The result of this master’s thesis is acquaintance with the issues of cement concrete resistance to high temperatures. This work describes the processes ongoing in the structure of concrete at extreme thermal loads and analysis of effects of high temperatures on the individual components of reinforced concrete structures is given, then influence of high temperatures and fire on the aggregates, matrix, reinforcement steel and the resulting changes in their properties. In the experimental part is given design of composition of concrete with a higher resistance to high temperatures and subsequent verification of the physico-mechanical properties of sample of concrete after exposure to temperatures at intervals of 200 ° C, 400 ° C, 600 ° C and 900 ° C. In individual recipes were observed changes of volume weight, changes of compressive strength and tensile strength flexural , tensile strength of surface layers and the occurrence of cracks and then were compared the results of thermally loaded and unloaded samples. The benefit in this issue is to evaluate the surface appearance of samples after heat load - study of area of crack and measurement of their width - was used according to the methodology's authors Xing, Hebert, Noumowe a Ledesert given in Cement and Concrete Research. This methodology allows to quantify changes of surface, after temperature load.

The North American Wall mafic dikes and the diorite of the Rockslides mafic complex in the intrusive suite of Yosemite Valley show evidence of mixing with their host granites as well as with earlier components. Whole rock major element variation diagrams indicate the mafic rocks mixed with a more silicic component, but extrapolating to the silica end member does not yield the same result with each element. Trace element concentrations show a wide variation in concentration of Cr and Ni, with two samples showing enrichment in Cr (>300 ppm) and Ni (~44 ppm) compared to other samples (Cr =13-94 ppm; Ni = 5-26 ppm). These samples have the most primitive epsilon Nd values (-3.3, -3.5 at 100 Ma) analyzed thus far for the intrusive suite, indicating the suite has a larger range of isotopic values than previously thought. Delta 18 oxygen for Rockslides samples vary from 6.6 to 7.5 per mille (6 samples, average 7.03), higher than the 5.5 + 0.3 range for the mantle, indicating the presence of a crustal component in the system. Plagioclase phenocrysts within each unit display bimodal compositional populations. Subhedral to euhedral partially resorbed calcic cores (mode = An84-88) are reminiscent of a mafic magma, while sodic rims (mode = An48-50) are the product of a more silicic component. Very little to no intermediate zoning is present between cores and rims. Mineral-scale 87Sr/86Sr analysis of plagioclase cores and rims are consistent with previously published enriched bulk-rock ratios for the suite (0.7065-0.7078), but are unable to distinguish between mixing components. The plagioclase isotopic data show no direct evidence for a depleted mantle melt component contaminated by crustal assimilation. However, the mafic rocks are comparable to high-alumina basalts, whose generation involves crystal fractionation and magma mixing/crustal assimilation. The evolution of these high-alumina basalts provides an opportunity for magma contamination to take place before plagioclase crystallization, thus explaining why plagioclase core-rim analysis could not distinguish between mixing components. Therefore, it is possible but not necessary to derive the rocks from an enriched mantle source, especially since the bulk-rock oxygen isotopic values indicate a significant crustal component is present.

Compression strength after impact tests were conducted on unidirectional composite rods with sleeves. These elements represent local members of open three-dimensional composite lattice structures (e.g., based on isogrid or IsoTruss® technologies). The unidirectional cores composed of carbon, glass, or basalt fiber/epoxy composites were co-cured in aramid sleeves. Sleeve patterns included both bi-directional (unsymmetric) braids and unidirectional spiral wraps with sleeve coverage ranging from nominally half to full. The diameters were nominally 8 and 11 mm (5/16 and 7/16 in). The larger diameter had nominally twice the cross-sectional area, to quantify the effects of scaling. The specimens were long enough to encourage local buckling failure as expected in members of typical composite lattice structures. The unsupported lengths varied from 127 mm (5.0 in) to 160 mm (6.3 in). Specimens were radially impacted at mid-length with energy levels ranging from 0 to 20 J (0 to 14.8 ft-lbs) and tested in longitudinal compression to quantify the effects of local impact damage on the buckling strength. In undamaged specimens, sleeve type and sleeve coverage have no effect on the ultimate compression strength of carbon, glass, or basalt composites (7% or less standard deviation for each material). When impacted, the influence of sleeve type and sleeve coverage varies with the type of fiber in the unidirectional core. Sleeve type and coverage did not affect the compression strength after impact for fiberglass composites. On the other hand, both carbon and basalt composites exhibited improved performance with braided (vs. spiral) sleeves (up to 34% stronger) and full (vs. half) coverage (up to 38% stronger). The compression strength of carbon configurations decreases with increasing impact energy regardless of sleeve type or coverage. The higher flexibility of glass and basalt composites, however, allowed some configurations to maintain the same compression strength after impact as their undamaged counterparts, at lower impact energy levels. Doubling cross-sectional area of basalt composites significantly improves the stiffness and compression strength after impact, more than doubling the impact energy required to achieve the same compression strength.

