Download or read book The Stress deformation Characteristics of Asphaltic Mixtures Under Various Conditions of Loading written by Leonard E. Wood and published by . This book was released on 1956 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deformation and Volume Change Characteristics of a Sand asphalt Mixture Under Constant Direct and Triaxial Compressive Stresses written by Yang Hsien Huang and published by . This book was released on 1968 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Permanent Deformation Properties of Asphalt Concrete Mixtures written by Rabbira Garba and published by . This book was released on 2002 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rutting is recognized to be the major distress mechanism in flexible pavements as a result of increase in tire pressures and axle loads. Rutting is caused by the accumulation of permanent deformation in all or some of the layers in the pavement structure. The accumulation of permanent deformation in the asphalt surfacing layer is now recognized to be the major component of rutting in flexible pavements. This is a consequence of increased tire pressures and axle loads, which subjects the asphalt surfacing layer nearest to the tire-pavement contact area to increased stresses. Thus the study of permanent deformation properties of asphalt mixtures has become the focus of research, which aim to mitigate or reduce rutting in flexible pavements. The research work reported in this thesis aims to contribute towards understanding of the material properties and factors affecting permanent deformation in asphalt mixtures, mechanisms of the permanent deformation, and methods of its prediction. The specific objectives of this research work include; review and evaluation of available models for permanent deformation of asphalt concrete mixtures, investigation of the effect of volumetric composition, loading and temperature conditions on the permanent deformation of asphalt concrete, and the identification and definition of simple measures of resistance to permanent deformation. To meet the objectives of the study a laboratory investigation is conducted on several asphalt concrete specimens with varying volumetric composition. Two testing procedures are adopted; the repeated load triaxial and triaxial creep and recovery tests. The tests were conducted at two temperature levels of 25 and 50oC under varying stress conditions. A review of literature on factors affecting permanent deformation and available models for prediction of the permanent deformation is also conducted. The literature review indicated that most of the research work done so far concentrated on evaluation of the effect on permanent deformation response of component material properties such as aggregate gradation, aggregate angularity and binder type (or grade). Most of the studies conducted on permanent deformation properties of asphalt mixtures were also found to be based on different testing procedures and methods of evaluation, which makes it difficult to compare them and draw firm conclusions. The literature also indicated that, as yet, there is no comprehensive model for deformation of asphalt concrete. Results of tests conducted in this study are analysed to investigate the effect of volumetric composition, particularly binder content and void content, and loading conditions on the permanent deformation response of the mixture. Both the binder content and void content are found to significantly influence the permanent deformation characteristics. The effect of loading conditions, i.e., the confining stress and the deviatoric stress, is also found to be significant. Throughout this study emphasis is placed on methods and parameters that are used to evaluate mixtures for their resistance to permanent deformation. The traditionally used parameters such as the slope and intercept of the power model are evaluated for their sensitivities to changes in volumetric composition. This evaluation is based on the premises that any measure of resistance to permanent deformation should be sensitive to changes in volumetric composition to be good enough. It is found that most of these parameters are not sensitive to changes in volumetric composition and therefore are not suitable for comparison of mixtures made from the same materials but with varying proportion of the components. Permanent deformation in asphalt concrete is caused by both densification and shear deformation. The mode of deformation in asphalt concrete pavements, for greater part of their service life, is considered to be the shear deformation. Therefore it is necessary to evaluate mixtures for their susceptibility to shear deformation. The shear deformation manifests itself in the form of large lateral deformation relative to axial deformation. It is found that one dimensional analysis, which does not take the lateral deformation into account may lead to misleading results regarding the resistance to permanent deformation of mixtures. Therefore parameters which include volumetric and lateral strain are proposed for use in evaluation of mixtures. Substantial effort is put into modelling the accumulation of permanent deformation under repeated loading. For this purpose two approaches were selected: the cyclic hardening model based on bounding surface plasticity concept and an elasto-viscoplastic model based on strain decomposition approach. The bounding surface plasticity approach is found to be a convenient method to model the accumulation of permanent deformation. It is demonstrated that deformations calculated using cyclic hardening model based on bounding surface plasticity fits the measured deformation quite well. The elasto-viscoplastic model, which is based on strain decomposition approach, provides a suitable method for analysis of creep and recovery test results. Deformations calculated using this model also fit the measured deformation quite well. Finally a new composite measure of resistance to permanent deformation is developed. The resistance index is based on strain decomposition approach and is simple to calculate. The index incorporates a parameter related to shear susceptibility of mixtures and is sensitive to changes in volumetric composition. It is believed that this index can be used to compare and select mixtures at mixture design stage. If its applicability to other materials is proved by further research, it can also be linked to performance related specifications, as a simple measure of performance with regard to rutting.

