O objetivo deste estudo foi avaliar se o novo material nanoparticulado Carbômero de Vidro pode aumentar a taxa de sobrevida de restaurações ART ocluso-proximais quando comparado com um material resinoso modificado por poliácido - Compômero e o Cimento Ionômero de Vidro de alta viscosidade. Um total de 286 crianças de 5 a 7 anos apresentando ao menos uma lesão de cárie ocluso-proximal foram selecionadas no município de Barueri, SP. Os pacientes foram distribuídos aleatoriamente em três grupos: CIV de alta viscosidade (CIV - Fuji IX Extra - GC Corp), Compômero (COM - Dyract Extra - Dentsply) e Carbômero de Vidro (CAR - Glass Carbomer - GCP Dental). Todos os tratamentos foram feitos seguindo os preceitos do ART e as recomendações dos fabricantes. As restaurações foram avaliadas após 2, 6 e 12 meses por um examinador treinado. Para verificação da sobrevida das restaurações foi utilizada a análise de sobrevida de Kaplan-Meier e teste log-rank. Para avaliar a associação entre o desfecho e as variáveis características do paciente foi aplicado o teste de Regressão de Cox. O nível de significância para os testes foi considerado 5%. Após 12 meses de acompanhamento, a sobrevida geral das restaurações foi de 52,8%. A taxa de sobrevida do CIV, COM e CAR foram de 62,6%, 61,3% e 36,3%, respectivamente. A análise estatística mostrou diferença significante entre os materiais, onde o CAR apresentou pior desempenho (HR=1,84; IC 1,19-2,85; p=0,006) e nenhuma diferença foi encontrada entre os materiais CIV e COM. Além disso, foram encontradas diferenças estatísticas para a variável volume da cavidade, onde cavidades menores apresentaram maiores chances de insucesso (p<0,03). Podemos concluir que o novo material Carbômero de Vidro não é adequado para o uso em restaurações ART proximais de molares decíduos em comparação com CIV de alta viscosidade e o Compômero. / The aim of this study was to evaluate if the new nanoparticulate material, the glass carbomer can increase the survival rate of occlusal-proximal-ART restorations compared with compomer - a polyacid resin modified material and a high viscosity glass ionomer cement (GIC). A total of 286 children aged 5 to 7 years presenting at least one occlusal-proximal carious lesion were selected in the city of Barueri, SP. Patients were randomized into three groups: high viscosity GIC (GIC - Fuji IX Extra - GC Corp), Compomer (COM - Dyract Extra - Dentsply) and Glass Carbomer (CAR - Glass Carbomer - GCP Dental). All treatments were made following the precepts of ART and manufacturers\' recommendations. The restorations were evaluated after 2, 6 and 12 months by a trained examiner. To verify the survival of the restorations was used Kaplan-Meier survival analysis and log-rank test. To evaluate the association between the outcome and patient variables was applied Cox regression test. The significance level for the tests was 5%. After 12 months of follow-up, overall survival rate of the restorations was 52.8%. The GIC, COM and CAR survival rate were 62.6%, 61.3% and 36.3%, respectively. Statistical analysis showed significant differences between the materials, where the CAR had a worse performance (HR = 1.84, CI 1.19 to 2.85; p = 0.006) and no difference was found between the CIV and COM materials. Moreover, statistical differences were found for the variable volume of the cavity, where smaller cavities had higher chances of failure (p <0.03). We conclude that the new glass carbomer material is not suitable for use in ART occlusal-proximal restorations in primary molars compared to high viscosity GIC and the compomer.

