Download or read book NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF MOISTURE TRANSPORT IN ASPHALT MIXTURES written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Water in the asphalt pavement is highly concerning, as it often causes the debonding between asphalt film and aggregate surface or early rutting/fatigue cracking because of reduced mix strength. Moisture transport is the processes that occurs when moisture in liquid or vapor state infiltrates the asphalt binder, through the interface of binder-aggregate, and the asphalt mixture. This dissertation investigated the water permeability of asphalt mixtures in vertical direction, and effect of moisture conditioning on asphalt mixtures. Additionally, relationships between coefficient of permeability, porosity, and air void content of fine-graded hot-mix asphalt were studied. The coefficient of permeability increases as the air void and porosity values increase. After the second moisture conditioning, it was observed that specimens have a reduced porosity and coefficient of permeability. In addition, this dissertation predicted the coefficient of permeability of asphalt mixtures using the Lattice Boltzmann Method (LBM). The numerical method was verified by simulating fluid flow in Poiseuille flow, parallel tubes, and sandstone samples. The experimental results and simulation results were very similar. The LBM can be a powerful tool to understand the fluid flow in asphalt mixtures. Coefficients of permeability in three different directions (longitudinal, transverse and vertical direction) were also studied. The studied asphalt mixtures were isotropic in two horizontal directions (x- and y- directions) and anisotropic comparing horizontal and vertical directions. The coefficients of permeability in horizontal directions were about two times than that in vertical direction. Image analysis techniques were used to analyze X-ray CT images of asphalt mixtures and obtain their effective percent air voids, average void diameter, Euler number, degree of anisotropy, specific surface area, and tortuosity. Pearson's correlation coefficients were used to evaluate the correlation between the selected parameters. The air void content, connected air void, and average void diameter were highly correlated with the coefficients of permeability, which were valuable to understand the fluid flow properties in asphalt mixtures.

Download or read book Numerical and Experimental Investigation of Production and Blending Mechanisms of Asphalt Mixtures with Reclaimed Asphalt Pavement written by Kun Zhang and published by . This book was released on 2016 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigated the production and blending mechanisms for asphalt mixtures that contain reclaimed asphalt pavement (RAP). The numerical and experimental methods used in this study can be used to assist asphalt plant design and operations to produce high quality RAP mixtures.

Download or read book Compaction Effects on Uniformity Moisture Diffusion and Mechanical Properties of Asphalt Pavements written by Emad Abdel-Rahman Kassem and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Field compaction of asphalt mixtures is an important process that influences performance of asphalt pavements; however there is very little effort devoted to evaluate the influence of compaction on the uniformity and properties of asphalt mixtures. The first part of this study evaluated relationships between different field compaction patterns and the uniformity of air void distribution in asphalt pavements. A number of projects with different asphalt mixture types were compacted, and cores were taken at different locations from these projects. The X-ray Computed Tomography (X-ray CT) system was used to capture the air void distributions in these cores. The analysis results have revealed that the uniformity of air void distribution is highly related to the compaction pattern and the sequence of different compaction equipment. More importantly, the efficiency of compaction (reducing air voids) at a point was found to be a function of the location of this point with respect to the compaction roller width. The results in this study supported the development of the "Compaction Index (CI)," which quantifies the degree of field compaction. The CI is a function of the number of passes at a point and the position of the point with respect to the compaction roller width. This index was found to correlate reasonably well with percent air voids in the pavement. The CI calculated from field compaction was also related to the slope of the compaction curve obtained from the Superpave gyratory compactor. This relationship offers the opportunity to predict field compactability based on laboratory measurements. The compaction of longitudinal joints was investigated, and recommendations were put forward to improve joint compaction. The air void distributions in gyratory specimens were related to the mixture mechanical properties measured using the Overlay and Hamburg tests. The second part of this study focused on studying the relationship between air void distribution and moisture diffusion. A laboratory test protocol was developed to measure the diffusion coefficient of asphalt mixtures. This important property has not measured before. The results revealed that the air void phase within the asphalt mixtures controls the rate of moisture diffusion. The measured diffusion coefficients correlated well with the percent and size of connected air voids. The measured diffusion coefficient is a necessary parameter in modeling moisture transport and predicting moisture damage in asphalt mixtures. The last part of this study investigated the resistance of asphalt mixtures with different percent air voids to moisture damage by using experimental methods and a fracture mechanics approach that accounts for fundamental material properties.

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 Bearing Capacity Of Roads written by A. Gomes Correia and published by CRC Press. This book was released on 2020-12-17 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an outcome of the sixth conference on bearing capacity of roads and airfield held in Lisbon, Portugal. It covers the following topics: bearing capacity policies, concepts, costs and condition surveys; analysis and modelling; design and environmental effects; and asphalt mixtures.

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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Advances in Unsaturated Soils written by Bernardo Caicedo and published by CRC Press. This book was released on 2013-02-01 with total page 612 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 perspective (e.g., swelling or collapsible soils and compacted soils or pavements materials), and they have also shown their efficiency to study new energy-related problems like CO2 sequestration and nuclear waste disposal. Advances in Unsaturated Soils is a collection of papers from the 1st Pan-American Conference on Unsaturated Soils organized in Cartagena de Indias, Colombia, in February 2013. The volume includes 76 research papers coming for all over the world, as well as 7 keynotes papers by well known international researchers. The contributions present a variety of topics including: • Advances in testing techniques • Unsaturated soil behavior • Constitutive modeling and microstructure • Numerical modeling • Geotechnical problems Advances in Unsaturated Soils is expected to become a useful reference to academics and professionals involved in Unsaturated Soil Mechanics.

