The aim of this work is to develope fast-setting geopolymeric binders applicable in the chemical wall clamp. This clamping systems are big trend because of easy application, ability to transfer big forces and short setting time. Binders of this systems are based on polymeric resin. Their raw materials are expensive, toxic and flammable substances. Based on this consideration an anorganic fast-setting geopolymeric binder was developed. This binders consist of mixture of metakaolin and precipitated silica activated by potassium hydroxide. Binder were characterized by suitable analytic methods (XRD, SEM, DTA). The results of this metods were used for optimalization of binder properties.

Ce travail s’inscrit dans le cadre du conditionnement de liquides organiques radioactifs sans filière de gestion. Le procédé est basé sur une émulsification de liquide organique dans un silicate alcalin permettant la synthèse d’une matrice géopolymère. La première partie de ce travail consiste à effectuer un criblage sur différents liquides organiques. Un système modèle représentatif des différentes huiles et une formulation de référence de géopolymère sont définis. La seconde partie porte sur la structuration des enrobés de liquide organique, du mélange des réactifs jusqu’à l’obtention du matériau final, et vise à déterminer les phénomènes permettant la synthèse d’un composite homogène. Les deux dernières parties visent à caractériser le matériau en étudiant respectivement sa structure (structure chimique, porosité du géopolymère et dispersion de l’huile) et ses propriétés vis-à-vis de l’application à l’immobilisation de déchets radioactifs. Contrairement aux matrices cimentaires silico-calciques, la structuration du géopolymère n’est pas impactée par la nature chimique des liquides organiques. Seules les huiles acides inhibent ou freinent la réaction de géopolymérisation. Afin d’obtenir un matériau homogène la présence de molécules tensio-actives est obligatoire. Le mécanisme de stabilisation des émulsions, à la base du procédé, repose sur une synergie entre les molécules tensio-actives et les particules d’aluminosilicates présentes dans la pâte de géopolymère. Les cinétiques (chimique et mécanique) de la géopolymérisation ne sont pas impactées par la présence d’huile ou de tensio-actifs. Seule une augmentation des modules viscoélastiques et du caractère élastique des pâtes peut être constaté. Cette différence de comportement rhéologique est en majeure partie liée à la présence de tensio-actif. La structure de la matrice est identique à celle d’un géopolymère pur de même formulation. Le liquide organique est dispersé dans des inclusions sphériques dont le rayon est compris entre 5 et 15 μm. Ces gouttelettes sont séparées les unes des autres, et de l’environnement par le réseau mésoporal du géopolymère. Les propriétés mécaniques et de lixiviation ont aussi été évaluées. / This work is included in the management of radioactive organic liquids research field. The process is based on an emulsification of organic liquid in an alkali silicate solution allowing the synthesis of a geopolymer matrix. The first part of this work consists in carrying out a screening on different organic liquids. A model system representative of the various oils and a geopolymer reference formulation are then defined. The second part deals with the structuration of the organic liquid/geopolymer structuration, from the mixture of the reactants to the final material. It aims at determining the phenomena allowing the synthesis of a homogeneous composite. The last two parts aim at characterizing the composite by studying its structure (chemical structure, porosity of the geopolymer and dispersion of the oil) and its properties with respect to the application to the immobilization of radioactive waste. Unlike calcium silicate-based cementitious matrices, the structure of the geopolymer is not affected by the chemical nature of the organic liquids. Only acid oils inhibit or slow down the geopolymerization reaction. In order to obtain a homogeneous material, the presence of surfactant molecules is necessary. The emulsion stabilization mechanism at the base of the process is relying on a synergy between the surfactant molecules and the aluminosilicate particles present in the geopolymer paste. The kinetics (chemical and mechanical) of the geopolymerization are not impacted by the presence of oil or surfactants. Only an increase in the viscoelastic moduli and the elastic character of the pastes can be observed. This difference in rheological behavior is mainly due to the presence of surfactant. The structure of the matrix is identical to that of a pure geopolymer of the same formulation. The organic liquid is dispersed in spherical inclusions whose radius is between 5 and 15 μm. These droplets are separated from each other, and from the environment by the mesoporous network of the geopolymer. Mechanical and leaching properties were also evaluated.

Geopolymer cements present a unique opportunity to make concrete binders almost entirely out of waste stream materials. Geopolymers made from fly ash, a waste product of coal power generation, as the aluminosilicate source and caustic activating solution were the focus of this study. However, the use of waste stream materials presents many challenges. One major stumbling block is that fly ash is inherently variable in composition and difficult to comprehensively characterize. The purpose of this work was to clarify the relationship between fly ash composition and reactivity in geopolymer cements. Ten fly ashes comprising a wide compositional spectrum were selected for the study and were characterized using quantitative x-ray diffraction and multispectral image analysis (MSIA) of x-ray maps coupled with point compositional analysis. The fly ashes were mixed into geopolymer mortars to determine their reactivity when activated as geopolymers. I hypothesized that the fly ashes that performed well under geopolymer formation conditions would have similarities in the glassy phases identified in them. The fly ashes that resulted in geopolymers with high compressive strengths did have several glassy phases in common. The phases were typically high in calcium, high in silicon, and somewhat low in aluminum. To determine whether the common phases were soluble and therefore likely to be dissolved, a dissolution method was used in which fly ash was mixed with concentrated caustic solution and continuously agitated; after 7 d and 28 d, the solid residues from the dissolution were studied using MSIA. The results showed that most of the glassy phases hypothesized to react were reactive, although the results were somewhat complex due to the heterogeneity of fly ash. The MSIA method proposed in previous work was further developed through this study, and a new way of selecting the training classes for phase composition assignment in the images was proposed. / text

