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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.
351

Les dynamiques géomorphologiques de l'est des bas-plateaux tertiaires du Bassin de Paris : apports de l'approche souterraine / Spatial distribution of underground quarries in lutetian area (east of Soissons - Aisne - France) : interactions and relationships of sides geomorphologic process, lithology and types of exploitation.

Sosson, Christelle 26 September 2014 (has links)
Ce travail aborde les dynamiques géomorphologiques des bas-plateaux calcaires du Bassin parisien. Ces dynamiques géomorphologiques sont généralement étudiées à partir d'observations de surface avec l'étude des formes et des formations et la cartographie géomorphologique. Cependant, avec la disparition des sites d'extractions et des carrières, les affleurements se font rares, ce qui ne facilite pas l'interprétation des morphologies et des processus associés. Les chercheurs sont alors obligés de recourir à des procédés de reconnaissances lourds et coûteux comme l'instrumentation de géophysiques ou de profiter des sondages archéologiques. L'intérêt de cette contribution est de montrer l'apport de l'étude des carrières souterraines dans la compréhension des dynamiques géomorphologiques, hydrogéologiques et hydrologiques des bas plateaux tertiaires du Bassin parisien. La bibliographie fait souvent référence à des processus occultes, sous couverture, comme la crypto-corrosion, le soutirage ou l'hydrocompaction, difficilement observables en surface qui laissent souvent trop de place à l'interprétation. Le secteur de Reims, Laon, Soissons et Villers-Cotterêts est particulièrement intéressant car il regroupe plus de 400 carrières souterraines dans les calcaires lutétiens. Les héritages historiques y sont importants avec un patrimoine monumental très dense construit grâce aux géomatériaux calcaires locaux fournis par les carrières souterraines. / This work tackles the geomorphological dynamics of calcareous low-plateaus, in the Paris basin. These dynamics are usually studied from observations of surface, the study of shapes and superficial formations and geomorphological mapping. However, with the disappearance of sites and quarries, outcrops are scarce, which does not facilitate the interpretation of morphologies and associated processes. Researchers are forced to resort to methods of reconnaissance heavy and expensive, as instrumental geophysical or benefit of archaeological surveys. The value of this work is to show the contribution of the study of underground quarries in the understanding of geomorphological, hydrogeological and hydrological tertiary lowlands of the basin of Paris. The literature often refers to the process of hidden under cover as the crypto-corrosion, racking or hydrocompaction, easily observable on the surface or often leaving too much room for interpretation of fault outcrops. The area of Reims, Laon, Soissons and Villers-Cotterets is particularly interesting because it includes more than 400 underground quarries in the lutetian limestone. Historical legacies are important monuments with very dense built through geomaterials local limestone quarries provided by underground quarries.
352

Influência do uso de filler calcário como material cimentí­cio suplementar nas propriedades de fratura de pastas de cimento. / Influence of the use of limestone filler as a supplementary cementitious material on the fracture properties of cement pastes.

