A fundamental theoretical and experimental study on calcium sulphate scale formation in hydrometallurgical solutions containing various minerals was conducted. A new database for the Mixed Solvent Electrolyte (MSE) model of the OLI Systems® software was developed through fitting of existing literature data such as mean activity, heat capacity and solubility data in simple binary and ternary systems. Moreover, a number of experiments were conducted to investigate the chemistry of calcium sulphate hydrates in laterite pressure acid leach (PAL) solutions, containing Al2(SO4)3, MgSO4, NiSO4, H2SO4, and NaCl at 25–250ºC. The database developed, utilized by the MSE model, was shown to accurately predict the solubilities of all calcium sulphate hydrates (and hence, predict scaling potential) in various multicomponent hydrometallurgical solutions including neutralized zinc sulphate leach solutions, nickel sulphate–chloride solutions of the Voisey’s Bay plant, and laterite PAL solutions over a wide temperature range (25–250°C). The stability regions of CaSO4 hydrates (gypsum, hemihydrate and anhydrite) depend on solution conditions, i.e., temperature, pH and concentration of ions present. The transformation between CaSO4 hydrates is one of the common causes of scale formation. A systematic study was carried out to investigate the effect of various parameters including temperature, acidity, seeding, and presence of sulphate/chloride salts on the transformation kinetics. Based on the results obtained, a mechanism for the gypsum–anhydrite transformation below 100°C was proposed. A number of solutions for mitigating calcium sulphate scaling problems throughout the processing circuits were recommended: (1) operating autoclaves under slightly more acidic conditions (~0.3–0.5 M acid); (2) mixing recycled process solutions with seawater; and (3) mixing the recycling stream with carbonate compounds to reject calcium as calcium carbonate. Furthermore, aging process solutions, saturated with gypsum, with anhydrite seeds at moderate temperatures (~80°C) would decrease the calcium content, provided that the solution is slightly acidic.

Mechanically adaptable elastomer composites are a class of stimuli responsive polymer composites which can reversibly change its mechanical properties when it comes in contact with stimuli like electric field, light, water, solvents, ions and others. Mechanically adaptable composites are mainly inspired from the sea cucumber dermis which has the ability to change the stiffness of its dermis rapidly and reversibly (connecting tissue) when it is immersed in water. In this work, efforts have been made to develop mechano-adaptive elastomer composites using water as stimuli. In such a case, elastomer composite should absorb water significantly, in order to respond quickly to the stimuli. Therefore, as a first step, stable and repeatable water swellable elastomer composites have been developed by blending epichlorohydrin terpolymer (GECO) with an ethylene oxide based hydrophilic polymer resin (GEPO). Two different approaches have been thereafter explored to develop mechano-adapative composites based on the developed water swellable elastomer composite. In the first approach, the solid–liquid phase transition of the absorbed water is used to tune mechanical properties around 0 °C. The solidified absorbed water (ice crystals) below 0 °C, acts as reinforcing filler, enhancing the mechanical properties (hard state). The ice crystals liquefy above 0 °C and plasticize the polymer chain, thereby reducing the mechanical properties (soft state). In the second approach, the polymorphic transition of calcium sulphate (CaSO4) in presence of water/heat have been exploited by dispersing it as filler in the developed water swellable elastomer composite. Mechanical adaptability is realized by the reinforcement caused when the composite is exposed to water treatment process. Further, this mechanical strength (reinforcement) can be brought back to its initial soft state (unreinforced state) by the heat treatment process. This reversible reinforcing and non-reinforcing ability of the calcium sulphate filler is attributed to the differences in polymer–filler interaction, due to the in situ morphology transformation (micro to nano) of the filler particles. This study reveals the possibility of utilizing conventional rubber technology in developing mechanically adaptable