The paper evaluates the contribution of newly developed thermally conductive geopolymer (TCG) in high temperature energy thermal storage (HTTES). The work contains a review of energy storage principles with emphasis on storage in the form of heat. Evaluation of the benefits of the thermally conductive geopolymer was carried out by mathematical modeling. Both experiments and modeling itself progressed from simple to more complex. It was documented of knowledge and instrumentation experiments and their evaluation. Thanks to the mathematical modeling experiments are analyzed with simple rock samples, medium-sized experiment with a block of granite with artificial fracture filled by TCG to the actual prototype of thermal energy storage. It was demonstrated positive impact of TCG on distribution of heat in the storage core. The acquired knowledge was used to extrapolate the results and to predict accumulation options of medium-sized storage.

Made available in DSpace on 2015-05-08T14:59:52Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1300138 bytes, checksum: a02f160bb7ecd6feb685d3b961a96e97 (MD5) Previous issue date: 2009-03-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Known since the 70´s, geopolymers are excellent chemical, mechanical and thermal performance materials. Although they have mostly been used as coatings in many of these applications, the number of studies on adhesion mechanisms of geopolymers is considerably less than the use of their properties. The main objective of this work is to evaluate resistance to single joint with alkali-activated adhesives from metakoalinite (MK) and soils calcinated (SC) as precursors using the sodium and potassium silicate as activators in aluminum bonded joints. / Os geopolímeros são materiais com excelentes propriedades químicas, mecânicas e térmicas, conhecidos desde anos 70. Mesmo sendo amplamente utilizados como revestimento, esses materiais ainda não tiveram suas propriedades adesivas devidamente estudadas. Este trabalho tem como objetivo avaliar a resistência ao cisalhamento das juntas coladas com adesivos alcalinamente ativados a partir dos precursores Metacaulinita (MK) e Solo Calcinado (SC) utilizando como ativador o silicatos de sódio e potássio em substratos de alumínio.

Cette étude a pour objectif d'améliorer les connaissances sur l'effet des irradiations sur le comportement des géopolymères vis-à-vis du dégagement de dihydrogène et de la tenue générale du matériau afin de les envisager comme une solution alternative aux matrices d'enrobage cimentaires usuelles pour certains déchets nucléaires. A l'aide de diverses techniques de caractérisation du géopolymère (adsorption d'azote, DSC basse température, spectroscopie IRTF et RMN 1H) et au moyen d'irradiations de simulation (gamma, ions lourds), il a été montré que toute l'eau présente au sein du géopolymère était radiolysable et qu'il existait un effet du confinement sur la radiolyse de l'eau sous irradiation à faible TEL, dû probablement à des transferts d'énergie efficaces de la matrice solide vers la solution interstitielle. Trois régimes de production de dihydrogène ont été identifiés en fonction de la dose selon la concentration de dioxygène dissous et l'accumulation de dihydrogène dans la matrice géopolymère. La bonne tenue mécanique du géopolymère a été démontré jusqu'à 9 MGy en irradiation gamma et serait dû à sa grande stabilité sous irradiation. Ceci s'expliquerait par la recombinaison rapide des défauts observés par spectroscopie RPE. Cependant, des cristallisations de phases ont été révélées lors d'irradiations avec des ions lourds, pouvant induire une certaine fragilisation du réseau du géopolymère sous irradiation alpha. L'ensemble des résultats a permis d'appréhender la phénoménologie au sein d'un colis de déchets en conditions de stockage. / This study aims to improve knowledge about the radiation effect on geopolymer behavior in terms of dihydrogen release and general strength in order to consider them as an alternative to usual nuclear waste cementitious coating matrices. Using various characterization techniques (nitrogen adsorption, low temperature DSC, FTIR and 1H NMR spectroscopy) and by means of simulation irradiations (gamma, heavy ions), it has been shown that all the water present in the geopolymer could be radiolyzed and that there was a confinement effect on the water radiolysis under low LET irradiation, probably due to efficient energy transfers from the solid matrix to the interstitial solution. Three dihydrogen production rates have been identified with the absorbed dose, depending on the concentration of dissolved dioxygen and the dihydrogen accumulation in the geopolymer matrix. The good mechanical strength of the geopolymer has been shown up to 9 MGy under gamma irradiation and is due to its high stability under irradiation. This could be explained by the fast recombination of the defects observed by EPR spectroscopy. However, phase crystallization was revealed during irradiation with heavy ions, which may induce some weakening of the geopolymer network under alpha irradiation. The overall results helped to understand the phenomenology in a waste package under storage conditions.

