O presente trabalho contempla um estudo experimental de análise do comportamento de concretos projetados por via seca, através de ensaios indicadores dos principais parâmetros de durabilidade, constantes de especificações nacionais e internacionais. A pesquisa envolve a avaliação comparativa entre quatro tipos de cimento especialmente formulados para uso em concreto projetado, em relação a outros dois tipos de cimento tradicionalmente empregados na composição de misturas projetáveis, no que se refere ao atendimento aos requisitos relativos à durabilidade, normalmente especificados para o material. Os concretos projetados, elaborados com consumos de cimento de 300 kg/m³, 350 kg/m³, 400 kg/m³ e 450kg/m³ foram inicialmente caracterizados, no estado fresco, com base em ensaios de consistência e depois produzidas amostras, em condições similares às de obra e estas submetidas aos ensaios balizadores de parâmetros de durabilidade adotados neste estudo, a saber: Absorção por Imersão e Fervura, Índice de Vazios, Massa Específica Real; Absorção de Água por Capilaridade; Migração de Íons Cloreto; Resistividade Elétrica; Penetração de Água sob Pressão e Carbonatação Acelerada. Como alguns dos ensaios supracitados não são destrutivos, foi possível aproveitar corpos-de-prova, que foram depois submetidos a ensaios de resistência à compressão axial e à tração através da compressão diametral, que também contribuíram para caracterização do material. De um modo geral, os resultados foram satisfatórios e atenderam às especificações vigentes. Contudo, os concretos elaborados com cimentos especiais, formulados com granulometria mais fina e adição de metacaulim, apresentaram indicadores de durabilidade consideravelmente superiores aos dos concretos elaborados com cimentos convencionais ou mesmo cimentos especiais formulados com aditivos, inclusive para consumos relativamente baixos. Apesar de não ter sido o foco principal deste trabalho, vale ressaltar os surpreendentes resultados dos ensaios de resistência mecânica, obtidos para os concretos elaborados com cimentos especiais formulados com granulometria mais fina e adição de metacaulim, que atingiram valores de resistência à compressão nunca antes observados, fato que pode tornar o material bastante promissor. / The present work involves an experimental study with dry-mix shotcrete aiming at the behavior analysis, through indicative testing of the main durability parameters of national and international specifications. The research involves the use of four cement types especially formulated for use in shotcrete use in comparison with two other cements that are traditionally used in mix production for shotcrete spraying. The shotcrete mixtures were elaborated with cement consumptions of 300 kg/m³, 350 kg/m³, 400 kg/m³ and 450kg/m³. They were characterized initially, in the fresh state, in terms of stiffness tests, and later, cores were extracted to produce samples, in similar conditions and submitted to ordinary durability tests: Water Absorption, Volume of Voids, Specific Weight; Water Absorption by Capillarity; Chloride Migration; Electric Resistivity; Water Penetration under Pressure and Accelerated Carbonatation. As some of the tests are not destructive, some of the samples was used for compressive and tensile (Brazilian Test) strength determination, what also contributed to additional characterization of the material. In general, the results were very satisfactory and they fit to the specifications requirements. However, the shotcretes elaborated with special cements, formulated with finer gradation and metakaolin addition, presented a much better behavior in terms of durability indicators comparing to the shotcretes produced with conventional cements and cements formulated with accelerators, even when, relatively low consumption of cement was used. Despite not being the main focus of this work, it is worth mentioning the surprising results of the testing of mechanical resistance, obtained for the shotcretes elaborated with special cements formulated with finer gradation and metakaolin addition, which reached resistance values to the compression never observed, making it a promising material.

