In well cementing, the cement slurry is exposed to the conditions far different than those of ordinary Portland cement (PC) used in construction. After placement, hardened cement paste should preserve integrity and provide zonal isolation through the life of the well. American Petroleum Institute (API) Class G cement is the most common cement type used in various well conditions. Class G cement has a high degree of sulfate resistance which makes it more stable than PC when subjected to the compulsive well conditions. Ground granulated blast furnace slag (GGBFS) blended cement has a long history of use in the construction industry, but is not extensively used in well cementing applications. This study presents an experimental program to investigate the applicability of CEM I and GGBFS blended cement pastes in the well cementing industry. Class G cement and blends of CEM I and GGBFS with the proportions (80:20), (60:40), (40:60) and (20:80) are prepared with same water/cement ratio (0.44) as restricted for Class G cement in API Specification 10A to be tested. The cement pastes are cured for ages of 1 day, 7 days and 28 days at 80

Civil engineers are at times required to stabilize sulfate bearing clay soils with calcium based stabilizers. Deleterious heaving in these stabilized soils may result over time. This dissertation addresses critical questions regarding the consequences of treating sulfate laden soils with calcium-based stabilizers. The use of a differential scanning calorimeter was introduced in this research as a tool to quantify the amount of ettringite formed in stabilized soils. The first part of this dissertation provides a case history analysis of the expansion history compared to the ettringite growth history of three controlled low strength mixtures containing fly ash with relatively high sulfate contents. Ettringite growth and measurable volume changes were monitored simultaneously for mixtures subjected to different environmental conditions. The observations verified the role of water in causing expansion when ettringite mineral is present. Sorption of water by the ettringite molecule was found to be a part of the reason for expansion. The second part of this dissertation evaluates the existence of threshold sulfate levels in soils as well as the role of soil mineralogy in defining the sensitivity of soils to sulfate-induced damage. A differential scanning calorimeter and thermodynamics based phase diagram approach are used to evaluate the role of soil minerals. The observations substantiated the difference in sensitivity of soils to ettringite formation, and also verified the existence of a threshold level of soluble sulfates in soils that can trigger substantial ettringite growth. The third part of this dissertation identifies alternative, probable mechanisms of swelling when sulfate laden soils are stabilized with lime. The swelling distress observed in stabilized soils is found to be due to one or a combination of three separate mechanisms: (1) volumetric expansion during ettringite formation, (2) water movement triggered by a high osmotic suction caused by sulfate salts, and (3) the ability of the ettringite mineral to absorb water and contribute to the swelling process.

The measurement and monitoring of the elastic properties of cement-based materials is very important for assessing their quality, integrity and performance. Due to the nonhomogeneous and time-dependent characteristics of these materials, it is difficult to observe the developments in elastic properties with traditional destructive methods. The aim of this thesis is to determine and monitor elastic properties of mortar specimens made with different cements by using resonant frequency and ultrasonic pulse velocity test methods, and to obtain relationships between these elastic properties. For this purpose, eight different cement mortar mixtures were prepared with different constituent CEM I cements. Dynamic elastic moduli, static elastic moduli, dynamic Poisson&rsquo / s ratio and strength of these mixtures were observed for different ages. The relationships between these elastic properties are determined and the results obtained from two different nondestructive test methods are compared. Although nondestructive tests made it possible to obtain elastic properties of mortar mixtures, the results revealed that it is very difficult to develop a single relationship between different elastic properties of mortars with varying mixture proportions. This situation is mainly due to the anisotropy and nonlinear behavior of the mortar and the difficulty of describing the actual behavior of mortar by formulations defined for perfectly elastic materials.

