Download or read book Verification of Mechanistic Prediction Models for Permanent Deformation in Asphalt Mixes Using Accelerated Pavement Testing written by Mbakisya A. Onyango and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Permanent deformation (rutting) is the most critical load-associated distress that develops on asphalt pavements significantly affecting their performance. Past research work focused on estimating permanent deformation of asphalt mixes using empirical prediction models or prediction models based on linear elastic material models. In recent years, mechanistic and mechanistic-empirical prediction models have been developed to take into account the behavior of asphalt material (viscoelastic, viscoplastic or elasto-visco-plastic). This research project aims to evaluate existing mechanistic models that predict permanent deformation (rutting) in asphalt mixes by comparing computed permanent deformation to that measured in a full-scale accelerated pavement test. Six pavement sections were constructed in the Civil Infrastructure Systems Laboratory (CISL) of Kansas State University with six different asphalt mixes. The sections were loaded with up to 700,000 load repetitions of a 22,000lb single axle. The transverse profiles at the pavement surface were measured periodically. For material characterization, asphalt mix samples fabricated in the laboratory, were subjected to dynamic modulus (E*), static creep - flow time (Ft), dynamic creep - flow number (Fn), triaxial and uniaxial strength tests, repetitive shear at constant height (RSCH) and frequency sweep at constant height (FSCH). The finite element software, Abaqus, was used to simulate and evaluate four permanent deformation prediction models, which are: creep model, elasto-visco-plastic model, viscoelastic model and Drucker-Prager model. The predicted permanent deformation was then compared to permanent deformation measured in CISL for the six of asphalt pavement sections. It was found that, with some improvements, creep and elasto-visco-plastic models could be used to predict permanent deformation in asphalt mixes. The viscoelastic model greatly under-predict permanent deformation, and the Drucker-Prager model with hardening criteria over predicts permanent deformation as compared to values measured in CISL.
Download or read book Development and Validation of Performance Prediction Models and Specifications for Asphalt Binders and Paving Mixes written by Robert L. Lytton and published by Strategic Highway Research Program (Shrp). This book was released on 1993 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: A result of the Strategic Highway Research Program's asphalt research is the development of performance-based specifications for asphalt binders and mixtures to control 3 distress modes: rutting; fatigue cracking; and thermal cracking. The SHRP A-005 project developed detailed pavement performance models to support these binder and mixture specifications and performance-based mixture designs. This report documents the findings of this extensive research effort and provides supporting data for the performance-based specifications and mixture design procedure called SUPERPAVE. The A-005 contract developed and used a sophisticated, mechanistic-based pavement performance model to define the relationships between asphalt binder and mixture properties and pavement distress. A comprehensive pavement performance model was developed that predicts the amount of fatigue cracking, thermal cracking and rutting in asphalt concrete pavements with time, using results from the accelerated laboratory tests. The pavement performance models for each distress were also used to confirm the relevant binder and mixture properties established by other SHRP contractors. The model has 3 parts: a mixture evaluation model; a pavement response model; and a pavement distress model.
Download or read book Advances in Pavement Design through Full scale Accelerated Pavement Testing written by David Jones and published by CRC Press. This book was released on 2012-10-08 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pack: Book and CDInternationally, full-scale accelerated pavement testing, either on test roads or linear/circular test tracks, has proven to be a valuable tool that fills the gap between models and laboratory tests and long-term experiments on in-service pavements. Accelerated pavement testing is used to improve understanding of pavement behavior,
Download or read book Calibrating Mechanistic Empirical Design Guide Permanent Deformation Models Based on Accelerated Pavement Testing written by Feng Hong and published by . This book was released on 2009 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the challenges to the implementation of the mechanistic-empirical pavement design guide (MEPDG) comes from calibrating the transfer functions. This paper focuses on calibration of one of the major distress models in flexible pavement: permanent deformation or rutting. Two key aspects are critical to a successful rutting model calibration: data and method. Regarding the data, existing in-field information only provides total rut depth, which could not meet the requirement of permanent deformation in each structural layer by the MEPDG. Concerning the method, existing work either fails to address calibration factors from a holistic perspective by only focusing on individual sections separately or ignores variability inherent in those factors. In this study, layer-wise permanent deformation from instrumented pavement under accelerated pavement testing serves to accommodate the models calibration. A systematic calibration procedure is established, which globally optimizes all available information across all test sections. Through simulation and numerical optimization, optimal calibration shift factors for three typical flexible pavement materials, asphalt mixture, unbound granular base, and finegrain soil are obtained as 0.60, 0.49, and 0.84, respectively. This implies that the uncalibrated MEPDG is biased toward overprediction of rut depth. It is further suggested that a more rational result for each calibrated factor is to introduce an appropriate distribution to characterize its uncaptured variability. In addition, a case study involving using calibrated MEPDG to predict pavement performance or life indicates that (1) model calibration has a significant impact on the prediction and (2) the "fourth power law" is supported by the MEPDG.