Cecel, Rafael Testoni 21 May 2019 (has links)
Este estudo avaliou propriedades de fratura e seus parâmetros de superfície em composições de pasta de cimento de mesma porosidade capilar, variando o teor de filler calcário como substituinte ao cimento comercial. Ainda, para avaliação do efeito em composições de argamassa, foi avaliada a capacidade de redução de água que essa adição pode proporcionar e seu efeito na resistência mecânica. A avaliação dos parâmetros de fratura ocorreu por ensaio de flexão por carregamento em três pontos, com controle por taxa de deslocamento e as análises de superfície por ensaio de interferometria, em seções de fratura e entalhe. O aumento do teor de filler calcário proporcionou redução da demanda de água nas argamassas, para mesmo comportamento. A redução da demanda foi ainda maior para as composições dispersas com aditivo, em relação à referência com aditivo. As resistências à compressão das argamassas apresentaram boa correlação em relação ao ajuste com todas as composições, enquanto foi observado que argamassas de médio teor de filler podem apresentar mesma resistência à flexão que as argamassas de referência, mesmo que estas apresentem menor porosidade capilar. As pastas ensaiadas à flexão por carregamento três pontos não apresentaram comportamento quase-frágil, impedindo o cálculo da energia de fraturamento. Isto ocorreu devido ao método de ensaio adotado, com configuração inadequada, e que pode ser ajustada através da redução da taxa de deslocamento do ensaio, da geometria dos corpos de prova ou da geometria dos entalhes produzidos. Todas as composições apresentaram insensibilidade à profundidade de entalhe sob as condições de ensaio adotadas, possivelmente devido às falhas de configuração do método. As médias de resistência à flexão e do fator de intensidade de tensão crítico foram maiores para a composição de alto teor de filler, seguidos da referência e da composição de médio teor de filler, respectivamente. Em todas as análises e tipos de superfície estudadas, as composições de alto teor de filler apresentaram maior índice de rugosidade e amplitude entre picos e vales, enquanto não foi identificada diferença entre a referência e a composição de médio teor de filler. Estes dois parâmetros e a raiz quadrática da rugosidade indicaram que a rugosidade das superfícies fraturadas é maior que em superfícies cortadas com disco diamantado. / This study assesses fracture properties and their surface parameters in cement paste compositions of the same capillary porosity, varying the filler content of limestone as a substitute for commercial cement. Also, to evaluate the effect in mortar compositions, the water reduction capacity that this addition can provide and its effect on the mechanical resistance was evaluated. The evaluation of the fracture parameters was performed by three-point loading flexion test with displacement rate control and surface analysis by interferometry test in fracture and notch sections. The increase of limestone filler provided a reduction of the water demand in the mortars, in relation to the reference, for spreading of 265mm in table of consistency. The water demand reduction was even greater for compositions dispersed with admixture, relative to the reference with admixture. The compressive strength of the mortars presented a good correlation in the fit with all the compositions, while it was observed that mortars of medium filler content may have the same flexural strength as the reference mortars, even if they have lower capillary porosity. The pastes tested by three-point loading did not exhibit quasi-fragile behavior, preventing the calculation of fracturing energy. This was due to the inadequately configured test method adopted, which can be adjusted by reducing the test displacement rate, the geometry of the specimens or the geometry of the notches produced. All compositions presented insensitivity to the notch depth under the test conditions adopted, possibly due to method configuration failures. The averages of flexural strength and critical stress intensity factor were higher for the high filler composition, followed by the reference and medium filler composition, respectively. In all analyzes and surface types studied, high filler compositions presented higher roughness and amplitude index between peaks and valleys, while no difference between the reference and medium filler composition was identified. These two parameters and the quadratic root roughness indicated that the roughness of the fractured surfaces is greater than on surfaces cut with diamond disc.
353

Multi-scale characterization of dissolution structures and porosity distribution in the upper part of the Biscayne aquifer using ground penetrating radar (GPR)

Unknown Date (has links)
The karst Biscayne aquifer is characterized by a heterogeneous spatial arrangement of porosity, making hydrogeological characterization difficult. In this dissertation, I investigate the use of ground penetrating radar (GPR), for understanding the spatial distribution of porosity variability in the Miami Limestone presented as a compilation of studies where scale of measurement is progressively increased to account for varying dimensions of dissolution features. In Chapter 2, GPR in zero offset acquisition mode is used to investigate the 2-D distribution of porosity and dielectric permittivity in a block of Miami Limestone at the laboratory scale (< 1.0 m). Petrophysical models based on fully saturated and unsaturated. water conditions are used to estimate porosity and solid dielectric permittivity of the limestone. Results show a good correspondence between analytical and GPR-based porosity estimates and show variability between 22.0-66.0 %. In Chapter 3, GPR in common offset and common midpoint acquisition mode are used to estimate bulk porosity of the unsaturated Miami Limestone at the field scale (10.0-100.0 m). Estimates of porosity are based on the assumption that the directly measured water table reflector is flat and that any deviation is attributed to changes in velocity due to porosity variability. Results show sharp changes in porosity ranging between 33.2-60.9 % attributed to dissolution areas. In Chapter 4, GPR in common offset mode is used to characterize porosity variability in the saturated Biscayne aquifer at 100-1000 m field scales. The presence of numerous diffraction hyperbolae are used to estimate electromagnetic wave velocity and asses both horizontal and vertical changes in porosity after application of a petrophysical model. Results show porosity variability between 23.0-41.0 % and confirm the presence of isolated areas that could serve as enhanced infiltration or recharge. This research allows for the identification and delineation areas of macroporosity areas at 0.01 m lateral resolution and shows variability of porosity at different scales, reaching 37.0 % within 1.3 m, associated with areas of enhanced dissolution. Such improved resolution of porosity estimates can benefit water management efforts and transport modelling and help to better understand small scale relationships between ground water and surface water interactions. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
354

Avaliação do impacto do uso de fíler calcário como substituição ao cimento no comportamento reológico e retração de microconcretos. / Evaluation of the impact of the use of limestone fillers as replacement for cement in the rheological behavior and shrinkage of microconcretes.

