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Le béton est actuellement le matériau de construction le plus utilisé dans l'industrie, avec une production estimée à environ un milliard de tonnes pour l'Union Européenne seule. L'un des principaux constituants du béton sont les granulats naturels et le sable, dont la production atteignait 2,5 milliards de tonnes par an en Europe en 2021. Il en résulte que cette ressource devient rare, et assurer sa disponibilité dans le futur apparaît comme un défi important. En parallèle, d'autres problématiques environnementales, découlant en partie du secteur de la construction, ont reçu une attention croissante. Cela inclut les émissions de CO2 et la production de déchets par le secteur de la construction et de la démolition.

Pour répondre à ces nouveaux défis, le secteur de la construction recherche de nouveaux processus permettant la réutilisation et le recyclage des déchets de construction et de démolition dans les nouvelles constructions. Une des solutions étudiées est le remplacement des granulats naturels par des granulats provenant du broyage des déchets de construction ou de démolition en béton. Les granulats de béton recyclés sont composés de granulats naturels entourés de résidus de pâte de ciment, ce qui affecte négativement les propriétés du granulat recyclé. La substitution des granulats naturels par ces granulats recyclés dans le béton entraîne une augmentation de sa porosité et donc potentiellement une diminution de sa durabilité.

L'objectif de ce travail est d'étudier l'influence des granulats recyclés sur la carbonatation du béton en prenant en compte les courbes de rétention d'eau, la perméabilité et la porosité. Cela permettra de déterminer l'influence relative de ces différents paramètres sur la carbonatation et, surtout, l'effet général de la substitution par des granulats de béton recyclés sur la carbonatation. L'étude de la carbonatation est un préalable à celle du processus de corrosion, qui est l'un des principaux processus de dégradation des bétons.

Dans ce travail, un modèle numérique a été développé sur la base de divers modèles provenant de la littérature. Pour obtenir les informations nécessaires aux modèles numériques, des essais de sorption et de désorption statique ont été réalisés sur des échantillons de béton de différents types qui ont été carbonatés au préalable. Ces échantillons présentent des compositions différentes : un premier béton à base de granulats naturels, un second béton à base de granulats de béton recyclé de la même courbe granulométrique, et un mortier sans granulat. Les deux bétons disposent du même type de pâte de ciment ainsi que de la même teneur en pâte. Il est ainsi possible d'analyser l'effet du changement de granulat uniquement. La modélisation a été implémentée dans le logiciel de calcul par éléments finis non linéaires développé à l'Université de Liège. Les différents résultats expérimentaux ont ensuite été utilisés dans le modèle numérique. Concrete is currently the most widely used construction material in the industry, with an estimated production of around one billion tons for the European Union alone. One of the main components of concrete is natural aggregates and sand, whose production reached 2.5 billion tons per year in Europe in 2021. As a result, this resource is becoming scarce, and ensuring its availability in the future appears to be a significant challenge. At the same time, other environmental issues, partly stemming from the construction sector, have received increasing attention. This includes CO2 emissions and the production of waste by the construction and demolition sector.

To address these new challenges, the construction sector is seeking new processes that enable the reuse and recycling of construction and demolition waste in new constructions. One of the solutions being studied is the replacement of natural aggregates with aggregates derived from the crushing of construction or demolition concrete waste. Recycled concrete aggregates consist of natural aggregates surrounded by cement paste residues, which negatively affect the properties of the recycled aggregate. Substituting natural aggregates with these recycled aggregates in concrete leads to an increase in its porosity and thus potentially a decrease in its durability.

The objective of this work is to study the influence of recycled aggregates on the carbonation of concrete by taking into account water retention curves, permeability, and porosity. This will determine the relative influence of these different parameters on carbonation and, more importantly, the overall effect of substituting natural aggregates with recycled concrete aggregates on carbonation. The study of carbonation is a prerequisite for understanding the corrosion process, which is one of the main degradation processes of concrete.

In this work, a numerical model has been developed based on various models from the literature. To obtain the necessary information for the numerical models, static sorption and desorption tests have been conducted on different types of concrete samples that had been carbonated beforehand. These samples have different compositions: a first concrete with natural aggregates, a second concrete with recycled concrete aggregates of the same gradation curve, and a mortar without aggregate. Both concretes have the same type of cement paste and the same paste content. It is thus possible to analyze the effect of the aggregate change alone. The modeling has been implemented in the nonlinear finite element analysis software developed at the University of Liège. The different experimental results have then been used in the numerical model.

