Magister Scientiae Dentium - MSc(Dent) / To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. The volumetric change that occur during the polymerization of dental composite restorations are considered to be one of the most significant contributing factors when considering the failure in composite restorations. Volumetric shrinkage of more than 2% is considered to be enough to result in the occurrence of secondary caries resulting in fracture of restorations and failure in the adhesive layer of a resin restoration. The total volumetric change of dental resins can be attributed to three main factors: Firstly, the polymerization reaction that results in the formation of a polymer chain. Secondly, the increase of the exothermic thermal effects produced by the polymerization reaction and thirdly, light irradiance energy that is transferred to the dental resin.

Esta dissertação tem por objetivo a obtenção de parâmetros geotécnicos dos solos variegados da Formação São Paulo utilizando ensaios in situ, visando em especial estabelecer correlações entre os parâmetros de histórico de tensões, coeficiente de empuxo em repouso, módulos de deformabilidade e resistência não drenada do solo obtidos através de ensaios com o piezocone e dilatométricos. A realização de ensaios in situ tem como principal vantagem a obtenção de parâmetros do solo no local de projeto, minimizando os efeitos de perturbação de amostras \"indeformadas\", com todas as suas consequências nos ensaios de laboratório. Utilizando dados da expansão da Linha 2 Verde da Companhia do Metropolitano de São Paulo (Metrô-SP) foi possível obter valores da pressão de préadensamento (\'p), razão de sobreadensamento (OCR), coeficiente de empuxo em repouso (K0), módulo de elasticidade tangente inicial (Ei), módulo de cisalhamento tangente inicial (G0), módulo edométrico (M) e resistência ao cisalhamento não drenada (su) para os solos variegados da Formação São Paulo. Esses solos são marcados por intercalações centimétricas a métricas de argilas e areias, constituindo uma característica própria com parâmetros geotécnicos distintos e lençóis empoleirados. Por esse motivo, ainda existem lacunas de conhecimento nos parâmetros de projeto. Para concluir, foi possível validar correlações apropriadas envolvendo os parâmetros: coeficiente de empuxo em repouso, razão de sobreadensamento, módulo de elasticidade tangente inicial, módulo de cisalhamento tangente inicial (G0), resistência não drenada e pressão de pré-adensamento através de resultados de ensaios de campo e laboratório apresentados por outros autores. / The purpose of this research is to obtain geotechnical parameters of the variegated soils from São Paulos Formation through in situ tests (piezocone and dilatometer), aiming in particular to establish correlations between stress history parameters, earth pressure coefficients at rest, deformability modules and undrained strength. The in situ tests have the major advantage of obtaining soil parameters in the project site, minimizing the effects of soil disturbances that may affect the results of laboratory tests. Using data from geotechnical investigation carried out during the basic design of the Green Line expansion for the Metrô SP it was possible to obtain preconsolidation pressure (p), over consolidation ratio (OCR), earth pressure coefficients at rest (K0), Young´s module (Ei), initial shear module (G0), constrained module (M) and undrained shear strength (su) for the variegated soils from São Paulo Formation. These soils are characterized by alternate layers of clays and sands, being the heterogeneity their major characteristic with different geotechnical parameters and also perched water table. For this reason, there are still knowledge gaps in the design parameters. To conclude, it was possible to validate appropriated correlations between preconsolidation pressure (p), earth pressure coefficients at rest (K0), over consolidation ratio (OCR), Young´s module (Ei), shear module (G0), undrained shear strength (su) through field and laboratory testing from others authors.