O presente estudo mostra que o conceito de materiais com gradação funcional (MGF) pode ser aplicado no desenvolvimento de componentes de fibrocimento mais econômicos e com desempenho mecânico melhorado. Primeiramente, este trabalho estabelece o conceito de fibrocimento com gradação funcional. Depois, modelam-se, em elementos finitos, as tensões em telhas onduladas sob flexão estática e cargas de vento e mostra-se que, para esses tipos de carregamento, regiões específicas das telhas são submetidas a tensões de baixa intensidade justificando a aplicação do conceito de MGF para a otimização da distribuição da resistência em tais componentes. A parte experimental deste trabalho é constituída de quatro estudos: a) produção de fibrocimentos com o teor de fibras variando ao longo da espessura; b) desenvolvimento de um método de escolha de formulações para fibrocimentos com gradação funcional; c) desenvolvimento de compósitos cimentícios para extrusão em altas velocidades, destinados a gradação de fibrocimentos; e d) aplicação pré-industrial para avaliar a aplicabilidade de técnica de modificação local das propriedades de telhas com gradação funcional. Mostra-se, experimentalmente, que fibrocimentos contendo 1,0% de fibras de PVA, em massa, estrategicamente distribuídas ao longo da espessura, apresentam módulo de ruptura (MOR) similar ao dos fibrocimentos homogêneos com 1,8% de fibras, comprovando a eficácia deste tipo de gradação na redução do custo de placas de fibrocimento. O segundo trabalho experimental avalia formulações de fibrocimento constituídas de seis matérias-primas empregando-se a estratégia screening, uma metodologia promissora para gerar regras de mistura, otimizar custos e desempenho e facilitar a escolha de formulações locais para fibrocimentos com gradação funcional. Compósitos cimentícios com fibras de PVA ou vidro álcali resistente (AR), destinadas à extrusão em altas velocidades, foram desenvolvidos para aplicação pré-industrial. Aqueles contendo 4,0% de fibra de vidro, em volume, apresentaram resistência à tração média igual a 12,0 MPa, enquanto compósitos com 3,0% de fibras de PVA apresentaram resistência igual a 7,5 MPa. A aplicação destas misturas entre as camadas de telhas onduladas de fibrocimento, durante o experimento pré-industrial, resultou em melhoras substanciais do desempenho local. / The present study applies the functionally graded materials (FGM) concept on the development of fiber cements as an alternative to improve the mechanical performance and reduce cost of production of asbestos-free corrugated sheets. Primarily, this work establishes the concept of functionally graded fiber cement. Then, finite element modeling (FEM) is applied in the evaluation of the stresses distributions in corrugated sheets under bending and static wind loads. The simulations show that for these load cases, some regions of corrugated sheets are submitted to low stress intensities what justify the application of FGM concept for optimization of the strength distribution in such components. The experimental part of this work consists of four different studies: a) production of functionally graded fiber cements with gradation through thickness; b) development of a method for choosing formulations in functionally graded fiber cements; c) development of fiber reinforced cementitious composites for high speed extrusion and; d) pre-industrial application to evaluate the suitability of functionally graded fiber cements production. The first experimental study shows that functionally graded cementitious composites with 1.0% of PVA fibers, in mass, strategically distributed through thickness, presented similar modulus of ruptures (MORs) to that homogeneous ones with 1.8% of PVA fibers what proves that gradation of fiber content through thickness is a good approach to reduce cost of fiber cement pads without affecting the mechanical performance of the composite. The second experimental work examines sixcomponent fiber cement formulations employing the screening strategy which is a promising methodology to generate coherent mixture rules, optimize cost and performance and even facilitate the choosing of formulations for functionally graded fiber cements. PVA fibers and glass fiber reinforced cementitious composites for high speed extrusion were developed forpre-industrial application. Composites with 4.0% of alkali-resistant (AR) glass fiber, in volume, presented average tensile strength of 12.0 MPa while composites with 3.0% of PVA fibers presented 7.5 MPa. The application of these mixtures between layers of fiber cement corrugated sheets results in improvement of the performance of the product.

Secondary energy products are used in the construction industry for a long time. More strict environmental limits for emissions to air have created new technologies combustion of materials in thermal power plants. In this way combustion are produced a new secondary energy products. It is an attempt to find of suitable use for these products. Their use will have ecological impact on the environment and it will allow prepare of new compositions of higher utility properties. The aim of this study was to develop a new mixture, using the new secondary energy products, for production concrete with high utility properties.