O cimento Portland (CP) é um produto industrializado que não é só consumidor de energia e de matérias-primas, mas também responsável por grandes emissões de CO2. Além do impacto ambiental, a presença de alguns compostos hidratados que em contato com os sulfatos, produzem fases expansivas que reduzem a vida útil das estruturas. Adições minerais, como as escórias de alto-forno, têm sido adicionadas para reduzir o clínquer e aumentar a resistência aos sulfatos, porém nem todas as escórias conferem empregabilidade como adição devido a sua composição química. Cimentos com adições apresentam ganho de resistência muito lento nas primeiras idades, tornando-se desinteressante para a cadeia produtiva da construção civil. Assim, as limitações que o CP apresenta, somada ao aumento dos resíduos, incentivaram a busca por aglomerantes isentos de clínquer. A álcali ativação proporcionou a possibilidade de reaproveitamento de diversos subprodutos, pois a cinética de reação é similar ao CP, devido à semelhança química e liberação de calor. Pesquisas ligadas à durabilidade dos cimentos álcali ativados (CAT) ainda são bastante reduzidas, principalmente a eficácia dos métodos empregados para avaliação da resistência aos sulfatos em ambientais laboratoriais. Portanto, este trabalho teve como objetivo investigar o comportamento das pastas de escórias ativadas com 5% de NaOH e CP resistente a sulfatos (CPIV-RS) em ambientes sulfatados através do método NIST e comparar com o método acelerado em argamassas proposto pela NBR 13583:2014. As avaliações incluíram as análises microestruturais (DRX/MEV/DTG) e macroestrutural através de inspeções visuais, variação dimensional, variação de massa e resistência à compressão. Os resultados indicaram que nas condições ensaiadas, os métodos acelerados de avaliação da resistência aos sulfatos não apresentaram diferenças significativas entre as pastas e argamassas. Os CATs apresentaram desempenho superior antes e depois da exposição ao Na2SO4 comparados aos CPIV-RS, favorecendo a hidratação e a resistência à compressão. Por outro lado, a formação da gipsita parece ser o principal produto de degradação dos CATs na solução de MgSO4, originado pela descalcificação do C-S-H, afetando fortemente as propriedades físicas, químicas e mecânicas dos cimentos álcali ativados. / Portland cement (PC) is an industrialized product that is not so consuming of energy and raw materials, but also responsible for large CO2 emissions. Besides the environmental impact, the presence of some hydrated compounds that in contact with the sulfates, produce expansive phases that reduce the useful life of the structures. Minerals additions, such as blast furnace slag, have been added to reduce clinker and increase resistance to sulphates, but not all slags confer employability as addition because of their chemical composition. Cements with additions show very low resistance gain in the early ages, making it uninteresting for the productive chain of civil construction. Thus, the limitations that PC presents, together with the increase of residues, have encouraged the search for clinker-free binders. Alkali-activation provided the possibility of reuse of several by-products, because the reaction kinetics is similar to PC, due to chemical similarity and heat release. Researches related to the durability of alkaliactivated cements (AAC) are still very low, mainly the efficacy of the methods used to evaluate the resistance to sulfates in laboratory environments. Therefore, the objective of this work was to investigate the behavior of slag pastes activated with 5% NaOH and sulfate resistant PC (PCIV-SR) in sulphated environments using the NIST method and to compare with the accelerated mortar method proposed by NBR 13583:2014. The evaluations included microstructural analysis (XRD/SEM/DTG) and macrostructural analysis through visual inspection, dimensional variation, mass variation and compressive strength. The results indicated that under the conditions tested, the accelerated methods of sulfate resistance evaluation did not present significant differences between pastes and mortars. The AACs presented better performance before and after exposure to Na2SO4 compared to PCPIV-SR, favoring hydration and compressive strength. On the other hand, the formation of gypsum appears to be the main degradation product of the AACs in the MgSO4 solution, caused by the C-S-H decalcification, strongly affecting the physical, chemical and mechanical properties of the activated alkali cements.