Este trabalho visa estudar o emprego da escória de aciaria a oxigênio (EACN) na construção civil. Para isso, elaborou-se um programa experimental em seis etapas: a primeira compreendeu a caracterização da EACN, do cimento, do clínquer e do gesso; na segunda, a EACN foi cominuída até valores de tamanho de partículas inferiores a 0,075mm; em seguida, caracterizada física, ambiental, química, mineralógica, microestrutural e termicamente, e teve a sua atividade pozolânica determinada; a terceira compreendeu a ativação da escória com hidróxido de sódio; na quarta, foram realizados ensaios de pega expansibilidade, resistência axial à compressão e durabilidade de argamassas de cimento CP V-ARI com substituição parcial do cimento por EACN; na quinta, obteve-se uma primeira escória de aciaria modificada (EACM1) mediante o processo pirometalúrgico da EACN em forma de pó, para alterar a composição química e estrutura para amorfa, tornando-a mais reativa, sendo submetida aos mesmos ensaios da quarta etapa, à exceção dos ensaios de pega e expansibilidade; na sexta e última, obteve-se uma segunda escória modificada (EACM2) pirometalurgicamente: a composição química próxima da escória de altoforno e amorfa. A carga desse processo pirometalúrgico foi calculada pelo software Factsage. Parte dessa escória modificada foi cominuída adicionalmente, de modo que foram obtidas amostras sem moagem adicional (EACM2a) e com moagem adicional (EACM2b). A escória modificada foi submetida aos ensaios da quinta etapa, mais o grau de vitrificação e a reatividade por microscopia de luz transmitida. Os resultados obtidos mostraram que argamassas em que parte do cimento CP V-ARI é substituída por escórias de aciaria (naturais ou modificadas) atendem às especificações de resistência à compressão nos seguintes casos: escória natural e modificada 1: substituição de até 10% do cimento CP V-ARI; escória modificada 2a, substituição de até 20% de cimento; escória modificada 2b, substituição de até 40% do cimento. Observou-se que a escória modificada 2b apresentou resistência à compressão superior ao traço referência nas idades de 28 dias e 91 dias. Apresenta-se ainda a utilização da EACM2b com o clínquer. Outros ensaios e comparações são apresentados para discutir o comportamento observado das escórias em estudo. / This study aims at employing BOF steel slag (EACN) in civil construction. Thus, the study developed an experimental program in six stages: the first one comprised the characterization of BOF steel slag, cement, clinker and gypsum; in the second stage BOF steel slag was reduced to particles sized less than 0.075mm; then, it was physical, environmental, chemical, mineralogical, microstructural and thermally characterized, it also had its pozzolanic activity determined; the third stage comprised the activation of BOF steel slag with sodium hydroxide; during the fourth stage, we carried out setting time, expansibility, axial compressive strength and durability tests for mortars made with cement CP V-ARI and partial substitution with BOF steel slag; in the fifth stage, we obtained the first modified BOF steel slag (EACM1) through pyrometallurgical process of powdered BOF steel slag so as to alter its chemical and structural makeup, making it more reactive to be submitted to the same tests of the fourth stage, except the setting time and expansibility tests; in the sixth and final stage, we obtained the second pyrometallurgically modified BOF steel slag: chemical makeup close to blastfurnace slag. The load of this pyrometallurgical process was calculated using software Factsage. Part of this modified slag was ground additionally, so that samples without additional grinding (EACM2a) and with additional grinding (EACM2b) were obtained. The modified slag underwent the fifth-stage tests, and the degree of vitrification and transmitted light microscopy reactivity. The results obtained show that mortars in which part of CP V-ARI cement was replaced with BOF steel slag (natural or modified) meet the compressive strength specifications in the following cases: Natural and modified slag 1: substitution of up to 10% of CP V-ARI cement; Modified slag 2a, substitution of up to 20% cement; Modified slag 2b, substitution of up to 40% cement. We observed that modified slag 2b showed higher compressive strength than the reference mix at ages 28 and 91 days. We also present the use of EACM2b as clinker. Other tests and comparisons are presented so as to discuss the observed behaviors of the study slags.