Varhen Garcia, Christian Mario 31 March 2017 (has links)
Atualmente o maior impacto ambiental do concreto como material de construção origina-se das emissões de CO2 durante a produção do cimento. Uma das alternativas atualmente utilizadas para minimizar este impacto, é a utilização de adições minerais como substituição ao cimento. Entre as diferentes adições utilizadas, o uso de fíler calcário parece ser uma alternativa interessante para melhorar a sustentabilidade do uso do concreto na construção. Consequentemente, o presente estudo foca a análise do impacto da substituição do cimento por fílers de origem calcária (dolomita) no comportamento do concreto em estado fresco e endurecido, especialmente focando-se numa avaliação reológica e na retração por secagem do material. Para tal fim, foram formulados três microconcretos com teores de fíler calcário de 80%, 60% e 20% em relação ao peso dos finos totais (cimento mais fíler calcário). O teor de finos totais e de água foram mantidos constantes para todas as formulações resultando em misturas com similar volume de pasta. O comportamento reológico das misturas foi avaliado num reômetro de movimento planetário. Foram moldados corpos de prova para caracterização mecânica e acompanhamento da retração por secagem. A porosidade das pastas também foi avaliada usando a porosimetria por intrusão de mercúrio. As propriedades reológicas como a tensão de escoamento e a viscosidade foram influenciadas pelo teor de substituição de cimento por fílers. Maiores volumes de fílers na pasta produziram menores tensões de escoamento e, por consequência, maiores valores de abatimento foram obtidos. No entanto, a viscosidade plástica aumentou com teor de fílers. No estado endurecido, a maior substituição de cimento por fílers diminui a intensidade da retração por secagem devido ao menor teor de cimento na pasta e a modificações na estrutura porosa do material. Os resultados experimentais da retração foram comparados com os valores obtidos pelos modelos de previsão da retração: ACI 209, CEB-FIP, B3 e GL2000. Observou-se que os modelos superestimam os valores da retração conforme aumenta a substituição de cimento por fílers na pasta. Portanto, esses modelos devem ser calibrados considerando outros fatores, tais como: a quantidade de fíler utilizado em substituição de cimento. Esta consideração poderia otimizar o uso dos modelos em fase de projeto para verificar se os valores da retração esperados estão dentro dos limites normalmente aceitos. / Currently the biggest environmental impact of concrete as a building material originates in CO2 emissions during the production of cement. For this reason, one of the alternatives currently used to reduce these emissions is the use of mineral additions as cement replacement. Among the different additions used, the use of limestone fillers to replace cement appears to be an interesting alternative for improve the sustainability of the concrete used in construction. Consequently, this study focuses on the analysis of the impact of the replacement of cement by limestone fillers in fresh and hardened concrete, especially focusing on rheological behavior and shrinkage of the material. To this end, three microconcretos were formulated with fillers limestone content of 80%, 60% and 20% by weight relative to the total fine (limestone fillers and cement). The total content of fine and water were held constant for all formulations resulted in mixtures with similar volume of paste. The rheological behavior of the mixes was evaluated in a planetary motion rheometer. For mechanical characterization and measurement of shrinkage, specimens were molded. The porosity of the pastes was also evaluated using mercury intrusion porosimetry. The rheological properties such as yield stress and viscosity were influenced by the amount of cement that was replaced by fillers. Further filers volumes in the pulp produced smaller flow stress and, consequently, higher allowance values were obtained. Larger volumes of filler in the paste produced lower yield stresses and, consequently, higher slump values were obtained. However, the plastic viscosity increased with filers content. In the hardened condition, the largest cement replacement by limestone fillers reduced the intensity of shrinkage due to the lower content of cement paste and changes in the porous structure of the material. The experimental results of shrinkage were compared with the values obtained by shrinkage prediction models: ACI 209, CEB-FIP, B3 and GL2000. It was observed that the models overestimate the shrinkage values with increasing cement replacement by limestone fillers. Therefore, these models must be calibrated considering other factors such as the amount of fillers used as cement replacement This consideration would optimize the use of these models in the design phase to verify that the values of the expected shrinkage are within the limits normally accepted.
355

Produ??o de concreto autoadens?vel com uso de f?ler calc?rio de res?duo de serragem de Pedra Cariri

