Download or read book Permanent Deformation Response of Conventional and Modified Asphalt aggregate Mixtures Under Simple and Compound Shear Loading Conditions written by Alejandro José Tanco and published by . This book was released on 1992 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Permanent Deformation Response of Asphalt Aggregate Mixes written by Christine W. Curtis and published by National Research Council. This book was released on 1994 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the research conducted on permanent deformation of asphalt concrete mixes as part of the SHRP Asphalt Research Program. Divided into three sections the report addresses the following: the development of a series of accelerated performance tests to measure the permanent deformation response and a constitutive relationship to define it; validation of the binder properties included in the SHRP binder specification; and the use of the test methodology in an asphalt concrete mix design and analysis system.
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 of Asphalt Concrete Pavements written by Fenella Margaret Long and published by . This book was released on 2001 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Asphalt Paving Technology written by Association of Asphalt Paving Technologists and published by . This book was released on 2001 with total page 1004 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Permanent Deformation Characteristics of Binder aggregate Mixtures Containing Conventional Asphalts and Modified Asphalt Binders written by Alejandro José Tanco and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Report written by University of California, Berkeley. Institute of Transportation Studies and published by . This book was released on 1991 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Conventional Aggregates and Modified Asphalt Mixes Using the Marshall Method written by Joseph D. Armijo and published by . This book was released on 1990 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is phase I of a 3 part study. The purpose of the project is to study the permanent deformation characteristics of binder-aggregate mixtures containing conventional asphalt and modified asphalt binders subjected to repetitive applications of stresses resulting from increased tire pressure associated with increased truck axle loads and the use of radial tires.
Download or read book Viscoelastic and Permanent Deformation Characteristics of Asphalt Aggregate Mixes Tested as Hollow Cylinders and Subjected to Dynamic Axiel and Shear Loads written by Sirous Heydari Alavi and published by . This book was released on 1992 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laboratory based Unified Permanent Deformation Model for Hot Mix Asphalt Mixtures written by Elie Y. Hajj and published by . This book was released on 2007 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conventionally, the resistance of hot-mixed asphalt (HMA) mixtures to permanent deformation is measured by repeated load triaxial (RLT) or repeated shear at constant height (RSCH) testing. The data from these tests have been treated as independent datasets in the prediction of rutting potential in HMA layers. This paper presents a unified permanent deformation model using response measurements made from both tests. The new model quantifies the accumulated permanent shear strain as a function of number of load cycles and factor of safety (FOS). The factor of safety is defined in the q-p space and is evaluated based on the applied stresses and triaxial compression strength properties (cohesion and angle of internal friction). For the specific mixture used in this study, a good correlation was found between the cumulative permanent shear strain and the FOS level, irrespective of the stress conditions and the type of test used.
Download or read book Relationships Between Modified Asphalt Binders Rheology and Binder Aggregate Mixture Permanent Deformation Response written by and published by . This book was released on 1991 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Permanent Deformation Correlations Between Different Modes of Shearing in Asphalt Mixes written by Kyle Imhoff and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rutting is permanent deformation that develops by shear deformation and densification of repeated loading in the wheel path. Current performance testing devices for predicting rutting include the Asphalt Mixture Performance Tester (AMPT), Simple Shear Tester (SST), and the Dynamic Shear Rheometer (DSR). Testing along with empirical performance correlation will help predict rutting resistance of a pavement. Performance related testing for rutting, fatigue and stiffness of asphalt mixes gives the mix and pavement designer much better information to optimize a mix or pavement design than is available from current mix design tests. This study looked to correlate data from unconfined Repeated Load Triaxial (RLT) tests executed in the AMPT that are simple, inexpensive and quick to perform with the more complex, expensive, and time consuming Repeated Simple Shear Test at Constant Height (RSST-CH) which is performed in the SST. An alternative method is to look at the corresponding Fine Aggregate Matrix (FAM) phase of a mix to predict its behavior in a cheaper, faster, and reproducible manner. FAM mixes consist of asphalt binder, fine aggregates, and air voids and specimens are generally around 50mm long with a diameter of 12mm to facilitate testing in a DSR. This study began to investigate a relationship between unconfined RLT tests and FAM Repeated Creep Recovery (RCR) tests done in the DSR. The FAM RCR test, AMPT RLT test and the RSST-CH all subject specimens to different types of loading to measure a permanent strain, which is torsional, axial and direct shear, respectively. It was found that there is not a single shift factor that can be used to correlate between the different shearing modes of the different tests. Further investigation into the effects of the different modes of shearing may be necessary to capture the correlation.
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 Implication of Aggregates in the Design Construction and Performance of Flexible Pavements written by Hans G. Schreuders and published by ASTM International. This book was released on 1989 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Aggregates and Mineral Fillers on Asphalt Mixture Performance written by Richard C. Meininger and published by ASTM International. This book was released on 1992 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Resulting from the Symposium on [title], held in December 1991, at the ASTM Standardization Meetings in San Diego, this volume comprises 19 papers in four sections: aggregates; mineral fillers; mixture evaluation; and fatigue, modeling, and theoretical. Member price, $52. Annotation copyright Book N
