Download or read book Moisture Transport in Cement Based Materials written by Javier Eduardo Castro and published by . This book was released on 2011 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: The durability of concrete subjected to aggressive environments depends largely on the transport properties of the concrete. These transport properties are influenced by the volume of pores as well as the connectivity of the pore network. Three main mechanisms can be used to describe transport in cementitious systems: permeability, diffusion and absorption. Permeability is the measure of the flow of water under a pressure gradient. Diffusion is the movement of ions due to a concentration gradient. Absorption can be described as the ability to take in water by means of capillary suction. It is important to note that absorption occurs on a much faster time scale than diffusion. A large fraction of concrete in service is only partly saturated and the initial ingress of fluid is influenced, at least in part, by capillary absorption. As such, fluid (water) absorption has been used as an important factor for quantifying the durability of cementitious systems and it is being increasingly used by specifiers and in forensic studies to provide a parameter that can describe an aspect of concrete durability. For this reason the water absorption test is the focus of the first part of this thesis. The influence of preconditioning and initial moisture content was assessed as it relates to the water absorption test measurements. The results confirm that the test is considerably affected by the relative humidity of the samples before starting the test, which if not properly accounted for can lead to a misunderstanding of the actual absorption behavior. It was also observed that the conditioning procedure described in ASTM C1585 is not able to eliminate the "moisture history" of the samples. As such modifications to the standard test procedure are suggested. Further, the absorption behavior was investigated when salts were present in the samples or as a part of the absorbing fluid. Tests were performed on concrete using different aqueous solutions containing deicing salts. The rate of fluid absorption was generally lower for aqueous solutions containing deicing salts than it was for water (with the exception of low concentrations of NaCl). The change in the rate of aqueous fluid absorption was proportional to the square root of the ratio of surface tension and viscosity of the absorbed fluid. Experimental data indicates that concretes that had previously been exposed to deicing solutions can also exhibit reduced rate of absorption, even if water is the fluid being absorbed. The second part of this thesis is focused on the internal curing for concrete and its effect on the transport properties. The increased propensity for shrinkage cracking in low waterto- cement ratio (w/c) concrete has inspired the development of new technologies that can reduce the risk of early-age cracking. One of these is internal curing. Internal curing uses pre-wetted lightweight aggregate (LWA) to supply "curing water" to low w/c paste as it hydrates. Significant research has been performed to determine the effects of internal curing on shrinkage and stress development; however, relatively little detailed information exists about the effects of internal curing on fluid transport properties such as water absorption. In order to determine the mixture proportions for internally cured concretes information about the water absorption and water desorption properties of the lightweight aggregate is needed. Unfortunately, these properties are not easy to obtain accurately. This work studies the absorption and desorption properties of commercially available expanded shale, clay and slate lightweight aggregates. This research determines these properties so that they can be efficiently used in proportioning concrete for internal curing. Further, it was shown that by normalizing the results general trends on material behavior can be obtained that are quite useful in proportioning the mixtures. After characterizing the properties of the aggregates to be used for internal curing, this research examines the absorption of water into low w/c mortar specimens made with prewetted lightweight aggregates. These results indicate that the inclusion of LWA can reduce the water absorption of mortar specimens. This observation was reinforced with electrical conductivity measurements that exhibited similar reductions. In addition, this work analyzes the potential use of internal curing in concrete systems with w/c higher than normally used (w/c of 0.30, 0.36, 0.42 and 0.45) to increase the durability of the concrete. Test results show that internal curing can be useful to improve the durability of concretes prepared with this wider range of w/c. The benefits of using internal curing on the transport properties can be explained by an increase in the hydration of the cement. This was assessed using isothermal calorimeter, internal relative humidity, scanning electron microscopy and an atomic force microscopy. Further, in addition to reducing the porosity, the increased hydration appears to reduce the tortuosity by preferentially hydrating the interfacial regions around the lightweight aggregate.

