pavement performance is fatigue cracking. As this cracking generally takes place in the binder phase of the asphalt mixture, the binder fatigue behavior is assumed to be one of the main factors influencing the overall pavement fatigue performance. It is also known that aggregate gradation, mixture volumetric properties, and filler type and concentration can affect damage initiation and progression in the asphalt mixtures. This study was conducted to develop a tool to characterize the damage properties of the asphalt mixtures at all scales. In the present study the Viscoelastic continuum damage model is implemented into the well-known finite element software ABAQUS via the user material subroutine (UMAT) in order to simulate the state of damage in the binder phase under the repeated uniaxial sinusoidal loading. The inputs are based on the experimentally derived measurements for the binder properties. For the scales of mastic and mortar, the artificially 2-Dimensional images of mastic and mortar scales were generated and used to characterize the properties of those scales. Finally, the 2D scanned images of asphalt mixtures are used to study the asphalt mixture fatigue behavior under loading. In order to validate the proposed model, the experimental test results and the simulation results were compared. Indirect tensile fatigue tests were conducted on asphalt mixture samples. A comparison between experimental results and the results from simulation shows that the model developed in this study is capable of predicting the effect of asphalt binder properties and aggregate micro-structure on mechanical behavior of asphalt concrete under loading
Book Synopsis Fatigue Response of Asphalt-aggregate Mixes by :
Download or read book Fatigue Response of Asphalt-aggregate Mixes written by and published by Strategic Highway Research Program (Shrp). This book was released on 1994 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development process included a number of phases, which are described in the report. Included in this report are the following: 1) a state-of-knowledge review for fatigue response of asphalt aggregate mixes, 2) a description of a pilot test program and its results, 3) a description of an expanded test program using the equipment and methodology selected in the pilot test program, and 4) a description of a mix analysis and design system, which can be used to mitigate fatigue cracking.
Book Synopsis Fracture Properties and Fatigue Cracking Resistance of Asphalt Binders by : Arash Motamed
Download or read book Fracture Properties and Fatigue Cracking Resistance of Asphalt Binders written by Arash Motamed and published by . This book was released on 2012 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several different types of modifiers are increasingly being used to improve the performance of asphalt binders or to achieve desired mixture production characteristics (e.g., Warm Mix Asphalt). However, current Superpave performance specifications do not accurately reflect the performance characteristics of these modified binders. The main objective of this study was to evaluate the inherent fatigue cracking resistance of asphalt binders in the form of a matrix with rigid particle inclusions. The underlying rationale for this approach was to subject the binders to a state of stress that is similar to the one in a full asphalt mixture. This was achieved by fabricating and testing composite specimens of the asphalt binders and glass beads with a specified gradation. Four asphalt binders with similar true temperature grades but different modifiers were used in this study. The viscoelastic and fatigue cracking characteristics of the binders were measured using the glass bead-binder composite specimens in a dynamic shear rheometer at an intermediate temperature. The results demonstrate that the four asphalt binders modified using different methods had different damage characteristics despite the fact that these four binders were rated to have a similar performance grade based on the Superpave specifications. Fatigue cracking characteristics of the glass bead-binder test specimens used in this study were qualitatively very similar to the fatigue cracking characteristics of full asphalt mixtures using the same binders. The rank order of fatigue cracking resistance for the four glass bead-binder mixtures compared reasonably well to the rank order of fatigue cracking resistance for the full asphalt mixtures that incorporated these asphalt binders.
Book Synopsis Modeling the Effects of Temperature and Loading Rate on Fatigue Property of Asphalt Binder by : Haifang Wen
Download or read book Modeling the Effects of Temperature and Loading Rate on Fatigue Property of Asphalt Binder written by Haifang Wen and published by . This book was released on 2010 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue cracking is one of three major distresses for asphalt pavement. Asphalt binder is a very important component of asphaltic mixture. The fatigue performance of asphalt binder also greatly affects that of asphaltic mixture. Asphalt binder's fatigue characteristics are affected by external conditions, such as temperature and loading rate. It is warranted to study the effects of these external conditions on fatigue of asphalt binder and take them into account. New fatigue tests and properties have been proposed to characterize the fatigue behavior of asphalt binders, such as monotonic constant shear-rate tests. This study investigated the effects of temperature and shear rate on fatigue properties of asphalt binder. Two asphalt binders were tested with a range of temperature and shear rates. It was found that time-temperature superposition principle also applies to critical strain energy density and shear strength of asphalt binders. The values of shift factors for building the master curves of critical strain energy and shear strength are comparable.
Book Synopsis Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Based on Viscoelastic Analysis of Indirect Tensile Test by : Hafiang Wen
Download or read book Fatigue Performance Evaluation of WesTrack Asphalt Mixtures Based on Viscoelastic Analysis of Indirect Tensile Test written by Hafiang Wen and published by . This book was released on 2001 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: Indirect tensile test, Simple performance test, Asphalt concrete, WesTrack, Viscoelastic.
