The current technology for sprayed concrete cannot do without various types of concrete admixtures allowing that more demanding requirements for quality and overall characteristics of Sprayed Concrete can be met. These are mainly concrete plastificators and set acceleration admixtures. In practice these technologies are employed especially in construction of underground structures where the working conditions are often very restricted. In these days Sprayed Concrete is usually applied by wet spraying where the fresh concrete is made in a batching plant and then transported to the construction site. That is why it is also important to pay attention to rheology characteristics of sprayed concrete. The concrete is then placed by a special spraying plant while it is ensured that all requirements and technical specifications for sprayed concrete are complied with. The characteristics are most affected by the admixtures - both plastificators and accelerators and their compatibility with cement. In order to acquire new evidence in the field of sprayed concrete technology and use of admixtures and their effect in relation with various types of cement a number of combinations of admixtures and cements were tested. Gradually results were obtained and recorded for rheology of cement mortars and concrete, for characteristics of young sprayed concrete mixes and for the comparison between the laboratory tests and findings from daily practice.

The Cold-Gas Dynamic-Spray process also known as Cold Spray (CS) has been researched for three decades. The CS process is a solid-state deposition technique via supersonic velocity of powder particles at a temperature significantly below the melting point of the spray material. This thesis presents background on the overall CS process parameters, and additional information on the microstructural and mechanical properties of typical Cold Sprayed materials.This Thesis primarily presents a study on the microstructural annealing response of CS Al 6061. It should be noted that for this study, the term “annealing” is used in the sense of the classical metallurgical definition of annealing, and not a specific temper designation for the 6061 alloy. Cross sections of CS Al 6061 were imaged with a scanning electron microscope (SEM) in secondary electron (SE), backscatter electron (BSE), and electron backscatter diffraction (EBSD) imaging mode for quantitative and qualitative information on the grain size and orientation of the CS microstructure. The detailed SE, BSE and EBSD mode images present the grain size and grain orientation of the original powder, as received (AR) state and after heat treating at 200°C for 1 hour, 10 hours, and 100 hours. Three different regions, characterized with distinctly differing microstructures, are labeled as low, medium, and high deformation regions, and their microstructures, and evolving features are discussed. Vickers microhardness testing are performed to examine the differences in hardness values between different heat treatments, and for correlation with the level of deformation and grain refinement in the microstructure. SEM imaging was used in BSE mode to correlate microhardness variation to the different regions within the CS microstructure.

Made available in DSpace on 2014-07-29T15:18:20Z (GMT). No. of bitstreams: 1 antonio davi barbosa.pdf: 7758896 bytes, checksum: ca05d091a1db99ebc27e5221e6137f79 (MD5) Previous issue date: 2010-09-24 / The present work aims to analyse the durability parameters of the shotcrete, comparing the dry and wet projection systems, of the concrete resulting from the projection in plates and from the test specimens extracted from the tunnels structures of the North-South Railway, tract 01, in Anápolis-GO. This work considers an experimental research concerning the shotcrete behavior for dry-mix and wet-mix projection systems, by using testing indicators of the main durability parameters coming from national and international specifications. So, the experimental program involves a comparative assessment among the projection systems of current use in shotcrete, considering the comparative analysis between projected plates (control) and extracted test specimens from the tunnels on what refers to meeting the requirements related to durability. Therefore, the experimental program showed as independent variables: type of projection system (whether by means of dry-mix or wet-mix shotcrete) and the extraction of test specimen (from the control plates or from the tunnels structure). For each type of projection (dry-mix and wet-mix shotcrete), three plates were cast (normally used for concrete technological control) in conditions similar to the work-site, with the test specimens extraction been carried out according to pre-established ages. Eight test specimens were extracted from the just-builts tunnels generating thus samples to the durability associated tests, such as: capillary water absorption, immersion water absorption, concrete electric resistivity, water penetration under pressure, penetrability of chloride ions and concrete compressive strenght. Test specimens extracted from the tunnels and the from the plates were also submitted to testings of compressive strenght and mix-proportion reconstruction. The concrete extracted from tunnels showed worse results comparing to the parameters expected from the projected concrete requirements for road and rail tunnels, and it also demonstrated results which were inferior to the ones obtained from the plates. From a general assessment view, we could verify losses of durability properties of the shotcrete extracted from tunnels in reference to the projected plates. / O presente trabalho tem como objetivo analisar os parâmetros de durabilidade do concreto projetado, comparando os sistemas de projeção via seca e via úmida, dos concretos resultantes da projeção em placas e dos testemunhos extraídos das estruturas dos túneis da Ferrovia Norte-Sul, trecho 01, em Anápolis-GO. Este trabalho contempla um estudo experimental de análise do comportamento de concretos projetados por via seca e úmida, através de ensaios indicadores dos principais parâmetros de durabilidade, constantes das especificações nacionais e internacionais. O programa experimental envolve, portanto, a avaliação entre os sistemas de projeção de uso corrente em concreto projetado, considerando a análise comparativa entre as placas projetadas (de controle) e os testemunhos extraídos dos túneis, no que se refere ao atendimento aos requisitos relativos à durabilidade. Para tanto, o programa experimental teve como variáveis independentes: tipo de sistema de projeção (se por via seca ou por via úmida) e a extração dos corpos-de-prova de concreto (da placa ou do túnel). Para cada tipo de projeção (via seca e via úmida) foram moldadas três placas (normalmente utilizadas para os fins de controle tecnológico do concreto) em condições similares às da obra, tendo-se em seguida, nas idades preestabelecidas, executado-se a extração de corpos-de-prova. Foram também extraídos oito testemunhos dos túneis executados, gerando, assim, corpos-de-prova submetidos aos ensaios balizadores dos parâmetros de durabilidade adotados neste estudo, a saber: absorção de água por capilaridade, absorção por imersão e fervura, resistividade elétrica, penetração de água sob pressão, penetrabilidade de íons cloreto e resistência à compressão axial. Contribuíram também para a caracterização do material os corpos-de-prova extraídos dos túneis e das placas, que foram submetidos a ensaios de resistência à compressão axial e de reconstituição de traço. Os concretos extraídos dos túneis mostraram resultados abaixo dos parâmetros para os resultados esperados dos requisitos de concreto projetado para os túneis rodo-ferroviários, e ainda com resultados inferiores aos resultados obtidos das placas. Numa avaliação geral, constatou-se perdas de propriedades de durabilidade do concreto projetado extraídos dos túneis em referência aos das placas projetadas.