Download or read book Moisture Storage and Transport in Concrete written by Lutz H. Franke and published by John Wiley & Sons. This book was released on 2024-07-29 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive insight on moisture transport in cement-based materials by means of experimental investigations and computer simulations Moisture Storage and Transport in Concrete explores how moisture moves through cementitious materials, focusing on its absorption, storage, and distribution with the help of experimental investigations and computer simulations. The text discusses the different ways moisture moves, such as through vapor or capillary action, as well as how it affects the properties of cement-based materials, offering new insights and models to help understand and predict moisture behavior in these materials, which can be important for construction and maintenance. After a short introduction to the topic, the text is split into five parts. Part I covers surface energetic principles for moisture storage in porous materials. Part II explores real pore structure and calculation methods for composition parameters. Part III explains basic equations for the description of moisture transport. Part IV discusses experimental investigation results with regard to the modeling of moisture transport in concrete materials. Part V showcases modeling of moisture transport, taking into account sorption hysteresis and time-dependent material changes. Written by a highly qualified author, Moisture Storage and Transport in Concrete also includes discussion on: Dependence of surface energy of water on temperature, on relative humidity of air, and for aqueous salt solutions Calculation of the pore size dependent distribution of inner surfaces using the moisture storage function Temperature influence on the capillary transport coefficients and differences between capillary pressure and hydraulic external pressure Adsorption and desorption isotherms of the CEMI reference material and causes of differences between adsorption and desorption isotherms Sorption isotherms and scanning isotherms of hardened cement paste and concrete Moisture Storage and Transport in Concrete is an essential reference to help researchers and professionals to make informed decisions for the construction of concrete-based infrastructure, enabling them to avoid common issues such as corrosion of reinforcement steel, deterioration of concrete strength, and the growth of mold and mildew.

Download or read book Water Transport in Brick Stone and Concrete written by Christopher Hall and published by CRC Press. This book was released on 2011-10-31 with total page 381 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a unified description of transport processes involving saturated and unsaturated flow in inorganic building materials and structures. It emphasizes fundamental physics and materials science, mathematical description, and experimental measurement as a basis for engineering design and construction practice. Water Transport in Brick

Download or read book Moisture Storage and Transport in Concrete written by Lutz H. Franke and published by John Wiley & Sons. This book was released on 2024-04-23 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: Moisture Storage and Transport in Concrete Comprehensive insight on moisture transport in cement-based materials by means of experimental investigations and computer simulations Moisture Storage and Transport in Concrete explores how moisture moves through cementitious materials, focusing on its absorption, storage, and distribution with the help of experimental investigations and computer simulations. The text discusses the different ways moisture moves, such as through vapor or capillary action, as well as how it affects the properties of cement-based materials, offering new insights and models to help understand and predict moisture behavior in these materials, which can be important for construction and maintenance. After a short introduction to the topic, the text is split into five chapters. Chapter 1 covers surface energetic principles for moisture storage in porous materials. Chapter 2 explores real pore structure and calculation methods for composition parameters. Chapter 3 explains basic equations for the description of moisture transport. Chapter 4 discusses experimental investigation results with regard to the modeling of moisture transport in concrete materials. Chapter 5 showcases modeling of moisture transport, taking into account sorption hysteresis and time-dependent material changes. Written by a highly qualified author, Moisture Storage and Transport in Concrete also includes discussion on: Dependence of surface energy of water on temperature, on relative humidity of air, and for aqueous salt solutions Calculation of the pore size dependent distribution of inner surfaces using the moisture storage function Temperature influence on the capillary transport coefficients and differences between capillary pressure and hydraulic external pressure Adsorption and desorption isotherms of the CEMI reference material and causes of differences between adsorption and desorption isotherms Sorption isotherms and scanning isotherms of hardened cement paste and concrete Modeling of vapor transport and drying by evaporation of concrete Moisture Storage and Transport in Concrete is an essential reference to help researchers and professionals to make informed decisions for the construction of concrete-based infrastructure, enabling them to avoid common issues such as corrosion of reinforcement steel, deterioration of concrete strength, and the growth of mold and mildew.

Download or read book Experimental Studies of Sorption and Transport of Moisture in Cement Based Materials with Supplementary Cementitious Materials written by and published by . This book was released on 2015 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Creep and Hygrothermal Effects in Concrete Structures written by Zdeněk P. Bažant and published by Springer. This book was released on 2018-01-17 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive treatise covers in detail practical methods of analysis as well as advanced mathematical models for structures highly sensitive to creep and shrinkage. Effective computational algorithms for century-long creep effects in structures, moisture diffusion and high temperature effects are presented. The main design codes and recommendations (including RILEM B3 and B4) are critically compared. Statistical uncertainty of century-long predictions is analyzed and its reduction by extrapolation is discussed, with emphasis on updating based on short-time tests and on long-term measurements on existing structures. Testing methods and the statistics of large randomly collected databases are critically appraised and improvements of predictions of multi-decade relaxation of prestressing steel, cyclic creep in bridges, cracking damage, etc., are demonstrated. Important research directions, such as nanomechanical and probabilistic modeling, are identified, and the need for separating the long-lasting autogenous shrinkage of modern concretes from the creep and drying shrinkage data and introducing it into practical prediction models is emphasized. All the results are derived mathematically and justified as much as possible by extensive test data. The theoretical background in linear viscoelasticity with aging is covered in detail. The didactic style makes the book suitable as a textbook. Everything is properly explained, step by step, with a wealth of application examples as well as simple illustrations of the basic phenomena which could alternate as homeworks or exams. The book is of interest to practicing engineers, researchers, educators and graduate students.