Béton --- Granulats de béton recyclé --- Carbonatation --- Modélisation par éléments finis non-linéaires --- Courbe de rétention d'eau --- Durabilité --- Concrete --- Recycled concrete aggregates --- Carbonation --- Nonlinear finite element modeling --- Water retention curve --- Durability --- Ingénierie, informatique & technologie > Ingénierie civile

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Concrete is the most widely utilized construction material in the world. Thus, any action intended to enhance the sustainability of the construction industry must consider the supply chain, production, distribution demolition and eventual disposal, landfilling or recycling of this composite material. High-performance concrete may be one of the most effective options to make the construction sector more sustainable. Experience proves that the use of recycled concrete aggregates, as well as the partial replacement of ordinary Portland cement with other supplementary cementitious materials or alternative binders, are generally accepted as the most realistic solutions to reduce the environmental impacts, leading to sufficiently high mechanical performances. In structural applications such as those concerning the seismic and energy retrofitting of existing buildings, the use of high-performance cementitious composites often represents the more cost-effective solution, which allows us to minimize the costs of the intervention and the environmental impact. Eventually, the challenge of enhancing sustainability by raising durability of concrete structures is particularly relevant in those applications where maintenance is particularly expensive and impactful, in terms of both direct intervention costs and indirect costs deriving from downtime. The present Special Issue aims at providing readers with the most recent research results on the aforementioned subjects and further foster a collaboration between the scientific community and the industrial sector on a common commitment towards sustainable concrete constructions.

Technology: general issues --- History of engineering & technology --- recycled concrete aggregate --- recycled aggregate concrete --- durability --- freeze-thaw cycles --- mechanical properties --- concrete --- recycled concrete --- recycled aggregate --- shrinkage --- slags --- cement replacement --- existing beams --- retrofitting method --- environmental assessment --- fly ash --- moment–curvature relationship --- precast elements --- basalt --- concrete properties --- recycled natural basalt --- recycled concrete powder --- seismic retrofitting --- multilayer coating --- Steel Fiber Reinforced Mortar --- energy performance of buildings --- point thermal bridges --- thermal behavior in summer --- case study --- prestressed concrete --- prestress losses --- bridges --- flexural strength --- shear strength --- drying and autogenous shrinkage --- creep --- sustainability --- shear bond --- UHPFRC --- push-off test --- tensile bond strength --- concrete overlay --- strengthening --- existing infrastructures --- digital microscopy --- surface roughness --- mortars --- MSWI bottom ash --- pozzolanic activity --- supplementary cementing materials --- water-retaining structures --- aggressive environment --- n/a --- moment-curvature relationship

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This book, Green Concrete for a Better Sustainable Environment, aims to cover recent advances in the development of green concrete solutions and discuss the best ways to leverage opportunities in this domain. Concrete can be described as green concrete if it has one of the following features; it uses waste material as at least one of its components, its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability. At present, natural resources are running out. Cement and concrete made from industrial and construction waste can be regarded as valuable resources for civil infrastructure construction. Green concrete will not only contribute to a circular economy, but can also help to reduce the amount of embodied energy and CO2 emissions associated with cement manufacturing and aggregate quarrying. Using green concrete can also mitigate the environmental threats associated with industrial waste materials. This book covers the theoretical, experimental, applied and modelling research studies on the materials, products and structures related to sustainable cement-based composites.

