Pastas compósitas cimento/sílica/polímero para cimentação de poços de baixa profundidade sujeitas à injeção de vapor

The production of heavy oil fields, typical in the Northeastern region, is commonly stimulated by steam injection. High bottom hole temperatures are responsible not only for the development of deleterious stresses of the cement sheath but also for cement strength retrogression. To overcome this unfavorable scenario, polymeric admixtures can be added to cement slurries to improve its fracture energy and silica flour to prevent strength retrogression. Therefore, the objective of the present study was to investigate the effect of the addition of different concentrations of polyurethane (5-25%) to cement slurries containing 40% BWOC silica flour. The resulting slurries were characterized using standard API (American Petroleum Institute) laboratory tests. In addition to them, the mechanical properties of the slurries, including elastic modulus and microhardness were also evaluated. The results revealed that density, free water and stability of the composite cement/silica/polyurethane slurries were within acceptable limits. The rheological behavior of the slurries, including plastic viscosity, yield strength and gel strength increased with the addition of 10% BWOC polyurethane. The presence of polyurethane reduced the fluid loss of the slurries as well as their elastic modulus. Composite slurries also depicted longer setting times due to the presence of the polymer. As expected, both the mechanical strength and microhardness of the slurries decreased with the addition of polyurethane. However, at high bottom hole temperatures, the strength of the slurries containing silica and polyurethane was far superior than that of plain cement slurries. In summary, the use of polyurethane combined with silica is an interesting solution to better adequate the mechanical behavior of cement slurries to heavy oil fields subjected to steam injection

Efeito da adição de cargas minerais leves na resistência mecânica de grautes para cimentação de poços offshore

The preparation of cement slurries for offshore well cementing involves mixing all solid components to be added to the mixing water on the platform. The aim of this work was to study the formulation of pre-prepared dry mixtures, or grouts, for offshore oilwell cementing. The addition of mineral fillers in the strength of lightweight grouts applied for depths down to 400 m under water depths of 500 m was investigated. Lightweight materials and fine aggregates were selected. For the choice of starting materials, a study of the pozzolanic activity of low-cost fillers such as porcelain tile residue, microsilica and diatomaceous earth was carried out by X-ray diffraction and mechanical strength tests. Hardened grouts containing porcelain tile residue and microsilica depicted high strength at early ages. Based on such preliminary investigation, a study of the mechanical strength of grouts with density 1.74 g/cm3 (14.5 lb/gal) cured initially at 27 °C was performed using cement, microsilica, porcelain tile residue and an anti-foaming agent. The results showed that the mixture containing 7% of porcelain tile residue and 7% of microsilica was the one with the highest compressive strength after curing for 24 hours. This composition was chosen to be studied and adapted for offshore conditions based on testes performed at 4 °C. The grout containing cement, 7% of porcelain tile residue, 7% of active silica and admixtures (CaCl2), anti-foaming and dispersant resulted satisfactory rheology and mechanical strength after curing for 24 hours of curing

Efeito da adição de argila expandida e adições minerais na formulação de concretos estruturais leves autoadensáveis

The search for alternative materials with lower density, reduction in heat transfer and propagation of noise associated with the ease of handling and application in concrete structures, represents an enormous challenge in the formulation and knowledge of the performance of self-compacting lightweight concrete, which has technology little known nationally, and appears on the international scene as an innovative material and alternative to conventional concrete. Based on these, this study set out to study self-compacting lightweight concrete made with two distinct grades of expanded clay associated with the addition of plasticizing/superplasticizers additives and mineral additions of metakaolin and bagasse ash of sugar cane. There is also an object of study, evaluation of pozzolanic activity of mineral admixtures and their influence on the durability characteristics of concrete. The rheological, physical, mechanical and microstructural analysis in this study served as basis in the classification of concretes autoadensáveis, targeting the national technical requirements for their classification in the category autoadensável and lightweight structural. The inclusion of mineral admixtures (metakaolin and bagasse ash of sugar cane), partial replacement of cement, pozzolanic activity and demonstrated maintenance of mechanical properties through the filler effect, a reduction of up to 76% of the nitrogen gas permeability in blend with 20% bagasse ash. All concretes had rheology (cohesion and consistency) suitable for self-adensability as well as strength and density inherent structural lightweight concrete without presenting phenomena of segregation and exudation

Produção de grês porcelanato a partir de matérias-primas do Rio Grande do Norte e queima a gás natural

