Enhanced Viscoelastic Modeling Of Hot Mix Asphalt PDF Download
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| Author | : Tito P. Nyamuhokya |
| Publisher | : |
| Total Pages | : 188 |
| Release | : 2015 |
| Genre | : Pavements, Asphalt |
| ISBN | : |
Download Enhanced Viscoelastic Modeling of Hot Mix Asphalt Book in PDF, ePub and Kindle
The primary objective of this research is to investigate the relationships between Compressive (CDM) and Tensile Dynamic Moduli (TDM) of Hot Mix Asphalt (HMA) and develop a material model that predicts tensile dynamic modulus from known compressive dynamic modulus. Moreover, the research develops an enhanced visco-hyper-elastic Finite element model that incorporates both CDM and computed TDM to predict the structural response of a perpetual pavement structure subjected to wheel loading. In the laboratory, the Compressive and Tensile Dynamic Modulus parallel to the direction of compaction and Tensile dynamic modulus perpendicular to the direction of compaction were determined at different temperature and frequencies. The results of the experiments were used to develop relationships between Compressive and Tensile dynamic modulus at 10°C, 20°C, 30°C, 35°C and all temperature combined. The research found that the data correlation at each temperature levels increased with temperature from fair to good (R2 = 0.5-0.85) whereas the correlation at all temperature combined was strong (R2 = 0.91). The model corresponding to the highest R2 was evaluated for accuracy and rationality. This research incorporated both Compressive and computed Tensile Dynamic Moduli (based on the best model) into a visco-hyper-elastic FE model to predict strain responses of the Kansas US75 perpetual pavement sections. This research developed mathematical models that may be used by engineers and researchers to estimate tensile dynamic modulus from known compressive dynamic modulus. In addition, the research demonstrated that the enhanced visco-hyper-elastic finite element model that incorporates both Compressive and Tensile moduli can predict HMA pavement responses.
| Author | : Saradhi Koneru |
| Publisher | : |
| Total Pages | : |
| Release | : 2011 |
| Genre | : |
| ISBN | : |
Download Modeling Hot Mix Asphalt Compaction Using a Thermodynamics Based Compressible Viscoelastic Model Within the Framework of Multiple Natural Configurations Book in PDF, ePub and Kindle
Hot mix asphalt (HMA) is a composite material that exhibits a nonlinear response that is dependent on temperature, type of loading and strain level. The properties of HMA are highly influenced by the type and amount of the constituents used and also depend on its internal structure. In such a material the variable effects of the compaction process assume a central importance in determining material performance. It is generally accepted that the theoretical knowledge about material behavior during compaction is limited and it is therefore hard to predict and manage (the effect of) a compaction process. This work makes an attempt to address such a specific need by developing a continuum model that can be adapted for simulating the compaction of hot mix asphalt (HMA) using the notion of multiple natural configurations. A thermodynamic framework is employed to study the non-linear dissipative response associated with HMA by specifying the forms for the stored energy and the rate of dissipation function for the material; a viscoelastic compressible fluid model is developed using this framework to model the compaction of hot mix asphalt. It is further anticipated that the present work will aid in the development of better constitutive models capable of capturing the mechanics of processes like compaction both in the laboratory and in the field. The continuum model developed was implemented in the finite element method, which was employed to setup a simulation environment for hot mix asphalt compaction. The finite element method was used for simulating compaction in the laboratory and in various field compaction projects.
| Author | : U.s. Department of Transportation |
| Publisher | : |
| Total Pages | : 114 |
| Release | : 2018-07-25 |
| Genre | : |
| ISBN | : 9781724222237 |
Download Modeling of Hot-mix Asphalt Compaction Book in PDF, ePub and Kindle
Modeling of hot-mix asphalt compaction : a thermodynamics-based compressible viscoelastic model /
| Author | : |
| Publisher | : |
| Total Pages | : 116 |
| Release | : 2010 |
| Genre | : Compacting |
| ISBN | : |
Download Modeling of Hot-mix Asphalt Compaction Book in PDF, ePub and Kindle
Compaction is the process of reducing the volume of hot-mix asphalt (HMA) by the application of external forces. As a result of compaction, the volume of air voids decreases, aggregate interlock increases, and interparticle friction increases. The quality of field compaction of HMA is one of the most important elements influencing asphalt pavement performance. Poor compaction has been associated with asphalt bleeding in hot weather, moisture damage, excessive aging and associated cracking, and premature permanent deformation. This study was conducted to develop a model within the context of a thermomechanical framework for the compaction of asphalt mixtures. The asphalt mixture was modeled as a nonlinear compressible material exhibiting time-dependent properties. A numerical scheme based on finite elements was employed to solve the equations governing compaction mechanisms. The material model was implemented in the Computer Aided Pavement Analysis (CAPA-3D) finite-element (FE) package. Due to the difficulty of conducting tests on the mixture at the compaction temperature, a procedure was developed to determine the model's parameters from the analysis of the Superpave® gyratory compaction curves. A number of mixtures were compacted in the Superpave® gyratory compactor using an angle of 1.25 degrees in order to determine the model's parameters. Consequently, the model was used to predict the compaction curves of mixtures compacted using a 2-degree angle of gyration. The model compared reasonably well with the compaction curves. FE simulations of the compaction of several pavement sections were conducted in this study. The results demonstrated the potential of the material model to represent asphalt mixture field compaction. The developed model is a useful tool for simulating the compaction of asphalt mixtures under laboratory and field conditions. In addition, it can be used to determine the influence of various material properties and mixture designs on the model's parameters and mixture compactability.