No description available.

Tunnels in hard and jointed rock are normally excavated in an arch shape to enable the rock mass to support its weight. Since the beginning of the 1980's, fibre reinforced shotcrete (FRS) in combination with rock bolts have been the dominating support method for hard rock tunnels. This type of rock support is a complex composite structure in which the structural behaviour depends on interaction between shotcrete, rock and bolts. The design is commonly based on a rock mass classification system in combination with analytical solutions or finite element (FE) modelling. However, the in-situ variations of important properties of the shotcrete are normally neglected.The aim of this thesis was to increase the understanding regarding the environmental impact of different fibre types used as reinforcement in shotcrete. First, a brief introduction to rock support and the role of shotcrete is presented. Along with this the technical performance and a short review regarding the production process involved in producing steel, synthetic and basalt fibres. To understand the environmental impact with respect to the production of different fibre types, environmental product declaration (EPD) from various producers were studied. Here, the environmental performance was studied from cradle to gate for the different fibres. The goal of this thesis was to study the global warming potential of fibres during the production stages and EPDs were used to compare the environmental performance for different fibres of different types and materials. For each fibre type different producers are also compared.To study the environmental impact, a case study in which the shotcrete should fulfil a specified residual flexural strength, or a minimum energy absorption was used. Within this thesis, any potential effects of deterioration of fibres or the need of technical improvement during the technical lifespan was not included. Fibre dosages to fulfil the structural performance were selected based on the experimental testing from the literature. Finally, a detailed discussion regarding the optimum dosages of the different fibre types and their environmental impact is presented.

