Doctor of Philosophy(PhD) / Soil Stiffness is an important parameter for any geotechnical engineering design. In laboratory tests it can be derived from stress-strain curves or from dynamic measurement based on wave propagation theory. The second method is a more accurate and direct method for measuring stiffness at very small strains. Until now dynamic measurements have usually been obtained manually from the triaxial test. Attempts have been made to automate the procedure but have apparently failed due to the high level of variability in dynamic measurements. Moreover, triaxial tests of soil can be very lengthy and manual dynamic measurements can be very tedious and impractical for long stress-path tests. In this research a computer program has been developed to automate the stiffness measurement (using bender elements) based on the cross- correlation technique. In this method the program records all the peaks and corresponding arrival times in the cross-correlation signal during the test. The stiffness is calculated and displayed on the screen continuously. The Bender Element enabled to get the small strain shear modulus. An arbitrary “Chirp” waveform of 4 kHz frequency was used for this purpose. Subsequently Bender Element test results were checked by ‘Sine’ waveforms of frequencies 5kHz to 20kHz, as well as by manual inspection of the arrival time. This thesis discusses the method and some of the difficulties in truly automating the process. Finally some results from a number of stress path tests on uncemented and cemented calcareous sediments are presented. Bender elements have been used by many researchers to determine the shear modulus at small strain. Most previous studies have used visual observation of arrival time, which is time consuming and often requires some judgement from the operator. This thesis will describe the use of cross-correlation as a method for automation of Gmax measurement. Cross-correlation has been claimed to be unreliable in the past. However, it will be shown that provided several peaks in the cross-correlation signal are monitored it is possible to follow the variation of Gmax throughout consolidation and shearing. The measurement can be made at regular intervals within the software controlling a stress-path apparatus. Details of the apparatus used and practical considerations including selection of waveform and frequency are discussed. A series of drained cyclic triaxial tests was carried out on artificially cemented and uncemented calcareous soil of dry unit weights 13, 15, and 17 kN/m3 and sheared with constant effective confining stress 300 kPa. Gypsum cement contents of 10%, 20% and 30% of the dry soil weight were used. In addition a series of stress path tests were performed on Toyuora sand samples. Results will be presented for two uncemented and one cemented sand. In addition to the bender elements, all tests had internal instrumentation to monitor axial and lateral strains. Results will be presented for Toyura sand to show that the measurements are consistent with those obtained by other methods. Results will also be presented for carbonate sand subjected to a wide range of stress paths. Finally, results will be presented for the carbonate sand cemented with gypsum. The degradation of Gmax of the cemented soil subjected to variety of monotonic and cyclic stress-paths is presented. Analysis of the results includes assessment of the factors influencing Gmax for uncemented sand. Preliminary analysis indicates that in order of importance these are the mean effective stress, the stress history, void ratio and stress ratio. For cemented sand, Gmax is initially constant and independent of stress path. After yielding the modulus degrades, becoming increasingly stress level dependent and eventually approaches the value for uncemented sand. Factors influencing the rate of degradation are discussed. For the Toyuora sand samples the effects of end restraint on the stress-strain response at small strains were investigated. The conventional method of mounting triaxial specimen has the effect of introducing friction between sample and end platen during a compression test. This inevitably restricts free lateral movement of the specimen ends. Frictional restraint at the sample ends causes the formation of 'dead zones' adjacent to the platens, resulting in non-uniform distribution of stress and strain (and of pore pressure if undrained). On the other hand the specimen with 'free' ends maintain an approximate cylindrical shape instead of barrelling when subjected to compression, resulting in a more uniform stress distribution.