O objetivo deste estudo foi avaliar se o novo material nanoparticulado Carbômero de Vidro pode aumentar a taxa de sobrevida de restaurações ART ocluso-proximais quando comparado com um material resinoso modificado por poliácido - Compômero e o Cimento Ionômero de Vidro de alta viscosidade. Um total de 286 crianças de 5 a 7 anos apresentando ao menos uma lesão de cárie ocluso-proximal foram selecionadas no município de Barueri, SP. Os pacientes foram distribuídos aleatoriamente em três grupos: CIV de alta viscosidade (CIV - Fuji IX Extra - GC Corp), Compômero (COM - Dyract Extra - Dentsply) e Carbômero de Vidro (CAR - Glass Carbomer - GCP Dental). Todos os tratamentos foram feitos seguindo os preceitos do ART e as recomendações dos fabricantes. As restaurações foram avaliadas após 2, 6 e 12 meses por um examinador treinado. Para verificação da sobrevida das restaurações foi utilizada a análise de sobrevida de Kaplan-Meier e teste log-rank. Para avaliar a associação entre o desfecho e as variáveis características do paciente foi aplicado o teste de Regressão de Cox. O nível de significância para os testes foi considerado 5%. Após 12 meses de acompanhamento, a sobrevida geral das restaurações foi de 52,8%. A taxa de sobrevida do CIV, COM e CAR foram de 62,6%, 61,3% e 36,3%, respectivamente. A análise estatística mostrou diferença significante entre os materiais, onde o CAR apresentou pior desempenho (HR=1,84; IC 1,19-2,85; p=0,006) e nenhuma diferença foi encontrada entre os materiais CIV e COM. Além disso, foram encontradas diferenças estatísticas para a variável volume da cavidade, onde cavidades menores apresentaram maiores chances de insucesso (p<0,03). Podemos concluir que o novo material Carbômero de Vidro não é adequado para o uso em restaurações ART proximais de molares decíduos em comparação com CIV de alta viscosidade e o Compômero. / The aim of this study was to evaluate if the new nanoparticulate material, the glass carbomer can increase the survival rate of occlusal-proximal-ART restorations compared with compomer - a polyacid resin modified material and a high viscosity glass ionomer cement (GIC). A total of 286 children aged 5 to 7 years presenting at least one occlusal-proximal carious lesion were selected in the city of Barueri, SP. Patients were randomized into three groups: high viscosity GIC (GIC - Fuji IX Extra - GC Corp), Compomer (COM - Dyract Extra - Dentsply) and Glass Carbomer (CAR - Glass Carbomer - GCP Dental). All treatments were made following the precepts of ART and manufacturers\' recommendations. The restorations were evaluated after 2, 6 and 12 months by a trained examiner. To verify the survival of the restorations was used Kaplan-Meier survival analysis and log-rank test. To evaluate the association between the outcome and patient variables was applied Cox regression test. The significance level for the tests was 5%. After 12 months of follow-up, overall survival rate of the restorations was 52.8%. The GIC, COM and CAR survival rate were 62.6%, 61.3% and 36.3%, respectively. Statistical analysis showed significant differences between the materials, where the CAR had a worse performance (HR = 1.84, CI 1.19 to 2.85; p = 0.006) and no difference was found between the CIV and COM materials. Moreover, statistical differences were found for the variable volume of the cavity, where smaller cavities had higher chances of failure (p <0.03). We conclude that the new glass carbomer material is not suitable for use in ART occlusal-proximal restorations in primary molars compared to high viscosity GIC and the compomer.

Objetivos: o presente estudo teve como objetivo determinar a aplicabilidade e eficácia adesiva de diferentes monômeros ácidos quando aplicados em formulações de cimentos resinosos autoadesivos experimentais sob o grau de conversão, propriedades físico-químicas e resistência de união à dentina e à zircônia tetragonal policristalina estabilizada por ítrea (Y-TZP), após um período de 3 meses de armazenamento em água. Material: dois tipos de cimentos do tipo pasta-pasta foram formulados contendo monômeros convencionais UDMA, HEMA, BISGMA, TEGDMA e monômeros ácidos 2MP e GDMAP como matriz orgânica. Um grupo contendo apenas monômeros convencionais foi formulado como grupo controle. Os componentes canforoquinona/EDMAB e peróxido de benzoíla/DHPT foram empregados como sistema de ativação dual. O sal sódico do ácido benzenosulfônico 98% (BAS) foi incorporado nos grupos experimentais. Partículas de carga foram incorporadas na proporção ±55% em peso final. Método: A técnica de espectroscopia no infravermelho (FT-IR) foi empregada para análise do grau de conversão (n=3) imediato e após 24 h. A avaliação do pH (n=3) foi feita através do emprego de um equipamento medidor de pH. Os corpos de provas foram imersos em água destilada e o pH foi analisado de forma imediata e após 5 min, 24 h e 48 h. Os testes de sorção e solubilidade (n=6) e espessura de película (n=5) seguiram as recomendações da ISO 4049. A análise de resistência de união (n=12) foi realizada em dentina e Y-TZP, através do teste de cisalhamento em área reduzida após um protocolo de envelhecimento em água destilada por 3 meses. No caso da Y-TZP, metade dos espécimes receberam um tratamento superficial cojet (30 ?m), associado a aplicação de um agente de união silano. O