Merc?s , Uiliana M?rcia da Silva 20 March 2017 (has links)
Submitted by Jadson Francisco de Jesus SILVA (jadson@uefs.br) on 2018-01-30T22:07:52Z No. of bitstreams: 1 Uiliana M?rcia da Silva Merc?s Farias_2017.pdf: 5844655 bytes, checksum: 1df6b86cb5dfd9f89a7bbd299fa1bf93 (MD5) / Made available in DSpace on 2018-01-30T22:07:52Z (GMT). No. of bitstreams: 1 Uiliana M?rcia da Silva Merc?s Farias_2017.pdf: 5844655 bytes, checksum: 1df6b86cb5dfd9f89a7bbd299fa1bf93 (MD5) Previous issue date: 2017-03-20 / The use of waste from Dimension Stone Industry as an inert material can be a good way to promote the sustainability of the construction sector. The Cariri stone is one of the dimension stones explored in state of Ceara, in Brazil. Thus, this work was developed with the main goal of studying a self-compacting concrete production (SCC) using Cariri stone sawdust waste (CSSW) in partial replacement with the natural fine aggregate. The SCC was designed using the method proposed by Melo (2005) considering two w/c ratios (0.57-0.70), and 10% of CSSW. The study was carried out in three stages: material characterization, mortar phase evaluation and SCC phase evaluation. In the fresh state, SCC was evaluated for fluidity, plastic viscosity, blocking capacity and segregation resistance, using V funnel, J-Ring, L-box and segregation column. In the hardened state, the SCC was evaluated for axial compressive strength, splitting tensile strength and water absorption, void index and specific density. The results showed that CSSW improve SCC cohesiveness and homogeneity, and it is feasible to apply up to 10% of CSSW in SCC production. / No sentido de promover a sustentabilidade do setor da constru??o civil, procura-se alternativas para diminuir o impacto ambiental gerado, atrav?s da descoberta de novos materiais alternativos, como os res?duos da ind?stria de beneficiamento de rochas ornamentais. Dentre os tipos de rochas ornamentais exploradas no Brasil, destaca-se um calc?rio laminado conhecido como ?Pedra Cariri?, que ? explorado no estado do Cear?. Assim, esse trabalho foi desenvolvido com o objetivo de estudar a produ??o de concreto autoadens?vel (CAA) utilizando res?duos de serragem de pedra Cariri (RSPC) em substitui??o parcial ao agregado mi?do natural. Utilizando a metodologia de Melo (2005) para produ??o de CAA, foram definidas as rela??es a/c (0,57-0,70). O estudo se deu em tr?s etapas: caracteriza??o dos materiais, fase argamassa e fase CAA. No estado fresco, o CAA foi avaliado quanto ? fluidez, viscosidade pl?stica, habilidade passante e resist?ncia ? segrega??o, por meio do ensaio de espalhamento, funil V, Anel J, Caixa L e coluna de segrega??o. No estado endurecido, o CAA foi avaliado quanto ? resist?ncia ? compress?o axial, ? resist?ncia ? tra??o por compress?o diametral e ? absor??o de ?gua, ?ndice de vazios e massa espec?fica. Os resultados indicaram a possibilidade da aplica??o de at? 10% de RSPC na produ??o de CAA.
356

Efeito da concentração de SO2 nas reações de calcinação e sulfatação de calcários em reator de leito fluidizado / Effect of the concentration of S02 in the reactions of calcination and sulfatation in a fluidized bed reactor