composites with an easily accessible stimulus like water. The two strategies explored here present huge opportunities in developing future smart materials.:Contents 1 Introduction 1 1.1 General introduction 1 1.2 Aim and motivation of the work 3 1.3 Scope of the work 5 2 Literature review 7 2.1 Mechanically adaptive polymer composites 7 2.1.1 Mechanical adaptability triggered by different stimuli 7 2.1.2 Water induced mechano-adaptive composites 10 2.1.3 Possible future applications of mechanically adaptive systems 14 2.2 Water absorption in elastomer composites 16 2.2.1 Strategies used for developing water swellable elastomer composites 17 2.2.2 States of water present in the polymers 20 2.2.3 Effect of water absorption on the thermal and mechanical properties 22 2.2.4 Kinetics of diffusion of water in the hydrophilic polymers 24 2.2.5 Application of water swellable elastomer composites 25 2.3 Calcium sulphate and its polymorphic transition 26 3 Experimental 30 3.1 Materials 30 3.1.1 Polymers 30 3.1.2 Fillers 31 3.2 Preparation of rubber composites 32 3.2.1 Compounding and mixing 32 3.2.2 Curing study and molding 34 3.3 Characterization 35 3.3.1 Water swelling studies 35 3.3.2 Thermal analysis (DSC and TGA) 36 3.3.3 Dynamic mechanical analysis (DMA) 36 3.3.4 Stress–strain studies 37 3.3.5 Fourier transform infrared spectroscopy (FTIR) 38 3.3.6 Morphological analysis 39 3.3.7 X-ray diffraction (XRD) 40 3.3.8 Raman spectroscopy 40 4 Results and discussions 42 4.1 Development of novel water swellable elastomer composites based on GECO/GEPO 42 4.1.1 Miscibility of the polymer blend (GECO/GEPO) systems 42 4.1.2 Water absorption behavior of GECO/GEPO blends 49 4.1.3 Effect of water swelling on thermal and mechanical properties 54 4.1.4 Cyclic water swellable characteristics 58 4.2 Thermo-responsive mechano-adaptable composites based on solid–liquid phase transition of absorbed water. 60 4.2.1 Quantitative analysis of in situ formed ice crystals 61 4.2.2 Characterization of the filler (ice crystals) morphology 64 4.2.3 Polymer–filler interaction 68 4.2.4 Mechanical adaptability analysis 71 4.3 Utilization of in situ polymorphic alteration of the filler structure in designing mechanically adaptive elastomer composites 77 4.3.1 Process and conditions for mechanical adaptability 79 4.3.2 Investigation of phase transition characteristics of CaSO4 filler 83 4.3.3 In situ morphology transformation analysis 86 4.3.4 Mechanical adaptability investigations 89 5 Conclusions and outlook 96 5.1 Conclusions 96 5.2 Outlooks 99 6 References 100 7 Appendix 109 8 Abbreviations 111 9 Symbols 114 10 Figures 117 11 Tables 123 12 Publications 124 / Mechanisch-adaptive Elastomer-Verbundwerkstoffe sind eine Klasse von stimuli-responsiven Polymer-Verbundwerkstoffen, welche ihre mechanischen Eigenschaften reversibel verändern können, wenn sie mit Stimuli, wie z.B. einem elektrischem Feld, Licht, Wasser, Lösungsmitteln oder Ionen angeregt werden. Mechanisch anpassbare Verbundwerkstoffe sind hauptsächlich von der Haut der Seegurke inspiriert, welche in der Lage ist, die Steifigkeit ihrer Dermis (Bindegewebe) beim Eintauchen in Wasser schnell und reversibel zu verändern. Ziel dieser Arbeit war, mechanisch-adaptive Elastomer-Verbundwerkstoffe zu entwickeln, welche Wasser als Stimulus nutzen. Für diese Anwendung sollte das Elastomermaterial Wasser in einer signifikanten Menge aufnehmen können, um schnell auf den externen Reiz zu reagieren. Daher wurden in einem ersten Schritt stabile und reversibel wasserquellbare Elastomerblends hergestellt, indem ein Epichlorhydrin-Terpolymer (GECO) mit einem hydrophilen Polymerharz auf Ethylenoxidbasis (GEPO) verschnitten wurde. In der Folge wurden zwei verschiedene Ansätze zur Entwicklung mechanisch-adaptiver Verbundwerkstoffe auf Basis des so entwickelten wasserquellbaren Elastomerkomposites verfolgt. Beim ersten Ansatz wird der Fest-Flüssig-Phasenübergang des aufgenommenen Wassers genutzt, um die mechanischen Eigenschaften im‚ Bereich von 0 °C einzustellen. Das erstarrte absorbierte Wasser (Eiskristalle) wirkt unter 0 °C als verstärkender Füllstoff und verbessert die mechanischen Eigenschaften (harter Zustand). Die Eiskristalle verflüssigen sich oberhalb von 0 °C und plastifizieren das Polymer, wodurch die mechanische Verstärkung wieder herabgesetzt wird (weicher Zustand). Im zweiten Ansatz wurde der polymorphe Übergang von Calciumsulfat (CaSO4) in