padrão de fratura foi analisado com o auxílio de um estereomicroscópio. Resultados: O grupo controle (91,7%) e o grupo formulado com 2MP (92%) apresentaram superiores valores de grau de conversão em relação ao grupo GDMAP (77,7%). O pH dos grupos experimentais 2MP e GDMAP se apresentou mais ácido após 48 h em comparação ao grupo controle. Em contrapartida, esses grupos experimentais apresentaram uma maior sorção e solubilidade em relação ao grupo controle. A espessura da película formada foi semelhante em todos os grupos testados (p=0,266). Em dentina o grupo controle (27,0 MPa) e GDMAP (24,1 MPa) não apresentaram diferença estatística após 3 meses de estocagem. O grupo 2MP (13,7 MPa) apresentou resultados inferiores aos demais grupos. O tratamento de superfície empregado não foi capaz de manter ou de elevar os valores de resistência de união à Y-TZP após o período de envelhecimento em água. Todos os grupos experimentais apresentaram falhas precoces ou baixos valores de resistência de união após 3 meses, independente da presença ou não do tratamento de superfície. Conclusão: os grupos experimentais 2MP e GDMAP apresentaram resultados promissores. Entretanto, a adesão dos CRAs experimentais testados em Y-TZP ainda se apresenta frágil e instável. / Objectives: the purpose of this study was to evaluate the applicability and adhesive efficiency of different acid monomers utilized in formulations of experimental self-adhesive resin cement under degree of conversion, physico-chemical properties and bond strength to dentin and Y-TZP after 3 months aging period. Materials: two paste-paste luting agents were formulated containing UDMA, HEMA, BISGMA, TEGDMA and acid adhesive monomers 2MP and GDMAP as organic matrix. The control group was formulated containing only conventional monomers. Camphoroquinone/EDMAB and benzoyl peroxide/DHPT were used as dual activation system. BAS salt was incorporated into the experimental groups. Filler particles were added in a proportion of ±55% final weight. Method: Infrared spectroscopy technique (FTIR) was employed for degree of conversion analysis (n=3) immediately and after 24 hours. The pH assessment (n=3) was made using a pH meter. All the specimens were immersed in distilled water and pH assessment was performed immediately and after 5 min, 24 h and 48 h. Tests for sorption and solubility (n=6) and thickness (n=6) were carried out according to ISO 4049 recommendations. Bond strength analysis (n=12) was performed in dentin and Y-TZP through microshear after an aging 3 months protocol in distilled water. Regarding Y-TZP, half of the specimens were submitted to a cojet surface treatment (30 ?m) in association to silane bonding agent application. Fracture toughness standard was evaluated with the assistance of a stereomicroscope. Results: The control (91,7%) and 2MP (92%) groups presented higher degree of conversion than GDMAP group (77,7%). The 2MP and GDMAP experimental groups showed the highest pH compared to control group. In contrast, experimental groups showed a high hydrolytic degradation. The thickness of the formed film was similar among all the tested groups (p=0,266). Regarding the dentin, control and GDMAP groups had statistically similar bond strength (27,0 and 24,1 MPa respectively) after 3 months storage. While 2MP group (13,7 MPa) showed lower results compared the other groups. The surface treatment employed was not capable to maintain or elevate bond strength to Y-TZP results after the aging period in water. All experimental groups showed low bond strength values and even early failures after 3 months, regardless the surface treatment or its abscence. Conclusion: the experimental groups 2MP and GDMAP presented promising results. However, chemical adhesion to Y-TZP still remains weak and instable.

Nos defeitos bucomaxilofaciais, a intervenção cirúrgica utilizando enxertos ou substi-tutos ósseos é indicada para reestabelecer a forma e a função perdidas. Nesse con-texto, enxertos auto?genos e alo?genos te?m sido substituídos por biomateriais osteo-condutores e reabsorvíveis. O objetivo deste trabalho foi avaliar por meio de micro-tomografia e dos aspectos histológicos do reparo ósseo, se um novo cimento bifási-co composto por sulfato de cálcio e beta fosfato tricálcico com controle de potencial zeta, poderia induzir ou conduzir a neoformação óssea em defeitos críticos, produzi-dos em calvárias de ratos. Foi realizado um defeito crítico de 8mm de diâmetro na calvária de 40 ratos Wistar machos. No grupo teste (n=20) os defeitos foram preen-chidos pelo cimento. No grupo controle (n=20) os defeitos não foram preenchidos e permaneceram apenas com o coágulo. Os animais sofreram eutanásia em 7, 14, 21 e 42 dias do pós operatório. Espécimes da região da ferida foram microtomografa-dos e posteriormente as amostras foram preparadas para análise histológica. A aná-lise histomorfológica incluiu a avaliação morfológica da histopatologia do reparo, a avaliação morfométrica da área de formação das trabéculas ósseas comparativa-mente entre os grupos. Realizamos ainda a coloração com fosfatase tartrato-resistente (TRAP) para identificação de osteoclastos. Os resultados mostraram que os defeitos preenchidos pelo cimento não apresentaram diminuição significativa da área de acordo com a progressão dos