In this study, the goal is to optimize the process and to reduce the clogging tendency during the continuous casting process. The focus is on clogging when the refractory base material (RBM) in the SEN is in contact with the liquid steel. It is difficult or impossible to avoid non-metallic inclusions in the liquid steel, but by a selection of a good RBM in the SEN clogging can be reduced.   Different process steps were evaluated during the casting process in order to reduce the clogging tendency. First, the preheating of the SEN was studied. The results showed that the SEN can be decarburized during the preheating process. In addition, decarburization of SEN causes a larger risk for clogging. Two types of plasma coatings were implemented to protect the RBM, to prevent reactions with the RBM, and to reduce the clogging tendency. Calcium titanate (CaTiO3) mixed with yttria stabilized zirconia (YSZ) plasma coatings were tested in laboratory and pilot plant trials, for casting of aluminium-killed low-carbon steels. For casting of cerium alloyed stainless steels, YSZ plasma coatings were tested in laboratory, pilot plant and industrial trials. The results showed that the clogging tendency was reduced when implementing both coating materials.   It is also of importance to produce clean steel in order to reduce clogging. Therefore, the steel cleanliness in the tundish was studied experimentally. The result showed that inclusions originated from the slag, deoxidation products and tundish refractory and that they were present in the tundish as well as in the final steel product. / VINNOVA

Production wastes for which a direct use in another production is found become secondary raw materials. There are several institutions in Czech Republic and in the world, which are currently dealing with the issue. This thesis deals with the issue of cementitious spray concrete mixtures and deals with the possibilities of using secondary raw materials and waste from production as partial replacement of binder and filler in these mixtures. The aim of this theses is to optimize the composition of additives in the recipe of the commercially produced pray mixture and to verify the influence of the degree of substitution of binder or filler by secondary raw materials on its physical-mechanical properties. The aim is to maintain or increase these properties while substituting the binder and filler as much as possible. After the evaluation of results, it is possible to say, by suitable optimization of the additives it is possible to achieve a significant improvement of the physical-mechanical properties of the mass and furthermore, from the results of this thesis follows, that by substitution of 100% fine filler in combination with substitution of 30% binder it is possible to maintain or increase the physical-mechanical properties after 28 days of curing and to significantly increase these properties after 90 days of curing. The results of this thesis are also related to the reduction of economic impact on production of the spray mixture, mainly due to the use of secondary raw materials.

The thesis focuses on the design of the underground garage in the centre of Brno under the Petrov hill. The main target of the thesis is to design spatial arrangement of the underground space and its feasibility study. In the following parts the design of the structural solution and its check calculation is carried out.