No Brasil emprega-se, quase que exclusivamente, o N do SPT para o cálculo e estimativa da capacidade de carga e recalques em estacas. Os ensaios de campo fornecem estimativas rápidas dos parâmetros geotécnicos para o dimensionamento das fundações, sendo que seu uso tem crescido lentamente em algumas empresas da construção civil. A utilização do Dilatômetro de Marchetti no país ainda não é muito difundida, esperando-se, com a apresentação desse trabalho, poder contribuir para tornar a técnica mais utilizável no meio técnico nacional. O trabalho mostra que uma melhor caracterização do local pode ser obtida com o uso do DMT. Com os dados do ensaio dilatométrico os projetos de fundação ficam mais precisos ocorrendo em alguns casos economias na execução da fundação. O presente trabalho apresenta uma revisão bibliográfica do ensaio dilatométrico, contemplando publicações recentes sobre o assunto. A obtenção de parâmetros geotécnicos do solo, fornecidos por intermédio de ensaios de DMT, permitiu o emprego dos conceitos clássicos da Mecânica dos Solos em metodologias teóricas de previsão da capacidade de carga e a estimativa de recalques em estacas ensaiadas no Campo Experimental da USP. O objetivo desta pesquisa é apresentar uma alternativa de se projetar com auxílio de ensaios dilatométricos e obter resultados tão bons ou melhores do que os obtidos até o presente momento com as sondagens à percussão e, principalmente, com o intuito de apresentar mais uma ferramenta como suporte para os projetistas. / In Brazil, it is employed almost exclusively the \"N\" (number of blows required to drive the sampler the last 30 cm into the soil) of SPT to calculate and estimate the bearing capacity and settlement in piles. The field tests provide quick estimates of the geotechnical parameters for the foundation designs, this practice has been growing slowly in some of Civil Construction Companies. The use of Flat Dilatometer Test in the country is very rare and it is expected that this work will contribute to increase its use among us. In this work is shown that a better characterization of the site can be obtained with DMT. With the flat dilatometer test, the foundation designs may be carried out within a more precise base and in some cases economy may be achieved. The current work starts with a bibliography review of the flat dilatometer test. It also contemplates recent papers about the subject. The geotechnical parameters of the soil were supplied through DMT\'s, allowing the employment of the classical concepts of Soil Mechanics in theoretical methodologies of bearing capacity prediction and the elastic settlements of piles tested in full size at the Foundation Experimental Site of EPUSP. The aim of this research is to present an alternative to design with the help of dilatometer test, obtaining as good results or even better than the ones achieved so far with the Standard Penetration Test, and mainly to show one more tool as a support to the designers.

No Brasil emprega-se, quase que exclusivamente, o N do SPT para o cálculo e estimativa da capacidade de carga e recalques em estacas. Os ensaios de campo fornecem estimativas rápidas dos parâmetros geotécnicos para o dimensionamento das fundações, sendo que seu uso tem crescido lentamente em algumas empresas da construção civil. A utilização do Dilatômetro de Marchetti no país ainda não é muito difundida, esperando-se, com a apresentação desse trabalho, poder contribuir para tornar a técnica mais utilizável no meio técnico nacional. O trabalho mostra que uma melhor caracterização do local pode ser obtida com o uso do DMT. Com os dados do ensaio dilatométrico os projetos de fundação ficam mais precisos ocorrendo em alguns casos economias na execução da fundação. O presente trabalho apresenta uma revisão bibliográfica do ensaio dilatométrico, contemplando publicações recentes sobre o assunto. A obtenção de parâmetros geotécnicos do solo, fornecidos por intermédio de ensaios de DMT, permitiu o emprego dos conceitos clássicos da Mecânica dos Solos em metodologias teóricas de previsão da capacidade de carga e a estimativa de recalques em estacas ensaiadas no Campo Experimental da USP. O objetivo desta pesquisa é apresentar uma alternativa de se projetar com auxílio de ensaios dilatométricos e obter resultados tão bons ou melhores do que os obtidos até o presente momento com as sondagens à percussão e, principalmente, com o intuito de apresentar mais uma ferramenta como suporte para os projetistas. / In Brazil, it is employed almost exclusively the \"N\" (number of blows required to drive the sampler the last 30 cm into the soil) of SPT to calculate and estimate the bearing capacity and settlement in piles. The field tests provide quick estimates of the geotechnical parameters for the foundation designs, this practice has been growing slowly in some of Civil Construction Companies. The use of Flat Dilatometer Test in the country is very rare and it is expected that this work will contribute to increase its use among us. In this work is shown that a better characterization of the site can be obtained with DMT. With the flat dilatometer test, the foundation designs may be carried out within a more precise base and in some cases economy may be achieved. The current work starts with a bibliography review of the flat dilatometer test. It also contemplates recent papers about the subject. The geotechnical parameters of the soil were supplied through DMT\'s, allowing the employment of the classical concepts of Soil Mechanics in theoretical methodologies of bearing capacity prediction and the elastic settlements of piles tested in full size at the Foundation Experimental Site of EPUSP. The aim of this research is to present an alternative to design with the help of dilatometer test, obtaining as good results or even better than the ones achieved so far with the Standard Penetration Test, and mainly to show one more tool as a support to the designers.