Lindo Samaniego, Julio Edgardo 21 November 2003 (has links)
Foi realizado um estudo sobre o efeito das concentrações de SO2 na sua absorção por calcários em fornalhas de leito fluidizado. Para observar a influência do SO2 sobre os diferentes parâmetros físicos e químicos do processo, foram criadas atmosferas compostas por quatro concentrações diferentes de SO2, que foram de 500, 1.000, 2.000 e 4.000 ppm. Utilizou-se ainda dois tipos de calcários, o Dolomítico-DP e o Calcítico-CI. O leito fluidizado borbulhante utilizado, possuía 160 mm de diâmetro interno e foi fluidizado com ar à temperatura de 850ºC, contendo SO2 na concentração desejada. Como material do leito foi utilizada areia de quartzo (99,9%), com diâmetro de 385 &#956m e aproximadamente 3,0 Kg de massa. O calcário foi adicionado em bateladas de 50 g com o reator já pré-aquecido, enquanto as variações das concentrações dos gases SO2, CO2, CO e O2 e suas descargas foram monitoradas continuamente na saída do ciclone que era utilizado para retenção do particulado fino. Para adquirir esses dados foi desenvolvido um programa em LabView. O modelo matemático escolhido possibilitou a determinação da conversão, da taxa de conversão e do coeficiente global de taxa de reação para todas as condições testadas. / A study of the effect of the concentrations of SO2 in its absorption by limestones in fluidized bed furnaces was conducted. For the determination of the SO2 influence on the different physical and chemical parameters of process, such as calcinations and sulfatation four different atmospheres were used in the reator with concentrations of SO2 of 500, 1.000, 2.000 and 4.000 ppm. Two types of limestones were used : Dolomitico-DP and Calcitico-CI. The bench scale bubbling fluidized bed reactor had a 160 mm internal diameter and was fluidized with air at 850ºC containing the required concentration of SO2. Bed material was quartz sand (99,9%), with 385 &#956m diameter and approximately 3 Kg of mass. The limestone was introduced in samples of 50 g, in the reactor previously stabilized, and the concentration of the gases SO2, CO2, CO and O2 and their discharges in the reactor exit were continually monitored. For the recording of this parameters a data acquisition program in LabView was developed. A mathematical model was used to allow the determination of the conversion, the conversion rate and the global coefficient of reaction rate for all the tested conditions.
357

Proposta de um sistema passivo para o tratamento da drenagem ácida de mina gerada no depósito de rejeitos de Capão da Roça, Charqueadas/RS, Copelmi mineração Ltda

Segredo, Artur Estacha Armindo Estacha January 2014 (has links)
A drenagem ácida de mina (DAM) gerada no processo de mineração de carvão, na presença de minerais sulfetados, tem provocado danos ambientais significativos no ecossistema de sua abrangência. Tecnologia de tratamento ativo baseada em processos de Neutralização, Precipitação e Sedimentação tem sido empregada para atenuar a carga de poluentes no efluente, antes do seu descarte em corpos receptores. A mesma, apesar da sua eficiência vem se mostrando bastante onerosa quando aplicada durante um longo período, devido aos custos com insumos, manutenção, potencial humano e energia. Nos últimos anos, vem sendo desenvolvidos sistemas que socorrem-se da ocorrência natural de processos químicos, biológicos e físicos para purificar água de mina contaminada. Estes são designados sistemas passivos, cuja implantação e funcionamento tem se mostrado menos onerosa em relação ao sistema ativo. Capão da Roça, situado no município de Charqueadas é uma das regiões do Brasil onde ocorre contaminação de solos e rios pela DAM gerada a partir de um depósito de rejeitos. Aplicando o fluxograma recomendado por diversos autores para a seleção do sistema passivo, tomando em conta as características do efluente achou-se viável instalar um canal aberto de calcário para o tratamento da DAM do Capão da Roça em virtude de a mesma apresentar acidez maior que a alcalinidade, oxigênio dissolvido maior que 5mg/l, Fe+3 maior que 25% em relação ao Fe2+. A quantidade de efluente e a declividade do terreno da área estudada permite que se opere com vazão maior que 12m3/h no sistema passivo. De acordo com a acidez do efluente foi determinado o tempo de detenção de 1hora para o tratamento da DAM no sistema. A partir de estudos similares sobre o uso de calcário em sistemas passivos, encontrou-se a massa de 338,6 toneladas para o empreendimento funcionar em 10 anos, considerando uma dissolução de calcário de 100%, num canal com 10% de declividade, 1m de profundidade e 2, 5 metros de largura para tamponar uma solução de DAM com vazão de 1000 L.min-1 num canal de 47metros de cumprimento. De acordo com cálculos baseados num modelo empírico, ficou demonstrado que o diâmetro e área de superfície do calcário poderão diminuir ao longo do tempo, considerado a sua dissolução. / Acid mine drainage (AMD) generated in the coal mining process in the presence of sulfide minerals, have been causing significant environmental damages to the ecosystem of its coverage. Active treatment technology based on neutralization, precipitation and sedimentation processes, has been used to alleviate the load of pollutants in the effluent prior to discharges into receiving bodies. Despite their efficiency has proved quite costly when applied over a long period due to input costs, maintenance, manpower and energy. In recent years project defined 'passive treatment' has been developed as the improvement of water quality using only naturally occurring chemical, biological and physical processes, hence, the deployment and operation have been less costly compared to the active systems. Capão da Roça, located in the municipality of Charqueadas is one of the regions of Brazil where occurs contamination of soils and rivers by AMD generated from a waste dump. Using the flowchart recommended by several authors for selecting the passive system, taking into account the wastewater characteristics, was found to be feasible to install an open limestone channel for the treatment of AMD because it has higher acidity than alkalinity, dissolved oxygen greater than 5mg / l, Fe3+ greater than 25 % in relation to Fe2+. The amount of effluent and the slope of the study area terrain allows to operate with a flow rate greater than 12m3/ h in the passive system. According to the acidity of the effluent was determined retention time of 1 hour for the treatment of the AMD system. From similar studies on the use of limestone in passive systems, was found the mass of 338.6 tons for the enterprise operating over 10 years, assuming a 100% limestone dissolution channel with a 10% slope, 1 meter deep and 2,5 meters wide to buffer an AMD solution with a flow rate of 1000 L.min-1 in channel with 47 meters of length. According to the calculations based on empirical model, it was shown that the diameter and the surface area of limestone may decline over time, considering its dissolution.
358