Download or read book Cement Based Materials written by Hosam El-Din M. Saleh and published by BoD – Books on Demand. This book was released on 2018-10-10 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cement-based materials have been used by humans nearly since the dawn of civilization. The Egyptians used lime and gypsum cement to bind their aggregate materials, mud and straw, resulting in bricks that are used for building their famous Egyptian pyramids (between 3000 and 2500 BC). Hydrated cement is a cement material bonded together with water and used for building construction; it is characterized by acceptable chemical, physical, thermal, mechanical, and structural stability. It plays a main role in the creation of vessels for storage, roads to travel on, weather-resistant structure for protection, inert hard stabilizer for hazardous wastes, and so on. Due to the composition of these materials and their advantages, it has been practiced in different applications. Cement is an essential component of making concrete, the single most prevalent building material used worldwide for construction, skyscrapers, highways, tunnels, bridges, hydraulic dams, and railway ties. Besides their numerous desired properties, there are some undesirable features. To overcome these disadvantages, several studies were established to prepare, improve, and evaluate innovative cement-based materials. Despite its oldness and deep research, every year several methods and materials evolve and so do cement technology. This book intends to provide a comprehensive overview on recent advances in the evaluation of these materials.

Download or read book Cement Based Materials for Nuclear Waste Storage written by Florence Bart and published by Springer Science & Business Media. This book was released on 2012-08-16 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the re-emergence of nuclear power as an acceptable energy source on an international basis continues, the need for safe and reliable ways to dispose of radioactive waste becomes ever more critical. The ultimate goal for designing a predisposal waste-management system depends on producing waste containers suitable for storage, transportation and permanent disposal. Cement-Based Materials for Nuclear-Waste Storage provides a roadmap for the use of cementation as an applied technique for the treatment of low- and intermediate-level radioactive wastes. Coverage includes, but is not limited to, a comparison of cementation with other solidification techniques, advantages of calcium-silicate cements over other materials and a discussion of the long-term suitability and safety of waste packages as well as cement barriers.

Download or read book Interface Influence on Moisture Transport in Building Components written by João M. P. Q. Delgado and published by Springer Nature. This book was released on 2019-09-10 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The knowledge of moisture migration inside building materials and construction building components is decisive for the way they behave when in use. The durability, waterproofing, degrading aspect and thermal behaviour of these materials are strongly influenced by the existence of moisture within their interior, which provoke changes in their normal performance, something that is normally hard to predict. Due to the awareness of this problem, the scientific community have per-formed various studies about the existence of moisture inside porous materials. The complex aspects of moisture migration phenomenon tended to encompass monolithic building elements, since the existence of joints or layers contributes to the change of moisture transfer along the respective building element that contribute to the change of mass transfer law. The presentation of an experimental analyses concerning moisture transfer in the interface of material that makes up masonry is described in such a way as to evaluate the durability and/or avoid building damages. In this work it was analysed, during the wetting process, the influence of different types of interface, commonly observed in masonry, such as: perfect con-tact, joints of cement mortar, lime mortar, and the air space interface. The results allow the calculation of the hygric resistance. With these results, it is possible to use any advanced hygrothermal simulation program to study the water transport in building elements, considering different interfaces and their hygric resistance.