Gegenwart von Wasser bzw. Wärme genutzt, indem es als Füllstoff in einem wasserquellbaren Elastomerkomposit dispergiert wurde. Die mechanische Adaptierbarkeit wird durch die mechanische Verstärkung erreicht, welche bei der Wasseraufnahme des Verbundwerkstoffes entsteht. Anschließend kann diese mechanische Festigkeit (Verstärkung) durch eine Wärmebehandlung wieder in ihren ursprünglichen weichen Zustand (unverstärkter Zustand) zurückgeführt werden. Diese reversible Schaltbarkeit der Verstärkungswirkung des Calciumsulfat-Füllstoffes wird auf die Unterschiede in der Polymer-Füllstoff-Wechselwirkung aufgrund der Transformation der in situ-Morphologie (Mikro zu Nano) der Füllstoffpartikel zurückgeführt. Die vorliegende Arbeit verdeutlicht die Möglichkeiten des Einsatzes konventioneller Kautschuktechnologie bei der Entwicklung mechanisch anpassbarer Komposite mit einem leicht zugänglichen Stimulus wie Wasser. Die beiden hier untersuchten Strategien eröffnen enorme Perspektiven bei der Konzeption zukünftiger intelligenter Materialien.:Contents 1 Introduction 1 1.1 General introduction 1 1.2 Aim and motivation of the work 3 1.3 Scope of the work 5 2 Literature review 7 2.1 Mechanically adaptive polymer composites 7 2.1.1 Mechanical adaptability triggered by different stimuli 7 2.1.2 Water induced mechano-adaptive composites 10 2.1.3 Possible future applications of mechanically adaptive systems 14 2.2 Water absorption in elastomer composites 16 2.2.1 Strategies used for developing water swellable elastomer composites 17 2.2.2 States of water present in the polymers 20 2.2.3 Effect of water absorption on the thermal and mechanical properties 22 2.2.4 Kinetics of diffusion of water in the hydrophilic polymers 24 2.2.5 Application of water swellable elastomer composites 25 2.3 Calcium sulphate and its polymorphic transition 26 3 Experimental 30 3.1 Materials 30 3.1.1 Polymers 30 3.1.2 Fillers 31 3.2 Preparation of rubber composites 32 3.2.1 Compounding and mixing 32 3.2.2 Curing study and molding 34 3.3 Characterization 35 3.3.1 Water swelling studies 35 3.3.2 Thermal analysis (DSC and TGA) 36 3.3.3 Dynamic mechanical analysis (DMA) 36 3.3.4 Stress–strain studies 37 3.3.5 Fourier transform infrared spectroscopy (FTIR) 38 3.3.6 Morphological analysis 39 3.3.7 X-ray diffraction (XRD) 40 3.3.8 Raman spectroscopy 40 4 Results and discussions 42 4.1 Development of novel water swellable elastomer composites based on GECO/GEPO 42 4.1.1 Miscibility of the polymer blend (GECO/GEPO) systems 42 4.1.2 Water absorption behavior of GECO/GEPO blends 49 4.1.3 Effect of water swelling on thermal and mechanical properties 54 4.1.4 Cyclic water swellable characteristics 58 4.2 Thermo-responsive mechano-adaptable composites based on solid–liquid phase transition of absorbed water. 60 4.2.1 Quantitative analysis of in situ formed ice crystals 61 4.2.2 Characterization of the filler (ice crystals) morphology 64 4.2.3 Polymer–filler interaction 68 4.2.4 Mechanical adaptability analysis 71 4.3 Utilization of in situ polymorphic alteration of the filler structure in designing mechanically adaptive elastomer composites 77 4.3.1 Process and conditions for mechanical adaptability 79 4.3.2 Investigation of phase transition characteristics of CaSO4 filler 83 4.3.3 In situ morphology transformation analysis 86 4.3.4 Mechanical adaptability investigations 89 5 Conclusions and outlook 96 5.1 Conclusions 96 5.2 Outlooks 99 6 References 100 7 Appendix 109 8 Abbreviations 111 9 Symbols 114 10 Figures 117 11 Tables 123 12 Publications 124

Användningen av biobränslen har ökat för att minska utsläppen från fossila bränslen. Biobränslen kan dock leda till beläggningar inuti injektorn, vilka påverkar fordonets  körbarhet. Den mest trodda hypotesen bakom beläggningsbildningen är att förorening av motorolja i bränslesystemet leder till bildning av kalciumsulfatkristaller som mjuka partiklar fäster till. Dessutom påstås det att temperaturen har en signifikant påverkan på beläggningsbildningen. För att ställa om till mer förnyelsebara bränslen krävs mer förståelse bakom beläggningarnas mekanism. Därför var syftet med denna studie att undersöka mekanismen bakom interna injektorbeläggningar med en nydesignad rigg i laboratorieskala för att få en djupare förståelse av mekanismen, och i synnerhet rollen av kalciumsulfat och temperatur. Syftet uppnåddes genom att dela upp det experimentella arbetet i två