períodos pós-operatórios, pelo contrário, em alguns animais, o defeito aparentemente aumentou. A histomorfologia do reparo mostrou agrupamentos mais expressivos de células gigantes no grupo teste suge-rindo resposta a corpo estranho e osso neoformado mais maduro no grupo controle No grupo teste houve permanência do material e resposta corpo estranho até os úl-timos períodos de observação. Na histomorfometria, a área total de neoformação óssea na região da ferida foi significativamente maior e crescente com o passar do tempo experimental no grupo controle do que no grupo teste. As células gigantes apresentaram expressão histoquímica positiva para TRAP e não foram identificados osteoclastos. Concluímos que neste modelo de estudo, o cimento cerâmico não in-duziu ou conduziu a neoformação óssea de defeitos ósseos críticos criados em cal-vária de ratos sob o ponto de vista microtomográfico e histológico. / Surgical intervention employing grafts and bone substitutes is the best choice in oral and maxillofacial bone defects reconstruction for structural and functional lost. Re-garding this, autogenous and alogenous grafts have been used as osteocondutive and resorbable biomaterials. The aim of this study was to evaluate if a new bone bi-phasic composite of calcium sulfate and beta tricalcium phosphate with zeta potential control could induce or conduct bone formation in rats\' calvarias critical defects mod-el. Forty male Wistar rats underwent 8mm diameter calvaria perforation under gen-eral anesthesia. Animals were randomly allocated to group test (n=20), when the de-fects were filled with the biphasic phosphate and group control (n=20) when the wound was left just with blood clot. Animals underwent euthanasia 7, 14, 21 and 42 days after surgery. Bone calvaria specimens underwent microtomography and histo-logical processing for analysis. Histomorphological and histomorphometry were per-formed regarding aspects of bone healing evolution and new bone total area within the defect. Additionally, histological samples were tartrate-resistant phosphatase (TRAP) stained for osteoclasts identification. The results showed that defects filled by the composite did not present significant bone formation considering postoperative evolution, on the contrary it seemed that the defect area increased in some animals. The bone repair histomorphology in test-group showed expressive giant cells nests involving the ceramic material suggesting foreign body reaction. A mature bone tis-sue neoformation was significantly more intense in the control-group. In the test-group the permanence of the exogenous material caused the sustained foreign body reaction until the last observational periods. Histomorphometric analysis showed that in control-group the total area of bone formation was significantly greater and pro-gressive along the experiment than the test-group. Osteoclasts were not identified but the giant cells presented positive reaction to TRAP. It was possible to conclude that the biphasic ceramic with zeta potential control was not capable to induce or conduct bone neoformation in critical defects created in rats\' calvaria.

In order to avoid the occurrence of early-age damage, cement-treated base (CTB) materials must be allowed to cure for a period of time before the pavement can be opened to traffic. The purpose of this research was to evaluate the utility of the soil stiffness gauge (SSG), heavy Clegg impact soil tester (CIST), portable falling-weight deflectometer (PFWD), dynamic cone penetrometer, and falling-weight deflectometer for assessing early-age strength gain of cement-stabilized materials. Experimentation was performed at four sites on a pavement reconstruction project along Interstate 84 near Morgan, Utah, and three sites along Highway 91 near Richmond, Utah; cement stabilization was used to construct CTB layers at both locations. Each site was stationed to facilitate repeated measurements at the same locations with different devices and at different curing times. Because of the considerable attention they have received in the pavement construction industry for routine quality control and quality assurance programs, the SSG, CIST, and PFWD were the primary focus of the research. Statistical techniques were utilized to evaluate the sensitivity to curing time, repeatability, and efficiency of these devices. In addition, the ruggedness and ease of use of each device were evaluated. The test results indicate that the CIST data were more sensitive to curing time than the SSG and PFWD data at the majority of the cement-treated sites during the first 72 hours after construction. Furthermore, the results indicate that the CIST is superior to the other instruments with respect to repeatability, efficiency, ruggedness, and ease of use. Because the CIST is less expensive than the SSG and PFWD, it is more likely to be purchased by pavement engineers and contractors involved with construction of CTBs. For these reasons, this research suggests that the CIST offers greater overall utility than the SSG or PFWD for monitoring early-age strength gain of CTB. Further research is needed to identify appropriate threshold CIST values at which CTB layers develop sufficient strength to resist permanent deformation or marring under different types of trafficking.