Made available in DSpace on 2014-12-17T14:06:52Z (GMT). No. of bitstreams: 1 FernandoAML.pdf: 704139 bytes, checksum: 56133b8802fd230583fd96ae8805d657 (MD5) Previous issue date: 2009-04-30 / Several problems related to the loss of hydraulic seal in oilwells, causing gas migration and/or contamination of the production zone by water, have been reported. The loss of the hydraulic seal is a consequence of cracks which can be occasioned either by the invasion of gas during the wait on cement or by the expansion of the casing causing the fracture of the cement sheath. In case of the pressure of the formation is higher than the pressure in the annulus, gas can migrate into the slurry and form microannulus, which are channels where gas migrates after the cement is set. Cracks can be also occasioned by the fracture of the cement sheath when it does not withstand the thermal and dynamic loads. In reservoirs where the oil is heavy, steam water injection operation is required in order to get the oil flowing. This operation increases the temperature of the casing, and then it expands and causes the fracture of the cement sheath in the annulus. When the failures on the cement are detected, remedial cementing is required, which raise costs caused by the interventions. Once the use of cement in the construction civil sector is older than its use in the petroleum sector, it is common to bring technologies and solutions from the civil construction and apply them on the petroleum area. In this context, vermiculite, a mineral-clay widely encountered in Brazil, has been used, on its exfoliated form, in the civil construction, especially on the manufacture of lights and fireproof concretes with excellent thermal and acoustical properties. It has already been reported in scientific journals, studies of the addition of exfoliated vermiculite in Portland cements revealing good properties related to oilwell cementing operations. Thus, this study aimed to study the rheological behavior, thickening time, stability and compressive strength of the slurries made of Portland cement and exfoliated vermiculite in 5 different compositions, at room temperature and heated. The results showed that the compressive strength decreased with the addition of exfoliated vermiculite, however the values are still allowed for oiwell cementing operations. The thickening time of the slurry with no exfoliated vermiculite was 120 min and the thickening time of the slurry with 12 % of exfoliated vermiculite was 98 min. The stability and the rheological behavior of the slurries revealed that the exfoliated vermiculite absorbed water and therefore increased the viscosity of the slurries, even though increasing the factor cement-water. The stability experiment carried out at 133 ?F showed that, there was neither sedimentation nor reduction of the volume of the cement for the slurry with 12 % of exfoliated vermiculite. Thus, the addition of exfoliated vermiculite accelerates the set time of the cement and gives it a small shrinkage during the wait on cement, which are important to prevent gas migration / Muitos problemas relacionados ? perda do isolamento hidr?ulico em po?os de petr?leo, causando migra??o de g?s e contamina??o da zona produtora por migra??o de ?gua, t?m sido reportados. A perda do isolamento hidr?ulico ? conseq??ncia de trincas que por sua vez s?o conseq??ncias de uma cimenta??o mal feita, onde houve invas?o de g?s durante a pega da pasta gerando trincas tamb?m chamadas de microanulares que s?o os caminhos por onde a migra??o de g?s ocorre. Essas trincas tamb?m s?o ocasionadas pela fratura do cimento quando este n?o suporta as cargas t?rmicas e din?micas, as quais o cimento ? submetido durante sua vida. Em reservat?rios onde o ?leo encontrado ? bastante viscoso, opera??es de inje??o de vapor de ?gua s?o requeridas a fim de facilitar o escoamento do ?leo. Essa opera??o aumenta a temperatura da malha de po?os, fazendo com que o revestimento dilate e frature o cimento no anular, ocasionando a perda do isolamento hidr?ulico. Uma vez detectada falhas no isolamento hidr?ulico, opera??es de corre??o s?o requeridas o que acaba gerando custos, perda de tempo com a interven??o e lucro cessante. Como o setor de constru??o civil trabalha com cimento a muito mais tempo que o setor de petr?leo, ? comum lan?ar-se m?o de tecnologias e solu??es apresentadas na constru??o e aplicar com os devidos ajustes no ramo do petr?leo. Nesse contexto, a vermiculita, um argilomineral encontrado em abund?ncia no Brasil, tem sido aplicado, na sua forma expandida, na constru??o civil para confec??o de concretos leves, resistentes a fogo e com excelentes propriedades de isolamento t?rmico e ac?stico. J? tem sido reportado em revistas cient?ficas, estudos de sua adi??o em cimento portland com boas propriedades relacionadas ? cimenta??o de po?os de petr?leo. Dessa