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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigation Of Relationship Between Aggregate Shape Parameters And Concrete Strength Using Imaging Techniques

Ozen, Murat 01 April 2007 (has links) (PDF)
In this study, relationships between aggregate shape parameters and compressive strength of concrete were investigated using digital image processing and analysis methods. The study was conducted based on three mix design parameters, gradation type, aggregate type and maximum aggregate size, at two levels. A total of 40 cubic concrete specimens were prepared at a constant water-cement ratio. After the compressive strength tests were performed, each specimen was cut into 4 equal pieces in order to obtain the digital images of cross sections using a digital flatbed scanner. A number of aggregate shape parameters were then determined from the digital image of the cross sections to investigate their relationships with the compressive strength. The results indicted that even though the aggregate type was found to give strong correlation with the compressive strength, weak correlations, however, exist between the compressive strength and the aggregate shape parameters. The study suggested that the analyses of relationships should be further investigated by including the effects of aggregate distribution within the specimen cross sections.
2

Fatores controladores dos aspectos texturais em rochas siliciclásticas deformadas por bandas cataclásticas.

SILVA, Andrezza Sousa. 29 August 2018 (has links)
Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-08-29T23:45:59Z No. of bitstreams: 1 ANDREZZA SOUSA SILVA – DISSERTAÇÃO (PPGEPM) 2018.pdf: 5233631 bytes, checksum: 12ad47a8373c6479a15d2cbfeba06e8d (MD5) / Made available in DSpace on 2018-08-29T23:45:59Z (GMT). No. of bitstreams: 1 ANDREZZA SOUSA SILVA – DISSERTAÇÃO (PPGEPM) 2018.pdf: 5233631 bytes, checksum: 12ad47a8373c6479a15d2cbfeba06e8d (MD5) Previous issue date: 2018-03-19 / A Bacia Rio do Peixe (BRP) apresenta diversas estruturas rúpteis, dentre elas as bandas de deformação, que podem controlar as propriedades petrofísicas e aspectos texturais das rochas. Portanto, o objetivo deste trabalho é identificar os efeitos causados pelos diferentes tipos de bandas de deformação cataclásticas, em função da cinemática, sobre os aspectos texturais, distribuição de tamanho de grãos e poros, bem como porosidade em arenitos conglomeráticos. As propriedades dos grãos e dos poros foram extraídas através da análise de imagens em seções delgadas no Avizo Fire 8.1. No total foram analisadas 23 amostras, 19 com bandas de deformação (CB) com orientação definida (NW, NE, NS e EW), 2 amostras deformadas, porém sem bandas (SB) e 2 amostras da rocha hospedeira (ND). As rochas deformadas (CB e SB), apresentam redução no tamanho de grãos e pequeno acréscimo nos valores dos aspectos texturais em comparação a rocha não deformada (ND). Em relação à porosidade foi encontrada redução de 66% nas amostras CB e acréscimo de 13% nas SB. Ambos agrupamentos possuem maior conexão de grãos, permitindo o surgimento da macroporosidade, que não havia sido detectada nas amostras ND. Dentre as amostras com banda de deformação e cinemática definida, a rochas associadas ao sistema transcorrente dextral, de direção NW, possuem maior redução de diâmetro de grão, e menor redução de porosidade, cerca de 29%. As amostras com bandas de deformação NE e NS, formadas por cinemática transtensiva, são as amostras nas quais houve a menor quebra dos grãos, entretanto caracterizam-se pela presença de porosidade por fraturamento de grãos, gerando altos picos de macroporosidade. As amostras oriundas do sistema distensivo de direção EW possuem segunda maior redução de grãos, maior redução de porosidade e ausência de macroporosidade. Os aspectos texturais (circularidade, convexidade e razão de aspecto) das amostras com banda (NW, NE, NS e EW) é dependente da intensidade de cisalhamento provocado por diferentes sistemas deformacionais, quanto mais intenso mais cominuído será o grão, e consequentemente mais convexo, circular e menos alongado. Logo, é possível observar que a cinemática e a presença de bandas de deformação exercem controle sobre os aspectos texturais e petrofísicos dos arenitos conglomeráticos da Formação Antenor Navarro. E esse controle é definido pela compactação da rocha, rearranjo dos grãos, intensidade da catáclase, presença de fraturamento de grãos e cinemática atuante. / The Rio do Peixe Basin (RPB) presents several rump structures, among them the deformation bands, which can control the petrophysical properties and textured aspects of the rocks. Therefore, the objective of this work is to identify the effects caused by the different types of cataclastic deformation bands, as a function of kinematics, on the textural aspects, grain and pore size distribution, as well as porosity in conglomeratic sandstones. The grain and pore properties were extracted by thin section image analysis in Avizo Fire 8.1. In total, 23 specimens were analyzed, 19 with deformation bands (CB) with defined orientation (NW, NE, NS and EW), 2 deformed samples, but without bands (SB) and 2 samples of host rock (ND). The deformed rocks (CB and SB), present a reduction in grain size and small increase in the values of the textured aspects in comparison to the non-deformed rock (ND). In relation to the porosity, a reduction of 66% was found in the CB samples and a 13% increase in the SB. Both clusters have a larger grain connection, allowing the appearance of macroporosity, which had not been detected in the ND samples. Among the samples with deformation band and defined kinematics, the rocks associated to the dextral transcurrent system, NW direction, have a larger reduction of grain diameter, and a smaller reduction of porosity, about 29%. The samples with NE and NS deformation bands, formed by transtensive kinematics, are the samples with the lowest grain breakage. However, they are characterized by the presence of porosity by grain fracturing, generating high peaks of macroporosity. The samples from the EW steering distance system have the second largest grain reduction, greater reduction of porosity and absence of macroporosity. The textural aspects (roundness, convexity and aspect ratio) of the banded samples (NW, NE, NS and EW) are dependent on the shear strength caused by different deformation systems, the more intense the grain is, the more convex, circular and less elongated. Therefore, it is possible to observe that kinematics and the presence of deformation bands exert control over the texture and petrophysical aspects of the conglomeratic sandstones of the Antenor Navarro Formation. And this control is defined by the rock compaction, rearrangement of the grains, the intensity of the catachase, presence of grain fracture and active kinematics.

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