delar:a) Köra riggen med testbränslen följt av analyser av de körda proverna med huvudsakligen SEM-EDX och FTIR, för att förstå rollen av temperatur och motorolja för beläggningarnas mekanism. b) Löslighetsstudier av kalciumsulfat för att förstå rollen av kalciumsulfat för beläggningarnas mekanism. Resultaten visade att den nydesignade testriggen fungerade bra med resultat som överensstämde med litteratur och erbjöd repeterbarhet. Därmed rekommenderas riggen för framtida studier av interna injektorbeläggningar. En djupare förståelse av mekanismen bakom interna injektorbeläggningar uppnåddes framgångsrikt. För första gången utfördes en FTIR och SEM-EDX studie över en temperaturgradient, vilket gjorde det möjligt att se starttemperaturen för olika reaktioner och identifiera beläggningar i olika temperaturintervall. Det visades att beläggningsbildningen var temperaturberoende med olika typer av beläggningar i olika temperaturintervall. Vid temperaturer under 100°C var zinksulfat och oreagerat metallkarboxylat de dominanta ämnena. Över 100°C ändrade metallkarboxylatet form och blev mer koncentrerat medan koncentrationen av zinksulfat minskade. Dessutom visades det att kalciumsulfat bildades i stor utsträckning när temperaturen översteg 100°C. Temperaturstudien och resultaten är unika och okända i litteraturen. Ostwald-mognad har föreslagits som en möjlig mekanism i litteraturen men visade sig vara osannolik. Upplösningen av kalciumsulfat av motoroljans additiv följt av utfällning i bränslet visade sig vara en mer sannolik mekanism. Det visades också att tvålbeläggningar främjade beläggningsbildning av kalciumsulfatkristaller, vilket överensstämmer med fältobservationer då de vanligtvis samexisterar. / The use of biofuels has increased to reduce the emissions from fossil fuels. However, the use of biofuels results in deposit formation inside the injector, which leads to issues with the drivability of the vehicle. The most believed hypothesis behind the deposit formation is that engine oil contamination in the fuel system leads to formation of calcium sulphate crystals that soft particles adhere to. Moreover, temperature is claimed to have a significant effect on the deposit formation. To ease the shift towards more renewable fuels, more understanding behind the deposit mechanism is needed. Therefore, this study aimed to investigate the mechanism behind internal injector deposits with a newly designed lab scale rig to get a deeper understanding of the mechanism, and especially the role of calcium sulphate and temperature. The aim was achieved by dividing the experimental work into two parts:a) Running the test-rig with test fuels followed by analyses of the samples with mainly SEM-EDX and FTIR, to understand the role of temperature, and engine oil for the deposit mechanism. b) Solubility studies of calcium sulphate to understand the role of calcium sulphate for the deposit mechanism. The results showed that the newly designed test rig worked well, where the results were consistent with literatureand offered repeatability. Thereby, the rig is recommended for future studies of internal injector deposits. A deeper understanding of the mechanism behind the internal injector deposits was successfully achieved. For the first time, a FTIR and SEM-EDX study was performed over a temperature gradient, which made it possible to see the onset temperature for different reactions and to identify deposits in different temperature ranges. It was showed that the deposit formation was temperature dependent with different types of deposits in different temperature ranges. At temperatures below 100°C, zinc sulphate and unreacted metal carboxylates were the dominant species. Above 100°C, the metal carboxylates changed form and became more concentrated while the concentration of zinc sulphate decreased. Moreover, calcium sulphate showed to be formed to a large extent when the temperature exceeded 100°C. The temperature study and results are unique and unknown in the literature. Ostwald ripening has been proposed as a possible mechanism in the literature but turned out to be unlikely. The dissolution of calcium sulphate by engine oil additives followed by precipitation in the fuel showed to be a more likely mechanism. It was also shown that soap deposits promoted the deposit formation of calcium sulphate crystals, which is in line with the field observations since they normally coexist.