forma o presente trabalho objetivou estudar o comportamento reol?gico, tempo de pega e a resist?ncia a compress?o de pastas com vermiculita expandida e cimento portland classe especial em quatro composi??es diferentes, fazendo um comparativo com as propriedades existentes da pasta padr?o contendo apenas cimento portland e ?gua, em duas temperaturas, ambiente e aquecida. Os resultados mostraram que a resist?ncia ? compress?o dos corpos de prova diminuiu com o aumento da concentra??o de vermiculita, por?m ainda dentro da faixa permitida para cimenta??o de po?os de petr?leo. Os ensaios de consistometria indicaram que o tempo de pega para a pasta padr?o foi de 120 min, enquanto que para a pasta com 12% de vermiculita expandida foi de 98 min. Os ensaios de estabilidade e a avalia??o do comportamento reol?gico das pastas mostraram que a vermiculita expandida por absorver ?gua, aumenta a viscosidade da pasta, mesmo aumentando o fator ?gua-cimento. O ensaio de estabilidade realizado ? 133 ?F mostrou que n?o houve rebaixamento e nem sedimenta??o para a pasta com 12% de vermiculita expandida. Logo a adi??o de vermiculita expandida ? pasta cimentante favorece a cura r?pida e a baixa retra??o do volume da pasta durante a pega, importantes para evitar migra??o de g?s

Made available in DSpace on 2014-12-17T14:07:00Z (GMT). No. of bitstreams: 1 GuilhermeFM.pdf: 1361832 bytes, checksum: 90befe7961c07f2510ca8f988b71da6b (MD5) Previous issue date: 2009-03-23 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This work addresses the production of lightweight concrete building elements, such as plates, prefabricated slabs for pre-molded and panels of fencing, presenting a singular concrete: the Lightweight Concrete, with special properties such low density and good strength, by means of the joint use of industrial waste of thermosetting unsaturated polyesters and biodegradable foaming agent, named Polymeric Lightweight Concrete. This study covered various features of the materials used in the composition of the Polymeric Lightweight Concrete, using a planning of factorial design 23, aiming at studying of the strength, production, dosage processes, characterization of mechanical properties and microstructural analysis of the transition zone between the light artificial aggregate and the matrix of cement. The results of the mechanical strength tests were analyzed using a computational statistics tool (Statistica software) to understand the behavior and obtain the ideal quantity of each material used in the formula of the Polymeric Lightweight Concrete. The definition of the ideal formula has the purpose of obtaining a material with the lowest possible dry density and resistance to compression in accordance with NBR 12.646/92 (≥ 2.5 MPa after 28 days). In the microstructural characterization by scanning electron microscopy it was observed an influence of the materials in the process of cement hydration, showing good interaction between the wrinkled face of the residue of unsaturated polyesters thermosetting and putty and, consequently, the final strength. The attaining of an ideal formula, given the Brazilian standards, the experimental results obtained in the characterization and comparison of these results with conventional materials, confirmed that the developed Polymeric Lightweight Concrete is suitable for the production of building elements that are advantageous for construction / Neste trabalho ? abordada a aplica??o da tecnologia dos concretos leves ? produ??o de elementos construtivos, tais como placas pr?-fabricadas para lajes pr?-moldadas, pain?is de veda??o e pe?as pr?-moldadas, e ao desenvolvimento de um concreto celular com propriedades especiais de baixa densidade e boa resist?ncia mec?nica, em fun??o da utiliza??o conjunta de res?duo industrial de poli?ster insaturado termofixo (PIT) e espuma biodegrad?vel incorporadora de ar, denominado de Concreto Celular Polim?rico (CCP) . O estudo abrangeu diferentes tra?os dos materiais empregados na composi??o do CCP, sendo utilizado um planejamento fatorial 23, para an?lises dos processos de dosagem e produ??o, caracteriza??o das propriedades mec?nicas, bem como an?lises microestruturais da zona de transi??o entre o agregado artificial leve (PIT) e a matriz de cimento. Os resultados dos testes de resist?ncia mec?nica foram analisados utilizando-se uma ferramenta computacional de estat?stica (Statistica Software) para compreens?o do comportamento e obten??o da concentra??o ideal de cada material utilizado na formula??o do CCP. A defini??o da f?rmula ideal teve como finalidade a obten??o de um material com a menor densidade a seco poss?vel e resist?ncia ? compress?o que atendesse ? norma NBR 12.646/92 (≥ 2,5 MPa aos 28 dias). Na caracteriza??o microestrutural por microscopia eletr?nica de varredura, observou-se a influ?ncia dos materiais no processo de hidrata??o do cimento, onde constatou-se boa intera??o entre o res?duo de PIT, cuja face ? enrugada, e a pasta de cimento. A obten??o da formula??o de um novo material que atende ? norma brasileira, os resultados experimentais obtidos nas caracteriza??es e compara??o desses resultados com materiais convencionais, comprovaram que o Concreto Celular Polim?rico desenvolvido ? adequado ? produ??o de elementos construtivos que apresentam vantagens quando aplicados ? constru??o civil

