Download or read book A Coupled Micromechanical Model of Moisture induced Damage in Asphalt Mixtures written by Silvia Caro Spinel and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The deleterious effect of moisture on the structural integrity of asphalt mixtures has been recognized as one of the main causes of early deterioration of asphalt pavements. This phenomenon, usually referred to as moisture damage, is defined as the progressive loss of structural integrity of the mixture that is primarily caused by the presence of moisture in liquid or vapor state. Moisture damage is associated with the development of different physical, mechanical, and chemical processes occurring within the microstructure of the mixture at different intensities and rates. Although there have been important advancements in identifying and characterizing this phenomenon, there is still a lack of understanding of the damage mechanisms occurring at the microscopic level. This situation has motivated the research work reported in this dissertation. The main objective of this dissertation is to formulate and apply a numerical micromechanical model of moisture-induced damage in asphalt mixtures. The model focuses on coupling the effects of moisture diffusion-one of the three main modes of moisture transport within asphalt mixtures-with the mechanical performance of the microstructure. Specifically, the model aims to account for the effect of moisture diffusion on the degradation of the viscoelastic bulk matrix of the mixture (i.e., cohesive degradation) and on the gradual deterioration of the adhesive bonds between the aggregates and the asphalt matrix (i.e., adhesive degradation). The micromechanical model was applied to study the role of some physical and mechanical properties of the constitutive phases of the mixtures on the susceptibility of the mixture to moisture damage. The results from this analysis suggest that the diffusion coefficients of the asphalt matrix and aggregates, as well as the bond strength of the aggregate-matrix interface, have the most influence on the moisture susceptibility of the mixtures. The micromechanical model was further used to investigate the influence of the void phase of asphalt mixtures on the generation of moisture-related deterioration processes. Two different probabilistic-based approaches were used to accomplish this objective. In the first approach, a volumetric distribution of air void sizes measured using X-Ray Computed Tomography in a dense-graded asphalt mixture was used to generate probable void structures in a microstructure of an asphalt mixture. In the second approach, a stochastic modeling technique based on random field theory was used to generate probable air void distributions of the mixture. In this second approach, the influence of the air void was accounted for by taking the physical and mechanical properties of the asphalt matrix dependent on probable void distributions. Although both approaches take into consideration the characteristics of the air void phase on the mechanical response of the mixtures subjected to moist environments, the former explicitly introduces the air phase within the microstructure while the latter indirectly includes its effects by modifying the material properties of the bulk matrix. The results from these simulations demonstrated that the amount, variability and location of air voids are decisive in determining the moisture-dependent performance of asphalt mixtures. The results from this dissertation provide new information on the kinetics of moisture damage mechanisms in asphalt mixtures. In particular, the results obtained from applying the micromechanical model permitted identification of the relative influence of the characteristics of the constitutive phases of a mixture on its moisture-related mechanical performance. This information can be used as part of design methodologies of asphalt mixtures, and/or as an input in life-cycle analysis models and maintenance programs of road infrastructure.

