Modelling of Sorption Hysteresis and Its Effect on Moisture Transport Within Cementitious Materials PDF Download
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Author: Zhidong Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The durability of reinforced concrete structures and their service life are closely related to the simultaneous occurrence of many physical and chemical phenomena. These phenomena are diverse in nature, but in common they are dependent on the moisture properties of the material. Therefore, the prediction of the potential degradation of cementitious materials requires the study of the movement of liquid-water and gas-phase transport in the material which is considered as a porous medium. In natural environment, structures are always affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on the drying process. There are few researches considering both drying and wetting, although these conditions represent natural RH variations. Even few studies take into account hysteresis in moisture transport. Thus, this work is devoted to better understand how the moisture behaviour within cementitious materials responds to the ambient RH changes through both experimental investigations and numerical modelling. In particular, hysteretic effects will be included in numerical modelling. In this thesis, we first recalled a complicate multi-phase continuum model. By theoretical analysis and experimental verification, a simplified model can be obtained for the case of that the intrinsic permeability to liquid-water is smaller than the intrinsic permeability to gas-phase. The review of commonly-used hysteresis models enabled to conclude a set of best models for the prediction of water vapour sorption isotherms and their hysteresis. After that, the simplified model was coupled with selected hysteresis models to simulate moisture transport under drying and wetting cycles. Compared with experimental data, numerical simulations revealed that modelling with hysteretic effects can provide much better results than non-hysteresis modelling. Among different hysteresis models, results showed that the use of the conceptual hysteresis model, which presents closed form scanning loops, can provide more accuracy predictions. Further simulations for different scenarios were also performed. All comparisons and investigations enhanced the necessity of considering hysteresis to model moisture transport for varying relative humidity at the boundary. The investigation of moisture penetration depth could provide a better understanding of how deep moisture as well as ions can move into the material. Furthermore, the analysis revealed that the consideration of Knudsen effects for diffusion of vapour can improve the prediction of the apparent diffusivity.
Author: Zhidong Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The durability of reinforced concrete structures and their service life are closely related to the simultaneous occurrence of many physical and chemical phenomena. These phenomena are diverse in nature, but in common they are dependent on the moisture properties of the material. Therefore, the prediction of the potential degradation of cementitious materials requires the study of the movement of liquid-water and gas-phase transport in the material which is considered as a porous medium. In natural environment, structures are always affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on the drying process. There are few researches considering both drying and wetting, although these conditions represent natural RH variations. Even few studies take into account hysteresis in moisture transport. Thus, this work is devoted to better understand how the moisture behaviour within cementitious materials responds to the ambient RH changes through both experimental investigations and numerical modelling. In particular, hysteretic effects will be included in numerical modelling. In this thesis, we first recalled a complicate multi-phase continuum model. By theoretical analysis and experimental verification, a simplified model can be obtained for the case of that the intrinsic permeability to liquid-water is smaller than the intrinsic permeability to gas-phase. The review of commonly-used hysteresis models enabled to conclude a set of best models for the prediction of water vapour sorption isotherms and their hysteresis. After that, the simplified model was coupled with selected hysteresis models to simulate moisture transport under drying and wetting cycles. Compared with experimental data, numerical simulations revealed that modelling with hysteretic effects can provide much better results than non-hysteresis modelling. Among different hysteresis models, results showed that the use of the conceptual hysteresis model, which presents closed form scanning loops, can provide more accuracy predictions. Further simulations for different scenarios were also performed. All comparisons and investigations enhanced the necessity of considering hysteresis to model moisture transport for varying relative humidity at the boundary. The investigation of moisture penetration depth could provide a better understanding of how deep moisture as well as ions can move into the material. Furthermore, the analysis revealed that the consideration of Knudsen effects for diffusion of vapour can improve the prediction of the apparent diffusivity.
Author: Lutz H. Franke
Publisher: John Wiley & Sons
ISBN: 3527846859
Category : Technology & Engineering
Languages : en
Pages : 357
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Book Description
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.
Author: Lutz H. Franke
Publisher: John Wiley & Sons
ISBN: 352735378X
Category : Technology & Engineering
Languages : en
Pages : 357
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Book Description
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.
Author: Pierre Rossi
Publisher: Springer Nature
ISBN: 3031077466
Category : Technology & Engineering
Languages : en
Pages : 397
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Book Description
This volume highlights the latest advances, innovations, and applications in the field of sustainable concrete structures, as presented by scientists and engineers at the RILEM International Conference on Numerical Modeling Strategies for Sustainable Concrete Structures (SSCS), held in Marseille, France, on July 4-6, 2022. It demonstrates that numerical methods (finite elements, finite volumes, finite differences) are a relevant response to the challenge to optimize the utilization of cement in concrete constructions while checking that these constructions have a lifespan compatible with the stakes of sustainable development. They are indeed accurate tools for an optimized design of concrete constructions, and allow us to consider all types of complexities: for example, those linked to rheological, physicochemical and mechanical properties of concrete, those linked to the geometry of the structures or even to the environmental boundary conditions. This optimization must also respect constraints of time, money, security, energy, CO2 emissions, and, more generally, life cycle more reliably than the codes and analytical approaches currently used. Numerical methods are, undoubtedly, the best calculation tools at the service of concrete eco-construction. The contributions present traditional and new ideas that will open novel research directions and foster multidisciplinary collaboration between different specialists.
Author: Rajesh Chaube
Publisher: CRC Press
ISBN: 1482272164
Category : Architecture
Languages : en
Pages : 325
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Book Description
Proposing a simplified but intergrated scenario of concrete life cycle simulation method, this book examines and explains the vast amount of experimental observations related to hardening concrete using a common set of physical laws.
Author: A. V. Luikov
Publisher: Elsevier
ISBN: 1483225682
Category : Science
Languages : en
Pages : 541
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Book Description
Heat and Mass Transfer in Capillary-Porous Bodies describes the modern theory of heat and mass transfer on the basis of the thermodynamics of irreversible processes. This book provides a systematic account of the phenomena of heat and mass transfer in capillary-porous bodies. Organized into 10 chapters, this book begins with an overview of the processes of the transfer of heat and mass of a substance. This text then examines the application of the theory to the investigation of heat and mass exchange in walls and in technological processes for the manufacture of building materials. Other chapters consider the thermal properties of building materials by using the methods of the thermodynamics of mass transfer. The final chapter deals with the method of finite differences, which is applicable to the solution of problems of non-steady heat conduction. This book is a valuable resource for scientists, post-graduate students, engineers, and students in higher educational establishments for architectural engineering.
Author: Advisory Committee on Technology and Society
Publisher: National Academies Press
ISBN: 9780309037860
Category : Social Science
Languages : en
Pages : 1298
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Book Description
Cities and Their Vital Systems asks basic questions about the longevity, utility, and nature of urban infrastructures; analyzes how they grow, interact, and change; and asks how, when, and at what cost they should be replaced. Among the topics discussed are problems arising from increasing air travel and airport congestion; the adequacy of water supplies and waste treatment; the impact of new technologies on construction; urban real estate values; and the field of "telematics," the combination of computers and telecommunications that makes money machines and national newspapers possible.
Author: Paul Fazio
Publisher: CRC Press
ISBN: 1000116204
Category : Technology & Engineering
Languages : en
Pages : 1009
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Book Description
Buildings influence people. They account for one third of energy consumption across the globe and represent an annual capital expenditure of 7%-10% of GNP in industrialized countries. Their lifetime operation costs can exceed capital investment. Building Engineering aims to make buildings more efficient, safe and economical. One branch of this discipline, Building Physics/Science, has gained prominence, with a heightened awareness of such phenomena as sick buildings, the energy crisis and sustainability, and considering the performance of buildings in terms of climatic loads and indoor conditions. The book reflects the advanced level and high quality of research which Building Engineering, and Building Physics/Science in particular, have reached at the beginning of the twenty-first century. It will be a valuable resource to: engineers, architects, building scientists, consultants on the building envelope, researchers and graduate students.
Author: Lars-Olof Nilsson
Publisher: Springer
ISBN: 3319742310
Category : Technology & Engineering
Languages : en
Pages : 285
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Book Description
RILEM TC 248-MMB was established in 2012 with the main aim to improve and distribute knowledge related to moisture measurement in construction materials in various scientific and industrial applications. Properties and performance of building materials and structures are influenced to a large extent by the moisture conditions in the materials. Obvious examples are heat conductivity, shrinkage and creep, transport properties, most types of deterioration, discoloration etc. For research and applications the moisture conditions must be quantified, by measurements in the laboratory or under field conditions. There is much variation in methods being used, even within the same topic, in different countries, both with regard to materials and to applications. No consensus whatsoever does exist. For the construction industry it is important to be able to quantify the moisture conditions in an accurate way in various applications. This state-of-the-art report is divided into two parts, Principles and Applications, with altogether 28 chapters on various moisture measuring principles and a number of applications.
Author: H. Jennings
Publisher: Springer Science & Business Media
ISBN: 9401586462
Category : Technology & Engineering
Languages : en
Pages : 554
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Book Description
From July 10th through July 13th, 1994, an informal workshop co-organized by RILEM committees 116-PCD and 123-MME was held at Saint-Remy-Ies Chevreuse, France, and attended by 38 delegates from 16 countries. Twenty-nine papers were presented, converging the general subjects of modelling micro structures and predicting durability of concrete and other cement-based materials. A short summary follows: G. M. Idom's paper entitled "Modelling Research for Concrete Engineering" serves as an introduction to the workshop, presenting an overview of modelling research with the conelusion that the broad practica1 objective is to produce high-quality concrete. This means that many characteristics, ranging from rheology to alkali-silica reaction, must be modelled. In other words, the system must be understood. Idom's paper sets the stage for papers in two general areas: 1) models and 2) transport properties. After this, abrief survey of the develop ment of microstructurally-based models is presented. A elose relationship between computer power and speed is suggested. The first group of papers on models covers the subjects of scale and resolution. Most models define and predict characteristics of the pore system, which range in scale from nanometer to millimeter. Various types ofnetworks are proposed in these papers. A good microstructural model must describe the pores and other phases at ascale appropriate to the properties that the model predicts. Also, a good model should be based on fundamental knowledge. In the case of cement-based materials, the important properties may depend on the microstructure, especially the porosity, at several scales.