Made available in DSpace on 2014-12-17T14:07:12Z (GMT). No. of bitstreams: 1 UlissesTB.pdf: 2103703 bytes, checksum: 784868c57be7336a1a7601f71664ac81 (MD5) Previous issue date: 2006-10-31 / The oil production in mature areas can be improved by advanced recovery techniques. In special, steam injection reduces the viscosity of heavy oils, thus improving its flow to surrounding wells. On the other hand, the usually high temperatures and pressures involved in the process may lead to cement cracking, negatively affecting both the mechanical stability and zonal isolation provided by the cement sheath of the well. The addition of plastic materials to the cement is an alternative to prevent this scenario. Composite slurries consisting of Portland cement and a natural biopolymer were studied. Samples containing different contents of biopolymer dispersed in a Portland cement matrix were prepared and evaluated by mechanical and rheological tests in order to assess their behavior according to API (American Petroleum Institute) guidelines. FEM was also applied to map the stress distribution encountered by the cement at bottom bole. The slurries were prepared according to a factorial experiment plan by varying three parameters, i.e., cement age, contents of biopolymer and water-to-cement ratio. The results revealed that the addition of the biopolymer reduced the volume of free water and the setting time of the slurry. In addition, tensile strength, compressive strength and toughness improved by 30% comparing hardened composites to plain Portland slurries. FEM results suggested that the stresses developed at bottomhole may be 10 to 100 times higher than the strength of the cement as evaluated in the lab by unconfined mechanical testing. An alternative approach is proposed to adapt the testing methodology used to evaluate the mechanical behavior of oilwell cement slurries by simulating the confined conditions encountered at bottornhole / A cimenta??o de po?os ? pr?tica comum na ind?stria do petr?leo. Po?os antigos que apresentam baixo rendimento passam a produzir mais quando se adota o processo de recupera??o secund?ria. Um dos procedimentos que pode ser adotado nestes po?os ? a introdu??o de vapor d'?gua sob press?o para que o petr?leo tenha sua viscosidade reduzida e flua com mais facilidade para os po?os da circunvizinhan?a. A temperatura elevada provoca fissura??o nas bainhas dos po?os e conseq?ente perda de estanqueidade devido ao car?ter r?gido das bainhas de cimento Portland. Comp?sitos de cimento Portland aditivados com biopol?mero foram analisados com rela??o a tr?s aspectos: propriedades mec?nicas previstas nas normas da ABNT e espec?ficas para a ind?stria do petr?leo; propriedades reol?gicas tamb?m previstas em norma e avalia??o num?rica por elementos finitos simulando bainhas de po?os de petr?leo. As pastas foram preparadas seguindo planejamento fatorial pr?vio, com varia??o de tr?s fatores: idade do cimento Portland, concentra??o de biopol?mero e fator ?gua/cimento. Os resultados mostraram que a presen?a do biopol?mero elimina forma??o de ?gua livre; funciona como acelerador de pega, reduzindo o tempo de espessamento; aumenta as resist?ncias ? compress?o e ? tra??o em at? 30 % e a tenacidade-resili?ncia em at? 30 %. A an?lise por elementos finitos mostrou que a ordem de grandeza das tens?es despertadas pela temperatura no fundo do po?o chega a ser 10 e 100 vezes superior ?s resist?ncias ? compress?o e ? tra??o, respectivamente, das pastas ensaiadas em laborat?rio. Isto levou ? constata??o de que os ensaios n?o confinados de propriedades mec?nicas n?o conseguem medir o comportamento real das pastas, sendo necess?ria a adapta??o dos mesmos para a condi??o confinada. Um ensaio alternativo ? proposto por meio de um equipamento (SCERB) que simula as condi??es de fundo de po?o