Download or read book A Continuum Coupled Moisture mechanical Constitutive Model for Asphalt Concrete written by Maryam Shakiba and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The presence and flow of moisture degrade engineering properties of asphalt concrete as part of thermodynamic, chemical, physical, and mechanical processes. This detrimental effect is referred to as moisture damage. The aim of this dissertation is the development of physically based constitutive relationships along with a computational tool for the fundamental analysis of combined mechanical and moisture induced damage of asphalt concrete. Such a tool can greatly contribute to an improved material selection procedure and give insight into the various damage inducing mechanisms in asphalt concrete. In this dissertation, thermo-hygro-mechanical constitutive relationships are developed based on the principle of virtual power and laws of thermodynamics in order to simulate moisture-induced damage of asphalt concrete. An evolution function is proposed to consider the detrimental effect of moisture diffusion and presence inside the material. The effect of pore water pressure is incorporated using Biot's coefficient. The Continuum Damage Mechanics (CDM) theory is extended to Continuum Moisture-Mechanical Damage Mechanics (CMMDM) to incorporate the moisture degradation effect and couple it to the mechanical response of asphalt concrete. The proposed moisture damage constitutive relationships are implemented in the Pavement Analysis using Nonlinear Damage Approach (PANDA) finite element (FE) package to model the moisture damage effect on the complex environmental-mechanical response of asphalt concrete. The developed constitutive relationship and framework are validated over different loading scenarios and a range of experimental measurements. The developed constitutive relationship and framework are applied to simulate pavement performance. The focus is on investigating the effects of various moisture conditioning periods on permanent deformation (rutting) and fatigue damage of asphalt pavements. The constitutive and computational models are used to develop a framework for the simulation of the effect of moisture on the microstructural response of asphalt concrete. This framework explicitly incorporates the material microstructural distribution and properties. The developed framework is used to perform two-dimensional (2D) and three-dimensional (3D) micromechanical simulations in order to study and investigate the capability of the proposed constitutive relationships to predict the microstructural response of asphalt concrete under combined effect of moisture diffusion and mechanical loading. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151963

Download or read book Advances in Unsaturated Soils written by Bernardo Caicedo and published by CRC Press. This book was released on 2013-01-17 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: New theories and testing techniques related with Unsaturated Soil Mechanics have proven to be valuable tools to study a broad spectrum of geo-materials which includes rocks, rock fills, frozen soils and domiciliary solid wastes. These new theories and testing techniques have permitted the analysis of several traditional problems from a new perspect

Download or read book Modeling and Design of Flexible Pavements and Materials written by Dallas N. Little and published by Springer. This book was released on 2017-09-25 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook lays out the state of the art for modeling of asphalt concrete as the major structural component of flexible pavements. The text adopts a pedagogy in which a scientific approach, based on materials science and continuum mechanics, predicts the performance of any configuration of flexible roadways subjected to cyclic loadings. The authors incorporate state-of the-art computational mechanics to predict the evolution of material properties, stresses and strains, and roadway deterioration. Designed specifically for both students and practitioners, the book presents fundamentally complex concepts in a clear and concise way that aids the roadway design community to assimilate the tools for designing sustainable roadways using both traditional and innovative technologies.

Download or read book Advances in Asphalt Materials written by Shin-Che Huang and published by Woodhead Publishing. This book was released on 2015-04-08 with total page 493 pages. Available in PDF, EPUB and Kindle. Book excerpt: The urgent need for infrastructure rehabilitation and maintenance has led to a rise in the levels of research into bituminous materials. Breakthroughs in sustainable and environmentally friendly bituminous materials are certain to have a significant impact on national economies and energy sustainability. This book will provide a comprehensive review on recent advances in research and technological developments in bituminous materials. Opening with an introductory chapter on asphalt materials and a section on the perspective of bituminous binder specifications, Part One covers the physiochemical characterisation and analysis of asphalt materials. Part Two reviews the range of distress (damage) mechanisms in asphalt materials, with chapters covering cracking, deformation, fatigue cracking and healing of asphalt mixtures, as well as moisture damage and the multiscale oxidative aging modelling approach for asphalt concrete. The final section of this book investigates alternative asphalt materials. Chapters within this section review such aspects as alternative binders for asphalt pavements such as bio binders and RAP, paving with asphalt emulsions and aggregate grading optimization. Provides an insight into advances and techniques for bituminous materials Comprehensively reviews the physicochemical characteristics of bituminous materials Investigate asphalt materials on the nano-scale, including how RAP/RAS materials can be recycled and how asphalt materials can self-heal and rejuvenator selection