Orientador: José Roberto Cury Saad / Banca: Victor Humberto Orbegoso Flores / Banca: Luiz Alberto Plácido Penna / Banca: Leonor de Castro Monteiro Loffredo / Banca: Welingtom Dinelli / Resumo: O objetivo deste estudo foi avaliar o efeito de cimentos provisórios e de métodos de limpeza dentinária na resistência de união de restaurações indiretas em resina à dentina. Foram selecionados 21 terceiros molares recém extraídos e isentos de cárie. A parte da coroa dental correspondente ao esmalte foi removida expondo-se toda superfície dentinária. Os dentes foram divididos aleatoriamente em sete grupos experimentais de acordo com o cimento provisório e o método de limpeza dentinária utilizado: (G1-controle) não recebeu restauração provisória nem limpeza dentinária; (G2) cimentação provisória com Life e limpeza com pasta de pedra-pomes; (G3) cimentação provisória com Life (Kerr) e limpeza com jato abrasivo; (G4) nenhum procedimento de limpeza foi executado após cimentação com Life; (G5) cimentação provisória com Temp Bond e limpeza com pasta de pedra-pomes; (G6) cimentação provisória com Temp Bond (Kerr) e limpeza com jato abrasivo e (G7) nenhum procedimento de limpeza foi executado após cimentação com Temp Bond. Após uma semana de armazenamento em água, restaurações de Solidex (Shofu) foram cimentadas com adesivo Single Bond (3M ESPE) e cimento Rely X ARC (3M ESPE). Todos os produtos foram manipulados de acordo com as instruções do fabricante. Os dentes foram seccionados obtendo-se espécimes de 1,0 mm2 para realização de teste de microtração. Os valores obtidos foram submetidos à análise de variância e teste de Tukey. Os resultados indicaram que o grupo contaminado com hidróxido de cálcio sem realização da limpeza dentinária apresentou os menores valores de resistência e foi estatisticamente diferente do grupo onde não houve contaminação. Qualquer dos cimentos e métodos de limpeza utilizados obteve as maiores médias de resistência, porém sem diferenças significativas entre elas. / Abstract: The purpose of this study was to evaluate the effect of provisional cements and dentin cleaning methods on the adhesion of resin bonded indirect restorations. Flat dentin surfaces were produced cutting extracted human molars. The teeth were divided randomly in seven experimental groups according with the provisional cement and the used dentin cleaning method: (G1- control) no provisional restoration and no dentin cleaning; (G2) pumice-water slurry cleaning after cementation with Life (Kerr); (G3) aluminum oxide sandblasting after cementation with Life; (G4) no cleaning procedure after Life cementation; (G5) pumice-water slurry cleaning after cementation with Temp Bond (Kerr); (G6) aluminum oxide sandblasting after cementation with Temp Bond and (G7) no cleaning procedure after Temp Bond cementation. After one week of storing in water, Solidex indirect restorations (Shofu) were cemented with Single Bond adhesive system (3M ESPE) and Rely X ARC cement (3M ESPE). All products were handled according with manufacturer's instructions. The teeth were sectioned resulting in adhesion area of 1,0 mm2 specimens for microtencile tests. The resulted values were submitted to variance analysis and Tukey's test. These values indicated the group which was contaminated with calcium hydroxide cement and had no dentin cleaning presented the lowest bond strength and was statistically different from the group with no contamination. Any of the used cements and cleaning methods got the highest means of bond strength, but with no relevant differences among them. With these results can be concluded that, after the treatment with provisional cements, the absence of dentin cleaning implies in lower bond strength values. / Doutor

Les normes en vigueur de la caractérisation environnementale des déchets s’appuient sur l’analyse de granulats ou réduits en poudre. La modification de propriétés du matériau risque de fausser le relargage d’éléments polluants. L’objectif principal de ce travail de thèse est de mettre au point une méthodologie de lixiviation sur matériau monolithique.Des formulations cimentaires de type mortier ou sous-couche routière incorporant des sédiments traités par le procédé NOVOSOL® (STN) ont été réalisées. Leur caractérisation montre l’augmentation de la porosité et la surface lors de l’ajout de STN. Les caractéristiques mécaniques sont proches de celles des matériaux de type routier.Une longue phase de mise au point a permis