A força de adesão entre resinas e ligas de metais básicos resulta do embricamento mecânico entre a superfície do metal e a resina e da interação química entre óxidos presentes na superfície dos metais e monômeros adesivos das resinas compostas. A literatura, entretanto, mostra que ainda persistem algumas dúvidas sobre a interação entre os diversos tipos de sistemas adesivos e metais básicos, por isso, essa pesquisa visa: verificar se a presença do Be na composição de ligas a base de Ni-Cr influencia a união metal básico/resina; comparar dois cimentos resinosos adesivos nessa função e verificar a influência da utilização de condicionadores (primers) adesivos metálicos para ligas nobres sobre essa união. Após 2500 termociclos, foram realizados testes de resistência à tração em 160 corpos-de-prova, que consistiam de dois discos de Ni-Cr-Be (Verabond – Aalba Dental Inc., Cordelia, CA-USA) com 6 mm de diâmetro e 2 mm de espessura cimentados entre si, e dois discos de Ni-Cr (Durabond - Odonto Comercial Importadora Ltda, São Paulo, SP), com as mesmas dimensões, cimentados entre si. Foram utilizadas diferentes marcas comerciais de sistemas adesivos: os cimentos resinosos adesivos, Panavia F (Kuraray Co. Ltd.), Bistite II DC (Tokuyama Corp.) e os agente de união (primers adesivos metálicos), Alloy Primer (Kuraray Co. Ltd. ), Metaltite (Tokuyama Corp.) e Cesead Opaque Primer (Kuraray Co. Ltd.). Discos cimentados sem primers serviram como grupo controle. Os resultados mostraram que houve diferença estatisticamente significante entre as duas ligas (Ni-Cr-Be –24,82 ± 7,6 MPa e Ni-Cr - 22,32 ± 7,9 MPa). Já para os cimentos houve superioridade adesiva do cimento Panavia F, que obteve média de resitência adesiva de 27,49 ± 4,8 MPa, sobre o cimento Bistite II, que obteve média de resistência adesiva de 19,63 ± 8,4 MPa. Os primers utilizados não apresentaram influência positiva sobre o Panavia F já que os grupos sem primer para esse cimento obtiveram média de 28,18 ± 5,6 MPa que é equivalente a média dos outros grupos com Panavia. Entretanto, para o cimento Bistite II DC os primers Alloy Primer e Metaltite obtiveram as menores médias, 12,7 ± 7,6 MPa e 15,71 ± 4,8 MPa respectivamente, enquanto sem primer, ou com o Cesead Opaque Primer, as médias foram significantemente superiores, 24.47 ± 6 MPa e 25.70 ± 6,8 Mpa respectivamente. Diante dos resultados conclui-se que os primers adesivos metálicos não potencializaram a adesão de cimentos resinosos adesivos sobre ligas de Ni-Cr. / The bond strength for resin and basic metals comes from the interaction between oxides in the metal surface and adhesive monomers in the composite resins composition. The literature shows that still are some questions about this interaction so this research intends to: verify if the presence of Be at Ni-Cr alloy plays some influence for this union, compare two resin luting cements at this function and study the influence the use of metal primers for noble metals in this mecanism of adhesion. After 2500 thermocycles, tensile bond strength tests were loaded at 160 specimens, which consisted of two metals discs with 6 mm in diameter and 2 mm thick from a Ni-Cr-Be alloy (Verabond – Aalba Dental Inc., Cordelia, CA-USA) bonded togheter and two metal discs from a Ni-Cr alloy (Durabond - Odonto Comercial Importadora Ltda, São Paulo, SP) bonded togheter. Diferent brand adhesive systems were used: the resin cements, Panavia F (Kuraray Co. Ltd.) and Bistite II DC (Tokuyama Corp.) and the metal primers, Alloy Primer (Kuraray Co. Ltd.), Metaltite (Tokuyama Corp.) and Cesead Opaque Primer (Kuraray Co. Ltd.). Nonprimed specimens served as control group. The results indicated that there is statiscal diferences beetwen the two alloys (Ni-Cr-Be –24,82 ± 7,6 MPa e Ni-Cr - 22,32 ± 7,9 MPa). Panavia F had founded greater bond strength (27,49 ± 4,8 MPa) than Bistite DC (19,63 ± 8,4 MPa). The metal primers did not show any positive influence for the Panavia bond strength when we considere that the no primer group had 28,18 ± 5,6 MPa bond strength media which were equivalente to the others Panavia´s groups. However for the Bistite cement, the bond strength for Alloy primer and Metaltite were the lower medias, 12,7 ± 7,6 MPa and 15,71 ± 4,8 MPa respectivally, while the no primer or the Cesead Opaque Primer groups showed superior medias 24,47 ± 6 MPa and 25,70 ± 6,8 MPa respectivally. The outcome of this research shows that the metal primers used did not incresead the bond strength between resin cements and Ni-Cr alloys.