Download or read book Significant Findings from Full scale Accelerated Pavement Testing written by Wynand JvdM. Steyn and published by Transportation Research Board. This book was released on 2012 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: "TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 433: Significant Findings from Full-Scale Accelerated Pavement Testing documents and summarizes significant findings from the various experimental activities associated with full-scale accelerated pavement testing (f-sAPT) programs that have taken place between 2000 and 2011. The report also identifies gaps in knowledge related to f-sAPT and where future research may be needed. NCHRP Synthesis 433 is designed to expand the f-sAPT base of knowledge documented in NCHRP Syntheses 325 and 235, both with the same title of Significant Findings from Full-Scale Accelerated Pavement Testing. f-sAPT is the controlled application of a wheel loading, at or above the appropriate legal load limit, to a pavement system to determine pavement response in a compressed time period. The acceleration of damage is achieved by one or more of the following factors: increased repetitions, modified loading conditions, imposed climatic conditions, and thinner pavements with a decreased structural capacity which have shorter design lives"--
Download or read book Accelerated Performance related Tests for Asphalt aggregate Mixes and Their Use in Mix Design and Analysis Systems written by University of California, Berkeley and published by National Research Council. This book was released on 1994 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report provides a brief summary of the processes that led to the selection of performance-related tests to define asphalt-aggregate interactions that result in fatigue, permanent deformation, thermal cracking, aging, and water sensitivity. Inherent in this test selection process was the emphasis on the ability of the tests to measure fundamental material properties that, when incorporated into prediction models, will depend less on empirical correlations than has been traditionally the case. Also included are the results of validation studies for each of the tests and frameworks for the use of the tests in mix design and analysis. Several levels of design are provided for each distress, some of which incorporate reliability 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 Significant Findings from Full scale Accelerated Pavement Testing written by Frederick Hugo and published by Transportation Research Board. This book was released on 2004 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 325: Significant Findings from Full-Scale Accelerated Pavement Testing documents and summarizes the findings from the various experimental activities associated with full-scale accelerated pavement testing programs.
Download or read book The Roles of Accelerated Pavement Testing in Pavement Sustainability written by José P. Aguiar-Moya and published by Springer. This book was released on 2016-09-15 with total page 877 pages. Available in PDF, EPUB and Kindle. Book excerpt: This compendium gathers the latest advances in the area of Accelerated Pavement Testing (APT), a means of testing full-scale pavement construction in an accelerated manner for structural deterioration in a very short term. Compiling novel research results presented at the 5th International Conference on Accelerated Pavement Testing, San Jose, Costa Rica, the volume serves as a timely and highly relevant resource for materials scientists and engineers interested in determining the performance of a pavement structure during its service life (10+ years) in a few weeks or months.
Download or read book Evaluation of Flow Number Fn as a Discriminating HMA Mixture Property written by Ramon Francis Bonaquist and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Materials and Pavement Prediction written by Eyad Masad and published by CRC Press. This book was released on 2018-07-16 with total page 879 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Materials and Pavement Performance Prediction contains the papers presented at the International Conference on Advances in Materials and Pavement Performance Prediction (AM3P, Doha, Qatar, 16- 18 April 2018). There has been an increasing emphasis internationally in the design and construction of sustainable pavement systems. Advances in Materials and Pavement Prediction reflects this development highlighting various approaches to predict pavement performance. The contributions discuss links and interactions between material characterization methods, empirical predictions, mechanistic modeling, and statistically-sound calibration and validation methods. There is also emphasis on comparisons between modeling results and observed performance. The topics of the book include (but are not limited to): • Experimental laboratory material characterization • Field measurements and in situ material characterization • Constitutive modeling and simulation • Innovative pavement materials and interface systems • Non-destructive measurement techniques • Surface characterization, tire-surface interaction, pavement noise • Pavement rehabilitation • Case studies Advances in Materials and Pavement Performance Prediction will be of interest to academics and engineers involved in pavement engineering.
Download or read book Prediction of Permanent Deformation in Flexible Pavement Materials written by RL. Lytton and published by . This book was released on 1989 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a method to predict the permanent deformation (rutting) in pavements using a mechanistic-empirical model of material characterization. Three permanent deformation parameters are developed through material testing to simply represent the curved relationship between permanent strains and the number of load cycles. Equations are developed by regression analysis which determine how these three parameters are affected by the material properties, environmental conditions (moisture and temperature), and stress state. These relations are important in calculating the permanent deformation of pavement layers since the relation between permanent deformation and cycles of load from the laboratory is usually examined in test conditions that are significantly different from field conditions. The permanent deformations calculated from the method presented are compared with results measured in the field in Florida and are found to be accurate.
Download or read book AASHTO Guide for Design of Pavement Structures 1993 written by American Association of State Highway and Transportation Officials and published by AASHTO. This book was released on 1993 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design related project level pavement management - Economic evaluation of alternative pavement design strategies - Reliability / - Pavement design procedures for new construction or reconstruction : Design requirements - Highway pavement structural design - Low-volume road design / - Pavement design procedures for rehabilitation of existing pavements : Rehabilitation concepts - Guides for field data collection - Rehabilitation methods other than overlay - Rehabilitation methods with overlays / - Mechanistic-empirical design procedures.