History of engineering & technology --- recycled aggregate concrete --- shrinkage and creep --- attached mortar --- prediction model --- construction and demolition wastes --- resource utilization --- recycled concrete hollow block --- masonry walls --- seismic performance --- steel frame --- infilled shear walls --- semi-rigid connection --- seismic behavior --- MSWI bottom ash --- concrete --- sulfate attack --- capillary transport --- crystallization --- husk mortar wallboard --- experiment --- lateral strength --- strain --- failure load --- full replacement ratio --- section steel and RAC --- bond behavior --- SRRC (Steel Reinforced Recycled Concrete) --- bond strength --- bond slip --- numerical simulation --- salt --- NaCl --- asphalt concrete --- freeze–thaw cycles --- winter road --- industrial waste --- sustainable concrete --- recycled expanded glass --- n/a --- freeze-thaw cycles

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This book, Green Concrete for a Better Sustainable Environment, aims to cover recent advances in the development of green concrete solutions and discuss the best ways to leverage opportunities in this domain. Concrete can be described as green concrete if it has one of the following features; it uses waste material as at least one of its components, its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability. At present, natural resources are running out. Cement and concrete made from industrial and construction waste can be regarded as valuable resources for civil infrastructure construction. Green concrete will not only contribute to a circular economy, but can also help to reduce the amount of embodied energy and CO2 emissions associated with cement manufacturing and aggregate quarrying. Using green concrete can also mitigate the environmental threats associated with industrial waste materials. This book covers the theoretical, experimental, applied and modelling research studies on the materials, products and structures related to sustainable cement-based composites.

recycled aggregate concrete --- shrinkage and creep --- attached mortar --- prediction model --- construction and demolition wastes --- resource utilization --- recycled concrete hollow block --- masonry walls --- seismic performance --- steel frame --- infilled shear walls --- semi-rigid connection --- seismic behavior --- MSWI bottom ash --- concrete --- sulfate attack --- capillary transport --- crystallization --- husk mortar wallboard --- experiment --- lateral strength --- strain --- failure load --- full replacement ratio --- section steel and RAC --- bond behavior --- SRRC (Steel Reinforced Recycled Concrete) --- bond strength --- bond slip --- numerical simulation --- salt --- NaCl --- asphalt concrete --- freeze–thaw cycles --- winter road --- industrial waste --- sustainable concrete --- recycled expanded glass --- n/a --- freeze-thaw cycles

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The current production and consumption models of building materials are causing severe environmental and social problems worldwide. In this sense, construction and demolition waste (C&DW) are part of the problem and can be part of the solution, particularly in developing countries where the construction industry is growing very rapidly. Although many efforts have been made by stakeholders to increase the use of C&DW in construction materials, articulated efforts are required at global, national, and local scales to develop truly sustainable construction sectors. Therefore, this e-book, which is based on the “Special Issue on Construction and Demolition Waste: Challenges and Opportunities”, is an effort to articulate knowledge on novel and innovative building materials using C&DW and management systems to develop circular economy models (CE) for the construction sector. In this e-book, it is concluded that even though the valorization of C&DW has been developed worldwide, more incentives need to be provided to really convert the local and national construction chains in sustainable sectors, which appropriate the circular economy for production and consumption systems that imrpove, at the least, efficiency in terms of materials, water and energy use.

Technology: general issues --- History of engineering & technology --- Conservation of buildings & building materials --- construction and demolition wastes --- alkali-activated materials --- recycling --- binder --- recycled aggregates --- paving stones --- aggregates --- C&amp --- DW --- sustainability --- mechanical properties --- concrete --- demolition waste --- management --- life cycle assessment --- circular economy --- recycled concrete aggregate --- recycled aggregate concrete --- residual mortar --- reusing --- workability --- compressive strength --- pavement --- green deal --- construction and demolition waste --- quantification --- waste management --- re-use --- material stock analysis --- multi-criteria decision-making --- local authorities --- urban metabolism --- interview --- building --- recycled concrete --- carbonation --- construction and demolition waste (C&DW) --- construction --- municipal solid waste incineration bottom ash --- supplementary cementitious material --- construction and demolition wastes --- alkali-activated materials --- recycling --- binder --- recycled aggregates --- paving stones --- aggregates --- C&amp --- DW --- sustainability --- mechanical properties --- concrete --- demolition waste --- management --- life cycle assessment --- circular economy --- recycled concrete aggregate --- recycled aggregate concrete --- residual mortar --- reusing --- workability --- compressive strength --- pavement --- green deal --- construction and demolition waste --- quantification --- waste management --- re-use --- material stock analysis --- multi-criteria decision-making --- local authorities --- urban metabolism --- interview --- building --- recycled concrete --- carbonation --- construction and demolition waste (C&DW) --- construction --- municipal solid waste incineration bottom ash --- supplementary cementitious material