Made available in DSpace on 2017-07-25T19:31:01Z (GMT). No. of bitstreams: 1 Shivelly Galetto.pdf: 3409300 bytes, checksum: 3a6b231c97f2d660f8aa073c74bf43f9 (MD5) Previous issue date: 2016-12-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The main objective of this work was to evaluate the efficiency of phosphate fertilization influenced by the application of agricultural gypsum for wheat and soybean crops under notillage system. For this, two experiments were carried out in the field and two in a greenhouse.The experiments in the field were installed in October 2013 in the municipality of Ponta Grossa – PR, in two Oxisols with different textural classes: a Red Oxisol (LV) clay texture and a Red-Yellow Oxisol (LVA) sandy-loam texture. The experimental design of the two soils was a randomized complete block in a split-plot, with three replications. In the plots,four rates of P (0, 30, 60 and 90 kg P2O5 ha-1) in the form of triple superphosphate (TSP) were applied at sowing and, in the subplots, four rates of agricultural gypsum (0, 2, 4 and 6 t ha-1),on the soil surface, before soybean sowing. In both soils, the immediate effects of treatments with P2O5 and gypsum in the soybean crop were evaluated. The effects of treatments on the succession of wheat (2014) – soybean (2014–15) were also evaluated in the clay Red Oxisol.In this case, in each crop (soybean and wheat), the same rates of P P2O5, in the form of TSP,were applied at the sowing, and the residual effect of the application of agricultural gypsum was evaluated. The experiments in greenhouse were carried out with wheat and soybean crops in undisturbed columns of soil. The PVC columns were taken from the Red Oxisol used in the field experiment. The experimental design used for each culture was in randomized blocks in a 3 × 2 factorial scheme, with four replications. The treatments were: control, agricultural gypsum and pure CaSO4.2H2O, without and with application of P2O5, in the form of TSP. The rate of agricultural gypsum and pure CaSO4.2H2O was corresponding to 6 t ha-1 and the rate of P was 90 kg ha-1 of P2O5. In all experiments, soil chemical attributes, plant attributes (nutrient extraction and dry mass production) and root attributes were evaluated. In the field experiments, nutritional diagnosis, nutrient exportation and grain yield of the crops were also evaluated. The P utilization efficiencies were calculated for wheat and soybean crops. In general, it was observed that, in the short term, gypsum did not influence P use efficiency (PUE) by soybean cultivated in RL and BL, but the residual effect of gypsum increased PUE by the rate of 5 t ha-1, and also the PUE of the soybean, up to the rate of 4.3 t ha-1. Adjusting the gypsum and P at sowing rates appropriately, it was possible to obtain high grain yields of wheat (above 4,5 t ha-1) and soybean (above 4 t ha-1) and provides economy of the phosphate fertilizer. However, it has been observed in all years that the highest rate of P at sowing (90 kg ha-1 of P2O5) associated with the highest rate of agricultural gypsum (6 t ha-1), in soils that had high levels of P, impaired root growth and wheat and soybean grain yields. In the experiments in greenhouse, it was verified that the application of pure CaSO4.2H2O and with 90 kg ha-1 of P2O5 at the sowing promoted improvement in the root system and in the production of wheat dry mass, and did not interfere in the soybean crop. These results have shown that the use of gypsum can increase PUE and improve the productive performance of wheat and soybean plants. However, the use of high rates of P at sowing associated with high rates of agricultural gypsum should be carried out with caution, especially in soils that already have adequate levels of available P, so that crop performance do not be impaired. / O objetivo principal deste trabalho foi avaliar a eficiência da adubação fosfatada influenciada pela aplicação de gesso agrícola para as culturas de trigo e soja, em sistema plantio direto. Para isso, foram realizados dois experimentos em campo e dois em ambiente protegido. Os experimentos no campo foram instalados em outubro de 2013 no município de Ponta Grossa – PR, em dois solos com diferentes classes texturais: um Latossolo Vermelho (LV) textura argilosa e um Latossolo Vermelho-Amarelo (LVA) textura franco-arenosa. O delineamento experimental foi em blocos completos ao acaso, no esquema de parcelas subdivididas, com três repetições. Nas parcelas, foram aplicadas, no sulco de semeadura, quatro doses de P (0,30, 60 e 90 kg P2O5 ha-1) na forma de superfosfato triplo (SFT) e, nas subparcelas, foram empregadas doses de gesso agrícola (0, 2, 4 e 6 t ha-1), antes da semeadura da soja. Em ambos os solos, foram avaliados os efeitos imediatos dos tratamentos com P2O5 e gesso na cultura da soja. No Latossolo Vermelho argiloso também foram avaliados os efeitos dos tratamentos na sucessão de culturas trigo (2014) – soja (2014–15). Nesse caso, em cada cultivo de soja e trigo, as mesmas doses de P2O5, na forma de SFT, foram aplicadas no sulco de semeadura, sendo avaliado o efeito residual da aplicação de gesso agrícola. Os experimentos em ambiente protegido foram realizados com as culturas de trigo e soja, em colunas indeformadas de solo. As colunas em PVC foram retiradas do Latossolo Vermelho utilizado no experimento de campo. O delineamento experimental utilizado, para cada cultura, foi em blocos ao acaso em esquema fatorial 3 × 2, com quatro repetições. Os tratamentos foram: controle, gesso agrícola e CaSO4.2H2O puro, sem e com aplicação de P2O5, na forma de SFT. A dose de gesso agrícola e de CaSO4.2H2O puro foi correspondente a 6 t ha-1 e a dose de P foi de 90 kg ha-1 de P2O5. Em todos os experimentos foram avaliados atributos químicos de solo, atributos de planta (extração de nutrientes e produção de massa seca) e atributos de raízes. Nos experimentos no campo foram ainda avaliados a diagnose nutricional, a exportação de nutrientes e o rendimento de grãos das culturas. As eficiências de aproveitamento do P também foram calculadas paras culturas de trigo e soja. De maneira geral, observou-se que,em curto prazo, o gesso não influenciou a eficiência de uso do P (EUP) pela soja cultivada nos solos LV e LVA, mas o efeito residual do gesso aumentou a EUP pela cultura do trigo,até a dose de 5 t ha-1, e também a EUP da soja, até a dose de 4,3 t ha-1. Ajustando-se adequadamente as doses de gesso e as doses de P na semeadura, além da economia do fertilizante fosfatado, foi possível obter altas produtividades de grãos de trigo (acima de 4,5 t ha-1) e soja (acima de 4 t ha-1). Porém, observou-se, em todos os anos, que a dose mais elevada de P na semeadura (90 kg ha-1 de P2O5) associada à dose mais elevada de gesso agrícola (6 t ha-1), em solos que continham altos teores de P, prejudicou o crescimento radicular e o rendimento de grãos de trigo e soja. Nos experimentos em ambiente protegido, constatou-se que a aplicação de CaSO4.2H2O puro juntamente com 90 kg ha-1 de P2O5 na semeadura promoveu melhoria no sistema radicular e na produção de massa seca da parte área de plantas de trigo, e não interferiu na cultura da soja. Esses resultados comprovaram que a utilização de gesso pode aumentar a EUP e melhorar o desempenho produtivo das plantas de trigo e soja. Porém, a utilização de altas doses de P na semeadura associada com altas doses de gesso agrícola deve ser realizada com cautela, principalmente em solos que já apresentem teores adequados de P disponível, para que o desempenho das culturas não seja prejudicado.

Les propriétés mécaniques des ciments hydratés nécessitent d'être optimisées suivant la nature des ciments produits. Parmi les facteurs d'optimisation, l'ajout de sulfate de calcium destiné à réguler la réactivité de l’aluminate tricalcique (C3A), en quantité et en qualité, dans le ciment est un paramètre primordial. Enjeu industriel majeur, cette notion d'Optimum de sulfatage mérite aujourd'hui du fait de l'avancement des connaissances sur les mécanismes d'hydratation de chacune des phases du ciment qu'une étude lui soit entièrement consacrée. La démarche adoptée pour répondre à cette problématique a été l’étude de système simple que l’on a compliqué petit à petit. L’évolution de l’hydratation du ciment, de la porosité et des propriétés mécaniques du ciment ont été déterminés à différentes échéances. Le premier système étudié était le mélange C3S/gypse, l'objectif était de déterminer s'il existait un effet optimal du sulfate de calcium sur l'hydratation et les résistances mécaniques du C3S tel que présenté dans la littérature [1]. Les résultats ont montré qu’il n’existait pas d’optimum de sulfatage dans le système C3S/gypse mais qu’il existait un effet spécifique du sulfate de calcium sur l’hydratation et les propriétés mécaniques du C3S. L’adsorption des sulfates à la surface des C-S-H serait à l’origine de la modification du processus de germination croissance des C-S-H qui aurait pour conséquence l’augmentation du degré d’hydratation du C3S et des résistances en compression. Le deuxième système étudié était le clinker biphasique C3S/C3A cobroyé avec du semi-hydrate et avec du gypse. Un optimum de sulfatage a bien été observé, cet optimum se décale avec le temps vers les fortes teneurs en sulfate comme dans les cimenteries. L’optimum de sulfatage a été constaté lorsque l’hydratation du C3S, pendant la période accélérée, a lieu simultanément ou légèrement avant le pic exothermique dû à la forte dissolution du C3A et à la précipitation d’Afm. Il a été montré que la présence d’AFm pendant la période accélérée de l’hydratation du C3S, serait à l’origine de la modification observée de la microstructure de la pâte de ciment : la porosité augmente avec l’ajout du sulfate de calcium mais l’assemblage des hydrates est plus dense / The mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whether there was an optimal effect of calcium sulfate on hydration and mechanical strength of C3S as presented in the literature [1]. The results showed there was not optimum sulfate in the C3S/gypsum system but there was a specific effect of calcium sulfate on the hydration and the mechanical properties of C3S. The sulfate adsorption on the C-S-H surface is the cause of the change nucleation and growth process of C-S-H. This has resulted in increasing hydration degree of C3S and compressive strength. The second system studied was biphasic clinker C3S/C3A ground with hemi-hydrate and gypsum. An optimum sulfate has been observed, which move out with time to high rate of sulfate. The optimum sulfate was observed when the hydration of C3S, during the accelerated period, takes place simultaneously or slightly before the exothermic peak due to the high dissolution of C3A and precipitation of AFm. We showed the presence of AFm during the accelerated hydration of C3S, is the cause of the microstructure modification in the cement paste: the porosity increases with calcium sulfate addition but the hydrate assembly is more dense.

The object of the thesis is a description of preparation process, realization and subsequent treatment of floors based on calcium sulphate, including problems related to the issue. The aim of the work is to closely acquaint the reader with methods used in diagnostics of flooring failures and defects in the housing and civic construction, including practical applications of these methods on real structures. The work also includes experimental analysis of a real floor construction during local load effect.

