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During the last decades, innovative concrete applications have been the result of technological developments as new processing techniques, the use of concrete admixtures and advanced materials. All these improvements increase the demand for better performing concrete with enhanced workability. However, the lack of reliable engineering tools in traditional concrete production methods has led to some inconsistent control of the workability. Therefore, todays research is increasingly investigating advanced models that capture the flow behavior of fresh concrete as accurately as possible. These models are continuously improving but generally keep facing problems which are linked to the agglomeration of the cement particles and to the implementation of combined concrete admixtures. The objective of this work is to investigate the rheological mechanism in cement paste for the combined use of superplasticizer, retarder and accelerator. In particular, an effect on the particle agglomeration is aimed for in order to contribute to a more fundamental understanding of the concretes flow behavior. Concerning the superplasticizer impact on cement paste, thermodynamic modelling and mineralogy studies led to the conclusion that the superplasticizer can change the hydrate morphology to such an extent that the interparticle contact forces are modified. The extra addition of retarder led to a densified polymer layer at the cement grain surface which contributed to the steric stabilization of the cement paste. An additional electrostatic effect and the induced changes in hydrate morphology are also demonstrated to contribute to the low paste viscosity. With the extra addition of a calcium salt accelerator to the cement paste, an interstitial structure was assumed to diminish the rheological effect of the polymer layer.All the developed conceptual mechanisms were implemented in a coherent agglomeration model, based on measurable parameters. In this model, the internal and external hydrates in a cement agglomerate were defined and quantified. Generally, the cumulative amount of hydrates within the agglomerates influenced the agglomerate stability and the amount of external hydrates determined the reagglomeration rate. For the superplasticizer only, a proportional relation was found between the change in agglomeration rate and the external agglomerate connectivity while, for the extra addition of retarder and accelerator, a reverse relation was found. The latter was attributed to a mechanical contribution of the interstitial volume. On the one hand, the retarder creates a source of slowly hydrating nuclei and particles in that volume and, on the other hand, these particles are expected to coagulate due to the accelerator addition. In the second case, the interstitial volume also delivered a contribution to the stress resistance of the cement paste at rest.This fundamental research combines dedicated analytical methods and conceptual models to improve the understanding of particle agglomeration and contributes to a more extensive insight into the concrete rheology.
691.54 --- Academic collection --- Cements. Pozzolanic materials --- Theses --- 691.54 Cements. Pozzolanic materials
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691 --- 691.7 --- 72.04 --- Bouwmaterialen (architectuur) --- Staalconstructies --- Staal --- Architectuurdetails --- Details (architectuur)
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691.5 --- 691.5 Binders. Bedding materials --- Binders. Bedding materials --- Bindmiddelen ( bouw)
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Internet --- Websites --- Informatica --- Informaticasector --- Informatiemaatschappij --- Kennis --- Kennismanagement --- 691 Informatiemaatschappij --- Website
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#A0103A --- 691 Internet --- #KVHA:Journalistiek --- #KVHA:Research --- #KVHA:Onlinejournalistiek
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691.1 --- #ECO:04.02:sectoren chemie --- #A9803A --- Materials of organic origin --- 691.1 Materials of organic origin
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onderwijsvernieuwing --- Teacher education. Teacher's profession --- Action research in education --- -691 --- Lerarenopleiding --- algemeen. --- 691 --- Pedagogie en didactiek
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Aside from water the materials which are used by mankind in highest quantities arecementitious materials and concrete. This book shows how the quality of the technical product depends on mineral phases and their reactions during the hydration and strengthening process. Additives and admixtures infl uence the course of hydration and the properties. Options of reducing the CO2-production in cementitious materials are presented and numerous examples of unhydrous and hydrous phases and their formation conditions are discussed.This editorial work consists of four parts including cement composition and hydration, Special cement and binder mineral phases, Cementitious and binder materials, and Measurement and properties. Every part contains different contributions and covers a broad range within the area.
Cement. --- Cement --- Concrete. --- Beton --- Building materials --- Hydraulic cement --- Adhesives --- Mechanical properties. --- 69 --- 691 --- 691.5 --- Bouwtechniek --- Bouwmaterialen (architectuur)
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Die Vorhangfassade - eine nichttragende Wand, die dem Gerüst eines Skelettbaus als Verkleidung vorgehängt wird - ist aus dem Vokabular der modernen Architektur nicht wegzudenken. Die Entwicklung der Elastomere hat das Traggerüst stark reduziert und die Voraussetzung für rein gläserne Hüllen geschaffen. In diesem Buch werden etwa zwanzig beispielhafte Fassadenlösungen des Büros Cesar Pelli & Associates dokumentiert. Nach den verschiedenen Fassadenmaterialien - Glas, Metall, Stein - geordnet, werden die jeweiligen Konstruktionsdetails ausführlich und mit vielen Zeichnungen dargestellt. Beleuchtet wird auch der Entwicklungsprozess der jeweiligen Fassadenlösung, die meist sehr individualisiert ist in Entwurf ebenso wie in Fertigung. Zu den dokumentierten Bauten gehören der Nakanoshima Mitsui Tower in Osaka, das Cheung Kong Center in Hongkong, die Bank Boston in Buenos Aires, der Mori Tower in Tokio, Heron Quay 3 in London oder das Gebäude 731 Lexington Avenue in New York.Michael J. Crosbie ist Architekt und hat zahlreiche Bücher über Architektur geschrieben. Früher Redakteur der Architekturzeitschrift Progressive Architecture, schreibt er heute regelmäßig für Zeitschriften wie Domus, Architectural Record und Landscape Architecture.
Curtain walls. --- Pelli, Cesar --- Themes, motives. --- Cesar Pelli and Associates. --- Cladding (Building) --- Claddings (Building) --- Enclosure walls --- Window walls --- Exterior walls --- Pelli and Associates --- Cesar Pelli & Associates --- 692.2 --- 692 --- 691.2 --- 691.4 --- 691.6 --- 691.7 --- 691 --- Gevels --- Buitenmuren --- Vliesgevels --- Gordijngevels --- Constructiedelen --- Natuursteen --- Leisteen --- Tegels --- Glas --- Metaal --- Bouwmaterialen (architectuur)
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Building, Wooden --- Wooden-frame buildings --- 691 --- 691.1 --- 691.11 --- 72.039 --- Houtarchitectuur ; 21ste eeuw --- Bouwmaterialen ; hout --- Houtconstructies ; houtarchitectuur ; 2000-2014 --- Bouwmaterialen (architectuur) --- Hout --- Houtconstructies --- Architectuurgeschiedenis ; 2000 - 2050 --- Building, Wooden.