Impact du stockage de CO₂ dans les systèmes réservoirs carbonatés : interactions et transport d'éléments traces, effets sur les propriétés réservoirs / Impact of CO₂ geological storage in limestone reservoir systems : interactions and trace elements transport, consequences on reservoir properties

Auffray, Baptiste 29 January 2014 (has links)
Depuis une dizaine d'années, une volonté internationale de réduction des émissions de gaz à effet de serre s'est développée, afin de limiter leur concentration dans l'atmosphère. Ainsi, il est envisagé de récupérer le CO₂ issu d'activités humaines fortement émettrices afin de le réinjecter dans le sous-sol à l'état supercritique. Hors du panache de CO₂ supercritique, ce gaz se dissout dans la saumure et l'acidifie. Deux phénomènes ont alors lieu. Ils constituent la base des études menées au cours de cette thèse : (i) le devenir des espèces chimiques mobilisées par la dissolution des minéraux, et (ii) les variations des propriétés d'écoulements induites par la réactivité de la roche encaissante. Pour étudier ces phénomènes, des expériences ont été menées sur les carbonates de Lavoux et de St-Emilion. Ces deux échantillons naturels ont été sélectionnés pour leur composition minérale modèle qui assure une forte réactivité dans le contexte de l'étude, et l'absence d'argile et de matière organique qui limite la complexité du système géochimique. Les expériences menées sont de deux types. En autoclave, la compétition entre dissolution et sorption des éléments traces est mise en avant et permet d'investiguer des conditions variant de celles de la surface (20°C – 1 atm) à celles d'un site de stockage (40°C – 90 bar de CO₂) en passant par des intermédiaires de pression (30 et 60 bar). Les effets de la salinité de la saumure, de la concentration initiale en cations divalents ainsi que de l'état de l'échantillon solide (poudre, plug) sont étudiés. D'autre part, un dispositif expérimental a été développé au cours de cette thèse. Il permet d'étudier les propriétés de diffusion d'éléments traces à travers une carotte dans des conditions représentatives de celles d'un réservoir de stockage de CO₂. Les résultats expérimentaux obtenus mettent en évidence à la fois l'impact de la dissolution sur la mobilisation des espèces chimiques, la compétition entre différents cations pour la sorption et les conséquences de cette sélectivité sur le transport et la disponibilité des espèces chimiques. L'étude pétrophysique des échantillons réagis met en évidence une augmentation de la porosité, et une tendance à l'uniformisation du réseau de pore. Les données obtenues dans les expériences en batch permettent d'obtenir par simulation les paramètres de sorption du système pour les différents éléments traces, en fonction des conditions de pression. Grâce à ces différents résultats, la surveillance de sites de stockage géologique de CO₂ est possible dans différentes formations, et permet un suivi à la fois des flux des espèces chimiques et des propriétés d'écoulement. / Over the last decade, an international will to reduce the emissions of greenhouse gases in the atmosphere developed, in order to limit their atmospheric concentration. Thus, to deal with the large amounts of CO₂ produced by human activities, this gas is to be injected under supercritical state in the underground. Outside the CO₂ plume, this gas dissolves within brine and acidifies it. Two phenomena occurs then. They are the main subject of this work: (i) the fate of chemical species mobilized by mineral dissolution, and (ii) the evolution of flooding properties induced by mineral reactivity. To study those phenomena, experiments were carried out on the Lavoux and the Saint-Emilion carbonates. Those two natural samples were selected because their mineralogical composition ensures a high reactivity and limits the complexity of the geochemical system, as they contain neither clays nor organic matter. Two types of experiments were carried out. Competition between dissolution and sorption was studied in batch reactors, from conditions similar to those of the surface (20°C – 1 atm) to those of a storage site (40°C – 90 bar of CO₂), passing by intermediate pressures (30 and 60 bar). The parameters investigated are salinity, initial concentration of divalent cations, and the state of solid samples (powder, core). On the other hand, an experimental setting was developed during the thesis project. It allows the study of trace elements diffusion through a core in CO₂ geological storage conditions. The experimental results evidence the impact of dissolution on chemical species mobilization, competition between those species regarding sorption and consequences of this selectivity on transport and availability of those chemical species. The petrophysical study of reacted samples evidence a porosity increase and the homogenization of the porous network. The data resulting from the batch experiments are used as input data for simulations, in order to estimate sorption parameters of trace elements in the systems investigated. Thanks to those results, the monitoring of CO₂ geological storage sites is possible within several different geological formations, and allows to track both flux of chemical species and flooding properties evolution.
359

