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 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 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 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 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 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 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 Engineering and Transport Properties of the Interfacial Transition Zone in Cementitious Composites written by International Union of Testing and Research Laboratories for Materials and Structures and published by RILEM Publications. This book was released on 1999 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transport Processes in Concrete written by Robert Cerny and published by CRC Press. This book was released on 2002-04-25 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transport Processes in Concrete presents a comprehensive survey of the physical and chemical processes and transport mechanisms in concrete, and analyses their significance for the movement of heat, moisture and chemical compounds.A critical analysis of the available mathematical models is given, and from this analysis the most suitable models to d

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 Moisture Transport in Concrete Experiment Investigations and Simulation Programs written by Parnthep Julnipitawong and published by . This book was released on 2010 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hygroscopic Moisture in Concrete written by Lars-Olof Nilsson and published by . This book was released on 1980 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work has been concentrated on developing a method of calculating the drying of moisture in hydrating concrete. A great number of theories have been available but could not be used because the necessary material properties regarding moisture were missing. By extensive laboratory investigations the most essential material properties in respect to moisture have been determined.--The sorption isotherms for concrete of different composition and age have been evaluated as well as the progress of hydration of some cements. Flow measurements and several drying experiments have given the effect on the diffusivity of different factors in the composition. Especially the water-cement ratio and the air content have been found most important.--Using these material properties a computerized calculation model has been developed for the drying of concrete. At a comparison to a number of control experiments in a full scale a good correspondence has been found.--Hygrometric methods of moisture measurements are shown to have several advantages. The state of moisture is expressed in a far better way, small samples can be used and the accuracy is much better than when measuring the moisture content. (author abstract).

Download or read book Influence of elevated temperatures up to 100 C on the mechanical properties of concrete written by Acosta Urrea, Fernando and published by KIT Scientific Publishing. This book was released on 2018-08-03 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments to characterize the effects of moisture content and temperature on the mechanical properties of concrete were conducted. Based on these experiments, a new overall material model capable of predicting the mechanical behaviour of concrete subject to elevated temperatures up to 100 °C was developed. The material model estimates the time, temperature and moisture dependency of the compressive and tensile strength, creep and shrinkage of concrete.

Download or read book Redistribution of Moisture and Ions in Cement Based Materials written by Magnus Åhs and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transport Properties and Concrete Quality written by Barzin Mobasher and published by John Wiley & Sons. This book was released on 2006-12-22 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title is based on the workshop on Transport Properties & Concrete Quality, held at the campus of Arizona State University on October 10-12, 2005. During this meeting, scientific aspects of the relevant relationships between materials, mechanisms, processes, and service life were discussed. * Provides a useful resource for understanding the most valuable aspects of cement-based materials, with topics ranging from the current state of practice, to theory, simulation, and testing and specifications. * Logically organized and carefully selected articles give insight into the need to better integrate aspects of materials science, mechanics, modeling, and testing in developing tools of understanding the durability in cement-based materials.