de concevoir la cellule d’essai et le protocole permettant de tester des matériaux monolithiques en percolation à débit contrôlé. Un protocole de traçage couplé à une modélisation par un logiciel de transport permet de déterminer les caractéristiques hydrodynamiques des matériaux durant percolation.Les résultats d'essais mettent en évidence la bonne stabilité des métaux lourds contenus dans les STN comparés aux métaux apportés par le liant cimentaire. Ainsi, pour certains métaux, l’introduction de STN tend à diminuer les quantités relarguées, pour d’autres la teneur en polluant des percolats soit stable, soit en augmentation. Même si la complexité des phénomènes mis en jeu nous amène à considérer les données avec précaution, certains résultats tendent à montrer l’existence d’un lien entre surface de contact et relargage. La comparaison des résultats obtenus en laboratoire et des mesures réalisés in situ atteste de la représentativité du test mis au point / The standards of environmental characterisation of wastes recommend the sieving of granular material or the crushing of monolithic material to match a required granulometry. The modification of material characteristics is likely to distort the release of pollutants. The main objective of this thesis is to develop a methodology to test monolithic material by percolation.Various mortar-type and/or under-layer road-type materials incorporating sediment treated by the process NOVOSOL® (STN) designed by the Solvay company have been designed. Their characterization has highlighted the increase of porosity, the decrease of bulk density and the increase of specific area with the addition of STN. The mechanical properties are close to those expected for road type materials.The use of a reference material has allowed designing the test cell and the protocol for testing monolithic materials in percolation with a controlled rate of flow. A breakthrough protocol using an inert salt coupled with a transport modelling software has also been defined, to determine the hydrodynamic characteristics of materials during the percolation.The results of tests showed a good stability of heavy metals contained in the STN compared to metals carried by the cement binder. Thus, for some metals, the introduction of STN tends to reduce the leached quantities, for others, the content of pollutant of leachates either stable or increasing. Despite the complexity of the involved phenomena, some results tend to prove the relation between specific area and heavy metals leaching. Comparison of laboratory results and measurements made in situ demonstrates the representativeness of the test developed

Made available in DSpace on 2014-12-17T14:07:19Z (GMT). No. of bitstreams: 1 EduardoRDN_TESE.pdf: 2710171 bytes, checksum: 09b5f50c7446d0f076dc4edac8718d45 (MD5) Previous issue date: 2014-02-10 / The gas migration during the cementing of wells is one of the main problems of oil wells engineering. Its occurrence can cause severe problems since shortly to loss of control of the well after cementation. Recently, 20/04/2010 In an accident of major proportions in the Gulf of Mexico, among other factors, faulty cementing operation provided the gas migration, causing the accident, in which 11 people died and 17 were injured occurred. Besides the serious consequences that can be caused by gas migration, remediation of the problem, which is made by injecting cement in damaged areas, usually involves additional costs and is not always effective. Therefore, preventing gas migration to be preferred. Some methods are used to prevent the migration of the pressurized gas as the annular space, application of pressure pulses, reducing the height of the cement column compressible cement pastes of low permeability, pastes and to control free filtered water, and binders of thixotropic cement expandable and flexible. Thus, the cement pastes used to prevent gas migration must meet the maximum these methods. Thus, this study aimed to formulate a cement paste to prevent gas migration, using the expanded vermiculite, and evaluate the behavior of the folder trials necessary for use in oil wells. Free water content, rheological properties, compressive strength, loss of liquid phase sedimentation of solids, specific weight, thickening time and gas migration: The following tests were performed. The results show that meets the specifications paste formulated for use in oil wells and the use of expanded vermiculite