Abstract Millions of tons of mine tailings are generated worldwide annually. Since many valuable metals such as Ag, Cu, Pb, Zn, Au and Ni are usually incorporated into sulphidic minerals, a large proportion of the tailings generated contain high amounts of sulphates and heavy metals. Some of these tailings are used as paste backfill material at mining sites, but large amounts are still being deposited into the tailings dams under water coverage. Sulphidic minerals are stable underground but after mining of the ore and several processing steps these minerals can be oxidized when they come into contact with water and air. This oxidation generates acid and thus reduces the pH of the surrounding environment. Furthermore, the heavy metals present in the mine tailings can be leached into the environment. This phenomenon, called Acid Mine Drainage (AMD), is one of the most critical environmental issues related to the management of sulphidic-rich tailings. Since AMD generation can still occur hundreds of years after closure of the mine, the mine tailings need stable, sustainable and economically viable management methods in order to prevent AMD production in the long term. The aim of this PhD thesis was to study various solidification/stabilization (S/S) methods for the immobilization of sulphidic mine tailings. The main focus was to develop a suitable chemical environment for achieving effective heavy metal (mainly arsenic) and sulphate immobilization while simultaneously ensuring good mechanical properties. Three treatment methods were tested: alkali activation, stabilization using hydrated lime (Ca(OH)2) and blast furnace slag (GBFS), and calcium sulphoaluminate-belite (CSAB) cement stabilization. The mine tailings used in this study contained large amounts of sulphates and heavy metals such as Cr, Cu, Ni, Mn, Zn, V and As. The leaching of arsenic and sulphates from powdered tailings exceeded the legal limits for regular and inert waste. All treatment methods were found to generate a hardened matrix that was suitable for use as a backfilling or construction material, but the calcium-based binding system was the most suitable for effective immobilization of all the heavy metals (including arsenic) and the sulphates. Precipitation in the form of calcium sulphates/calcium arsenate and the formation of ettringite are the main stabilization methods employed in calcium-based stabilization/solidification (S/S) systems. Some evidence of physical encapsulation occurring simultaneously with chemical stabilization was noted. These results can be exploited further to develop more sustainable mine tailing management systems for use in the future. The tailings could be stored in a dry landfill area instead of in tailing dams, and in this way a long-term decrease in AMD generation could be achieved, together with a high potential for recycling. / Tiivistelmä Monet arvometallit kuten kulta, kupari ja nikkeli ovat sitoutuneena sulfidipitoisiin mineraaleihin. Louhittaessa ja rikastettaessa näitä sulfidimineraaleja syntyy miljoonia tonneja sulfidipitoisia rikastushiekkoja vuosittain. Rikastushiekat voivat sisältää myös runsaasti erilaisia raskasmetalleja. Osa rikastushiekoista hyödynnetään kaivostäytössä, mutta suurin osa rikastushiekoista läjitetään edelleen ympäristöön rikastushiekka-altaisiin veden alle. Kun sulfidipitoinen malmi kaivetaan ja käsitellään, sulfidiset mineraalit hapettuvat ollessaan kosketuksissa veden ja hapen kanssa. Hapettuessaan ne muodostavat rikkihappoa, laskien ympäristön pH:ta jolloin useimmat raskasmetallit liukenevat ympäristöön. Muodostuvia happamia kaivosvesiä voi syntyä vielä pitkään kaivoksen sulkemisen jälkeen ja ovat näin ollen yksi suurimmista kaivosteollisuuteen liittyvistä ympäristöongelmista. Lisäksi suuret rikastushiekka-altaat voivat aiheuttaa vaaraa myös ihmisille, mikäli altaan rakenteet pettävät. Rikastushiekkojen kestäviä ja ympäristöystävällisiä varastointimenetelmiä täytyy kehittää, jotta näitä ongelmia voidaan tulevaisuudessa ehkäistä. Tässä työssä tutkittiin menetelmiä, joilla kultakaivoksella syntyvät sulfidipitoiset vaaralliseksi jätteeksi luokitellut rikastushiekat saataisiin stabiloitua tehokkaasti. Työssä keskityttiin kolmeen erilaiseen menetelmään: alkali-aktivointiin, stabilointiin kalsiumhydroksidin ja masuunikuonan avulla ja stabilointiin CSAB sementin avulla. Valmistettujen materiaalien mekaanisia ja kemiallisia ominaisuuksia arvioitiin. Tavoitteena oli ymmärtää, miten eri menetelmät soveltuvat raskasmetallien (erityisesti arseenin) ja sulfaattien sitoutumiseen ja mikä on eri komponenttien rooli reaktioissa. Alkali-aktivoimalla rikastushiekkaa sopivan sidosaineen kanssa saavutettiin hyvät mekaaniset ominaisuudet ja useimmat haitta-aineet sitoutuivat materiaaliin. Ongelmia aiheuttivat edelleen sulfaatit ja arseeni. Kalsiumpohjaiset menetelmät sitoivat raskasmetallit (myös arseenin) ja sulfaatit tehokkaimmin. Sulfaatit ja arseeni saostuivat muodostaen niukkaliukoisia komponentteja kalsiumin kanssa. Samanaikaisesti rakenteeseen muodostui ettringiittiä, jolla on tutkitusti hyvä kyky sitoa erilaisia raskasmetalleja rakenteeseensa. Raskasmetallit myös kapseloituivat rakenteen sisään. Työn tuloksia voidaan hyödyntää, kehitettäessä rikastushiekkojen turvallista varastointia. Kun materiaalille saavutetaan riittävän hyvä lujuus ja kemiallinen stabiilius, rikastushiekat voitaisiin läjittää tulevaisuudessa kuivalle maalle altaan sijaan. Näin vältyttäisiin rikastushiekka-altaiden rakentamiselta ja voitaisiin vähentää happamien kaivosvesien muodostumista pitkällä ajanjaksolla. Saavutettujen tulosten perusteella rikastushiekkoja voidaan mahdollisesti tulevaisuudessa hyödyntää myös erilaisissa betonin tapaisissa rakennusmateriaaleissa.