Download or read book An Assessment of Moisture Induced Damage in Asphalt Pavements written by Yar Zar Moe Htet and published by . This book was released on 2015 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Moisture-induced damage is one the major causes of deterioration of asphalt pavements and extensive research has been conducted on this topic. Theoretical and experimental results have led the researchers to believe that moisture-induced damages are caused mainly by the generation of pore water pressure in asphalt mixtures when traffic passes over a pavement. The Moisture Induced Sensitivity Tester (MIST) has been recently developed to simulate the phenomenon of repeated pore pressure generation and deterioration in the laboratory. The objective of this study was to evaluate moisture-induced damage in typical Maine Department of Transportation (DOT) asphalt mixes, with the use of MIST, pre and post testing, and analysis of data. The MIST was used to condition Hot Mix Asphalt (HMA) samples that were compacted from eight typical Maine DOT mixes, with different types of aggregates and asphalt binder. A modified Dynamic modulus test in Indirect Tensile Mode was used for the determination of damage. A layered elastic model, along with a fatigue-cracking criterion, was utilized to assess the total impact on the pavement lives. Monte Carlo analysis was conducted to determine the distribution of number of repetitions to failure of pavements that are subjected to moisture damage. The major conclusions are that most of the mixes are likely to experience a reduction in their life due to the effect of moisture and that the Micro-Deval and the fine aggregate absorption test results can be related to such damage. A composite factor, consisting of both of these test results, is recommended for regular use by the DOT to screen mixes with high moisture damage potential.

Download or read book Handbook of Research on Advanced Computational Techniques for Simulation Based Engineering written by Samui, Pijush and published by IGI Global. This book was released on 2015-11-30 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent developments in information processing systems have driven the advancement of computational methods in the engineering realm. New models and simulations enable better solutions for problem-solving and overall process improvement. The Handbook of Research on Advanced Computational Techniques for Simulation-Based Engineering is an authoritative reference work representing the latest scholarly research on the application of computational models to improve the quality of engineering design. Featuring extensive coverage on a range of topics from various engineering disciplines, including, but not limited to, soft computing methods, comparative studies, and hybrid approaches, this book is a comprehensive reference source for students, professional engineers, and researchers interested in the application of computational methods for engineering design.

Download or read book Influence of Moisture on Bond Strength of Asphalt aggregate Systems written by Audrey R. Copeland and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Moisture is a major source of degradation of hot mix asphalt (HMA) used in highway pavements. Moisture damage occurs when there is a loss of bond either at the asphalt-aggregate interface or within the asphalt mastic. The presence of moisture may strip asphalt binder from the aggregate (adhesive failure) and/or weaken the asphalt mastic (cohesive failure) resulting in pavement cracking and deformation. Bond strength is determined via a direct tensile test utilizing the Pneumatic Adhesion Tensile Testing Instrument (PATTI). The usefulness of the direct tensile test is determined for asphalt binders and mastics and the influence of moisture on tensile strength of asphalt binders and mastics and between asphalt and aggregate pairs is evaluated. The results of the experiments verify that moisture degrades the bond strength of asphalt binders, mastics, and between asphalt and aggregate. Results from the direct tensile test experiments are then linked to moisture diffusion simulations and bond strength degradation as a function of the amount of moisture at the asphalt-aggregate interface is established. Based on this relationship, the amount of damage that occurs over time in regards to the amount of moisture at the interface is quantified. Finally, limit-state based reliability analysis concepts are introduced to formulate a performance criterion for moisture-induced damage of asphalt-aggregate systems. The moisture-induced damage parameter is an integral part of a larger framework developed for predicting moisture-induced damage in asphalt mixtures.

Download or read book Moisture Damage in Asphalt Concrete written by Russell G. Hicks and published by Transportation Research Board. This book was released on 1991 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This synthesis will be of interest to pavement designers, construction engineers, maintenance engineers, and others interested in avoiding or limiting moisture damage in asphalt concrete. Information is provided on physical and chemical explanations for moisture damage in asphalt concrete, along with a discussion of current practices and test methods for determining or reducing the susceptibility of various asphalt concrete components and mixtures to such damage. Moisture damage in asphalt concrete is a nationwide problem which often necessitates premature replacement of highway pavement surfaces. This report of the Transportation Research Board describes the underlying physical and chemical phenomena responsible for such damage. Current test methods used to determine the susceptibility of asphalt concretes, or their constituents, to moisture damage are described and evaluated. Additionally, current practices for minimizing the potential for moisture damage are examined.