contribute to the absorption of free water, thixotropy and low density. The absorption of free water is proven to result in zero percentage test free water content, thixotropy is observed with the high value of the initial gel strength (Gi) in testing rheological properties and low density is proven in test weight specific / A migra??o de g?s durante a cimenta??o de po?os ? um dos principais problemas da engenharia de po?os de petr?leo. Sua ocorr?ncia pode causar desde problemas pouco severos at? a perda de controle do po?o ap?s a cimenta??o. Recentemente, Em 20/04/2010 ocorreu um acidente de grandes propor??es no Golfo do M?xico, que dentre v?rios fatores, a falha na opera??o de cimenta??o proporcionou a migra??o de g?s, causando o acidente, onde 11 pessoas morreram e 17 ficaram feridas. Al?m das s?rias consequ?ncias que podem ser causadas pela migra??o de g?s, a remedia??o do problema, que ? feita pela inje??o de cimento nas zonas danificadas, geralmente envolve custos adicionais e nem sempre ? efetiva. Por isso, a preven??o da migra??o de g?s deve ser preferida. Alguns m?todos s?o utilizados para evitar a migra??o de g?s como a pressuriza??o do espa?o anular, aplica??o de pulsos de press?o, redu??o da altura da coluna de cimento, cimento compress?vel, pastas de baixa permeabilidade, pastas com controle de filtrado e ?gua livre, e pastas de cimento tixotr?picas, expans?veis e flex?veis. Deste modo, as pastas de cimento utilizadas para evitar migra??o de g?s devem atender ao m?ximo estes m?todos. Assim, este trabalho teve como objetivo formular uma pasta de cimento para evitar a migra??o de g?s, utilizando a vermiculita expandida, e avaliar o comportamento da pasta em ensaios necess?rios ? utiliza??o em po?os petrol?feros. Foram realizados os seguintes ensaios: teor de ?gua livre, propriedades reol?gicas, resist?ncia a compress?o, perda da fase liquida, sedimenta??o dos s?lidos, peso especifico, tempo de espessamento e migra??o de g?s. Os resultados mostram que a pasta formulada atende as especifica??es para utiliza??o em po?os de petrol?feros e que a utiliza??o da vermiculita expandida contribuiu para a absor??o da ?gua livre, tixotropia e baixa densidade. A absor??o da ?gua livre ? comprovada com o resultado de porcentagem zero no ensaio de teor de ?gua livre, a tixotropia ? verificada com o alto valor da for?a gel inicial (Gi) no ensaio de propriedades reol?gicas e a baixa densidade ? comprovada no ensaio de peso especifico

Alguns materiais, constituídos quase que exclusivamente por sílica, são empregados, de forma suplementar ao cimento Portland, por promoverem melhorias ao concreto, devido aos seus efeitos físicos e pozolânicos, além de atenderem a questões ambientais. No entanto, essa sílica pode gerar produtos indesejados na presença de álcalis, sendo este fenômeno conhecido como reação álcali sílica (RAS). Na presença de água, esses produtos são capazes de expandir no interior da massa de concreto, provocando fissuras internas e externas e, em casos mais graves, a degradação do elemento estrutural. Com a finalidade de evitar essa manifestação patológica, o presente trabalho propõe-se avaliar o potencial reativo frente à RAS da sílica ativa e dois tipos de cinzas da casca do arroz (CCA), uma comercial e outra residual. Nessa investigação foram adotados os teores de 5 a 50 %, utilizados como substituição parcial ao cimento Portland padrão. Os métodos de ensaio adotados nesta pesquisa foram o método acelerado em barras de argamassa segundo a NBR 15577 - 4/5, e dois novos métodos acelerados (cubos de pasta e prismas). O métodos acelerado em cubos de pasta avaliou a resistência à compressão, enquanto o método em prismas de pasta avaliou a variação dimensional. Os resultados obtidos em barras de argamassa apontaram que ambas as CCA investigadas, foram reativos frente à RAS. No entanto, o teor de 50 %, em ambas as CCA, se mostrou inócuo para essa reação. A sílica ativa foi considerada inócua em todos os teores avaliados. O aditivo superplastificante empregado não foi eficiente em reduzir a expansão provocada pela CCA. Os ensaios que avaliaram a expansão em prismas de pasta apresentaram uma ótima correlação positiva com o método normalizado em barras de argamassa. Nos prismas de pasta com 25 % de CCA industrial foram identificados os compostos franzinite, chessexite e thaumasite. Estes compostos apresentaram morfologia de acículas ora tortuosas ora delgadas e retilíneas compondo todas as amostras