The State of Rio Grande do Norte, Brazil, possess major deposits of feldspar, clay, kaolin and talc, all raw materials used in the production of porcelainized stoneware tiles. Conversely, state industries manufacture only low added value red ceramics. Porcelainized stoneware tiles is one of the noblest ceramics, depicting low water absorption (typically below of 0,5%), in addition to excellent staining resistance and mechanical strength. The present work aims at investigating the potential of local raw materials for the production of porcelainized stoneware tiles. To that end, these materials were characterized by X-ray fluorescence, X-ray diffraction, particle size analysis, thermal gravimetric analysis and thermal differential analysis. Admixtures containing different compositions were prepared and fired at three temperatures, 1150, 1200 and 1250°C for 30 min. After firing, tests samples were characterized by water absorption tests, linear retraction, dilatometric analysis, apparent porosity, apparent specific mass, flexural strength, and microstructural analysis by XRD and SEM. The results revealed that ceramics with porcelainized stoneware tiles characteristics could be produced from raw materials originated in the State of Rio Grande do Norte

Produção de grês porcelanato a partir de matérias-primas do estado da Bahia

The State Bahia, Brazil, presents different geological sites it with a very expressive variety minerals. It is situated among the very important States which produces minerals for industries, such as pointed aggregate, ornamentals stones and ceramics raw materials. Nowadays only four companies producting ceramics tiles. Porcelainized stoneware tiles is one of the noblest ceramics, depicting low water absorption (typically below of 0,5%), in addition to excellent staining resistance and mechanical strength. The present work aims at investigating the potential of local raw materials for the production of porcelainized stoneware tiles. For this purpose, these materials were characterized by X-ray fluorescence, X-ray diffraction, particle size analysis, thermal gravimetric analysis, thermal differential analysis and dilatometric analysis. Admixtures containing different compositions were prepared and fired at four temperatures, 1100 ºC, 1150 ºC, 1200 ºC and 1250 ºC with isotherm for 60 minute and heathing rate of 5 oC/min. After firing the samples, they were characterized by water absorption tests, linear retraction, analysis, apparent porosity, apparent specific mass, flexural strength, and microstructural analysis by X-ray diffraction and scanning electron microscopy . The results revealed three ceramics with porcelainized stoneware tiles characteristics and porcelain tile will be produce from raw materials originated in the State of Bahia

Influência da adição no comportamento reológico da pasta autoadensável de alto desempenho

Influence of admixture on the rheological behavior of high performance self-compacting paste. This research proposes to study the influence of the specific area, mould and surface texture of admixtures on the rheological behavior of high performance self-compacting paste (HPSCP). The selected admixtures are calcareous filler and basalt filler, which are industrial residues, thus contributing to sustainable development. The paste is made up of cement, silica fume, calcareous filler or basalt filler, water and superplasticizer additive. For this study, the water/cement ratios are fixed = 0.40 L kg(-1); silica fume/cement = 0.10 kg kg(-1); the filler/cement and superplasticizer/cement ratios are determined through Marsh cone and mini-slump tests. The results show that for same filler/cement ratios, the ratios of superplasticizer to paste with calcareous filler are significantly lower than those of paste with basalt filler. The results show that the specific area, mould and surface texture of these admixtures significantly influence the rheological behavior of HPSCP.

Estudo dos efeitos do nitrato de lítio na expansão de argamassas sujeitas a reação álcali-sílica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Does ethnic ancestry play a role in smoking?

A maior proporção de fumantes entre negros no Brasil tem sido atribuída a desigualdades socioeconômicas, mas fatores genéticos também poderiam contribuir para esse achado. Este estudo visou investigar associações entre status tabágico com ancestralidade definida geneticamente e características socioeconômicas em brasileiros. Amostras de sangue foram colhidas de 448 voluntários (66,7% homens; idade: 37,1±11,4 anos) classificados como fumantes atuais (FA: 60,9%), ex-fumantes (EF:8,9%) e não fumantes (NF:30,1%).Misturas éticas individuais foram determinadas empregando-se um painel informativo de ancestralidade composto por 48 polimorfismos de deleções e inserções. FA mostraram menor proporção de ancestralidade europeia do que NF (0,837±0,243 X 0,883±0,194; p≤0,05) e EF (0,837±0,243 X 0,864±0,230; p≤0,05), e maior proporção de ancestralidade africana sub-saárica do que EF (0,128±0,222 X 0,07±0,174, p≤0,05) e NF (0,128±0,222 X 0,085±0,178, p≤0,05). NF informaram maior número de anos de escola do que FA (11,2±3,7 X 8,9±3,8; p≤0,001). FA foram menos comuns na Classe econômica A (30%) e mais comuns na Classe B (56,8%). Em análise multivariada, apenas menor número de anos escolares e menor classe econômica estiveram associados com chances maiores para FA. O uso de marcadores de genética molecular para caracterizar o background étnico confirmou que diferenças socioeconômicas são os principais determinantes de maiores taxas de tabagismo entre negros no Brasil.