Download or read book Permanent Deformation Characteristics of Asphalt Mixtures by Repeated load Indirect Tensile Test written by Joaquín Vallejo and published by . This book was released on 19?? with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Pavement Design written by E. J. Yoder and published by John Wiley & Sons. This book was released on 1991-01-08 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a complete coverage of all aspects of the theory and practice of pavement design including the latest concepts.

Download or read book Mechanistic Model to Predict the Impact of the Aggregate Matrix on the Permanent Deformation of Asphalt Mixtures written by Samer Hassan Dessouky and published by . This book was released on 2005 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot mix asphalt (HMA) is a granular composite material stabilized by the presence of asphalt binder. The behavior of HMA is highly influenced by the microstructure distribution in terms of the different aggregate particles present in the mix, the directional distribution of aggregates, the distribution of voids, and the nucleation and propagation of cracks. Conventional continuum modeling of HMA lacks the ability to explicitly account for the effect of aggregate microstructure distribution features. This report presents the development of elastic and visco-plastic models that account for important aspects of the aggregate and microstructure distribution in modeling the macroscopic behavior of HMA. The objective of Project 0-1707 is to develop tools by which engineers can judge the impact of the aggregate on the performance of HMA based on simple and repeatable tests. Of greatest concern in Project 0-1707 is the ability of the HMA to resist permanent deformation or to rut, which leads to safety concerns, especially under wet surface conditions. In this report, the research team develops an approach is developed to introduce a length scale to the elasticity constitutive relationship in order to capture the influence of aggregate particle sizes on HMA response. A finite element (FE) analysis is used to analyze the microstructure response and predict the macroscopic properties of HMA. Each point in the microstructure is assigned effective local properties that are calculated using an analytical micromechanical model that captures the influence of the number of particles on the microscopic response of the HMA. The moving window technique and autocorrelation function are used to determine the microstructure characteristic length scales that are used in strain gradient elasticity. A number of asphalt mixes with different aggregate types and size distributions are analyzed . An elasto-visco-plastic continuum model is developed to predict HMA response and performance. The model incorporates a Drucker-Prager yield surface that is modified to capture the influence of stress path direction on the material response. Parameters that reflect the directional distribution of aggregates and damage density in the microstructure are included in the model. The elasto-visco-plastic model is converted into a numerical formulation and is implemented in FE analysis using a user-defined material subroutine (UMAT). A fully implicit algorithm in time-step control is used to enhance the efficiency of the FE analysis. The FE model used in this project simulates experimental data and pavement section.

Download or read book Influence of Rheological Properties of Modified Asphalt Binders on the Load deformation Characteristics of the Binder aggregate Mixtures written by Akhtarhusein Asgarali Tayebali and published by . This book was released on 1990 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Viscoelastic Properties of Asphalts Based on Penetration and Softening Point written by Boris Radovskiy and published by Springer. This book was released on 2017-11-11 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Stress Deformation Characteristics of Sand Bituminous Mixtures written by Jake Allen Carpenter and published by . This book was released on 1958 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strength and Deformation Characteristics of Compacted Soils Under the Action of Repeated Axial Loads written by Hiram Gordon Larew and published by . This book was released on 1960 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deformation Characteristics of Sand asphalt Mixtures Under Constant Tensile Stresses written by Yang Hsien Huang and published by . This book was released on 1964 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impact of Different Loading Patterns with Short Duration on the Permanent Strain of Asphalt Mixture written by Ali Mansourkhaki and published by . This book was released on 2015 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The suggested procedure for measuring the permanent deformation of asphalt concrete mixtures in the standard laboratory tests are based on using a single-hump loading. This loading type can only simulate the single-axle load, whereas pavements are subjected to single, tandem, and tridem axles at different speeds. On the other hand, the behavior of asphalt mixtures is affected by the loading pulse duration as a function of moving speed. Therefore, the laboratory investigation of permanent deformation is more logical under similar loading conditions. Accordingly, in this study, the effect of the type and duration of loading on the permanent strain of asphalt mixture have been examined at three stress levels. To investigate, the unconfined cyclic creep test was performed on asphalt specimens and, finally, the impacts of each variable on the permanent strain were evaluated, as discussed here in detail. Based on the findings of this research, it is concluded that for various loading patterns, the permanent deformation caused by the tridem axles can be greater than that caused by single and tandem axles, and under tandem axles it can be greater than that under single axles; the effects are dependent on the loading duration indeed. Also, this study showed that the impact of pulse duration on the changing trend of permanent strain is dependent on loading pattern and stress level.

