Techn. Universiẗat, Diss., 2005--Berlin.

The aim of this study is to examine the possibilities of using fly ash and slag from municipal waste incinerators in the building industry. In the theoretical part waste incinerator, concrete and its elements are described. The practical part is focused on the description of preparation of concrete blocks into which are added fly ash and slag from an incinerator, and description of the final product size and legislation introducing a new product to the Czech market. Fourteen samples of concrete blocks were created and tested for leaching tests and strength tests. Results of the strength test showed a low value because the samples preparation was not followed by proper technological procedure. Mercury and polycyclic aromatic hydrocarbons have been observed in the leaching test. The leachates were compared with Decree No. 294/2005 Coll. and values met the required limits. Formula clause:I do not agree with the publication of the work in accordance with Directive no. 3 / 2017- Publishing undergraduate theses in order to protect trade secrets of the company in its entirety ie. Both in electronic and printed form to the maximum possible period of 3 years.

Spa areal in Yverdon is a peculiar green isle in the context of the town, which is surrounded by a build-up area, so it is the part of the town in the same time. So I decided to propose the spa in more than one object to create a piece of the town - but lying in the park, which can bring diverse situations to the place and enrich the park not just for the users of the spa itself. There are three basic parts of the spa project content - so that three houses. Public spa with wellness, therapeutic spa and the hotel. There is large water face interconnecting the spa houses and a big hard surface as the counter balance of the water. In the design of the space arrangement my aim was to propose simple spaces with easy orientation within. Frequent motiv is the contrast of the opened and enclosed or the view-throughs into the further spaces.

Die vorliegende Arbeit zeigt Forschungsergebnisse zur Materialveränderung normaler und hochfester Betone unter Impulsbelastung gegenüber einer quasi-statischen Beanspruchung. Die Untersuchung wurde an speziellen eingeschnürten Prismen unter zentrischem Zug vorgenommen. Die Untersuchungen belaufen sich auf die generelle Festigkeitssteigerung und Modifikation der Spannungs-Dehnungs-Beziehung infolge veränderter Belastung. Neben den Betrachtungen des Materialverhaltens wurde auf die entstehenden Bruchflächen ein genaueres Augenmerk gerichtet, um Unterschiede des Materialverhaltens durch Änderungen beim Bruchvorgang zu erkennen. Zur Beurteilung der Bruchfläche werden die fraktale Analyse und ein Ortsfrequenzspektrum genutzt. / The present paper exhibits results of the latest research into the modification of the behaviour of normal and high-strength concrete on impact versus quasi-static loads. This examination has been carried out at tensile stress on special constricted specimens. The enquiries amount to the general strength increase and modification of the stress-strain-relationship due to a changing of load history. Further on, a special attention was turned to the crack surface to get differences of the material behaviour during the cracking process. The fractal analysis and a spatial frequency spectrum were used for the description of the surface.

Among the most impressive developments observed in the last 20 years, the improvement of the installation methods of monolithic refractories is certainly to be taken into account. However, this evolution, from vibratable castables to shotcrete and drycrete was not applied to materials based on magnesia, which are still mostly commercialized as ramming mixes, or as pouring castables with poor properties due to excessive water use. The major issues associated to this lack of technology is the scarcity of submicrometric powders compatible to magnesian systems, and the expansion followed by hydration of the magnesia, which is a disruptive reaction. By a thorough research on the literature, some potential additives were identified to be tested as anti-hydration additives. Hydration tests of powders in autoclave, complemented by pH and rheological measurements on magnesia pastes have identified five possible additives which can be used to inhibit the hydration: tartaric acid, citric acid, boric acid, magnesium fluoride and microsilica. Salts from the organic acids can also be successfully used. Of these, microsilica also presented the advantage of providing the submicrometric particles necessary to improve the flow of the castable, and to improve the bond of the castable. The three acids are very effective in inhibiting the formation of magnesium hydroxide, but affect negatively flow properties and mechanical resistance after cure. Microsilica prevented hydration cracks due to the reaction between the silicic acid generated under basic environment with the newly formed brucite, leading to the precipitation of a magnesium-silica-hydrated phase of poor crystallinity between the magnesia grains. This phase does not promote volumetric change, and also enable water release at a wider temperature range. Due to its nature close to serpentine minerals, it forms forsterite and enstatite at low temperatures, thus generating suitable strength between room temperature and at least 1400 °C. Magnesium fluoride changed the nature of this magnesium-silica-hydrated phase, by being incorporated to it and forming a phase more similar to the humite minerals. These minerals present higher MgO:SiO2 molar ratio than serpentine, and their formation requires a lower content of microsilica for a same effect against hydration, which is beneficial for the overall properties of the castable. The properties of the castable, as well as the influence of a number of other variables (for instance, refractoriness under load, creep, cold crushing strength, cold modulus of rupture, bulk density and apparent porosity) were also studied and hereby reported. It is believed that this technology can be further developed for industrial use, provided that some issues regarding the properties at high temperatures are solved. Not only had the study and comprehension of the nature of the bond between microsilica and magnesia, and the role of magnesium fluoride been pioneered by this work, but also the methodology used to evaluate the hydration after the drying process of castings, which was close to real refractory components.

Darmstadt, Techn. Universiẗat, Diss., 2007.

Zugl.: Dortmund, Techn. Univ., Diss., 2008

The diploma thesis follows up on the bachelor thesis and deals with the issue of light-transmitting concrete LTC. The aim of thesis determines the transparency and its decrease due to durability. The terotical part deals with extension of LTC issues and follows up reserch from bachelor thesis. The teory is also focused on the issue of glass optical fibers. The experimental part deals with the influence of selected durability test on transparency of LTC. Transparency is determined by mesuring devise called black box. In the conclusion is summarized influences witch affects transparency and evaluation of whether the selected fibers are suitable for outdoor use.

La durabilité des structures en béton du génie civil est conditionnée par la diffusion d'espèces chimiques dans le réseau poreux du matériau cimentaire. C'est en particulier le cas avec le transport des ions chlore dans les bétons et avec la lixiviation et le séchage des matériaux à base de ciment. Des modélisations de ces phénomènes, basées sur la méthode des volumes finis, sont présentées dans ce travail dans le but de fournir des outils de prédiction de la dégradation des matériaux cimentaires. La dégradation chimique d'un matériau poreux est d'abord étudiée à partir d'un modèle simplifie de diffusion et de dissolution non instantanée. Des solutions analytiques correspondant à des cas limites sont comparées à celles obtenues par un schéma numérique de volumes finis. La concordance des résultats montre que cette méthode numérique simule parfaitement la progression de fronts de dissolution raides. Le modèle simplifie est ensuite étendu au cas de la lixiviation d'une pâte de ciment, permettant ainsi la restitution de résultats expérimentaux. Le transport des ions chlore est modélisé par une équation de diffusion-sorption. Le cas d'une isotherme de fixation de Freundlich conduit à un front de pénétration des chlorures, observe sur des résultats expérimentaux et une simulation numérique. Une modélisation des transferts hydriques en milieu poreux non sature est décrite dans la seconde partie et est appliquée au séchage isotherme de matériaux cimentaires faiblement perméables. La comparaison entre les résultats de cette modélisation et d'expériences de séchage sur bétons et pates de ciment permet l'identification du mode de transfert de l'humidité dans ces matériaux. Ce travail débouche sur une méthode de caractérisation de la perméabilité à l'eau des bétons faiblement perméables, paramètre difficilement accessible par les moyens d'investigation classiques.

Zugl.: Hannover, Univ., Diss., 2006