Mid-Late Triassic-age alkali-basalt dikes were emplaced along the coast of New England between 240-200 Ma. Known as the Coastal New England (CNE) magmatic province, this dike swarm is the immediate magmatic predecessor to the formation of the Central Atlantic Magmatic Province large igneous province at 201 Ma and the breakup of Pangea. The intent of this study is to determine the melt source and mechanisms for melting which produced the Triassic coastal dikes. To achieve this goal, major and trace element compositions were analyzed for 53 CNE dikes from Maine and Nova Scotia. Radiogenic Nd-Sr-Pb-Hf ratios, representing some of the first 176Hf/177Hf data for CNE, are reported for 12 of the dikes. Taken together, the compositional data implicate melting of a deep mantle source that is relatively enriched in incompatible elements, such as a mantle-plume similar to those hypothesized as the source of melting in modern ocean-island basalts (i.e. Hawaii). Dike compositions are inconsistent with melts generated at typical spreading-center ridges (i.e. MORB). Modeling suggests that CNE melts ascended through thick continental crust, consistent with the incipient stages of rifting of Pangea, as evidenced by a heterogeneous mix of melting and crystallization depths, between 0-70km, with no clear geographic pattern. Radiogenic isotope data are relatively consistent and represent a mixture between HIMU, EMI and DMM mantle reservoirs, implying component consisting of relict subducted oceanic crust (or other similarly evolved material). CNE magmatism may have contributed to the breakup of Pangea by destabilizing the lower crust in the limited local area where it erupted, but its true relationship with the breakup of Pangea and later CAMP event requires more study. / Master of Science / Approximately 200-250 million years ago, hundreds of sheets of lava, called dikes, erupted along what is today the coast of New England. As these volcanic dikes rose up from the Earth’s mantle, they traveled along cracks and weak areas of the Earth’s crust. Today, these dikes are found along the New England coast as far south as Rhode Island and as far north as Nova Scotia, Canada. Based on the similarity of their geochemistry and petrology, as well as their geologic age and geography of their eruption, geologists group these dikes and similar volcanics together as a single, related magmatic event. This magmatic event produced the Coastal New England (CNE) magmatic province. 250 million years ago, the coast of New England was actually an interior part of the supercontinent known as Pangea. Around 250 m.yr. ago, Pangea slowly began rifting apart, which is when CNE volcanism began. By 200 m.yr. ago, Pangea had broken up, and CNE volcanism had ended. Further complicating the story, a large-igneous province (LIP) also erupted 200 m.yr. ago. Known as the Central Atlantic Magmatic Province (CAMP), this volcanism consisted of enormous volumes of lava that flooded over the entire east coast of the United States. The intent of this study is to determine what geological conditions led to the CNE volcanism. By learning which part of the Earth melted and why, CNE volcanism’s role in the breakup of Pangea, and the much larger CAMP eruptions that coincided with it, will become clearer. For instance, did the geologic events that resulted in CNE volcanism contribute to the breakup of Pangea, or did the breakup of Pangea cause CNE volcanism followed by CAMP volcanism? To achieve this goal, the geochemical compositions of 53 CNE dikes from Maine and Nova Scotia were analyzed. Radiogenic Nd-Sr-Pb-Hf ratios for a subset of the dikes (12) were also analyzed. This study presents some of the first radiogenic hafnium data for rocks from CNE. The data indicate that the melting which produced the CNE dikes began in the deep mantle, similar to the melting of mantle plumes beneath modern ocean-islands such as Hawaii. In contrast, shallow mantle melting, like the melting at mid-ocean ridges where oceanic crust is produced, is not consistent with the geochemical evidence presented for CNE in this study. Modeling suggests that CNE magmas rose through thick continental crust, which caused them to begin forming crystals at relatively high depths. Radiogenic isotope data suggests that part of the mantle that melted was old, recycled oceanic crust or similar mantle material. CNE magmatism may have contributed to the breakup of Pangea by destabilizing the lower crust in the limited local area where it erupted, but its true relationship with the breakup of Pangea and later CAMP event requires more study.

[pt] Embora uma vasta área do Brasil esteja localizada em regiões que a formação de basalto se faz presente, são raros os estudos em perfis contendo solo e / ou rochas de caráter básico objetivando correlacionar características químicas e mineralógicas com características geotécnicas. A área do presente estudo localiza-se em um corte em solo na Ferrovia Norte-Sul, no Município de Arguianópolis-TO, em que durante sua execução ocorreram diversos escorregamentos. O maciço de solo do corte em questão é composto em sua maior parte por solos provenientes de alteração de basalto. O presente estudo foi realizado em duas etapas. A primeira refere-se à visita ao local do corte, onde foram realizadas coletas de amostras de solo de caráter indeformado e deformado, com as respectivas descrições morfológicas dos mesmos. A segunda refere-se aos trabalhos desenvolvidos nos laboratórios de Geotecnia e Meio Ambiente do DEC da PUC-Rio, EMBRAPA SOLOS e Departamento de Geologia do Instituto de Geociências da UFRJ, abrangendo ensaios de caracterização; ensaios mineralógicos; análises químicas; obtenção das curvas características solo-água; ensaios de erodibilidade; ensaios especiais para a determinação de parâmetros de resistência e de compressibilidade. A partir dos resultados obtidos, espera-se que os mesmos proporcionem uma contribuição para o melhor entendimento de perfis intempéricos em rochas de caráter básico. / [en] In spite of the fact that basalt formations are found in several regions in Brazil, it is difficult to find investigations on the subject relating chemical and mineralogical characteristics with geotechnical ones. The site of the present study comprises a soil slope on the North-South Railroad, at Arguianópolis, Tocantins State. Several landslides occurred during the construction of the railway. The soil mass is mostly composed by soils resulting from basalt alterations. The present study was developed in two stages. The first stage comprised a visit to the site, when a morphologic description of profiles was made and undisturbed and remoulded soil samples were extracted. The second stage refers to works developed at the Geotechnical and Environmental Laboratory of PUC-Rio, at EMBRAPA Soils and at the Geology Department of the Institute of Geosciences of the UFRJ. Such works comprised soil characterization tests; mineralogical tests; chemical analyses; definition of soil-moisture characteristic curves; erodobility tests and special tests to determine strength and compressibility parameters. The results obtained provide a contribution to a better understanding of weathering profiles in rocks of basic character.