Emission of carbon dioxide gas has been a source of major concern for the construction industry. To curb this emission, geopolymer concrete has been deemed as a potential alternative in the recent studies. Previous research also indicates that silica and fibers provide strength benefits to ordinary Portland cement concrete OPC. This study was undertaken to recognize the benefits of adding silica and basalt fibers in Class F fly ash based geopolymer concrete and comparing it with OPC concrete. One OPC and four Geopolymer mixtures were prepared. The results show a tremendous potential of using geopolymer concrete in place of OPC concrete with Nano silica proving to be the most advantageous. Nano silica provided 28% increase in compressive strength, 8% increase in resistivity when compared with normal Fly ash based geopolymer concrete. The SEM analysis of geopolymer concrete indicates that nano silica improved the compactness of concrete providing a dense microstructure.

The ability of alumino-silicate systems to immobilize hazardous compounds has been investigated since 1990s. The aim of this work is to develope alumino-silicate system (matrix) based on industrial waste products with ability to immobilize hazardous compounds (heavy metals). This ability of the matrix was confirmed by leaching tests based on the law 294/2005 Sb. Concentration of heavy metals in leachates was determined by ICP-MS method. Alumino-silicate system prepared in this work consists of high-temperature fly ash and blast furnace slag activated by mixture of alkaline activators (hydroxide and water glass). Matrixes were characterized by suitable analytic methods (XRD, SEM, FT-IR, DTA-TGA-EGA). The same analytic methods were used to describe the mechanism of immobilization of selected elements (Ba, Cu, Pb) in prepared systems.

abstract: Nanostructured zeolites, in particular nanocrystalline zeolites, are of great interest due to their efficient use in conventional catalysis, separations, and emerging applications. Despite the recent advances, fewer than 20 zeolite framework types have been synthesized in the form of nanocrystallites and their scalable synthesis has yet to be developed and understood. Geopolymers, claimed to be “amorphous cousins of zeolites”, are a class of ceramic-like aluminosilicate materials with prominent application in construction due to their unique chemical and mechanical properties. Despite the monolith form, geopolymers are fundamentally nanostructured materials and contain zeolite nanocrystallites. Herein, a new cost-effective and scalable synthesis of various types of nanocrystalline zeolites based on geopolymer chemistry is presented. The study includes the synthesis of highly crystalline discrete nanorods of a CAN zeolite framework structure that had not been achieved hitherto, the exploration of the Na−Al−Si−H2O kinetic phase diagram of hydrogels that gives SOD, CAN and FAU nanocrystalline zeolites, and the discovery of a unique formation mechanism of highly crystalline nanostructured FAU zeolite with intermediate gel products that possess an unprecedented uniform distribution of elements. This study demonstrated the possibility of using high-concentration hydrogels for the synthesis of nanocrystalline zeolites of additional framework structures. Moreover, a comprehensive study on nanostructured FAU zeolites ion-exchanged with Ag+, Zn2+, Cu2+ and Fe2+ for antibacterial applications is presented, which comprises metal ion release kinetics, antibacterial properties, and cytotoxicity. For the first time, superior metal ion release performance was confirmed for the nanostructured zeolites compared to their micron-sized counterparts. The metal ion-exchanged FAU nanostructured zeolites were established as new effective antibacterial materials featuring their unique physiochemical, antibacterial, and cytotoxic properties. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2019

No / Degrading infrastructure and applications of structural demolition create tremendous amounts of construction and demolition waste (CDW) all around the world. To address this issue in an effective way, recycling CDW in a most appropriate way has become a global concern in recent years. To this end, this study focused on the utilization of CDW-based materials such as hollow brick (HB), red clay brick (RCB), roof tile (RT), glass (G) and concrete (C) in the production of geopolymer mortars. These materials were first collected from an urban transformation area and then subjected to an identical two-step crushing-milling procedure to provide sufficient fineness for geopolymerization. To investigate the influence of blast furnace slag (S) addition to the CDW-based mixtures, 20% S substituted mixture designs were also made. Fine recycled concrete aggregates (FRCA) obtained from crushing and sieving of the waste concrete were used as the aggregate. A series of mixtures were designed using different proportions of three distinct alkali activators such as sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and calcium hydroxide (Ca[OH]2). To improve their applicability, the mixtures were left to cure at room temperature rather than the heat curing which is frequently applied in the literature. After 28 days of ambient curing, the 100% CDW-based geopolymer mortar activated with three different activators reached a compressive strength of 31.6 MPa, whereas the 20% S substituted geopolymer mortar achieved a compressive strength of 51.9 MPa. While the geopolymer mortars activated with only NaOH exhibited poor performance, it was found that the use of Na2SiO3 and Ca(OH)2 improved the compressive strength. Main geopolymerization products were related to NASH, CASH, and C(N)ASH gel formations. Our results demonstrated that mixed CDW-based materials can be employed in the manufacturing geopolymers, making them potential alternatives to Portland cement-based systems by being eco-friendly, energy-efficient, and comparable in compressive strength. / This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100.