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 Sustainable Designed Pavement Materials Volume 2 written by Yue Xiao and published by MDPI. This book was released on 2020-12-06 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue “Sustainable Designed Pavement Materials” has been proposed and organized as a means to present recent developments in the field of environmentally-friendly designed pavement materials. For this reason, articles included in this special issue relate to different aspects of pavement materials, from industry solid waste recycling to pavement materials recycling, from pavement materials modification to asphalt performance characterization, from pavement defect detection to pavement maintenance, and from asphalt pavement to cement concrete pavement.

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 Modeling of Hot mix Asphalt Compaction written by and published by . This book was released on 2010 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Manual for Design of Hot Mix Asphalt with Commentary written by and published by Transportation Research Board. This book was released on 2011 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of Aggregate Texture and Its Influence on Hot Mix Asphalt HMA Permanent Deformation written by T. Fletcher and published by . This book was released on 2002 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aggregate shape has a significant effect on the performance of asphalt mixes. Designing well-performing asphalt pavements requires developing methods to quantify rapidly and accurately the different aggregate shape properties, and most importantly, relate these properties to performance. Aggregate texture has been identified in several studies to be the shape property that has the most significant influence on asphalt mix performance. This study presents a new procedure for measuring aggregate texture using image analysis techniques. The main advantages of this new procedure are the ability to capture the different sizes of texture elements, to separate the true texture from the color variations on the aggregate surface, and to characterize both fine and coarse aggregates. The procedure is used to measure texture for a wide range of fine and coarse aggregates, and the results are compared with the laboratory performance of asphalt mixes. The analysis shows that the procedure yields detailed information on aggregate texture in a short time. The texture measurements have very good correlation with the resistance of asphalt mixes to permanent deformation measured in the laboratory using different wheel tracking devices.

Download or read book Influence of Aggregate Gradation and Particle Shape texture on Permanent Deformation of Hot Mix Asphalt Pavements written by Randolph C. Ahlrich and published by . This book was released on 1995 with total page 464 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 Evaluation of Permanent Deformation Characteristics of Hot Mix Asphalt Mixtures Using Superpave Technology written by William Marty McNamara and published by . This book was released on 1999 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Permanent Deformation of Asphalt Mixtures written by Patrick Mwangi Muraya and published by . This book was released on 2016-04-22 with total page 280 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 Prediction of Permanent Deformation in Asphalt Mixtures written by Hasan Al-Mosawe and published by . This book was released on 2017-11-04 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Rutting Potential in Asphalt Mixes Using Finite Element Modeling written by and published by . This book was released on 2003 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quality of asphalt mix (HMA) is one of the main factors that affects the flexible pavement performance. Use of poor quality mix and finding their consequences through pavement performance evaluation is often too costly. Therefore, the remedy is to evaluate the quality of the mix at the design stage of a project. In recent years, performance-based testing has gained popularity so that problematic mixes can be identified and eliminated. Asphalt Pavement Analyzer (APA) has been successfully used in recent years for evaluation of permanent deformation or rutting in both hot mix and cold mix asphalt specimens. In view of layered pavement systems encountered in practice, three-dimensional finite element models (FEM) can be used to relate the APA test results with the in-service performance of the pavement. The primary objectives of this study are to develop a finite element model to simulate the laboratory testing of asphalt mixes in APA for rutting and to relate the test results to basic material properties. For the covering abstract of this conference see ITRD number E211395.

Download or read book Proceedings of the RILEM International Symposium on Bituminous Materials written by Hervé Di Benedetto and published by Springer Nature. This book was released on 2021-09-25 with total page 1806 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume highlights the latest advances, innovations, and applications in bituminous materials and structures and asphalt pavement technology, as presented by leading international researchers and engineers at the RILEM International Symposium on Bituminous Materials (ISBM), held in Lyon, France on December 14-16, 2020. The symposium represents a joint effort of three RILEM Technical Committees from Cluster F: 264-RAP “Asphalt Pavement Recycling”, 272-PIM “Phase and Interphase Behaviour of Bituminous Materials”, and 278-CHA “Crack-Healing of Asphalt Pavement Materials”. It covers a diverse range of topics concerning bituminous materials (bitumen, mastics, mixtures) and road, railway and airport pavement structures, including: recycling, phase and interphase behaviour, cracking and healing, modification and innovative materials, durability and environmental aspects, testing and modelling, multi-scale properties, surface characteristics, structure performance, modelling and design, non-destructive testing, back-analysis, and Life Cycle Assessment. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster new multidisciplinary collaborations.

Download or read book Prediction of Asphalt Mixture Compactability from Mixture Asphalt and Aggregate Properties written by Andrew James Muras and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The underlying purpose of any pavement is to provide a safe, smooth and reliable surface for the intended users. In the case of hot mix asphalt (HMA) pavements, this includes producing a surface that is resistant to the principal HMA distress types: permanent deformation (or rutting) and fatigue damage (or cracking). To protect better against these distress types, there have recently been changes in HMA mixture design practice. These changes have had the positive effect of producing more damage resistant mixtures but have also had the effect of producing mixtures that require more compaction effort to obtain required densities. It is important to understand what properties of an HMA mixture contribute to their compactability. This study presents analysis of the correlation between HMA mixture properties and laboratory compaction parameters for the purpose of predicting compactability. Mixture property data were measured for a variety of mixtures; these mixtures were compacted in the laboratory and compaction parameters were collected. A statistical analysis was implemented to correlate the mixture data to the compaction data for the purpose of predicting compactability. The resulting model performs well at predicting compactability for mixtures that are similar to the ones used to make the model, and it reveals some mixture properties that influence compaction. The analysis showed that the binder content in an HMA mixture and the slope of the aggregate gradation curve are important in determining the compactability of a mixture.

Download or read book A New Mix confined Repeated Load Test for Evaluating Permanent Deformation of Asphalt Mixture written by G. Y. Liao and published by . This book was released on 2012 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Existing tests for evaluating the permanent deformation of an asphalt mixture have many problems, such as the fixed confining pressure for repeated load triaxial tests (RLTTs). The main objectives of this paper are to develop a new "mix-confined" test and to compare the accuracy and sensitivity of this test with those of RLTTs. A new mix-confined repeated load test (MCRLT) is developed to measure the permanent deformation of two types of test specimens, including field cores extracted from asphalt pavement and lab-mixed specimens. The accuracy and sensitivity of the MCRLT are compared with those of an RLTT. The results show that during the MCRLT the test specimen can provide some (but not enough) confining pressure itself (so-called mix-confined). MCRLTs have slightly higher accuracy and lower sensitivity than RLTTs. The MCRLT can be a good alternative to the RLTT for evaluating the permanent deformation of asphalt mixtures, especially when there is no RLTT equipment available.

Download or read book Effect of Laboratory Compaction Method on Permanent Deformation Characteristics of Asphalt aggregate Mixtures written by and published by . This book was released on 1991 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: