Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Chemical engineering. --- Energy transfer. --- Mass transfer. --- Convective flow --- Momentum transfer --- Transport properties --- Convective flow --- Momentum transfer --- Transport properties

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Concrete is the most used building material in the construction industry, with a production estimated to be about 1 billion tons/year in the European Union. Natural aggregate (NA) is one of the main ingredients of concrete, whose production reached about 2.8 billion tons in Europe in 2017. It is today evident that natural aggregates and sand are becoming a scarce resource and their availability becomes therefore an important challenge.
Furthermore, environmental concerns regarding the construction industry have risen, particularly regarding CO2 emissions and waste production from construction and demolition activities (C&D Waste).
That’s why the construction industry needs to develop and implement processes able to incorporate recycled products into its building materials. Recycled Concrete Aggregates (RCA) produced from crushed C&DW as a replacement of natural aggregates is one of those solutions which has made it a thoroughly studied field.
RCA consist of coarse particles containing natural aggregates as well as residual cement paste which impairs negatively their properties compared to NA. Indeed, the use of RCA inside concrete increases the porosity and may therefore reduce its durability. The focus of this master thesis is to analyse the influence of RCA on transfer properties (water retention curves, permeability and porosity) and drying behaviour of concrete. Indeed, a better knowledge of those properties will help to determine the effect of RCA on the durability of concrete as water and vapour transfers are the necessary condition to observe degradation processes like carbonation, chloride ion diffusion or alkali-aggregate reaction.
A numerical model for drying phenomena of concrete samples with recycled aggregates is developed in this thesis. To support this modelling, an experimental programme with sorption and desorption tests as well as porosity and permeability determination, is implemented.
To better study the influence of the RCA alone, several concrete mixes are studied: a reference composition with natural aggregates and the same composition with RCA (same granulometric curve), a mix with natural aggregates but another cement type and, finally, a mortar without any aggregates. The three concrete compositions have the same paste content and type as it highlights the influence of the change of aggregates/cement type.
The modelling is performed with a nonlinear finite element software developed at the University of Liège (called Lagamine). It follows the theory of nonlinear finite elements modelling of flows in porous media and consists of a coupled thermo-hydraulic study of the material.
An application is also carried out in the form of an exterior parking lot's column subjected to real outdoor conditions: at constant and variable temperature, the relative humidity will vary between 40% and 95%, with multiple cycles of 6 months.
Results show that, as predicted, concrete made from Recycled Concrete Aggregates (RCA) is more porous than its Natural Aggregates (NA)-based counterpart. Its water absorption and intrinsic permeability are also superior than for regular concrete. In terms of water retention properties, both concretes are similar, with no significant differences.
The first indicator of durability measured in this thesis is the resistance to carbonation, which showed that concrete made from RCA is more prone to carbonation than concrete with NA.
Nota Bene: this master thesis has been performed during the COVID-19 period when lockdown was applied from March 19th to May 31st, 2020. Le béton est le matériau de construction le plus utilisé dans l’industrie du bâtiment, avec une production estimée à environ 1 milliard de tonnes/an dans l’Union européenne. Les granulats naturels sont l’un des principaux ingrédients du béton, dont la production a atteint environ 2,8 milliards de tonnes en Europe en 2017. Il est aujourd’hui évident que les granulats naturels et le sable deviennent une ressource rare et leur disponibilité devient donc un défi important.
En outre, les préoccupations environnementales concernant l’industrie de la construction ont augmentées, notamment en ce qui concerne les émissions de CO2 et la production de déchets provenant des activités de construction et de démolition (déchets C&D).
C’est pourquoi l’industrie de la construction doit développer et mettre en œuvre des processus capables d’incorporer des produits recyclés dans ses matériaux de construction. Les granulats de béton recyclés produits à partir de déchets C&D broyés en remplacement des granulats naturels sont l’une de ces solutions qui en ont fait un domaine soigneusement étudié.
Les granulats de béton recyclés sont constitués de particules grossières contenant des agrégats naturels ainsi que des résidus de pâte de ciment qui modifient négativement leurs propriétés par rapport aux granulats naturels. En effet, l’utilisation de ces granulats recyclés à l’intérieur du béton augmente sa porosité et peut donc réduire sa durabilité. L’objectif de ce travail de fin d’étude est d’analyser l’influence des granulats recyclés sur les propriétés de transfert (courbes de rétention d’eau, perméabilité et porosité) et le comportement au séchage du béton. En effet, une meilleure connaissance de ces propriétés permettra de déterminer l’effet de ceux-ci sur la durabilité du béton car les transferts d’eau et de vapeur sont la condition nécessaire pour observer des processus de dégradation comme la carbonatation, la diffusion d’ions chlorure ou la réaction alkali-agrégats.
Un modèle numérique pour les phénomènes de séchage d’échantillons de béton avec des agrégats recyclés est développé dans ce travail. Pour soutenir cette modélisation, un programme expérimental comprenant des tests de sorption et de désorption ainsi que la détermination de la porosité et de la perméabilité, est mis en œuvre.
Pour mieux étudier l’influence des granulats recyclés seule, plusieurs mélanges de béton sont étudiés : une composition de référence avec des granulats naturels et la même composition avec les recyclés (même courbe granulométrique), un mélange avec des granulats naturels mais un autre type de ciment et, enfin, un mortier sans aucun granulat. Les trois compositions de béton ont la même teneur en pâte et le même type de pâte car elles mettent en évidence l’influence du changement de type de granulats/ciment.
La modélisation est réalisée à l’aide d’un logiciel d’éléments finis non linéaires développé à l’Université de Liège (appelé Lagamine). Il suit la théorie de la modélisation par éléments finis non linéaires des écoulements dans les milieux poreux et consiste en une étude thermo-hydraulique couplée du matériau.
Une application est également réalisée sous la forme d’une colonne de parking extérieur soumise à des conditions extérieures réelles : à température constante et variable, l’humidité relative variera entre 40 et 95%, avec de multiples cycles de 6 mois.
Nota Bene: ce travail de fin d’étude a été réalisé durant la période de COVID-19 pendant laquelle le confinement a été mis en place du 19 Mars au 31 Mai 2020.

Concrete --- Recycled Concrete Aggregates --- Nonlinear Finite Element Modelling --- Drying Phenomena --- Water Retention Curve --- Convective Drying --- Transfer Properties --- Durability --- Béton --- Modélisation par éléments finis non linéaires --- Phénomènes de séchage --- Courbes de rétention d'eau --- Séchage convectif --- Propriétés de transfert --- Durabilité --- Granulats de béton recyclés --- Ingénierie, informatique & technologie > Ingénierie civile

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This book offers a comprehensive exploration of geochemical kinetics--the application of chemical kinetics to geological problems, both theoretical and practical. Geochemical Kinetics balances the basic theories of chemical kinetics with a thorough examination of advanced theories developed by geochemists, such as nonisothermal kinetics and inverse theories, including geochronology (isotopic dating), thermochronology (temperature-time history), and geospeedometry (cooling rates). The first chapter provides an introduction and overview of the whole field at an elementary level, and the subsequent chapters develop theories and applications for homogeneous reactions, mass and heat transfer, heterogeneous reactions, and inverse problems. Most of the book's examples are from high-temperature geochemistry, with a few from astronomy and environmental sciences. Appendixes, homework problems for each major section, and a lengthy reference list are also provided. Readers should have knowledge of basic differential equations, some linear algebra, and thermodynamics at the level of an undergraduate physical chemistry course. Geochemical Kinetics is a valuable resource for anyone interested in the mathematical treatment of geochemical questions.

Chemical kinetics --- Geochemistry --- Absorptivities. --- Activated complex. --- Activation energy. --- Advection. --- Arrhenius plot. --- Asymptotic cooling. --- Avogadro constant. --- Avrami equation. --- Backward reaction. --- Batch melting. --- Binary diffusivity. --- Boltzmann distribution. --- Catalyst. --- Chapman mechanism. --- Chemical reactions. --- Collision theory. --- Component exchange. --- Concordia. --- Conservation equations. --- Convective crystal growth. --- Cooling history. --- Darken equation. --- Decay chains. --- Decay reactions. --- Diffusion and flow. --- Diffusion distance. --- Diffusion. --- Diffusivity. --- Dodson’s equations. --- Eddy diffusion. --- Energy conservation. --- Equilibrium. --- Extinct nuclides. --- Falling sphere. --- Fick’s law. --- First-order precision. --- Ganguly’s method. --- Geochemical kinetics. --- Geochronology. --- Geospeedometry. --- Heat conduction. --- Heterogeneous reactions. --- Infrared spectroscopy. --- Integrated error function. --- Interstitial sites. --- Inverse problems. --- Isochrons. --- Jumping frequency. --- Kohlrausch’s law. --- Law of mass action. --- Many-body problems. --- Mass conservation. --- Nanoparticle aggregation.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Flows of thermal origin and heat transfer problems are central in a variety of disciplines and industrial applications. The present book entitled Thermal Flows consists of a collection of studies by distinct investigators and research groups dealing with different types of flows relevant to both natural and technological contexts. Both reviews of the state-of-the-art and new theoretical, numerical and experimental investigations are presented, which illustrate the structure of these flows, their stability behavior, and the possible bifurcations to different patterns of symmetry and/or spatiotemporal regimes. Moreover, different categories of fluids are considered (liquid metals, gases, common fluids such as water and silicone oils, organic and inorganic transparent liquids, and nanofluids). This information is presented under the hope that it will serve as a new important resource for physicists, engineers and advanced students interested in the physics of non-isothermal fluid systems; fluid mechanics; environmental phenomena; meteorology; geophysics; and thermal, mechanical and materials engineering.

Research & information: general --- Physics --- coating flow --- free surface --- boundary layer --- stress singularity --- matched asymptotic expansions --- computational fluid dynamics --- turbulence --- rotating thermal convection --- Rayleigh-Bénard --- heat enhancement --- nanofluid --- circular pipe --- twisted tape --- porous media --- metal foam --- convection-driven dynamos --- numerical simulations --- bistability --- mean-field magnetohydrodynamics --- spherical shells --- stochastic equations --- equivalence of measures --- nature of turbulence --- critical Reynolds number --- thermovibrational convection --- gravity modulation --- thermofluid-dynamic distortions --- patterning behavior --- stratified mixing layer --- non-modal instability --- Kelvin-Helmholtz instability --- Holmboe instability --- rotating thermal magnetoconvection --- linear onset --- sphere --- Rayleigh-Bénard convection --- time periodical cooling --- Lattice Boltzmann method --- thermocapillary-driven convection --- half-zone liquid bridges --- particles --- coherent structures --- particle accumulation structure (PAS) --- high Prandtl number fluids --- plane layer --- circular translational vibrations --- thermal vibrational convection --- convective patterns --- coating flow --- free surface --- boundary layer --- stress singularity --- matched asymptotic expansions --- computational fluid dynamics --- turbulence --- rotating thermal convection --- Rayleigh-Bénard --- heat enhancement --- nanofluid --- circular pipe --- twisted tape --- porous media --- metal foam --- convection-driven dynamos --- numerical simulations --- bistability --- mean-field magnetohydrodynamics --- spherical shells --- stochastic equations --- equivalence of measures --- nature of turbulence --- critical Reynolds number --- thermovibrational convection --- gravity modulation --- thermofluid-dynamic distortions --- patterning behavior --- stratified mixing layer --- non-modal instability --- Kelvin-Helmholtz instability --- Holmboe instability --- rotating thermal magnetoconvection --- linear onset --- sphere --- Rayleigh-Bénard convection --- time periodical cooling --- Lattice Boltzmann method --- thermocapillary-driven convection --- half-zone liquid bridges --- particles --- coherent structures --- particle accumulation structure (PAS) --- high Prandtl number fluids --- plane layer --- circular translational vibrations --- thermal vibrational convection --- convective patterns

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

The self-assembly process underlies a plethora of natural phenomena from the macro to the nano scale. Often, technological development has found great inspiration in the natural world, as evidenced by numerous fabrication techniques based on self-assembly (SA). One striking example is given by epitaxial growths, in which atoms represent the building blocks. In lithography, the use of self-assembling materials is considered an extremely promising patterning option to overcome the size scale limitations imposed by the conventional photolithographic methods. To this purpose, in the last two decades several supramolecular self-assembling materials have been investigated and successfully applied to create patterns at a nanometric scale. Although considerable progress has been made so far in the control of self-assembly processes applied to nanolithography, a number of unresolved problems related to the reproducibility and metrology of the self-assembled features are still open. Addressing these issues is mandatory in order to allow the widespread diffusion of SA materials for applications such as microelectronics, photonics, or biology. In this context, the aim of the present Special Issue is to gather original research papers and comprehensive reviews covering various aspects of the self-assembly processes applied to nanopatterning. Topics include the development of novel SA methods, the realization of nanometric structures and devices, and the improvement of their long-range order. Moreover, metrology issues related to the nanoscale characterization of self-assembled structures are addressed.

Technology: general issues --- block copolymer self-assembly --- analytical ultracentrifugation --- tannic acid --- 3D printing --- nano-resolution --- arbitrary distribution --- multimaterials --- deposition surface --- rapidity --- large scale --- conjugated polymers --- polyfullerenes --- processing by convective self-assembly --- thin films and microstructure --- photoluminescence quenching --- block copolymers --- self-assembly --- polymer interface --- nanostructure metrology --- line edge roughness LER --- (S)TEM --- STEM-EELS of PS and PMMA --- directed self-assembly --- nanospheres lithography --- colloidal nanospheres --- direct laser-writing --- directed self-assembly (DSA) --- block copolymers (BCPs) --- chemo-epitaxy --- polystyrene-block-polymethylmethacrylate (PS-b-PMMA) --- line/space patterning --- line edge roughness (LER) --- line width roughness (LWR) --- sequential infiltration synthesis --- block copolymer --- nanoparticles --- colloidal clusters --- colloidal molecules --- sedimentation --- separation --- classification of nanoparticles --- analytical centrifugation --- differential centrifugal sedimentation --- disk centrifuge --- density gradient centrifugation --- block copolymer self-assembly --- analytical ultracentrifugation --- tannic acid --- 3D printing --- nano-resolution --- arbitrary distribution --- multimaterials --- deposition surface --- rapidity --- large scale --- conjugated polymers --- polyfullerenes --- processing by convective self-assembly --- thin films and microstructure --- photoluminescence quenching --- block copolymers --- self-assembly --- polymer interface --- nanostructure metrology --- line edge roughness LER --- (S)TEM --- STEM-EELS of PS and PMMA --- directed self-assembly --- nanospheres lithography --- colloidal nanospheres --- direct laser-writing --- directed self-assembly (DSA) --- block copolymers (BCPs) --- chemo-epitaxy --- polystyrene-block-polymethylmethacrylate (PS-b-PMMA) --- line/space patterning --- line edge roughness (LER) --- line width roughness (LWR) --- sequential infiltration synthesis --- block copolymer --- nanoparticles --- colloidal clusters --- colloidal molecules --- sedimentation --- separation --- classification of nanoparticles --- analytical centrifugation --- differential centrifugal sedimentation --- disk centrifuge --- density gradient centrifugation