coletadas dessa pasta. A análise termogravimétrica apontou o alto poder adsorvente de água dessa pasta. Em conclusão, o ensaio em prismas de pastas a 48°C com 1,25 % de Na2Oeq demonstrou ser um método prático laboratorialmente e apresentou um grande potencial para avaliar os materiais suplementares ao cimento Portland frente a RAS, além de facilitar identificação dos produtos que provocaram expansão. / Some materials, consisting almost exclusively for silica, are employed, supplementary form to Portland cement, for promoting improvements to concrete, due to their physical and pozzolanic effects and environmental issues. However, this silica may generate unwanted products in presence of alkalis. This phenomenon is known as alkali-silica reaction (ASR). In the presence of water, these products are able to expand inside concrete, generating internal and external cracks and, in severe cases, structural element degradation. In order to prevent this pathologic manifestation, the aim of the present study was to evaluate reactive potential in ASR of fume silica and two types of rice husk ash (RHA), a manufacturing and residual. Levels of 5 to 50 % were used as partial replacement to standard Portland cement. In the present study, accelerated method in mortar bars according to NBR 15577 - 4/5 and two new accelerated methods (pastes cubes and prisms) were used. Accelerated method in paste cubes evaluated compressive strength, while method in paste prims evaluated dimensional change. Results in mortar bars demonstrated, both RHA, were reactive to ASR. However, level of 50 %, both RHA, was innocuous to ASR. Fume silica was innocuous to ASR at all levels evaluated. Superplasticizer additive was not effective to reduce to expansion caused by RHA. In the cubes assay was possible to evaluate the reactive potential to ASR by analysis of variation coefficient. Results demonstrated a positive correlation between expansion in paste prism and standard method in mortar bars. In the paste prism with 25 % of RHA manufacturing were identified compounds of franzinite, chessexite and thaumasite. These compounds presented morphology of needles sometimes tortuous and sometimes thin and straight in all samples. Thermogravimetric analysis showed the high adsorbent power of water in this paste. In conclusion, paste prims assay at 48ºC with Na2Oeq 1.25 % demonstrated to be a practical laboratory method and presented a great potential to evaluate additional material to Portland cement in front of ARS, and this assay facilitates the identifications of products that cause expansion.

This research investigates ways to reduce the carbon dioxide emissions from the cement industry. Cement is one of the largest sources of man-made greenhouse gases, contributing ~5% of the global total. 40% of emissions from cement come from the fuel used in the process, while the electricity used contributes a further 5%. The focus of the research is to find operational changes that can reduce emissions without the need for large capital investment. Three cement plants in the UK were investigated using four different mathematical models based on real data from the plants. A new metric for assessing the environmental impact of the fuel mix of a plant was proposed, and evidence indicates that it may be a better predictor of environmental performance than the metrics currently used in industry. The research found that consistently improving this fuel metric to best-observed levels, as well as reducing the excess air ratio to industry-standard levels had the potential to reduce fuel consumption by up to 7%, and fuel derived CO2 emissions by up to 12%. Increasing use of biomass to best-observed levels had the potential to reduce the net fuel derived CO2 emissions by up to 20%. Comparing the proposed improvements to the historic range of plant performance showed that this level of performance is within the normal operating range of the plants. A reduction of 2-4% in electricity costs and electricity derived emissions was also possible from operational changes. These savings would reduce operating costs as well as emissions, and require little to no capital investment, meaning they could be implemented directly. If successfully implemented in the near future the total savings by 2050 would be on a similar scale to those expected from much more expensive technology changes, such as upgrading to new cement plants, or installing carbon capture and storage technology.