| Author | : Shadi Abdel-Rahman Saadeh |
| Publisher | : |
| Total Pages | : 173 |
| Release | : 2006 |
| Genre | : |
| ISBN | : |
Download Characterization of Asphalt Concrete Using Anisotropic Damage Viscoelastic-viscoplastic Model Book in PDF, ePub and Kindle
A comprehensive material identification experimental program is developed in this study. The experimental program is designed such that the quantification and decomposition of the response into viscoelastic and viscoplastic components can be achieved. The developed experimental program and theoretical framework are used to analyze repeated creep tests conducted on three mixes that include aggregates with different characteristics.
| Author | : Boris Radovskiy |
| Publisher | : Springer |
| Total Pages | : 115 |
| Release | : 2017-11-11 |
| Genre | : Technology & Engineering |
| ISBN | : 3319672142 |
Download Viscoelastic Properties of Asphalts Based on Penetration and Softening Point Book in PDF, ePub and Kindle
This work deals with conventional and new relationships between various viscoelastic properties of road bitumen, determined under different test modes, such as constant stress, constant deformation or cyclic load. Approximate formulas have been derived for prediction of the rheological properties of asphalt based on its standard parameters such as penetration and softening point. The work is intended for researchers and engineers in road paving industry. It may be also of interest for teachers and Civil Engineering students.
| Author | : Minkyum Kim |
| Publisher | : |
| Total Pages | : 268 |
| Release | : 2011-09-09 |
| Genre | : |
| ISBN | : 9781243752802 |
Download Development of Differential Scheme Micromechanics Modeling Framework for Predictions of Hot-Mix Asphalt (Hma) Complex Modulus and Experimental Validations. Book in PDF, ePub and Kindle
The viscoelastic modulus of hot-mix asphalt (HMA) such as the complex modulus, E*, is an essential material parameter for better paving mixture design and asphalt pavement design. Under certain circumstances, it is desirable that a reasonable modulus value of certain HMA mixtures be estimated for this purpose. Empirical and semi empirical models have been proposed and used. However, these non-fundamental approaches have significant drawbacks, particularly with application of the model for materials that vary from those used in the calibration of the model, and their reliance on large calibration data sets, which led to introducing some fuzzy factors in their predictions. In order to overcome the limitations of an empirical approach, a fundamental micromechanics modeling framework based on the differential scheme effective medium theory has been developed and introduced herein. To verify and validate the prediction accuracy and applicability, a series of various asphalt-aggregate mixtures starting from the homogeneous asphalt binder phase up to a very highly packed composite of dense HMA mixtures were produced in the lab by progressively increasing the aggregate volume concentration in the composite from 0 to nearly 0.9. These various mixtures were tested in the Hollow Cylinder Tensile Tester (HCT) to obtain the extensional complex modulus (E*) at three low temperatures within -25 to 5C range and at various loading frequencies from 10 Hz to 0.01 Hz. Comparisons between the model predicted E* and the experimental E* showed good agreement with reasonable accuracies. Remaining challenges for the practical implementation of the proposed model such as the applicability at intermediate to high temperature materials property prediction and particle orientation effects were discussed based on the analysis and additional model predictions for an independent experimental data set.
| Author | : T. Mura |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 616 |
| Release | : 1987-11-30 |
| Genre | : Science |
| ISBN | : 9789024732562 |
Download Micromechanics of Defects in Solids Book in PDF, ePub and Kindle
This book stems from a course on Micromechanics that I started about fifteen years ago at Northwestern University. At that time, micromechanics was a rather unfamiliar subject. Although I repeated the course every year, I was never convinced that my notes have quite developed into a final manuscript because new topics emerged constantly requiring revisions, and additions. I finally came to realize that if this is continued, then I will never complete the book to my total satisfaction. Meanwhile, T. Mori and I had coauthored a book in Japanese, entitled Micromechanics, published by Baifu-kan, Tokyo, in 1975. It received an extremely favorable response from students and re searchers in Japan. This encouraged me to go ahead and publish my course notes in their latest version, as this book, which contains further development of the subject and is more comprehensive than the one published in Japanese. Micromechanics encompasses mechanics related to microstructures of materials. The method employed is a continuum theory of elasticity yet its applications cover a broad area relating to the mechanical behavior of materi als: plasticity, fracture and fatigue, constitutive equations, composite materi als, polycrystals, etc. These subjects are treated in this book by means of a powerful and unified method which is called the 'eigenstrain method. ' In particular, problems relating to inclusions and dislocations are most effectively analyzed by this method, and therefore, special emphasis is placed on these topics.