Utilização do calcário dolomítico em água doce e com alcalinidade e dureza extremamente baixas, para adequação ao cultivo do camarão marinho Litopenaeus vannamei

SILVA, Alexandre Duarte Rodrigues da 14 June 2010 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2017-02-07T11:34:15Z No. of bitstreams: 1 Alexandre Duarte Rodrigues da Silva.pdf: 439100 bytes, checksum: 1b2fd1350f22fda3959acac92bbccf28 (MD5) / Made available in DSpace on 2017-02-07T11:34:15Z (GMT). No. of bitstreams: 1 Alexandre Duarte Rodrigues da Silva.pdf: 439100 bytes, checksum: 1b2fd1350f22fda3959acac92bbccf28 (MD5) Previous issue date: 2010-06-14 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Culture of Litopenaeus vannamei in freshwater (0.0 g L-1) and low alkalinity and hardness (<50 mg L-1 CaCO3) were performed during 2008 to 2009, with the aim of evaluating the influence of adding of lime, to maximize production indices of shrimp. Post-larvae of this species, with 10 to 12 days (PL10-12), were initially acclimated to fresh water and then stored at density of 17 PL m-2, 12 experimental ponds of 60 m2. The concentrations of lime (4.0, 8.0, 12.0 and 16.0 t ha-1 cycle-1) were evaluated in the presence or absence of fertilizer-based K+ and Mg2+, in completely randomized. The diet was formed based pelleted feed, shrimp with 32% protein, and administered at feeders. The monitoring of physical and chemical qualities of water was carried out in different phases. After 60 days of cultivation,the best survival were observed in treatments of 8.0 and 12.0 t ha-1 without fertilizer, and application of 4.0 t ha-1 in crops with fertilizer. It was concluded that the use of lime favors the growth of L. vannamei in freshwater. / Cultivos do Litopenaeus vannamei, em água doce (0,0 g L-1) e com baixa alcalinidade e dureza (< 50 mg L-1 CaCO3) foram realizados no período de 2008 a 2009, com o objetivo de avaliar a influência da adição de calcário dolomítico, para maximizar os índices zootécnicos desses camarões. Pós-larvas dessa espécie, com 10 a 12 dias (PL10-12), foram inicialmente aclimatadas a água doce e, posteriormente, estocados a densidade de 17 PL m-2, em 12 viveiros experimentais de 60 m2. As concentrações de calcários (4,0, 8,0, 12,0 e 16,0 t ha-1 ciclo-1) foram avaliadas na presença ou não de fertilizantes a base de K+ e Mg2+, em experimentos inteiramente casualizados. A dieta foi constituída a base de ração peletizada,para camarão com 32% de proteína, e administrada em comedouros. O monitoramento das qualidades físicas e químicas da água foi realizado, nas diferentes fases experimentais. Após 60 dias de cultivo, as melhores sobrevivências foram observadas nos tratamentos de 8,0 e 12,0 t ha-1, sem fertilizante, e na aplicação de 4,0 t ha-1 em cultivos com fertilizante. Concluiu-se que a utilização do calcário dolomítico favorece o cultivo do L. vannamei em água doce.
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Accelerated change of limestone beige Bahia: a your loss prediction test intensity bright in fachadas under conditions tropical metropolitan in coastal edges / AlteraÃÃo acelerada do calcÃrio bege Bahia: um ensaio de prediÃÃo de perda de sua intensidade de brilho em fachadas sob condiÃÃes tropicais metropolitanas, em orlas litorÃneas