No presente trabalho foram comparadas as aderências e propriedades de cinco tipos de argamassas colantes para fixar ladrilhos de \"granitos e mármore\" em pisos e revestimentos de edificações. Uma das argamassas é industrializada e específica para granitos e mármores, outra preparada em laboratório para fixação de porcelanatos e mais três argamassas também desenvolvidas em laboratório, tendo como base a argamassa para porcelanato. Para a realização do ensaio de aderência foram escolhidos oito tipos diferentes de granitos e um mármore de grande aceitação comercial. Os resultados evidenciaram a excelente qualidade das argamassas colantes desenvolvidas em laboratório as quais superaram a industrializada. Verificou-se também que a aderência de todas as argamassas está relacionada à rugosidade das placas e às características mineralógicas dos \"granitos\". / In this paper, the adherence of five types of adhesive mortars used for fixing granite and marble tiles in floors and linings of buildings were compared. One of the mortars is industrialized and specific for granites and marbles, another one, is prepared in the laboratory for setting porcelains, and three other types of mortars, also developed in the laboratory, having the porcelain mortar as a base (were used). To carry out the adherence test, eight types of granites and one marble of large commercial acceptance were selected. The results of the tests showed the excellent quality of the adhesive mortars developed in the laboratory, which were considered superior than the industrialized type. Likewise, it was noted that the adherence of all types of mortars is related to the roughness of the plates and to the mineralogical characteristics of the granites.

Pressure is mounting in the construction industry to adopt more environmentally sustainable methods to reduce CO2 emissions. Portland cement (PC) often constitutes to more than two-thirds of the embodied energy of concrete, and its production generates 5% of global greenhouse gas emissions. One efficient strategy to reduce the cement content without sacrificing performance is the use of particle packing models (PPM) to mix- proportion concrete mixtures with low cement content, the so-called low cement content (LCC) concrete. If on the one hand LCC was seen to be an effective sustainable alternative to the construction industry, its mechanical behaviour, durability and long-term performance are still under debate and thus further research is needed in the area. In this project, continuous PPM theories were used to mix- design structural concrete mixes presenting distinct mechanical properties (i.e. 25 & 35 MPa) and cement contents. Their performance was evaluated in the fresh and hardened states, and gaps, recommendations, and further needs were highlighted. Results show that the use of PPM enables the development of LCC systems, showing impressive hardened state performance (i.e. higher compressive strength and modulus of elasticity and lower electrical resistivity) and low carbon footprint. However, challenges in the fresh state were faced, which may be potentially solved with the use of chemical admixtures, fillers and/or supplementary cementing materials (SCMs).

La bauxite est un minerai utilisé pour l’élaboration de l’aluminium ou en tant que matière première pour les ciments techniques. Elle est employée, sous sa forme naturelle, en blocs. Ces blocs se font de nos jours de plus en plus rares et leur manutention peut entraîner des pertes sous formes de poussières non valorisées. L’objectif de ce projet est de recycler ces fines particules minérales sous forme de compactés afin d’améliorer l’usage des ressources naturelles minérales qui se raréfient. Ces compactés sont obtenus par compression directe puis avec un procédé innovant couplant vibration et compression. La poudre de bauxite est mélangée à du ciment et de l’eau, puis subit une phase de compaction. Ces compactés doivent avoir des propriétés spécifiques en termes de masse volumique, porosité et résistance mécanique. La micro-tomographie à rayons X est utilisée pour décrire le réarrangement granulaire et l’homogénéité 3D des porosités. La distribution poreuse est caractérisée par analyse d’image et comparée avec les résultats de porosimétrie mercure. Cette étude concernant l’évolution des paramètres texturaux des compactés amène une compréhension des phénomènes liés à la phase de compression. Le stockage et la maturation de ces