Download or read book Characterization and Modeling of Moisture Flow Through Hydrating Cement based Materials Under Early age Drying and Shrinkage Conditions written by Mehdi Bakhshi and published by . This book was released on 2011 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early-age cracks in fresh concrete occur mainly due to high rate of surface evaporation and restraint offered by the contracting solid phase. Available test methods that simulate severe drying conditions, however, were not originally designed to focus on evaporation and transport characteristics of the liquid-gas phases in a hydrating cementitious microstructure. Therefore, these tests lack accurate measurement of the drying rate and data interpretation based on the principles of transport properties is limited. A vacuum-based test method capable of simulating early-age cracks in 2-D cement paste is developed which continuously monitors the weight loss and changes to the surface characteristics. 2-D crack evolution is documented using time-lapse photography. Effects of sample size, w/c ratio, initial curing and fiber content are studied. In the subsequent analysis, the cement paste phase is considered as a porous medium and moisture transport is described based on surface mass transfer and internal moisture transport characteristics. Results indicate that drying occurs in two stages: constant drying rate period (stage I), followed by a falling drying rate period (stage II). Vapor diffusion in stage I and unsaturated flow within porous medium in stage II determine the overall rate of evaporation. The mass loss results are analyzed using diffusion-based models. Results show that moisture diffusivity in stage I is higher than its value in stage II by more than one order of magnitude. The drying model is used in conjunction with a shrinkage model to predict the development of capillary pressures. Similar approach is implemented in drying restrained ring specimens to predict 1-D crack width development. An analytical approach relates diffusion, shrinkage, creep, tensile and fracture properties to interpret the experimental data. Evaporation potential is introduced based on the boundary layer concept, mass transfer, and a driving force consisting of the concentration gradient. Effect of wind velocity is reflected on Reynolds number which affects the boundary layer on sample surface. This parameter along with Schmidt and Sherwood numbers are used for prediction of mass transfer coefficient. Concentration gradient is shown to be a strong function of temperature and relative humidity and used to predict the evaporation potential. Results of modeling efforts are compared with a variety of test results reported in the literature. Diffusivity data and results of 1-D and 2-D image analyses indicate significant effects of fibers on controlling early-age cracks. Presented models are capable of predicting evaporation rates and moisture flow through hydrating cement-based materials during early-age drying and shrinkage conditions.

Download or read book Performance of Cement Based Materials in Aggressive Aqueous Environments written by Mark Alexander and published by Springer Science & Business Media. This book was released on 2012-12-18 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete and cement-based materials must operate in increasingly aggressive aqueous environments, which may be either natural or industrial. These materials may suffer degradation in which ion addition and/or ion exchange reactions occur, leading to a breakdown of the matrix microstructure and consequent weakening. Sometimes this degradation can be extremely rapid and serious such as in acidic environments, while in other cases degradation occurs over long periods. Consequences of material failure are usually severe – adversely affecting the health and well-being of human communities and disturbing ecological balances. There are also large direct costs of maintaining and replacing deteriorated infrastructure and indirect costs from loss of production during maintenance work, which place a great burden on society. The focus of this book is on addressing issues concerning performance of cement-based materials in aggressive aqueous environments , by way of this State-of-the-Art Report. The book represents the work of many well-known and respected authors who contributed chapters or parts of chapters. Four main themes were addressed: I. Nature and kinetics of degradation and deterioration mechanisms of cement-based materials in aggressive aqueous environments, II. Modelling of deterioration in such environments, III. Test methods to assess performance of cement-based materials in such environments, and which can be used to characterise and rate relative performance and inform long term predictions, IV. Engineering implications and consequences of deterioration in aggressive aqueous environments, and engineering approaches to the problem.

Download or read book Advances in Cement Based Materials written by Gideon P.A.G. Van Zijl and published by CRC Press. This book was released on 2009-11-02 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Collection of selected papers on current advances in high performance construction materials. Contributions deal with the development, characterization, application procedures, performance and structural design of materials with key potential in civil engineering works. Materials treated are fibre reinforced concrete, high performance concrete, sel

Download or read book Water Transport in Brick Stone and Concrete written by Christopher Hall and published by CRC Press. This book was released on 2021-07-21 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: Moisture dynamics in brick, stone and concrete has a controlling influence on the durability and performance of the built environment. Water Transport in Brick, Stone and Concrete provides a unified description of transport processes involving saturated and unsaturated flow in porous inorganic materials and structures. It sets out fundamental physics and materials science, mathematical description and experimental measurement as a basis for engineering design and construction practice. Now in its third edition, the book combines a systematic presentation of the scientific and technical principles with new analyses of topics such as sorption isotherms, temperature dependence of sorptivity, time-dependent properties of cement-based materials, layered materials, air-trapping and driving rain. It serves as an authoritative reference for research workers, practising engineers and students of civil, building, architectural and materials engineering. Much of the fundamental work is relevant to engineers in soil science and geotechnics, as well as oilfield, chemical and process engineering.