Este trabalho envolve os resultados de três diferentes ensaios clínicos randomizados: (1) restaurações ART em cavidades oclusais utilizando Fuji IX (GC), Vitro Molar (Nova DFL) e Maxxion R (FGM); (2) restaurações ART oclusoproximais utilizando Ketac Molar (3M ESPE) e Vitro Molar (Nova DFL) e (3) Restaurações ART em cavidades oclusais e ocluso-proximais utilizando Glass Carbomer (GCP), Dyract (Dentsply) e Equia Fill (GC). O objetivo desta tese foi avaliar se a escolha do material tem influência na sobrevida de restaurações ART em molares decíduos. Um total de 835 crianças de 4 a 8 anos de idade (estudo 1: n=150; estudo 2: n=117; estudo 3: n=568) com lesões de cárie em dentina sem sinais de envolvimento pulpar foram selecionadas e tratadas em escolas públicas do município de Barueri-SP. Os pacientes foram randomizados de acordo com o grupo de material restaurador de cada estudo. Todos os tratamentos foram feitos seguindo os preceitos do ART e as recomendações dos fabricantes. As restaurações foram avaliadas por examinador independente, treinado e calibrado (estudo 1 e 2: até 24 meses e estudo 3: até 36 meses de acompanhamento). Para verificação da sobrevida das restaurações foi utilizada a análise de sobrevida de Kaplan-Meier e teste log-rank. Para avaliar a associação entre o desfecho e as variáveis características do paciente foi aplicado o teste de Regressão de Cox (IC=95%). No estudo 1, a sobrevida de restaurações oclusais em molares dentes decíduos é maior ao utilizar o material Fuji IX (72,7%) quando comparado aos materiais VitroMolar (46,5%) e Maxxion R (39,6%). Não houve diferenças entre os materiais Maxxion R e Vitro Molar. No estudo 2, monstrou-se que sobrevida de restaurações oclusoproximais é maior ao utilizar o material Ketac Molar (48,6%) quando comparado ao VitroMolar (25,4%). Já no estudo 3, o material Glass Carbomer (CAR) apresenta menor sobrevida quando comparado ao cimento de ionômero de vidro de alta viscosidade (CIV)- Equia Fill e ao compômero (COM)- Dyract, tanto em cavidades oclusais (CIV=83%; COM=78%; CAR=62,5%) quanto em ocluso-proximais oclusais (CIV=56,19%; COM=56,15%; CAR=36,33%). Nenhuma diferença é observada entre o compômero e o cimento de ionômero de vidro de alta viscosidade. Outros fatores como sexo, arcada, lado, experiência de 38 cárie, operador e volume da cavidade não influenciaram a sobrevida das restaurações (p>0,05). Dessa forma, conclui-se que a sobrevida das restaurações ART em molares decíduos é influenciada pela escolha do material restaurador. Os materiais que apresentaram melhores resultados nestes ensaios clínicos randomizados foram: Fuji IX (GC Corp), Ketac Molar (3M ESPE), Equia Fill (GC Corp) e Dyract (Dentsply). Registro no ClinicalTrials.gov: Capítulo 1: NCT02377297; Capítulo 2: NCT02267720; Capítulo 3: NCT02217098. / This thesis compiles the results of three different randomized clinical trials: (1) ART occlusal restorations using Fuji IX (GC), Vitro Molar (Nova DFL) and Maxxion R (FGM); (2) ART occlusal restorations using Ketac Molar (3M ESPE) and Vitro Molar (Nova DFL) and (3) ART restorations in occlusal and occlusoproximal cavities using Glass Carbomer (GCP), Dyract (Dentsply) and Equia Fill (GC). The aim of this thesis was to evaluate if the restorative material can influence the survival of ART restorations in primary dentition. A total of 835 children 4 to 8 years of age (study 1: n = 150, study 2: n = 117, study 3: n = 568) with dentin carious lesions without pulp involvement were selected and treated in public schools of the city of Barueri-SP. Patients were randomized according to the restorative material group of each study. All treatments were done following the ART precepts and the manufacturers\' recommendations. Restorations were evaluated by single trained and calibrated examiner (study 1 and 2: up to 24 months and study 3: up to 36 months follow-up). Kaplan-Meier survival analysis and log-rank test were used to verify the survival of the restorations. The Cox Regression test was used to evaluate the association between the outcome and the independent variables (CI=95%). In study 1, the survival of occlusal restorations in primary molars was higher using Fuji IX (72.7%) when compared to VitroMolar (46.5%) and Maxxion R (39.6%). There were no differences between Maxxion R and VitroMolar. In study 2, it was shown that survival of occlusoproximais restorations is higher when using Ketac Molar (48.6%) when compared to VitroMolar (25.4%). In the study 3, Glass Carbomer (CAR) material presented lower survival when compared to the high viscosity glass ionomer (GIC) - Equia Fill and to compomer (COM) - Dyract, both in occlusal cavities (GIC = 83%, COM = 78%, CAR = 62.5%) and occlusal-proximal ones (GIC = 56.19%, COM = 56.15%, CAR = 36.33%). No difference is observed between the compomer and the high viscosity glass ionomer cement. Other factors such as sex, jaw, side, caries experience, operator and volume of the cavity did not influence the survival of the restorations (p> 0.05). Thus, it is concluded that survival of ART restorations in primary molars is influenced by the restorative material. The materials that showed 40 the best results in these randomized controlled trials were Fuji IX (GC Corp), Ketac Molar (3M ESPE), Equia Fill (GC Corp) and Dyract (Dentsply). ClinicalTrials.gov Registration: Chapter 1: NCT02377297; Chapter 2: NCT02267720; Chapter 3: NCT02217098.