Suely Andrade da Silva 03 August 2015 (has links)
CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / The mineralogical composition of the Beige Bahia (BB) limestone was characterized by petrographic analysis, XRD, total-rock (TR) chemical analysis, and SEM on figurative elements of lytic texture. The results demonstrated that this type of calcrete is dolomitic (dolomite > 10% in TR), reaching over 50% in its lumpy features. The matrix is primarily calcite, whereas quartz (< 5% TR) and palygorskite are the most common accessory minerals. The changing mechanisms of the BB, as a building covering, were investigated from the loss of brightness, using in natura polished boards in bench, for comparison with observations carried out in situ in a metropolitan coastal area (Recife-PE), under humid tropical climate. Tests of accelerated changeability involving atmospheres with saline saturation (NaCl) and in SO2, attacks by acid solutions (HCl, HNO3, H2SO4), rain water and sea water, were conducted according to the Brazilian Association of Technical Standards/ABNT or experimentally, involving in natura polished test specimen. By considering as critical a brightness intensity &#8804; 40, whether for test specimen or for applications carried out in situ, a reliable prediction is possible based on bench data. In most cases, this critical level is reached around the third testing cycle, corresponding to ten years in in situ changing conditions. The most active mechanisms were the gas chamber with SO2 saturation, and the sea water; and the critical brightness was reached between 2 and 2.5 cycles in bench. The set of results did not confirm if the ferric staining and black crusts are of lithogenic origin, whereas âwhite crustsâ are made of gypsum (CaSO4.H2O), by the reaction of H2SO4 with the calcite surface of the BB. Therefore, the inadequacy of the application of this product on external coverings is confirmed, particularly in the presence of sea spray or in metropolitan situations, where the atmosphere is mpregnated with SO2. / A composiÃÃo mineralÃgica do calcÃrio Bege Bahia (BB) foi caracterizada por anÃlise petrogrÃfica, DRX, anÃlises quÃmicas sobre rocha-total (RT), e MEV sobre elementos figurados da textura lÃtica. Os resultados demonstraram que este tipo de calcrete à dolomÃtico (dolomita > 10% em RT), atingindo mais de 50% em suas feiÃÃes grumosas. A matriz à essencialmente calcÃtica, enquanto quartzo (< 5% RT) e palygorskita sÃo os minerais acessÃrios mais frequentes. Os mecanismos de alteraÃÃo do BB, como revestimento de edificaÃÃes, foram investigados a partir da perda de brilho, utilizando-se placas lustradas in natura em bancada, para comparaÃÃo com observaÃÃes in situ em Ãrea litorÃnea metropolitana (Recife-PE), sob clima tropical Ãmido. Ensaios de alterabilidade acelerada envolvendo atmosferas com saturaÃÃo salina (NaCl) e em SO2, ataques por soluÃÃes Ãcidas (HCl, HNO3, H2SO4), Ãgua de chuva e Ãgua do mar, foram conduzidos segundo normas ABNT ou experimentalmente, envolvendo corpos de prova lustrados in natura. Considerando-se crÃtica uma intensidade de brilho &#8804; 40, seja para os corpos de prova quanto em aplicaÃÃes in situ, torna-se possÃvel uma confiÃvel prediÃÃo a partir dos dados de bancada. Na maior parte dos casos, este nÃvel crÃtico à atingido em torno do terceiro ciclo dos ensaios, correspondendo a 10 anos em condiÃÃes de alteraÃÃo in situ. Os mecanismos mais atuantes foram a cÃmara de gÃs com saturaÃÃo em SO2 e a Ãgua do mar, sendo o brilho crÃtico atingido entre 2 a 2,5 ciclos em bancada. O conjunto dos resultados nÃo confirmou se manchamentos fÃrricos e crostas negras sÃo de origem litogÃnica, enquanto que âcrostas brancasâ sÃo constituÃdas de gipsita (CaSO4.H2O), por reaÃÃo de H2SO4 com a superfÃcie calcÃtica do BB. Assim, confirma-se a inadequaÃÃo de aplicaÃÃo deste produto em revestimentos externos, particularmente em presenÃa de spray marinho ou situaÃÃes metropolitanas, onde a atmosfera apresenta-se impregnada com SO2.

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