compactés sous température et humidité contrôlées ont également été étudiés. L’optimisation des paramètres de compression et de formulation, comme la quantité d’eau ou de ciment dans le mélange et la pression de compression, a mené à l’amélioration des propriétés des compactés. Dans un second temps, la phase de compression et les propriétés des compactés ont été améliorées en utilisant une phase préliminaire de vibrations. Cette phase a été optimisée grâce à l’étude de plusieurs paramètres spécifiques comme le type, l’amplitude et la fréquence des vibrations. / The bauxite is used in aluminium elaboration or directly as a raw material for calcium aluminates in technical cements. It is used, as a raw material, as blocks. Recently bauxite blocks are rarer and rarer and their handling can lead to dust wastes that are not re-used. The objective of this project is to recycle the fine mineral particles in compacts to improve the use of natural mineral resources that are running out. These products are compacted by direct compaction and also with an innovative vibration and compaction process. The bauxite is mixed with cement and water, and then the mixture is compacted. They must have specific properties with higher density and mechanical resistance. X-Rays micro-tomography is used to describe the particle rearrangement and the 3D density homogeneity. The porous distribution is then characterized by image analysis and compared with the mercury intrusion porosimetry results. This study on textural parameters evolution of the compacts leads to improve an understanding about the phenomenon during the compaction stage. The storage with controlled temperature and humidity will also be studied. The optimization of the compression and mixture parameters, as amount of water or cement in the mixture and compression pressure, led us to get compacts with improved properties. In the final study, we improved the compression stage and the compacts properties by another stage using in-situ vibrations. The vibrations stage has been optimized studying several vibrational parameters especially the type, the duration, the amplitude and the frequency of the vibrations.

Issues concerning mechanisms of durability of hydrated cement phases in aggressive environments were studied. The possibility of using organic compounds in order to modify the micro- and nanostructure of the calcium-silicate-hydrate (C-S-H) phases was also investigated. Pure cement-based hydrated phases were synthesized and characterized by several analytical techniques such as X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. Compacted samples of the synthetic hydrated cement phases were also prepared and used for the assessment of durability and mechanical properties. This doctoral thesis is comprised of several research chapters which can be categorized into two main parts. The first part focuses on the development of novel organically modified C-S-H systems. The second part involves the mechanisms underlying the volume stability of phase pure sulfoaluminate and related phases. A brief description of each part is as follows: - development of novel organically modified C-S-H systems: The mechanisms of interaction of organic compounds with the nanostructure of C-S-H systems were studied. A model for the nanostructure of the resulting composite systems was proposed. In addition, the organically modified systems were tested for length-change, calcium-ion leaching and diffusion of isopropanol. Dynamic mechanical analysis and microindentation techniques were also used to determine the mechanical performance. Evidence of the superior engineering performance of the novel organically modified C S-H systems was provided. - mechanisms of the volume stability of sulfoaluminate and related phases: Volume stability and change in the microstructure of the synthetic ettringite, monosulfate and thaumasite was critically examined in de-ionized water as well as in highly concentrated gypsum- or lime-water. A new dissolution-based mechanism for the expansion of these phases was proposed. The volume stability of multicomponent systems comprised of the C-S-H-based system (prepared in part I) and these sulfate-based hydrated phases was also investigated. It was suggested that the systems containing the modified C-S-H rather than the phase pure C-S-H had better resistance to crack growth and disintegration originating from the presence of ettringite or thaumasite.