Esta dissertação tem por objetivo a obtenção de parâmetros geotécnicos dos solos variegados da Formação São Paulo utilizando ensaios in situ, visando em especial estabelecer correlações entre os parâmetros de histórico de tensões, coeficiente de empuxo em repouso, módulos de deformabilidade e resistência não drenada do solo obtidos através de ensaios com o piezocone e dilatométricos. A realização de ensaios in situ tem como principal vantagem a obtenção de parâmetros do solo no local de projeto, minimizando os efeitos de perturbação de amostras \"indeformadas\", com todas as suas consequências nos ensaios de laboratório. Utilizando dados da expansão da Linha 2 Verde da Companhia do Metropolitano de São Paulo (Metrô-SP) foi possível obter valores da pressão de préadensamento (\'p), razão de sobreadensamento (OCR), coeficiente de empuxo em repouso (K0), módulo de elasticidade tangente inicial (Ei), módulo de cisalhamento tangente inicial (G0), módulo edométrico (M) e resistência ao cisalhamento não drenada (su) para os solos variegados da Formação São Paulo. Esses solos são marcados por intercalações centimétricas a métricas de argilas e areias, constituindo uma característica própria com parâmetros geotécnicos distintos e lençóis empoleirados. Por esse motivo, ainda existem lacunas de conhecimento nos parâmetros de projeto. Para concluir, foi possível validar correlações apropriadas envolvendo os parâmetros: coeficiente de empuxo em repouso, razão de sobreadensamento, módulo de elasticidade tangente inicial, módulo de cisalhamento tangente inicial (G0), resistência não drenada e pressão de pré-adensamento através de resultados de ensaios de campo e laboratório apresentados por outros autores. / The purpose of this research is to obtain geotechnical parameters of the variegated soils from São Paulos Formation through in situ tests (piezocone and dilatometer), aiming in particular to establish correlations between stress history parameters, earth pressure coefficients at rest, deformability modules and undrained strength. The in situ tests have the major advantage of obtaining soil parameters in the project site, minimizing the effects of soil disturbances that may affect the results of laboratory tests. Using data from geotechnical investigation carried out during the basic design of the Green Line expansion for the Metrô SP it was possible to obtain preconsolidation pressure (p), over consolidation ratio (OCR), earth pressure coefficients at rest (K0), Young´s module (Ei), initial shear module (G0), constrained module (M) and undrained shear strength (su) for the variegated soils from São Paulo Formation. These soils are characterized by alternate layers of clays and sands, being the heterogeneity their major characteristic with different geotechnical parameters and also perched water table. For this reason, there are still knowledge gaps in the design parameters. To conclude, it was possible to validate appropriated correlations between preconsolidation pressure (p), earth pressure coefficients at rest (K0), over consolidation ratio (OCR), Young´s module (Ei), shear module (G0), undrained shear strength (su) through field and laboratory testing from others authors.

No description available.