Determinação de parâmetros reológicos de argamassas e concreto através de técnicas alternativas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Isotopic, trace element and nutrient characterization of coastal waters from Ubatuba inner shelf area, south-eastern Brazil

Stable isotopes, tritium, radium isotopes, radon, trace elements and nutrients data were collected during two sampling campaigns in the Ubatuba coastal area (south-eastern Brazil) with the aim of investigating submarine groundwater discharge (SGD) in the region. The isotopic composition (delta D, delta(18)O, (3)H) of submarine waters was characterised by significant variability and heavy isotope enrichment. The stable isotopes and tritium data showed good separation of groundwater and seawater groups. The contribution of groundwater in submarine waters varied from a few % to 17%. Spatial distribution of (222)Rn activity concentration in surface seawater revealed changes between 50 and 200 Bq m(-3) which were in opposite relationship with observed salinities. Time series measurements of (222)Rn activity concentration in Flamengo Bay (from 1 to 5 kBq m(-3)), obtained by in situ underwater gamma-spectrometry showed a negative correlation between the (222)Rn activity concentration and tide/salinity. This may be caused by sea level changes as tide effects induce variations of hydraulic gradients, which increase (222)Rn concentration during lower sea level, and opposite, during high tides where the (222)Rn activity concentration is smaller. The estimated SGD fluxes varied during 22-26 November between 8 and 40 cm d(-1), with an average value of 21 cm d(-1) (the unit is cm(3)/cm(2) per day). The radium isotopes and nutrient data showed scattered distributions with offshore distance and salinity. which implies that in a complex coast with many small bays and islands, the area has been influenced by local currents and groundwater-seawater mixing. SGD in the Ubatuba area is fed by coastal contaminated groundwater and re-circulated seawater (with small admixtures of groundwater). which claims for potential environmental concern with implications on the management of freshwater resources in the region. (C) 2007 Elsevier Ltd. All rights reserved.

Effect of EVA on the fresh properties of cement paste

The improved workability effect of latex in dry mortars has not been fully clarified. The purpose of this research was to investigate the influence cif the EVA copolymer on the cement hydration and on the rheological properties of cement pastes. The results pointed to a minor influence of EVA on cement hydration and to a ball-bearing effect. In fact, the shear thinning behavior of reference paste at 15 min after mixing changed to shear thickening owing to the EVA addition. This behavior could be explained by the decrease in the interparticle separation distance as consequence of the solid content increase in case of shearing detachment of weakly adhered EVA particles from the cement particles surfaces. The expected EVA plasticizing effect was observed at 60 min. Such behavior points to the stabilization of EVA on the cement particles surfaces, thus resulting in a steric barrier effect. (C) 2011 Elsevier Ltd. All rights reserved.

Viscosidade cinemática de pastas cimentícias com incorporadores de ar avaliadas em diferentes temperaturas

A presença de aditivos incorporadores de ar (AIA) em suspensões cimentícias torna esses materiais sensíveis às etapas de processamento e às condições ambientais de preparo das composições. Diversos estudos têm sido reportados em literatura avaliando o efeito de incorporadores de ar nas propriedades de materiais cimentícios, sobretudo no estado endurecido. Porém o efeito da temperatura na incorporação de ar e nas propriedades reológicas dessas composições tem sido menos investigado, sendo este o objetivo do presente trabalho. Para tanto, foram avaliadas as características de pastas cimentícias, compostas por cimentos CPIIF ou CPIIE e dois tipos de AIA, em função da variação da temperatura. O conceito de viscosidade cinemática foi adotado na análise dos resultados para compensar diferenças de inércia das pastas com densidades distintas. Os resultados mostraram que o tipo de cimento, a presença do aditivo e a temperatura influenciaram significativamente na incorporação de ar e nas propriedades reológicas.

Bau und Entwicklung eines Applikators zur Verabreichung hyperpolarisierter Gase in der MRT der Lunge

Im Rahmen meiner Dissertation habe ich gemäß dem Medizinproduktegesetz ein MR-kompatibles Verabreichungsgerät entwickelt, um Patienten hyperpolarisierte Gas Boli (He-3, Xe-129) als Kontrasgas zur MRT der Lunge zu applizieren. Das Gerät wurde dazu optimiert, die Gase oder Gasmischungen (z. B. HP Gas + N2) in definierten Mengen und zu definierten Zeitpunkten während der Inspiration mit hoher Reproduzierbarkeit und Zuverlässigkeit zu verabreichen, ohne dabei die MR-Qualität zu beeinträchtigen. Aus Sicherheitsgründen und zur späteren Datenanalyse werden die Atemflusskurven der Patienten kontinuierlich angezeigt und aufgezeichnet. Ein Kolbenkompressor ist integriert, um die gesamte gespeicherte He-3-Menge nutzen zu können. Weiterhin ist es möglich, die Polarisation vor Ort zu bestimmen und das abgeatmete He-3 zur späteren Rückgewinnung aufzufangen. Diese Auffangeffizienz konnte durch Untersuchungen mit He-4 (als He-3-Ersatz) gesteigert werden.rnDie ersten MR-Aufnahmen von 10 gesunden Probanden wurden mit diesem Aufbau imrnRahmen einer klinischen Studie durchgeführt. Die Analyse der bestimmten MR-Parameter Signal-Rausch-Verhältnis (SNR), Sauerstoffpartialdruck (pO2), Scheinbarer Diffusionskoeffizient (ADC=apparent diffusion coefficient) sowie die Signalanstiegszeit (rise-time) zeigt eine deutlich bessere Reproduzierbarkeit bei der Verabreichung des He-3 mit dem Applikators anstelle eines Tedlarbags (= kleine heliumdichte Plastiktüte).