Download or read book Permanent Deformation Characteristics of Asphalt Concrete written by David Brian McLean and published by . This book was released on 1974 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Engineering Properties of Asphalt Mixtures and the Relationship to Their Performance written by Gerald A. Huber and published by ASTM International. This book was released on 1995 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thirteen papers presented at the conference on [title], held in Phoenix, Arizona, December, 1994, discuss the products of the strategic highway research program, the Superpave method of mix design, and test methods for fatigue cracking and permanent deformation. Lacks an index. Annotation c. by Book

Download or read book Tensile Properties of Asphalt Films written by Umanath Sharan and published by . This book was released on 1965 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The object of the investigation was to study the behaviour of two asphalts in tension. These two asphalts were of the same penetration grade and used on two different sections of Highway 57A of the Province of Alberta. Although the pavement placement conditions were almost identical, the frequency of transverse cracking was very different. Since tensile stresses induced in the asphalt pavement are resisted or relieved by the asphalt binder, the tensile stress-strain properties of the asphalts recovered from the pavements were investigated. The effect of the rate of strain, film thickness and temperatures on the asphalt specimens were studied. Simple devices for recording the load-deformation characteristic of asphalt films were designed and fabricated. The tests indicated that the stress-strain characteristics of the two asphalts were not the same. Asphalt used in the cracked section developed more stress for the same amount of strain than the asphalt used in the uncracked section at all temperatures. The stiffness modulus of the material from the cracked section was greater than that of the latter at all temperatures and rates of strain. It is therefore concluded that asphalts having higher stiffness modulii are more likely to exhibit cracking in a pavement. The major recommendations are to investigate the tensile strength properties of more asphalt binders as well as asphalt mixtures of cracked and uncracked areas.

Download or read book Structural Behavior of Asphalt Pavements written by Lijun Sun and published by Butterworth-Heinemann. This book was released on 2016-08-09 with total page 1072 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural Behavior of Asphalt Pavements provides engineers and researchers with a detailed guide to the structural behavioral dynamics of asphalt pavement including: pavement temperature distribution, mechanistic response of pavement structure under the application of heavy vehicles, distress mechanism of pavement, and pavement deterioration performance and dynamic equations. An authoritative guide for understanding the key mechanisms for creating longer lasting pavements, Structural Behavior of Asphalt Pavements describes the intrinsic consistency between macroscopic performance and microscopic response, structure and material, as well as global and local performances, and demonstrates the process of pavement analyses and designs, approaching science from empirical analyses. - Analyzes the external and internal factors influencing pavement temperature field, and provide a review of existing pavement temperature prediction models - Introduces a "Bridge Principle through which pavement performance and fatigue properties are consolidated - Defines the intrinsic consistency between macroscopic performance and microscopic response, structure and material, as well as global and local performance - Summaries the mechanistic response of pavement structure under the application of heavy vehicle, distress mechanism of pavement, pavement deterioration performance and dynamic equations, and life cycle analysis of pavement

Download or read book Introduction to Unmanned Aircraft Systems Second Edition written by Douglas M. Marshall and published by CRC Press. This book was released on 2015-10-26 with total page 1944 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proliferation of technological capability, miniaturization, and demand for aerial intelligence is pushing unmanned aerial systems (UAS) into the realm of a multi-billion dollar industry. This book surveys the UAS landscape from history to future applications. It discusses commercial applications, integration into the national airspace system (NAS), System function, operational procedures, safety concerns, and a host of other relevant topics. The book is dynamic and well-illustrated with separate sections for terminology and web- based resources for further information.