Download or read book Physically Based Model for Predicting the Susceptibility of Asphalt Pavements to Moisture induced Damage written by Rashid Kamel Abu Al-Rub and published by . This book was released on 2010 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling of Combined Physical mechanical Moisture Induced Damage in Asphaltic Mixes written by Niki Kringos and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Moisture Damage in Asphalt Mixtures written by K. D. Stuart and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Procedures Used to Predict Moisture Damage in Asphalt Mixtures written by Kevin D. Stuart and published by . This book was released on 1986 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Procedures for evaluating the moisture susceptibility of asphalt mixtures were compared by performing them on mixtures having a known history of susceptibility. Data included the retained ratios, visual stripping, mechanical values (tensile strength, stability, etc.), saturation, and swell. The most promising procedures appeared to be the NCHRP 246 and NCHRP 274.

Download or read book Stripping and Moisture Damage in Asphalt Mixtures written by Robert Benton McGennis and published by . This book was released on 1984 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Critical Behavior of Asphalt Mixtures Undergoing Glass Transition and Physical Hardening written by and published by . This book was released on 2012 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study a device was developed that simultaneously tests two asphalt mixture beams; one unrestrained, and the other with restrained ends. The unrestrained beam is used to measure the one dimensional change of length with temperature, and consequently the glass transition temperature (Tg) and coefficients of expansion/contraction above and below the Tg. The restrained beam is used to capture the induced thermal stress buildup due to prevented contraction in the sample. The device, referred to as the Asphalt Thermal Cracking Analyzer (ATCA), was used to show how asphalt mixtures undergo isothermal contraction and physical hardening, and the consequences of this behavior for the buildup of thermal stress. A prediction model for the rate of physical hardening at different temperatures and conditioning times was developed based on a creep viscoelastic model, and was used to predict changes in binder stiffness and relaxation rate during isothermal conditioning. The model was then extended to mastics and a conversion factor was derived to shift results for applicability to asphalt mixture thermal strain calculation. The physical hardening model of binders was coupled with relaxation modulus master curves and glass transition measurements to propose a model for the calculation of thermal stress buildup in mixtures as a continuous function of conditioning time and temperature. The model was validated using an elaborate set of experimentally derived input properties for a number of mixtures at different cooling rates. An experimentally calibrated multiphase micro-mechanical model for asphalt mixture undergoing thermal shrinkage and glass transition was also developed in a finite element platform. The results where compared to experimental data measured using the ATCA device, which allowed measuring strain and stress build up during cooling. The results of this study indicate that physical hardening of binders has important effects on the thermal stress and thermal strain accumulation in mixtures during cooling cycles. Failure to consider this time dependent behavior, which varies among binders, could lead to failure in predicting performance. The existing modulus and strain used in predicting thermal cracking of asphalt pavements need revisions to integrate a function for the time dependent changes.

Download or read book Interpretation of Moisture Damage in Asphalt Mixtures Using Existing and Alternative Test Methods written by Shivpal Yadav and published by . This book was released on 2020 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Materials and Pavement Performance Prediction II written by K. Anupam and published by CRC Press. This book was released on 2020-12-08 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inspired from the legacy of the previous four 3DFEM conferences held in Delft and Athens as well as the successful 2018 AM3P conference held in Doha, the 2020 AM3P conference continues the pavement mechanics theme including pavement models, experimental methods to estimate model parameters, and their implementation in predicting pavement performance. The AM3P conference is organized by the Standing International Advisory Committee (SIAC), at the time of this publication chaired by Professors Tom Scarpas, Eyad Masad, and Amit Bhasin. Advances in Materials and Pavement Performance Prediction II includes over 111 papers presented at the 2020 AM3P Conference. The technical topics covered include: - rigid pavements - pavement geotechnics - statistical and data tools in pavement engineering - pavement structures - asphalt mixtures - asphalt binders The book will be invaluable to academics and engineers involved or interested in pavement engineering, pavement models, experimental methods to estimate model parameters, and their implementation in predicting pavement performance.