Enhanced Integration of Shear Wave Velocity Profiling in Direct-Push Site Characterization Systems Alexander V. McGillivray 370 Pages Directed by Dr. Paul W. Mayne Shear wave velocity (VS) is a fundamental property of soils directly related to the shear stiffness at small-strains. Therefore, VS should be a routine measurement made during everyday site characterization. There are several lab and field methods for measuring VS, but the seismic piezocone penetration test (SCPTu) and the seismic dilatometer test (SDMT) are the most efficient means for profiling the small-strain stiffness in addition to evaluating large-strain strength, as well as providing evaluations of the geostratigraphy, stress state, and permeability, all within a single sounding. Although the CPT and DMT have been in use for over three decades in the USA, they are only recently becoming commonplace on small-, medium-, and large-size projects as more organizations begin to realize their benefits. Regrettably, the SCPTu and the SDMT are lagging slightly behind their non-seismic counterparts in popularity, in part because the geophysics component of the tests has not been updated during the 25 years since the tests were envisioned. The VS measurement component is inefficient and not cost effective for routine use. The purpose of this research is to remove the barriers to seismic testing during direct-push site characterization with SCPTu and SDMT. A continuous-push seismic system has been developed to improve the integration of VS measurements with SCPTu and SDMT, allowing VS to be measured during penetration without stopping the progress of the probe. A new type of portable automated seismic source, given the name RotoSeis, was created to generate repeated hammer strikes at regularly spaced time intervals. A true-interval biaxial seismic probe and an automated data acquisition system were also developed to capture the shear waves. By not limiting VS measurement to pauses in penetration during rod breaks, it is possible to make overlapping VS interval measurements. This new method, termed frequent-interval, increases the depth resolution of the VS profile to be more compatible with the depth intervals of the near-continuous non-seismic measurements of the SCPTu and the SDMT.

A thesis submitted to the Faculty of Engineering, Cape Peninsula University of Technology, Cape Town, in partial fulfilment of the requirements for the M-Tech Degree in Civil Engineering” Cape Town 16 MAY 2011 / Dwellings in impoverished and upper class urban areas of the Western Cape have undergone serious structural failure due to problematic underlying sand deposits, generally known as Cape Flats windblown found in areas such as Delft, Blue Downs and the Atlantic Beach Golf Estate. The problem is compounded further when moisture penetrates below the footings and reaches saturation in the winter months. When poorly graded sand with a high fines content is coupled with vibration (through earth tremors), liquefaction may occur and without proper precautions, this can lead to inadequate foundation design, more than expected settlement and eventual structural failure. Some sand deposits are highly contaminated with organic debris, leading to compressible and collapsible conditions. Little knowledge is locally available of liquefiable conditions in windblown dune sand and what long-term settlement can be expected. The Western Cape is not known as an area exposed to serious seismic activity, but an updated (and more locally applicable set of data) is needed to eliminate possible erroneous foundation design. Samples have been extracted from typical sandy sites in the Western Cape where windblown dune sand is evident. Laboratory tests have been carried out on representative samples for closer examination and have been placed inside a purpose built calibration chamber that facilitates easy densification and probe testing. A DMT (flat blade dilatometer) was used to hydraulically penetrate the chamber sand sample to varying depths (up to 800 mm). The device can measure (with reduction formula) horizontal stress, angle of friction, bearing capacity and settlement. An accelerometer was attached to the chamber wall and vibration measured with the sand in varying states of moisture. The DMT is an unexplored in-situ soil testing device in South Africa and so far the outcome indicates favourably compared to other devices such as the Dynamic Cone Penetrometer (DCP. The DMT has the ability to measure the in-situ stiffness, strength and stress history parameters of soil for better site characterisation. Settlement within the chamber is easily measured. The DMT has, for example, indicated that sand from the Philippi area are a problematic founding soil and should be treated with special care at shallow founding levels. The horizontal stress index is low and according to the available knowledge on soil stress history, these sand, coupled with low densities, can liquefy easily and result in structural damage. The West Coast dune sand, being coarser and easily consolidated, poses less of a problem under liquefiable conditions. A suitable terrain device for easy on-site manoeuvrability is required to assist the DMT in further testing.