With rising concentrations of CO₂ in the Earth's atmosphere causing concern about climate change, many solutions are being presented to decrease emissions. One of the proposed solutions is to sequester excess CO₂ in geological formations such as basalt. The deep subsurface is known to harbor much of the microbial biomass on earth and questions abound as to how this deep life is going to respond to the injection of CO₂. Many studies have used model microorganisms to demonstrate the ability of microbes to aid in the safe, permanent sequestration of CO₂ in the subsurface. The objective of this research is to characterize the microbial community present in the basalts at the Wallula pilot carbon sequestration well prior to the injection of CO₂ and then perform laboratory studies to determine how the native microbial community will respond to carbon sequestration conditions. Six samples were collected from the Wallula pilot well prior to the injection of CO₂ into the system. The microorganisms in these samples were characterized by pyrosequencing of 16S rRNA genes, revealing a community dominated by the Proteobacteria, Firmicutes, and Actinobacteria. The organisms detected were related to microbes known to metabolize hydrogen, sulfur, and single carbon compounds. These microorganisms may be stimulated in formations located at the fringe of the pool of injected CO₂. Laboratory studies revealed that the native microbial community suffered a two order of magnitude loss of population upon exposure to CO₂ under carbon sequestration conditions. The community also shifted from being dominated by Proteobacteria prior to CO₂ exposure to being dominated by Firmicutes after exposure. Specifically, the genus Alkaliphilus, which was previously undetected, appeared after CO₂ exposure and became dominant. The dominance of Alkaliphilus, along with other rare organisms which did not compose a majority of the population prior to the introduction of CO₂ to the system, indicates that members of the rare biosphere may be better adapted to changing environmental conditions specific to CO₂ sequestration than other indigenous cells. Thus, the rare biosphere should be examined closely as part of any environmental study, as these minority microorganisms may be the first indication of perturbation or impact. / Graduation date: 2013

In alkalischen Lösungen führt die Reaktion von Hydroxylionen mit den Si-O-Si-Bindungen des Glasnetzwerks zur Bildung hydratisierter Oberflächen und gelöstem Silikat. Der Grad der Korrosion bzw. der Alterung der Glasfaser ist abhängig von der chemischen Zusammensetzung des Glases und Korrosionslösung sowie von Zeit und Temperatur. Die Untersuchung von Glasfasern verschiedener chemischer Zusammensetzung in NaOH- sowie Zementlösungen zeigte, dass die inhibierende Wirkung von Ca-Ionen zu einem veränderten Korrosionsmechanismus führt. Dies konnte anhand der mechanischen Eigenschaften der Glasfasern sowie rasterelektronenmikroskopischen Untersuchungen gezeigt werden. Während die Korrosion in NaOH-Lösung zu einer ausgeprägten Umwandlung der gesamten äußeren Glasfaserschicht in Reaktionsprodukte führte, zeigten Glasfasern in Zementlösung bei gleichem pH-Wert einen stark lokal begrenzten, punktförmigen Angriff. Daraus resultieren unterschiedliche mechanische Eigenschaften der Glasfasern in Abhängigkeit von der gewählten Korrosionslösung.

科学研究費補助金 研究種目:一般研究(B) 課題番号:63460053 研究代表者:日比野 倫夫 研究期間:1988-1989年度