Made available in DSpace on 2014-12-17T14:07:17Z (GMT). No. of bitstreams: 1 FlankML.pdf: 1510639 bytes, checksum: 80a343cff9d15e912e4b6cbd66703104 (MD5) Previous issue date: 2006-10-16 / The isolation of adjacent zones encountered during oilwell drilling is carried out by Portland-based cement slurries. The slurries are pumped into the annular positions between the well and the casing. Their rheological behavior is a very important component for the cementing process. Nowadays, several alternative materials are used in oilwell cementing, with goal the modification and the improvement of their properties, mainly the increase of the fluidity. And this can be reached by using plasticizers additives able to account for different oilwell conditions, yielding compatible cement slurries and allowing enough time for the complete cementing operation. If the rheological properties of the slurry are properly characterized, the load loss and flow regime can be correctly predicted. However, this experimental characterization is difficult. Rheological models capable of describing the cement slurry behavior must be capable of predicting the slurry cement deformation within reasonable accuracy. The aim of this study was to characterize rheologically the slurries prepared with a especial class of Portland cement, water and plasticizers based on lignosulfonate, melamine and polycarboxylate at temperatures varying from 27?C to 72?C. The tests were carried out according to the practical recommendations of the API RP 10B guidelines. The results revealed a great efficiency and the dispersive power of the polycarboxylate, for all temperatures tested. This additive promoted high fluidity of the slurries, with no sedimentation. High lignosulfonate and melamine concentrations did not reduce the rheological parameters (plastic viscosity and yield stress) of the slurries. It was verified that these additives were not compatible with the type of cement used. The evaluated rheological models were capable of describing the behavior of the slurries only within concentration and temperature ranges specific for each type of additive / Pastas de cimento do tipo Portland s?o usadas para isolamento de po?os de petr?leo. Esse procedimento ? realizado por meio do bombeio da pasta no espa?o anular entre o po?o e a coluna de revestimento, de modo a se obter fixa??o e veda??o eficiente e permanente. Para isso o comportamento reol?gico da pasta de cimento ? um componente de extrema import?ncia para o processo de cimenta??o. Atualmente, diversos materiais alternativos s?o utilizados em pastas para cimenta??o, objetivando a modifica??o e a melhoria de suas propriedades, principalmente no que diz respeito ao aumento de fluidez. Isso pode ser alcan?ado por meio da utiliza??o de novos aditivos do tipo plastificantes, capazes de suportar as diversas condi??es de po?os, promovendo ?s pastas propriedades compat?veis ?s condi??es encontradas, permitindo, ainda, um tempo suficiente de trabalhabilidade para a completa execu??o do servi?o de cimenta??o. Assim, se as propriedades reol?gicas da pasta s?o bem caracterizadas, a perda de carga e o regime de fluxo podem ser prognosticados corretamente. Contudo, essa caracteriza??o ? dif?cil do ponto de vista experimental. Modelos reol?gicas capazes de descrever o que ocorre, dever?o ser capazes de predizer a deforma??o da pasta de cimento com razo?vel exatid?o. Portanto, a finalidade deste trabalho foi o estudo e a caracteriza??o reol?gica de pastas constitu?das de cimento Portland classe especial, ?gua e aditivos do tipo plastificante, a base de lignossulfonato, melamina e policarboxilato, em temperaturas na faixa de 27?C a 72?C. Os testes foram realizados de acordo com as recomenda??es pr?ticas da norma API RP 10B. Os resultados dos ensaios demonstraram a grande efici?ncia e o poder dispersivo do policarboxilato, para todas as temperaturas estudadas. O aditivo promoveu uma alta fluidez, sem efeitos de sedimenta??o. O aumento das concentra??es de lignossulfonato e melamina n?o reduziu os par?metros reol?gicos (viscosidade pl?stica e limite de escoamento). Tamb?m foi verificado que esses aditivos n?o foram compat?veis com o tipo de cimento utilizado. Por fim, os modelos reol?gicos avaliados foram capazes de descrever o comportamento das pastas apenas para faixas de temperatura e concentra??o de cada tipo de aditivo

The Master thesis deals with utilization possibilities of fly ash after selective non-catalytic reduction (SNCR) process for Portland cement preparation as a correction component to the raw material with regard to contaminated fly ash by ammonium sulphate or ammonium hydrogensulfate that is one of the products from SNCR process. Presented thesis was focused on behaviour of raw meal with ammonia hydrogensulfate contaminated fly ash after SNCR during burning of Portland clinker in simulated kiln conditions. The thesis deals with Portland clinker preparation from this kind of raw mix and it studies mainly clinker quality, clinker phases and structure. Quantitative phase composition of prepared samples of clinker was performed by optical microscopy measurements using point counting method and XRD analysis (Rietveld method). Hydration heat flow of prepared clinker was measured by Isothermal Calorimetry. TG-DTA analysis of prepared raw meal was studied due to better comparison of prepared samples and better understanding of processes during burning process.