The development of composite materials by combining two or more constituents with improved mechanical properties, when compared to either of the constituents alone, has existed since biblical times when straw or horse hair was mixed with clay or mud to produce bricks. During the second half of the twentieth century, modern composites known as fiber reinforced polymers (FRP) - consisting of a reinforcing phase (fibers) embedded into a matrix (polymeric resin or binder) - were developed to meet the performance challenges of space exploration and air travel. With time, externally-bonded FRP applications for strengthening of reinforced concrete (RC) structures gained popularity within the construction industry. To date, the confinement of RC columns using FRP systems is a convenient and well established solution to strengthen, repair and retrofit structural concrete members. This technology has become mainstream due to its cost effectiveness, and relative ease and speed of application with respect to alternative rehabilitation techniques such as steel or concrete jackets. However, significant margins exist to advance externally-bonded composite rehabilitation technologies by addressing economic, technological, and environmental issues posed by the use of organic polymer matrices, some of which are addressed in this dissertation. Articulated in three studies, the dissertation investigates the development of a sustainable, reversible, and compatible fiber reinforced cement-based matrix (FRC) composite system for concrete confinement applications in combination with a novel test method aimed at characterizing composites under hydrostatic pressure. Study 1 develops and characterizes a FRC system from different fiber and inorganic matrix combinations, while evaluating the confinement effectiveness in comparison to a conventional FRP system. The feasibility of making the application reversible was investigated by introducing a bond breaker between the concrete substrate and the composite jacket in a series of confined cylinders. The prototype FRC system produced a substantial increase in strength and deformability with respect to unconfined cylinders. A superior deformability was attained without the use of a bond breaker. The predominant failure mode was loss of compatibility due to fiber-matrix separation, which points to the need of improving fiber impregnation to enable a more efficient use of the constituent materials. Additionally semi-empirical linear and nonlinear models for ultimate compressive strength and deformation in FRC-confined concrete are also investigated. Study 2 compares through a life cycle assessment (LCA) method two retrofitting strategies: a conventional organic-based, with the developed inorganic-based composite system presented in Study 1, applied to concrete cylinders by analyzing three life cycle impact indicators: i) Volatile Organic Compound (VOC) emissions, ii) embodied energy, and, iii) carbon foot print. Overall the cement-based composite provides an environmentally-benign alternative over polymer-based composite strengthening system. Results also provide quantitative information regarding the environmental and health impacts to aid with the decision-making process of design when selecting composite strengthening systems. Study 3 is divided into two parts, Part A presents the development of a novel "Investigation of Circumferential-strain Experimental" (ICE) methodology for characterization of circumferential (hoop) strain of composite laminates, while Part B uses the experimental data reported in Part A to explicitly evaluate the effect of FRP jacket curvature and laminate thickness on strain efficiency. Results showed that the proposed ICE methodology is simple, effective and reliable. Additionally, the ultimate circumferential strain values increased with increasing cylinder diameter, while being consistently lower when compared to similar flat coupon specimens under the same conditions. The ultimate FRP tensile strain was found to be a function of the radius of curvature and laminate thickness, for a given fiber ply density and number. The effect of these findings over current design guidelines for FRP confined concrete was also discussed.