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No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação - Géssica Batista.pdf: 4335597 bytes, checksum: 62909b0c2d9fe397881952f9f2118d70 (MD5) Previous issue date: 2016-12-12 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the process of water treatment for public supply, which is made in the water treatment plants (WTPs), a waste conventionally called sludge is formed. As in the soil, the main components of WTP sludge are silicon (Si), aluminum (Al) and iron (Fe). This composition allowed to suggest that this waste could be used in the production of inorganic polymers - the geopolymers. While conventional polymers are formed by carbon structures, geopolymers are composed of Si and Al structures. They are obtained by dissolving aluminosilicates materials in highly alkaline solution. Among the possible applications, they can be used as pastes, mortars and concretes, in replacement of Portland cement, which is the most used binder in civil construction worldwide. To verify the suitability of the sludge as a geopolymer precursor, this waste was properly benefited by means of mechanical grinding and calcination at 750 °C for 6 hours, being characterized before and after its processing. The results of chemical and mineralogical analyzes proved the adequacy of calcined WTP sludge as a geopolymeric raw material. To check the influence of the sources of raw water abstraction intake on the WTP sludge characteristics and consequently in the properties of materials produced from sludge-based, samples of this waste were collected under the influence of two different water sources. With these samples it produced of two geopolymeric mortars. The final products were properly characterized and the results proved that regardless of the peculiarities of water sources, WTP sludge can be used as a geopolymeric raw material. In the thermal tests the two mortars produced showed indications of refractory bahavior and have been free of calcium hydroxide, therefore, it can be inferred that they are free matrices of deleterious actions of this compound. In the mechanical tests, at 28 days of cure, they reached mechanical strengths of 57 and 79 MPa, on average. Some results evidenced the need for improvements in the formulation of mortars, but in general, it was verified that the use of WTP sludge as a geopolymer precursor material is a very promising alternative for the destination of this waste, making it valuable and useful product for society. / No processo de tratamento de água para abastecimento público, realizado em estações de tratamento de água – ETAs, gera-se um resíduo convencionalmente chamado de lodo. Da mesma forma que acontece no solo, os principais constituintes do lodo de ETA são o silício (Si), o alumínio (Al) e o ferro (Fe). Tal composição permitiu sugerir que este resíduo poderia ser usado na produção de polímeros inorgânicos – os geopolímeros. Enquanto os polímeros convencionais são formados por estruturas de carbono, geopolímeros são constituídos de estruturas de Si e Al. São obtidos através da dissolução de materiais aluminossilicatos em solução altamente alcalina. Dentre as possíveis aplicações, podem ser empregados como pastas, argamassas e concretos, em substituição ao cimento Portland, o material ligante mais utilizado mundialmente na construção civil. Para verificar a adequação do lodo de ETA como material precursor geopolimérico, este resíduo foi devidamente beneficiado por meio de moagem mecânica e calcinação a 750 ° C por 6 horas, sendo caracterizado antes e após seu beneficiamento. Os resultados de análises químicas e mineralógicas comprovarem a adequação do lodo de ETA calcinado como matéria-prima geopolimérica. A fim de avaliar a influência dos mananciais de captação de água bruta nas características do lodo de ETA e, consequentemente, nas propriedades de materiais produzidos à base deste resíduo, foram coletadas amostras de lodo sob influência de dois diferentes mananciais. Com estas amostras produziu-se duas argamassas geopoliméricas. Os produtos finais foram devidamente caracterizados e os resultados comprovaram que, independentemente das peculiaridades dos mananciais, o lodo de ETA pode ser utilizado como material precursor geopolimérico. Nos ensaios térmicos, as duas argamassas produzidas exibiram indícios de comportamento refratário e se mostraram isentas de hidróxido de cálcio, portanto, pode-se inferir que são matrizes livres das ações deletérias ocasionadas por este composto. Nos ensaios de resistência mecânica, aos 28 dias de cura, atingiram 57 e 79 MPa, em média. Alguns resultados evidenciaram a necessidade de melhorias na formulação das argamassas, mas de uma forma geral, constatou-se que o aproveitamento do lodo de ETA como matéria-prima geopolimérica é uma alternativa bastante promissora para a destinação deste resíduo, podendo torná-lo um produto com valor agregado e útil para a sociedade.