Shotcrete (sprayed concrete) was used for the first time in 1914 and has become of  growing importance in stabilizing the excavated tunnel sections over the past century.  Even though the technology develops, there are some difficult tasks such as the design of a bolt anchored tunnel lining made of shotcrete. A proven and established design method does not exist today; instead the design of tunnel linings are based on trial and error or experience from similar projects. One method used today, to determine the actual structural behavior of fiber reinforced shotcrete, is the standard beam test method. Previous studies have shown that the beam method gives scattered results since the testing volume are relatively small and the fibers might be unevenly distributed.  In 1998, an alternative to determine the actual structural behavior of reinforced shotcrete was proposed, based on using round determinate panels. In 2004 this method became a part of the American Society for Testing and Materials, ASTM, standards. The method has the potential of becoming a major, reliable test procedure that better reproduce the behavior of reinforced shotcrete in situ, compared to test beams. An experimental test series was performed to compare the different testing methods in terms of data variability and validity, in the laboratory of Vattenfall in Älvkarleby. The experiment was performed on 30 specimens in total, with five different concrete recipes. The difference in the recipe was the fiber and cement content. The round panels are designed according to ASTM C-1550 and the beams according to SS-EN14488-3. The results from the experiment is here presented and evaluated, and also including the data variability and validity for the proposed method. The two basic testing methods of using beams and round panels are investigated, compared and evaluated, and their advantages and disadvantages discussed. / Sprutbetong användes första gången år 1914 och har under det gångna århundradet blivit allt viktigare för att stabilisera utsprängda tunnelsektioner. Trots att tekniken utvecklas finns det svårigheter med att exempelvis utforma bultförankrade tunnelbeklädnader av sprutbetong. En beprövad och etablerad metod att konstruera sprutbetongbeklädnad existerar inte idag. Istället används erfarenhetsåterföring från tidigare projekt och/eller experimentella försök. En testmetod som används idag för att återskapa beteendet hos sprutbetong är balkförsök. Tidigare studier har däremot visat att resultaten från försöken oftast har stor spridning vilket kan bero på att brottytorna är små areor där fibrerna kan vara ojämnt fördelade vilket påverkar resultaten. År 1998 föreslogs en alternativ metod för att fastställa de mekaniska egenskaperna hos sprutbetong, baserat på användning av runda plattor. År 2004 blev denna metod en del av the American Society for Testing and Materials, ASTM, standarder. Metoden har potential att bli en viktigt och tillförlitligt testmetod som mer realistiskt efterliknar beteendet hos fiberarmerad sprutbetong jämfört med balkprovning. En experimentell försöksserie har genomförts hos Vattenfall i Älvkarleby, för att jämföra de två metoderna med avseende på mätosäkerhet. Försöksserien är på totalt 30 prover, där fem olika betongrecept använts. Cementmängden och fiberhalten varierade mellan de olika recepten. De runda plattorna är utförda enligt ASTM C-1550 och balkarna enligt SS-EN14488-3. Resultaten från försöken har redovisats och utvärderats, och en mätosäkerhersanalys presenteras för metoden ASTM C-1550. Korrelationen mellan resultaten från de två metoderna är beräknad och varianskoefficienten presenteras. För- och nackdelar mellan båda testmetoderna diskuteras.

The thesis contains analysis earthworks, foundations, carcass substructure of residential house on the street Kopečná 9 in Brno. The work also includes gradual changes in site equipment, detailed schedule of work for selected works, rough schedule of the whole building, construction budget, site equipment budget and details of construction. Specialization in the work addresses the specific use of roads and traffic signs.

The statue called The Cathedral is a natural extension of my work, which deals with organic morphology of the landscape, both the details and grand compositions, which in the countryside vyskytují.Stejně like most authors is my creative work reflection of my surroundings, both personal so near in geographical terms. Integrating these aspects arise impetus to creation. In the case of sculptures entitled The Cathedral is a rendering of the very strong impression of verticality, which dominates the landscape. Regularly clashing with seemingly ordinary natural objects such as trees, soil, hills or reliefs and reliefs such as landscapes, I got into an imaginary dialogue, which I decided to answer this statue and also portray already mentioned impressed. This feeling is for me identically comparable to a situation where the viewer stands in front of the high Gothic building and trying to accommodate the shape of a giant who stands before him. Its peak, it seems so distant, as if no end, and the broad base is a kind of sign of confidence in the form of stability. Parallels between these seemingly different topics I could not miss, so I decided to call the statue Cathedral. In this work, as in previous ones, I try to get into organic sculptures character with the help of the deformation of materials, or basically draping. Compacting elastic materials to try to create the statues of the tension that fascinates me in nature and creates the impression of growth, which is in the countryside of one of the strongest motives. Shape diversity, which is in the landscape, in my inexhaustible source of inspiration and has become lately a space that fills me. When I release the perception of various aspects of your imagination and build imaginary composition, which would then be identical expression perceived impressions.