Download or read book Transport and Interactions of Chlorides in Cement based Materials written by Caijun Shi and published by CRC Press. This book was released on 2019-07-26 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chloride-induced corrosion is the most important durability issue of reinforced concrete structures, and the prediction and prevention of chloride-induced corrosion has attracted considerable interest all over the world. Given that chloride penetrates through the concrete cover, the issues concerning its transport are crucial. These include testing methods, prediction, and the prevention of ingress. During the transport process, physical and chemical interaction occurs between chloride and cement hydrates, which in turn affects the further transport, so the transport of chloride and these interactions are closely related and underpin our understanding of chloride-induced corrosion in RC structures. This book provides in-depth discussion of chloride transport and its interaction in cement-based materials, and reviews and summarizes the state of the art. The mechanisms and testing methods for chloride transport, chemical interactions of chloride with cement hydrates, chloride binding isotherms, measurement of penetration depths, factors affecting chloride transport, and modeling of chloride transport are discussed in detail. This book serves as a reference for researchers or engineer, and a textbook for graduate students.

Download or read book Mechanics of Porous Continua written by Olivier Coussy and published by Wiley. This book was released on 1995-12-05 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a unified and systematic continuum approach for engineers and applied physicists working on the modelling of porous media. Self-contained, it sets out—from a macroscopic point of view—the main concepts and results of deformable porous media subject to the flow of one or several fluids. The theory presented includes developments in the areas of thermodynamics, poroelastoplasticity, poroviscoplasticity, wave propagation and surfaces of discontinuity, boundary value problems and numerical methods, as well as chemico-mechanical couplings. It can be used for numerous diversified applications in geophysics, civil engineering, biomechanics, material science, etc.

Download or read book Corrosion of Steel in Concrete written by Luca Bertolini and published by John Wiley & Sons. This book was released on 2013-02-26 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steel-reinforced concrete is used ubiquitously as a building material due to its unique combination of the high compressive strength of concrete and the high tensile strength of steel. Therefore, reinforced concrete is an ideal composite material that is used for a wide range of applications in structural engineering such as buildings, bridges, tunnels, harbor quays, foundations, tanks and pipes. To ensure durability of these structures, however, measures must be taken to prevent, diagnose and, if necessary, repair damage to the material especially due to corrosion of the steel reinforcement. The book examines the different aspects of corrosion of steel in concrete, starting from basic and essential mechanisms of the phenomenon, moving up to practical consequences for designers, contractors and owners both for new and existing reinforced and prestressed concrete structures. It covers general aspects of corrosion and protection of reinforcement, forms of attack in the presence of carbonation and chlorides, problems of hydrogen embrittlement as well as techniques of diagnosis, monitoring and repair. This second edition updates the contents with recent findings on the different topics considered and bibliographic references, with particular attention to recent European standards. This book is a self-contained treatment for civil and construction engineers, material scientists, advanced students and architects concerned with the design and maintenance of reinforced concrete structures. Readers will benefit from the knowledge, tools, and methods needed to understand corrosion in reinforced concrete and how to prevent it or keep it within acceptable limits.

Download or read book Damp Indoor Spaces and Health written by Institute of Medicine and published by National Academies Press. This book was released on 2004-10-01 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost all homes, apartments, and commercial buildings will experience leaks, flooding, or other forms of excessive indoor dampness at some point. Not only is excessive dampness a health problem by itself, it also contributes to several other potentially problematic types of situations. Molds and other microbial agents favor damp indoor environments, and excess moisture may initiate the release of chemical emissions from damaged building materials and furnishings. This new book from the Institute of Medicine examines the health impact of exposures resulting from damp indoor environments and offers recommendations for public health interventions. Damp Indoor Spaces and Health covers a broad range of topics. The book not only examines the relationship between damp or moldy indoor environments and adverse health outcomes but also discusses how and where buildings get wet, how dampness influences microbial growth and chemical emissions, ways to prevent and remediate dampness, and elements of a public health response to the issues. A comprehensive literature review finds sufficient evidence of an association between damp indoor environments and some upper respiratory tract symptoms, coughing, wheezing, and asthma symptoms in sensitized persons. This important book will be of interest to a wide-ranging audience of science, health, engineering, and building professionals, government officials, and members of the public.