Batch experiments have been used to assess the sorption properties of a potential repository backfill, NRVB (Nirex Reference Vault Backfill). In this study, UO22+, Eu3+, Am3+ and Th4+ have been used as model radionuclides and ethylenediaminetetraacetic acid (EDTA), isosaccharinic acid (ISA) and humic acid (HA) as competing ligands. The NRVB is an effective scavenger of all radionuclides, with the majority sorbed within minutes. Ultrafiltration showed that for solutions of U in contact with NRVB, for the small amount of U remaining in solution, nearly all (79 %) was present as clusters or colloidal material in a very narrow and relatively small size range (0.9 – 1.4 nm); for Eu (> 94 %) is attached to large NRVB derived colloids or particulates; for Th (82 %) is present in the true solution; whilst for Am 58 % is in the true solution. High concentrations of EDTA (>0.01 M) were able to reduce the extent of sorption at apparent equilibrium for all metal ions. ISA was very effective as a competing ligand for all metal ions, generally at a lower concentration than EDTA in equivalent systems. Humic acid was found to be ineffective as a competing ligand at any realistic concentration. In all systems, there was evidence of significant irreversibility, with concentrations of EDTA and ISA that were able to prevent sorption unable to remove radionuclides from contaminated NRVB. For the uranyl systems, luminescence spectroscopy was used to analyse the mechanism of sorption. For CSH (calcium silicate hydrate), the spectra were consistent with surface complexation, followed by some degree of incorporation. For NRVB, the spectrum was dominated by a feature that was similar to uranyl sorbed to CSH as a surface complex and/or incorporated into the structure. There was also a minor component that was assigned as a calcium uranate like surface precipitate. The sorption data were fitted with a simple surface complexation model, which had a single surface binding site. The modelling showed that the uptake of all radionuclides is consistent with surface complexation or surface precipitation. The model was less effective at predicting the effects of the competing ligands on sorption. Thermodynamic speciation and surface complexation modelling were able to explain the behaviour in the systems qualitatively, but cannot be used to predict sorption absolutely.

The effects of initial particle moisture content, wood-cement ratio and density on physical (thickness swelling and water absorption) and mechanical properties (MOE, MOR, IB and edgewise compression) were investigated. Five initial particle moisture content levels - 0-6%, 8-15%, 25-30%, 40-50% and 60-80%; three wood-cement ratios - 1:1, 1:1.5 and 1:2; and three density levels at each wood-cement ratio - 1:1 -0.472 g/cm³, 0.528 g/cm³ and 0.622 g/cm³, 1:1.5 - 0.636 g/cm³, 0.707 g/cm³ and 0.809 g/cm³; and 1:2 - 0.763 g/cm³, 0.847 g/cm³ and 0.939 g/cm³ were used. Combinations of the above variables gave 45 treatments. Three replicate boards were made for each treatment thus giving a total of 135 panels for the study. A total of 135 test specimens were used for each property tested. Results from the tests were compared to the German and ISO Standards for similar boards and to the Canadian Waferboard Standard. Initial particle moisture content was highly significant in the development of physical and mechanical properties of magnesite cement-bonded particleboard. Increasing initial particle moisture content from 0-6% to 60-80% resulted in the reduction of the physical and mechanical properties of the boards. The highest initial particle moisture content of (60-80%) yielded the lowest physical and mechanical properties. For manufacture of boards of favourable mechanical properties, an initial particle moisture content of not more than 15% is recommended. On the other hand, a higher initial particle moisture content (>40%) is considered desirable if board thickness and water absorption are to be minimized. All the mechanical properties tested consistently increased by increasing wood-cement ratio and density and were highest at 1:2 wood-cement ratio and density level 3 of each wood-cement ratio. Thickness swelling and water absorption were consistently reduced by increasing wood-cement ratio and density. In both physical properties tests, the 1:2 wood-cement ratio and density level 3 yielded the lowest values. Thirty-two of the forty-five treatment combinations of initial particle moisture content, density and wood-cement ratio pass the MOE requirement of the German Standard DIN 52 362 for Portland cement-bonded particleboard; forty-one treatments met the minimum MOE Canadian Waferboard Standard requirements, while no treatment meet the MOR requirements for this Standard. Eleven of the forty-five treatments met the minimum IB Canadian Waferboard Standard requirements. All the 45 treatments pass the ISO building board requirements in thickness swelling, while 18 treatments pass the water absorption requirements for this Standard. Most of the treatment combinations compare favourably with results obtained in tests conducted in Europe for cement-bonded particleboard. / Forestry, Faculty of / Graduate

This research includes the potential for resistance and the expansion that the soil presents, this evaluation was carried out through CBR tests. The soil cement technique was used to improve the physical and mechanical characteristics; this process consists in mixing the material with Portland cement type I. That combination forms soil cement 10%, 15% y 20%, which present an increase of the CBR (max: 138.7% and min: 91.9%) achieving a type of extraordinary subgrade to resist the structure of the pavement and a reduction of 7.18% in the expansion of the samples.