Orientador: Lafayette Nogueira Junior / Banca: Carlos Augusto Pavanelli / Banca: Paulo Sérgio Mutarelli / Resumo: O objetivo deste estudo foi avaliar e comparar a adaptação marginal de restaurações, confeccionadas em dois tipos de sistemas cerâmicos: CEREC inLab (VITA) e IPS Empress 2 (Ivoclar-Vivadent), após a cimentação com cimento resinoso RelyX (3M). Foram preparados 20 pré-molares humanos com cavidade MOD inlay, reproduzidos com silicone de adição, e obtidos modelos em gesso tipo IV, sobre os quais foram confeccionadas as restaurações conforme as recomendações dos fabricantes. Dez inlays no sistema IPS Empress 2 e 10 inlays no sistema CEREC inLab. As restaurações foram cimentadas sob pressão constante de 1,5 Kgf por 10 min, com cimento resinoso, com pré-tratamento. As desadaptações marginais foram avaliadas em MEV, com magnificação de 200x, em 50 pontos eqüidistantes. As médias foram analisadas pelo teste estatístico t(Student) de amostras dependentes.Resultando em uma diferenca estatisticamente significante entre as desadaptaçoes marginais no sistema IPS Empress (93,8'mais ou menos'15,5'mü'm)que se mostraram menores que no sistema CEREC inLab (114,4'mais ou menos'10,6'mü'm). Quando se comparou os valores médios entre as faces proximais (116,51.21,85'mü') e oclusal (112,26'mais ou menos'8,49'mü") do sistema Cerec Inlab, e faces proximais (87,12'mais ou menos'27,98,'mü') e oclusal (100,47'mais ou menos'22,23'mü')do sistema IPS Empress 2, verifica-se que esses valores não diferem estatisticamente. Ainda assim, conclui-se que as médias obtidas são aceitavéis clinicamente. / Abstract: This study has the proposal to evaluate the marginal adaptation of two system all-ceramic class II inlays one of laboratory-made heat-pressed ceramics (IPS Empress 2) and other computer-aided manufacturing ( CEREC inLab) after cementation with resin cement . Extracted human premolars were prepared to receive mesio occluso distal (MOD) ceramic inlays for 10 IPS Empress restorations and 10 CEREC inLab restorations. The impression material used was a polivinilsyloxane addition silicone by the double impression technique. The impressions of prepared teeth were cast in type IV dental stone. The restaurations were made following the manufacturer's recommendations. The inlays were luted on human premolars with resin cement in accordance with the manufacturer's recommended pré-treatment. The marginal gaps were investigated scanning electron microscopy with magnification of 200x. The results were analyzed by t (student) statistic test.The means marginal gap for IPS Empress 2 wal 93,8'mais ou menos'15,5'mü'm significantly smaller than that od 114,4'mais ou menos'10,6'mü'm calculated a the CEREC in Lab system.The gaps of the inlays at the occlusal margin and of the approximal margin showed no significantly differences in two system. It may be concluded that mensuarement value are clinically acceptable. / Mestre

Mining or industrial activity? This is not only an ancient question in Peruvian mining sector but a key issue for domestic and foreign private investment on cement. Since few years ago, cement manufacturing process has been being qualified and regulated by the Peruvian Mining Authority as a mining benefit process which implies the obligation to obtain a benefit mining concession previously. However, upon a review of the technical process aspects, the legal framework in force and a recent judgment enacted by the Constitutional Court of Peru regarding this topic, the position traditionally assumed by the Ministry of Energy and Miningcould be reconsidered. / ¿Es actividad minera o industrial? Ésta no es solo una antigua interrogante en el sector minero peruano sino una cuestión clave para la inversión privada local y extranjera del rubro cementero. Desde hace algunos años, la producción de cemento ha venido siendo calificada y regulada por la autoridad minera como beneficio minero, lo cual importa la obligación del titular de obtener previamente a la ejecución de la misma una concesión de beneficio. Sin embargo, a partir de una revisión de los aspectos técnicos del proceso, el marco normativo vigente y un reciente pronunciamiento del Tribunal Constitucional en relación a este tema, la tradicional posición adoptada por el Ministerio de Energía y Minas podría ser repensada.

Concrete, the major construction material used in the civil industry worldwide, displays remarkable performance and economic benefits. Yet, it also presents a huge environmental impact producing about 7% of the global carbon dioxide (CO2). Given the rise of global warming concerns, studies have been focusing on alternatives to reduce the amount of Portland cement (PC), which is the least sustainable ingredient of the mixture, for example by adopting particle packing model (PPM) techniques. Although a promising alternative, there is currently a lack of studies regarding the efficiently use of PPMs to reduce PC without compromising the fresh and hardened properties of the material. This work appraises the influence of PPMs and advanced mix-design techniques on the fresh (rheological behaviour) and hardened (compressive strength, modulus of elasticity, porosity, and permeability) state behaviours of systems with reduced amount of PC, the so-called low cement content (LCC) concrete. Results show that is possible to produce eco-efficient concrete maintaining and/or enhancing fresh and hardened properties of the material. Nevertheless, further durability and long-term behaviour must be performed on LCC systems.