The carbonation phenomenon, reaction between CO2 from the atmosphere in the presence of humidity with the Portland cement hydration products, induces pH reduction to levels that can cause the elimination of steel s protective layer, enabling the corrosion mechanism of the steel structure to start.. This is one of the main pathologies in the reinforced concrete and its occurrence depends on the existence of oxygen, humidity and potential difference between two different locations of the steel bar. This research analyzed the performance of different concrete mixtures produced with Portland cement with high levels of blast furnace slag, with and without the chemical activator sodium sulfate (Na2SO4), in relation to compressive strength, capillary absorption and carbonation. For comparison purposes, gray Portland cement concrete test samples were also cast. For the white Portland cement concrete, slag contents of 0% and 50%, without and with chemical activator at concentrations of 4% and 70% were chosen. With the gray Portland cement it was produced concrete with 0% and 50% of slag addition, with and without chemical activator. For each mixture was adopted water/binder ratios of 0.30, 0.42 and 0.55. The samples cast with white Portland cement, destined to the compressive strength tests were broken at 3, 7, 28 and 91 days and the capillary absorption tests were done 91 days after molding. The samples destined to accelerated carbonation tests, cast with the two kinds of cements, were submitted to an atmosphere with 2% CO2 concentration, temperature of 23±1ºC and relative humidity of 75±2%. The carbonation depths determination was realized in the ages of 0, 3, 6, 9 and 12 weeks, after entrance in the chamber. From results obtained it was noticed that compressive strength reduced as the slag content and water/binder ration increased. In more advanced ages, however, the difference in compressive strength between mixtures with slag and the reference mixture was smaller than in the first ages. The capillary absorption reduced with the slag content increase, as a consequence of the refinement pores. The carbonation depth, for the white and gray concretes, increased with the slag content and the chemical activator utilization. In a comparison between white and gray Portland cement concretes, for the same slag content and water/binder ratio, the higher carbonation depths were reached with the white concrete, and this difference was higher when the water/binder ratio was increased. / O fenômeno da carbonatação, reação entre o CO2 da atmosfera em presença de umidade com os produtos de hidratação do cimento Portland, provoca a redução do pH do concreto a níveis que podem causar a eliminação da película passivadora do aço, podendo ocorrer a instalação do mecanismo de corrosão das armaduras, uma das principais patologias em estruturas de concreto armado, desde que para isto, exista oxigênio, umidade e uma diferença de potencial entre dois pontos distintos da barra de aço. Esta pesquisa analisou o desempenho de diferentes misturas de concretos produzidos com cimento Portland branco com altos teores de escória de alto forno, com e sem ativador químico sulfato de sódio (Na2SO4), frente à resistência à compressão, absorção capilar e carbonatação. Para efeito de comparação da resistência à carbonatação, também foram moldadas amostras com concreto de cimento Portland cinza. Para o concreto de cimento Portland branco foram adotados os teores de adição de escória de 0%, 50% sem e com ativador químico no teor de 4% e 70%. Com o cimento Portland cinza foram produzidos concretos com 0% e 50% de adição de escória sem e com ativador químico. Para cada mistura foram adotadas três relações água/aglomerante, 0,30, 0,42 e 0,55. Os corpos-deprova, moldados com cimento Portland branco, destinados aos ensaios de resistência à compressão foram rompidos aos 3, 7, 28 e 91 dias e os ensaios de absorção capilar foram realizados 91 dias após a moldagem. As amostras destinadas ao ensaio de carbonatação acelerada, moldadas com os dois tipos de cimento, foram submetidas a uma atmosfera com concentração de 2% de CO2, temperatura de 23±1ºC e umidade relativa de 75±2%. A determinação da profundidade carbonatada foi realizada nas idades de 0, 3, 6, 9 e 12 semanas, após a entrada na câmara de carbonatação. Dos resultados obtidos constatou-se redução nos valores de resistência à compressão das misturas com escória com o aumento no teor de adição e da relação água/aglomerante, porém, em idades mais avançadas, a diferença entre as resistências das misturas com adição e aquelas da mistura de referência foi menor que nas primeiras idades. A absorção capilar diminuiu com o aumento no teor de adição de escória, conseqüência do refinamento dos poros. A profundidade de carbonatação, para os concretos branco e cinza, aumentou com o aumento no teor de escória e a utilização de ativador químico. Na comparação entre os concretos de cimento Portland branco e cinza analisados, para mesmo teor de adição e relação água/aglomerante, as maiores profundidades de carbonatação foram atingidas pelo concreto branco, e esta diferença foi maior à medida que aumentou a relação água/aglomerante.