Optimierung der inhalativen Therapie bei Patienten mit Cystischer Fibrose und bei Kleinkindern

Patienten mit Cystischer Fibrose müssen in der Regel verschiedene Arzneimittel mehrmals täglich inhalieren. Um den hohen Zeitaufwand dafür zu reduzieren werden die Arzneimittel häufig gemischt und simultan inhaliert. Die Kenntnis der physikalisch-chemischen Kompatibilität von Mischinhalationslösungen/ -suspensionen ist deshalb von großer Bedeutung. In der vorliegenden Arbeit wurden die Kompatibilitäten von Mischungen aus Colistimethat-Inhalationslösung (mikrobiologische Wertbestimmung) mit verschiedenen Tobramycin-Inhalationslösungen, Budesonid (HPLC) mit 5,85%-iger Natriumchlorid-Lösung sowie mit Colistimethat-Inhalationslösung und Dornase alfa (SE-HPLC, SDS-PAGE, UV-Spektrometrie, T-SCX-Chromatographie) mit verschiedenen Tobramycin-Inhalationslösungen (Fluoreszenzpolarisations-Immunoassay) nachgewiesen. Durch das Mischen mit Tobramycin-Inhalationslösungen wurden die aerodynamischen Eigenschaften (FPF, MMAD, GSD) von Dornase alfa bei simultaner Verneblung nicht verändert (bestimmt mittels Kaskadenimpaktion).rnDurch die physiologischen und anatomischen Gegebenheiten, sowie die kognitiven Fähigkeiten kleiner Kinder stellt die effektive inhalative Therapie eine große Herausforderung dar. Der Respimat® bietet mit seiner langen Sprühdauer und den kleinen Aerosolpartikeln eine vielversprechende Alternative für die Anwendung bei Kleinkindern. In der vorliegenden Studie wurde untersucht ob bei Kindern unter 5 Jahren der Respimat® als Inhalationsgerät verwendet werden kann und welchen Grad an Hilfestellung sie für ein erfolgreiches Inhalationsmanöver benötigen.rnDie Ergebnisse der Handhabungsuntersuchung, sowie die Bewertung aufgezeichneter Inhalationsprofile zeigten, dass der Respimat® für Kinder < 4 Jahre nur in Kombination mit einer Inhalierhilfe wie dem AeroChamber Plus® verwendet werden sollte. Kinder im Alter von 4 Jahren sind mit entsprechender Schulung in der Lage mit dem Respimat® alleine zu inhalieren.rn

Effects of adding Bauxite and Oyster shell on the properties of metakaolin-based geopolymer cements

This work has investigated the possibility of use bauxite and oyster shell as mineral admixtures,to enhance the properties of metakaolin-based geopolymer cements. Raw materials(metakaolin, bauxite and oyster shell) were characterized in the first time by determination of their chemical and mineralogical compositions, particles size distribution, specific surface area, thermal analysis and then in the second time use to synthesized geopolymers. Different methods of analysis such as Fourier Transform Infrared spectroscopy(FTIR), X-Ray Diffractometry (XRD), and Scanning Electron Microscopy (SEM) were used to assess the variation of setting time, linear shrinkage and 28 days compressive strength of geopolymer pastes. The results of these analysis has showed that bauxite and oyster shells are source of Al2O3 and CaO respectively, and also contain crystalline phases. The geopolymers obtained by mixing metakaolin and bauxite have their setting time between 235 and 420min and their compressive strength between 40 and 57MPa ; for those obtained by mixing metakaolin and oyster shell the setting time is between 330 and 485min and compressive strength between 40 and 58MPa . The addition of a moderate amount (20% by mass) of bauxite or oyster shell led to improve the compressive strength of a metakaolin-based geopolymer of 43% (metakaolin-bauxite-based geopolymers) and 45% (metakaolin-oyster shell-based geopolymers) and decrease the linear shrinkage. More than 20% mineral additive has a deleterious effect on compressive strength and increase the setting time. Keywords: Metakaolin ; Bauxite ; Oyster shell ; synthesis ; Optimization; Geopolymer cements.