A reação química que ocorre entre os hidróxidos alcalinos presentes nos poros do concreto e alguns minerais constituintes dos agregados tem causado sérios danos às estruturas. Até o presente momento a prevenção é a melhor forma de evitar que a reação se desencadeie, uma vez que as soluções remediativas ainda necessitam de estudos mais aprofundados para serem implementadas. Neste sentido, a utilização de adições pozolânicas no concreto tem se mostrado uma alternativa eficaz, sendo que a forma mais fácil de empregá-las é através do uso de cimentos compostos com adições. Porém, são poucos os estudos encontrados avaliando a capacidade desses cimentos na prevenção da reação. No Brasil, além dessa lacuna de conhecimento, faltam informações sobre a reatividade dos agregados utilizados no concreto. Então, o presente estudo avaliou a reatividade dos agregados mais utilizados para confecção de concreto nos estados do Paraná, Santa Catarina e Rio Grande do Sul frente à utilização de quatro tipos de cimento: CP V-ARI, CP V-ARI RS, CP IV e CP II-Z. Os métodos utilizados para essa avaliação foram a análise petrográfica, o ensaio acelerado das barras de argamassa, a microscopia eletrônica de varredura e a espectometria por dispersão de energia. Os resultados da análise petrográfica mostraram que todos os 40 agregados coletados possuem minerais reativos. As expansões medidas no ensaio acelerado acabaram por confirmar a potencialidade reativa desses minerais, pois todas as amostras moldadas com o CP V-ARI, o CP V-ARI RS e o CP II-Z foram classificadas como reativas ou potencialmente reativas, isto é, somente o CP IV foi eficaz para inibir as expansões deletérias. Por outro lado, as análises microscópicas mostraram que mesmo nos prismas menos expansivos houve a formação do gel sílico-alcalino, porém este ficou incluso nos poros da argamassa. Outra conclusão percebida foi a de que as maiores expansões ocorreram com os agregados de origem ígnea vulcânica, principalmente com os basaltos, que além de serem constituídos por minerais muito finos, apresentam em sua matriz mesóstases silicosas amorfas, também conhecidas como vidro vulcânico. / The chemical reaction that occurs between alkali hydroxides contained in concrete pores and some minerals contained in aggregates has been causing serious hazards to concrete structures. So far, prevention is the best way to avoid the occurrence of this reaction, once the solutions to repair the damage still need deeper researches to be implemented. Therefore, the use of Portland cements containing pozzolanic admixtures to produce has been an effective alternative. But there are few researches on the capability of those prevent reaction to occur. In Brazil, besides the lack of knowledge, there is little information about the reactivity of the aggregates applied in concrete production. So this research aimed to evaluate the reactivity of the most used aggregate to produce concrete in the states of Parana, Santa Catarina, and Rio Grande do Sul by testing four different types of cements as described: CP V-ARI, CP V-ARI RS, CP IV and CP II-Z. The methods applied to carry out this evaluation were the petrography analysis, the accelerated mortar bar test, scanning electron microscopy, and the dispersive energy spectrometry. The results obtained showed that all the forty aggregate samples collected have reactive minerals in their composition. The measured expansions during the accelerated test confirmed the reactive potentiality of these minerals, because all samples obtained from the CP V-ARI, CP V-ARI RS, and CP IV were classified as being reactive or potentially reactive, which means that CP IV was the only one capable of inhibit the hazardous expansion. On the other hand, the microscopic analyses showed, even in the less expansive prisms, that the formation of silica-alkaline gel has occurred, but this gel has remained in the pores of the mortar. Another conclusion of this research was that larger expansions occurred with the aggregates from volcanic igneous origin, especially basalts that, besides contained very fine minerals, presented in its matrix amorphous silica, also known as volcanic glass.