Download or read book Bearing Capacity of Roads Railways and Airfields written by Andreas Loizos and published by CRC Press. This book was released on 2017-07-20 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bearing Capacity of Roads, Railways and Airfields includes the contributions to the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields (BCRRA 2017, 28-30 June 2017, Athens, Greece). The papers cover aspects related to materials, laboratory testing, design, construction, maintenance and management systems of transport infrastructure, and focus on roads, railways and airfields. Additional aspects that concern new materials and characterization, alternative rehabilitation techniques, technological advances as well as pavement and railway track substructure sustainability are included. The contributions discuss new concepts and innovative solutions, and are concentrated but not limited on the following topics: · Unbound aggregate materials and soil properties · Bound materials characteritics, mechanical properties and testing · Effect of traffic loading · In-situ measurements techniques and monitoring · Structural evaluation · Pavement serviceability condition · Rehabilitation and maintenance issues · Geophysical assessment · Stabilization and reinforcement · Performance modeling · Environmental challenges · Life cycle assessment and sustainability Bearing Capacity of Roads, Railways and Airfields is essential reading for academics and professionals involved or interested in transport infrastructure systems, in particular roads, railways and airfields.

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 Experimental and Computational Investigations of High density Asphalt Mixtures written by and published by . This book was released on 2019 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compaction of asphalt mixtures represents a critical step in the construction process that significantly affects the performance and durability of asphalt pavements. In this research effort, the compaction process of asphalt mixtures was investigated using a combined experimental and computational approach. The primary goal was to understand the main factors responsible for achieving good density and was triggered by the success of a recently proposed Superpave 5 mix design method. First, a two-scale discrete element method (DEM) model was developed to simulate the compaction process of asphalt mixtures. The computational model was anchored by a fluid dynamics-discrete element model, which is capable of capturing the motion of aggregates in the viscous binder. The model was then calibrated and validated by a series of experiments, which included rheological tests of the binder and a compaction test of the mixture. It was concluded that the compaction process was significantly influenced by the rheological properties of the fine aggregate matrix and by the sphericity of the coarse aggregates. Finally, the mechanical properties of two high-density mixtures were determined and compared with mechanical properties of mixtures used for MnROAD 2017 National road Research Alliance (NRRA) test sections. It was found that the properties of high-density mixtures as a group were not significantly different compared to the properties of conventional 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 104 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 Sustainability Eco efficiency and Conservation in Transportation Infrastructure Asset Management written by Massimo Losa and published by CRC Press. This book was released on 2014-04-28 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt: Worldwide there is a growing interest in efficient planning and the design, construction and maintenance of transportation facilities and infrastructure assets. The 3rd International Conference on Transportation Infrastructure ICTI 2014 (Pisa, April 22-25, 2014) contains contributions on sustainable development and preservation of transportation in

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 Asphalt Materials and Mixtures 2014 written by National Research Council (U.S.). Transportation Research Board and published by . This book was released on 2014 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: "TRB's Transportation Research Record (TRR): Journal of the Transportation Research Board, No. 2446 consists of 10 articles that explore a method for evaluating moisture susceptibility and rutting using the Hamburg wheel tracking test; the influence of air void content on moisture damage susceptibility of asphalt mixtures; a performance-based moisture susceptibility evaluation of warm-mix asphalt concrete; a friction study of long-term pavement performance; and safety aspects of wet asphalt pavement surfaces through field and numerical modeling investigations. This TRR also examines a moisture susceptibility evaluation of nanosized hydrated lime-modified asphalt-aggregate systems; moisture susceptibility of cold-mix asphalt; warm-mix and rubber-modified open-graded friction course test sections made without fibers in South Carolina; development of asphaltic materials to resist studded tire wear; and reporting results from the Hamburg wheel tracking device."--Publisher's description.

Download or read book Characteristics of Asphalt Binders written by and published by . This book was released on 1996 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coal and Rock Dynamic Disasters Advances of Physical and Numerical Simulation in Monitoring Early Warning and Prevention Volume II written by Jingjing Meng and published by Frontiers Media SA. This book was released on 2024-05-01 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Research Topic is Volume II of a series. The previous volume can be found here: Coal and Rock Dynamic Disasters: Advances of Physical and Numerical Simulation in Monitoring, Early Warning, and Prevention With the soaring growth of global population and socioeconomy, energy consumption and demand has been rapidly rising, and coal would still remain a fundamental energy source for a long time into the future. Seeking deep coal resources becomes an inevitable trend due to the depletion of shallow coal resources. Deep mining of coal resources promotes socioeconomic development, whereas bringing a variety of security challenges. In deep underground, there is a significant risk increase in coal and rock dynamic disasters (CRDDs), owing to the changes in physical and mechanical properties of coal and rock. In this regard, it is of great importance and necessity to prevent and control CRDDs effectively and efficiently.