Dans le cadre du conditionnement des déchets nucléaires, les géopolymères représentent une alternative potentielle aux liants hydrauliques classiques. A ce jour, il est admis que la formation des géopolymères procède selon un mécanisme de dissolution - restructuration - polymérisation conduisant à un matériau solide. Cependant, les liens précis entre la composition de la solution d’activation, le déroulement des réactions de géopolymérisation et la microstructure finale doivent être déterminés du point de vue de la texturation et de l’évolution structurale du matériau. Ainsi plusieurs paramètres de formulation ont été étudiés : la nature de l’activateur alcalin, la concentration en silice et l’ajout d’une source d’aluminium. Il apparait que l’environnement chimique des précurseurs silicatés ou alumino-silicatés est contrôlé par les paramètres de formulation constitutifs de la solution d’activation. Lors de la formation du réseau géopolymérique, ces précurseurs jouent un rôle primordial sur la cinétique de dissolution du métakolin, la taille, l’arrangement et l’agrégation des oligomères alumino-silicatés participant à la formation du réseau poreux. A plus long terme, certaines caractéristiques du réseau poreux qui sont-elles même contrôlées par la taille et l’agencement des oligomères, varient légèrement au cours du temps. Le réarrangement de la structure poreuse associé d’une part à la densification du réseau solide, et d'autre part à la fermeture partielle de la porosité conduit à une légère augmentation de la taille des pores et à une diminution du volume poreux accessible. / In the context of conditioning of nuclear waste, geopolymers represent a potential alternative to conventional hydraulic binders. Currently, it is recognized that the formation of geopolymer proceeds according to a mechanism of dissolution - restructuring - polymerization resulting in a solid material. Despite the availability of many studies to understand these mechanisms, the precise relationship between the chemical nature of the activating solution, the geopolymerization process and the final microstructure should be determined from the point of view of the texturing and the structural evolution of the material. In this work, several parameters were studied: the nature of the alkali activator, the silica concentration and the addition of an aluminum source. It appears that the chemical environment of the silicate or aluminosilicate precursors is controlled by the activating solution composition. During the consolidation of the geopolymer network, these precursors play an important role on the dissolution rate of metakaolin, the size, the rearrange¬ment and the aggregation of aluminosilicate oligomers involved in the porous solid network formation. Subsequently, some characteristics of the porous network which are controlled by the size and the rearrangement of oligomers vary slightly over time. The refinement of the porosity associated to first, a densification of the solid network, and secondly, a partial closure of the porosity at the nanometer scale leads to an increase in the pore size and a decrease of the pore volume.

To support the concept of environmentally friendly materials and sustainable development, the low-carbon cementitious materials have been extensively studied to reduce amount of CO2 emission to the atmosphere. One of the efforts is to promote alternative cementitious binders by utilizing abundant alumina-silicate wastes from the industrial sectors (e.g. fly ash or furnace slag), among which “Geopolymer (GP) cement” has received most attention as it can perform a wide variety of behaviours, in addition to cost reduction and less environmental impacts. The most common geopolymer production, fly ash-based, gained some strength with very slow rate at ambient temperature, while the strength is evidently improved when cured in high (above room) temperature, e.g. over 40°C. The major challenge is to step over the limitation of heat curing process and inconvenience in practice. In this study, the testing schemes of (i) GP manufacturing in various processes, (ii) inclusion of ordinary Portland cement (OPC) in GP mixture, called GeoPC and (iii) GeoPC manufactured with dry-mixing method, have been intensively investigated through mechanical testing (Setting time, Compressive strength and Internal heat measurement) and mechanism analysis (XRD, FTIR, SEM and EDXA) in order to develop the geopolymers, achieving reasonable strength without external sources of heat curing. It is found that the proposed (dry) mixing process could have generated intensive heat liberation which was observed as a comparable factor to heat curing from any other external sources, enhancing the curing regime of the mixture. The additional calcium content in the developed GeoPC system not only resulted in an improvement of an early strength by the extra precipitation of calcium compounds (C,N-A-S-H), but also provided a latent heat from the reaction of its high potential energy compounds (e.g. OPC or alkaline activators). The developments from these approaches could lead to geopolymer production to achieve reasonable strength in ambient curing temperature known as “Self-cured geopolymer cement”, without external heat, and hence provide construction industry viable technologies of applying geopolymers in on-site and off-site construction.

No description available.

Preparation of geopolymers with main components of slug and metakaolin. After being alcali activated the raw materials are complemented by superplasticizers of different kind and concentracion.