| Author | : Jongeun Baek |
| Publisher | : |
| Total Pages | : |
| Release | : 2010 |
| Genre | : |
| ISBN | : |
Download Modeling Reflective Cracking Development in Hot-mix Asphalt Overlays and Quantification of Control Techniques Book in PDF, ePub and Kindle
Hot-mix asphalt (HMA) overlay is regarded as an efficient method to rehabilitate moderately deteriorated pavements. Despite the application of an adequately designed overlay, when HMA overlays are built on jointed concrete pavement (JCP) or a cracked surface, reflective cracking can develop shortly after the overlay application due to traffic loads and environmental changes. Several remedial techniques, including interlayer systems, have been incorporated into HMA overlays to control reflective cracking. This study examined the behavior of traffic-induced reflective cracking using a finite element (FE) model for an HMA overlay with and without interlayer systems, and evaluated the performance of interlayer systems in controlling reflective cracking. To achieve these objectives, a three-dimensional FE model was built for a typical HMA overlay constructed over JCP. A linear viscoelastic model and a bilinear cohesive zone model (CZM) were incorporated into the FE model to characterize continuum and fracture behavior of the HMA. Using the bilinear CZM, reflective cracking initiation and propagation were simulated. Transient moving vehicular loading was applied across a joint to develop reflective cracking. In order to force reflective cracking development by one pass of load application, various levels of overload were applied. Two distinct interlayer systems, sand mix and steel netting with slurry seal, were examined for their effectiveness in controlling reflective cracking. The sand mix was modeled with the LVE model and bilinear CZM. The steel netting interlayer system was modeled with beam elements for steel wires and membrane elements for slurry seal. To quantify the status of reflective cracking development, a representative fractured area (RFAOL), that is an equivalent stiffness degradation in the entire HMA overlay, was used. A limit state load approach was used to determine the resistance of the HMA overlay to reflective cracking in terms of normalized axle load of an overload equivalent to a 80-kN single-axle load. The service life of the HMA overlay regarding reflective cracking was specified by the number of load repetitions based on the Paris law. A reflective cracking control factor was defined as the ratio of the service life to the HMA overlay without an interlayer system; the factor was used to evaluate the performance effectiveness of these interlayer systems in controlling reflective cracking. It was found that the bearing capacity of existing JCP played an important role in developing reflective cracking. Reflective cracking potential increased inversely with the modulus of base and subgrade layers. Interface bonding conditions, especially bonding strength, affected the development of reflective cracking. Lower interface bonding strength resulted in greater potential for developing reflective cracking. The study concluded that the sand mix interlayer system extended the service life of the HMA overlay regarding reflective cracking due to its relatively high fracture energy. A macro-crack level of reflective cracking was initiated in the wearing course in the HMA, so-called crack jumping. The softer the sand mix, the tougher it may be, but it may cause shear rutting in HMA overlay. Hence, sand mix fracture energy and thickness thresholds should be identified. The steel netting interlayer system performed better than the sand mix; the performance of the latter is thickness and fracture energy dependent. When the steel netting interlayer system was installed properly, the reflective cracking service life of the HMA overlay was found to be six times longer than that of the HMA. The performance was still better than sand mix when localized deboning induced. However, severe debonding of steel netting can be detrimental to its performance.
| Author | : A. Scarpas |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 1340 |
| Release | : 2012-08-30 |
| Genre | : Technology & Engineering |
| ISBN | : 9400745664 |
Download 7th RILEM International Conference on Cracking in Pavements Book in PDF, ePub and Kindle
In the recent past, new materials, laboratory and in-situ testing methods and construction techniques have been introduced. In addition, modern computational techniques such as the finite element method enable the utilization of sophisticated constitutive models for realistic model-based predictions of the response of pavements. The 7th RILEM International Conference on Cracking of Pavements provided an international forum for the exchange of ideas, information and knowledge amongst experts involved in computational analysis, material production, experimental characterization, design and construction of pavements. All submitted contributions were subjected to an exhaustive refereed peer review procedure by the Scientific Committee, the Editors and a large group of international experts in the topic. On the basis of their recommendations, 129 contributions which best suited the goals and the objectives of the Conference were chosen for presentation and inclusion in the Proceedings. The strong message that emanates from the accepted contributions is that, by accounting for the idiosyncrasies of the response of pavement engineering materials, modern sophisticated constitutive models in combination with new experimental material characterization and construction techniques provide a powerful arsenal for understanding and designing against the mechanisms and the processes causing cracking and pavement response deterioration. As such they enable the adoption of truly "mechanistic" design methodologies. The papers represent the following topics: Laboratory evaluation of asphalt concrete cracking potential; Pavement cracking detection; Field investigation of pavement cracking; Pavement cracking modeling response, crack analysis and damage prediction; Performance of concrete pavements and white toppings; Fatigue cracking and damage characterization of asphalt concrete; Evaluation of the effectiveness of asphalt concrete modification; Crack growth parameters and mechanisms; Evaluation, quantification and modeling of asphalt healing properties; Reinforcement and interlayer systems for crack mitigation; Thermal and low temperature cracking of pavements; and Cracking propensity of WMA and recycled asphalts.