Download or read book Micromechanical and Probabilistic Approaches to Improve Asphalt Concrete Rutting Performance Prediction Procedures written by Erdem Coleri and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rutting is the load induced permanent deformation of pavements with asphalt concrete (AC) layers. Rutting can occur in the unbound layers of the pavement and in the AC surface layers, the latter of which is the focus of this thesis. The risk of rutting in the AC layers is highest just after construction and then generally diminishes as the materials harden due to traffic and environmental aging. AC rutting has a large impact on life cycle cost because it mostly occurs at the beginning of the life cycle and because failure by rutting often requires removal and replacement of the affected layers or other costly remedial construction, which makes rutting a crucial consideration. Although rutting performance of AC pavements has been characterized by various studies, there has been little study of the effects of AC micromechanical structure on in-situ rutting deformation accumulation mechanisms. In addition, the analysis of the predicted pavement performance variability and the development of a reliability-based design method considering all significant sources of variability have been lacking. The goal of this thesis was to explain the rutting accumulation mechanisms for pavements with conventional and modified asphalt mixes and develop a comprehensive rutting performance prediction procedure considering the fundamental material properties, in-situ deformation accumulation mechanisms and the effects of various sources of variability, based on investigation of the fundamental problems in current test methods, structural models and performance prediction procedures. An innovative method was developed to quantify the precision and bias in repeated simple shear test at constant height (RSST-CH) laboratory test results for specimens with different dimensions and to determine the effects of variability on predicted rutting performance. Specimen size requirements for two different asphalt mix types were proposed based on the results of the analysis. The effects of test temperature and specimen volume on test variability were also investigated. A reliability based rutting performance prediction procedure was developed that considers the variability in laboratory test results, layer thicknesses, stiffnesses, and measured in-situ performance. The effects of input design parameter variability on predicted performance were determined using the calculated distributions of calibration coefficients. By using these calibration coefficient distributions, asphalt layer design thicknesses for different reliability levels can be predicted without performing computationally intensive calculations, such as Monte Carlo simulations, facilitating incorporation of reliability into design software. The general procedure developed for specific tests and AC rutting in this thesis can be applied to other distresses. The use of X-ray computed tomography (CT) images was extended from previous work in a new empirical approach developed to investigate the changes in AC microstructure caused by full-scale accelerated pavement testing with a Heavy Vehicle Simulator (HVS), by using images taken before and after HVS rut tests. A viscoelastic micromechanical finite element model was also developed to investigate effects of binder and aggregate properties on shear resistance using the microstructural model developed from the imaging process with laboratory specimens. The approach was used to investigate the differences in performance under full-scale loading of two mixes, one dense graded with polymer modified binder and the other gap-graded with rubberized binder. It was found that shear related deformation appeared to control the long term rutting performance of the AC pavement layers while densification was primarily an initial contributor at the very early stages of the trafficking. A high concentration of aggregate interlock in the polymer modified mix, as a result of the dense gradation and larger aggregate sizes, appears to have resulted in greater dissipation of shear stresses and therefore greater shear resistance. The lack of this interlocking effect for the rubberized gap-graded mix is proposed to have caused the earlier failure in the full-scale HVS test sections. Important differences in aggregate movement and air-void changes were also observed between different overlay thicknesses indicating the depth of the rut phenomenon, important information for the design of overlays on aged AC as well as for asphalt overlays on concrete pavements. Recommendations are proposed to improve design and construction of asphalt surfaced pavements based on these findings.
Download or read book Asphalt Paving Technology 2014 written by Eugene Skok and published by DEStech Publications, Inc. This book was released on 2015-02-10 with total page 777 pages. Available in PDF, EPUB and Kindle. Book excerpt: New developments in asphalt with bio-oil, rubber and polymer componentsEmpirical data and models on binders, aggregates, RAP, WMA, HMA for pavementSpecial section on asphalt paving research in IndiaFully-searchable text on CD-ROM (included) The latest volume of the AAPT series features over two dozen research presentations devoted to the chemistry, engineering, modeling and testing of asphalt materials and processing. Developments in the use of components like bio-oil are discussed, as are strategies for testing asphalt components for wear and durability at low and high temperatures. The book offers new data on the performance of reclaimed/recycled materials in asphalt paving. A special section focuses exclusively on discussions of binder modifications. The CD-ROM displays figures and illustrations in articles in full color along with a title screen and main menu screen. Each user can link to all papers from the Table of Contents and Author Index and also link to papers and front matter by using the global bookmarks which allow navigation of the entire CD-ROM from every article. Search features on the CD-ROM can be by full text including all key words, article title, author name, and session title. The CD-ROM has Autorun feature for Windows 2000 with Service Pack 4 or higher products along with the program for Adobe Acrobat Reader with Search 11.0. One year of technical support is included with your purchase of this product.
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.