Le frittage micro-ondes est connu pour être une technique de frittage prometteuse. En effet, ce procédé présente comme avantages une réduction de la durée des traitements thermiques et un gain énergétique important par rapport aux procédés conventionnels. D'année en année, le frittage dans un environnement micro-ondes est étudié par un nombre croissant de chercheurs. Cependant, les raisons de l’effet bénéfique de ce type de frittage ne sont pas clairement identifiées.Dans ce contexte, l’objectif de ce travail a été de vérifier l’influence d’un champ électromagnétique à la fréquence de 2,45 GHz sur la densification de matériaux céramiques. Cet objectif passe donc par une étude comparative du frittage dans une enceinte micro-ondes et dans un four conventionnel. Cependant, la présence du champ électromagnétique dans un four micro-ondes ne permet pas l’utilisation des méthodes conventionnelles pour suivre le frittage. Ainsi, pour comparer les résultats, un dispositif expérimental original contenant un dilatomètre sans contact de haute résolution a été spécifiquement développé. Ce dispositif, permet aussi un suivi de la distribution de température à la surface de la pièce.Pour des cycles thermiques identiques, obtenus en frittage conventionnel et par micro-ondes, l’évolution de la densification de matériaux aux propriétés différentes a été comparée. Ces matériaux sont : l’alumine pure et dopée par 800ppm d’oxyde de magnésium, l’oxyde de zinc et l’hydroxyapatite silicatée. Pour chacun de ces matériaux, le couplage avec les micro-ondes et la répartition du chauffage à la surface de l’échantillon sont aussi discutés. Un effet bénéfique des micro-ondes sur l’évolution de la densification a été mis en évidence pour l’alumine avec ajout de MgO et de manière plus prononcée pour l’oxyde de zinc. / Microwave sintering is known to be a promising sintering technology. Indeed, this method has advantages such as reducing the duration of heat treatment and a significant energy saving compared with conventional processes. Year after year, sintering in a microwave environment is studied by a growing number of researchers. However, the reasons for the beneficial effect of this type of sintering are not clearly identified.In this context, the objective of this work was to verify the influence of an electromagnetic field at a frequency of 2.45 GHz on the densification of ceramic materials. This objective therefore involves a comparative study of sintering in a microwave chamber and in a conventional oven. However, the presence of electromagnetic field in a microwave oven does not allow the use of conventional methods to monitor the sintering. Thus, to compare the results, an experimental system containing a high resolution contactless dilatometer has been specifically developed. This system also allows monitoring of the temperature distribution on the sample surface.For identical thermal cycles, obtained by conventional and microwave sintering, the densification evolution of materials with different properties was compared. These materials are: pure alumina and doped with 800ppm magnesium oxide, zinc oxide and silicon-substituted hydroxyapatite. For each material, the coupling with the microwaves and the temperature distribution on the surface sample are also discussed. A beneficial effect of microwaves on the evolution of densification has been identified for alumina with addition of MgO and more pronounced for zinc oxide.

Due to its hardness, martensite, perhaps, is the most desirable structure, but at the same time, martensite is very brittle. Balancing between hardness and brittleness is a challenge that steel manufacturers must deal with it. To decrease brittleness and to solve this problem, designers purposely temper the steel. Heat treatment, e.g., slowing down the quenching quota/rate, will form a procedure of martensite formation incomplete phase and consequently a mixture of austenite-martensite. Tempering is another alternative to operate on martensite and make it malleable without losing hardness and preventing brittleness. As its seen, the heat treatment for controlling the mechanical chemical property is crucial. Managing the critical temperature, A1, A3, and Ms) during martensite formation, which influences the transformation process, must be considered. The Prior Austenite Grain Size also has been measured.  This project has examined the critical temperature for three wire steel specimens to determine the martensite start temperature (Ms), microstructure, and hardness. The project has mainly used dilatometry. Besides that, light optical microscopy (LOM), hardness measurement of specimens, and empirical equations for determining the critical temperatures have been used. This work has been made up of two main parts: literature review and experimental work/ project procedure.