Diploma thesis studies historical bonding agents on the base of geopolymers. The aim of the thesis is to find a proper material composition, especially made of natural clay materials (kaolinite, bentinite) and their modifications (metakaoline). These bonding agents have to have a suitable type of an activator that guarantees good bonding properties. Therefore testing of various kinds of alkaline activating ingredients on the same mineral composition was done. Except of usual hydroxides and a water glass, ancient natrons (mixtures of alkaline carbonate with addition of appropriate chlorides) and a lime mash were used as the activators. From the above mentioned mixtures, series of samples (columns 20 x 20 x 100 mm) stored at the laboratory temperature were prepared. In the prepared mashes, their workableness and moulding were investigated. In the developed samples, their surface appearance was observed together with a number of efflorescence and its types. An indivisible part of the research was formed by determination of mechanical properties of the experimental columns such as a compressive strength and a tensile strength in bending. Furthermore, phase composition of the samples and its changes with a temperature increase were investigated. For these tests, XRD and TG – DTA methods were used. A multi-seat isoperbolic calorimeter was used to study hydratation that was also the important part of the general evaluation of designed mixtures.

This thesis deals with preparation of geopolymeric binders for inhibition of toxic elements, especially arsenic. It studies influence of content progress of different phases in prepared binders on leachability of As during the setting. The aim of this study is to determine the type of inhibition or the cause of leachability of As in prepared binders respectively. Fly ash from high-temperature coal combustion, slag, cement kiln dust and sodium hydroxide solution were used for experimental works. FT-IR, TG-DTA, XRD analyses after different hydration times were used. The leachates were analyzed by ICP-MS. Calorimetric measurements of tested mixtures fresh pastes were implemented to learn about setting process. Hardened binder specimens were tested for bending and compressive strength.

This master thesis is concerns the preparation of Alkali Activated Materials, specifically Alkali Activated Slag (AAS), with the addition of fiber reinforcement. Alkali Activated Materials have great potential for use in construction practice. However, their use is limited by certain undesirable properties, which can be diminished by adding fiber reinforcement. This thesis deals with the influence of carbon fibers (2 % by weight of the binder) and carbon nanotubes (0,2 % by weigh of the binder) on the mechanical properties, microstructure and shrinkage of AAS. The results of the experiments which were carried out correspond with the literary research. Conclusions of this thesis agree with research published in original scientific papers.

Portland cement-based products are the most commonly used building materials. However, it is well known that the production of OPC not only consumes a significant amount of natural resources and energy but also releases high quantity of carbon dioxide (CO2) to the atmosphere. Purpose of this work is to develop new cementitious material similar to Portland cement-based concrete, which is convenient in terms of energy and is environmental-friendly at once. This work presents preparation, composition and properties of inorganic aluminosilicate polymer, called geopolymer, synthesized from blast furnace slag and fly ash, activated by sodium hydroxide and cement kiln dust. Study of the microstructure was based on SEM-EDX-WDX, TG-DTA-EGA and XRD analysis.

Les problèmes climatiques planétaires nous poussent à concevoir des systèmes constructifs à faible consommation d’énergie. L’utilisation des murs constitués d’écomatériaux (ossature bois avec un remplissage de brique de terre crue et assemblage parmortier minéral) apparaît comme une solution alternative intéressante et conforme aux objectifs en matière de développement durable. Dans une démarche de conception de ce type de système constructif, un outil de modélisation thermo-hydro-mécanique a été développé. Il vise d’une part à prédire la capacité de la paroi à réguler les conditions hygrothermiques ambiantes lors des alternances jour/nuit en fonction des différentes stratégies de ventilation, et d’autre part à identifier les différents scénarios décrits en termes de température et d’humidité pouvant induire l’apparition de fissures dans la paroi, aussi bien en phase de construction qu’en conditions de service. La rareté des travaux réalisés sur les propriétés de la terre crue nous a poussés à développer une campagne expérimentale multidisciplinaire pour caractériser les propriétés thermiques, hydriques et mécaniques sous différents états hydriques. Ces propriétés alimentent le modèle, dont les adaptations nécessaires sont présentées. Les résultats portent à la fois sur l’impact sur le confort hygrothermique et sur l’effet des variations hydriques sur la durabilité mécanique de la paroi. / Global climate problems push us to design energy-saving constructive systems. The use of walls made of eco-materials (wooden frame with a filling of brick of raw earth and assembled by mineral mortar) appears as an interesting alternative solution being in linewith the objectives in terms of sustainable development. In order to use a numerical simulation approach to this type of constructive system, a thermo-hydro-mechanical modeling tool was developed. On the one hand, it aims to predict the wall's ability to regulate the ambient hygrothermal conditions during day / night alternations according to the different ventilation assumptions and, on the other hand, to identify the various scenarios described in terms of temperature which can induce the appearance of cracks in the wall, both during construction and operating conditions. The originality of the work carried out on the properties of the raw earth make us able to develop a multidisciplinary experimental campaign to characterize the thermal, hydric and mechanical properties under different humidity conditions. These properties feed the numerical model with the necessary adaptations presented. The results present both the impact on hygrothermal comfort and to the effect of humidity changes on the mechanical durability of the wall.