The growth of ornamental plant market in Brazil is remarkable nowadays with strong participation of Northeast region, particularly in Alagoas State on the commercialization of tropical flowers. Taking into account this economic aspect, it is of great importance for the productive chain of ornamental species the study of aspects of post harvest activities. Alpinia purpurata (Viell) K. Schum (Zingiberaceae) which occupies the second place in economic importance amongst tropical flowers. It is the main flower for growing and harvesting. The main objective of this research programme is to study the different aspects of Alpinia post-harvesting: (1) time of harvesting and cut of the basis of the stems, and (2) the use of solutions of pulsing ; and/or maintenance of the floral stem by using: (2.1.) biocide compounds and pH of the solution; (2.2) carbohydrates and carbohydrates plus biocides; (2.3) anti-ethylene compounds and antiethylene compounds plus carbohydrates; (2.4) elements as calcium and silicon; and (2.5) senescence retarding growth regulators. It was evaluated the influence of these factors in the water relations, quality and longevity of the stems. Six experiments were carried out in the laboratory (CECA) of the Federal University of Alagoas. In the first experiment, the stems were harvested in three different times and they were cut periodically on their basis. In the second experiment different biocide substances were tested (8- hydroxyquinoline sulphate, aluminum sulphate, salicilic acid and sodium hipocloride) associated to pH variation of the maintenance solution. In the third experiment the stems received sucrose solutions pulsing from 2 to 20% for 12, 24 and 48 hours, following by maintenance in distilled water or in solution of 8- hidroxikinolin (HQS). The fourth experiment comprised three times of exposition (30, 60 and 120 min) with STS 1mM following by the presence or absence of pulsing in sucrose 20% for 12 hours. In the fifth experiment it was evaluated the effect of the addition of Ca (calcium sulphate 50 and 100mM), Si (sodium silicate 1,25 and 2,50 mM) and Ca+Si in maintenance solution. In the sixth experiment the stems were submitted to gibberellins, solutions (GA3), 10, 30 and 60 μm and cytokinin (benzyladenine 6-BA), 10, 20 and 100μm in 24 hours pulsing under continuous light. In all experiments the fresh biomass and the quality (scale of values) of the stems were determined daily or every two days until the end of the experiment. The amount of water was also determined for the floral bracts and dry biomass. The experiments were analised by completely randomized design and the data submitted to the variance analysis, test of averages and , when necessary, to the regression analysis. It was observed that the stems harvested at the end of the afternoon had shown greater commercial value; however, the regular cuts of the basis of the stems reduced their longevity. The use of HQS provided greater durability and humidity of the stems. On the other hand the other biocides did not improve the quality when compared to the control. The reduction of the pH by using citric acid did not interfere with the studied parameters. The use of sucrose in pulsing was only effective when the stems had been kept in distilled water. In this case the concentration sucrose of 20% for 12 hours showed better results. Silver thiosulphate when in pulsing for 30 minutes produced an increase of water contents and for 60 minutes or plus, or when addition of sucrose, caused dehydration of the stems. The only use of calcium sulphate or in association with sodium silicate in maintenance solution caused high improvement of the quality of the stems in comparison to the control and sodium silicate treatment. The use of cytokinin and gibberellins even considering it improved the water contents of the stems did not affect the commercial durability of them. / É notável o crescimento do mercado de plantas ornamentais no Brasil. Com participação efetiva da região Nordeste, destacando-se as exportações de flores tropicais, onde o Estado de Alagoas vem se firmando, com Alpinia purpurata (Viell) K. Schum (Zingiberaceae) como a principal flor de corte, e que ocupa o segundo lugar em importância econômica dentre as flores tropicais. Levando-se em conta esse aspecto econômico, verifica-se ser de grande importância para a cadeia produtiva desses cultivos, o estudo de aspectos relativos à da pós-colheita. Assim sendo, a presente pesquisa, objetivou estudar diferentes aspectos do manejo pós-colheita dessas flores, testando: (1) hora de colheita e corte da base das hastes, e (2) o uso de soluções de pulsing ; e/ou manutenção das hastes florais - neste caso ainda associado (2.1) a substâncias biocidas com o pH na solução sob controle; (2.2) a carboidratos e carboidratos mais biocidas; (2.3) a substâncias anti-etileno e substâncias anti-etileno mais carboidratos; (2.4) a elementos como cálcio e silício; e (2.5) a fitorreguladores retardantes da senescência. Avaliou-se a influência destes fatores nas relações hídricas, qualidade e longevidade das hastes cortadas, através de seis experimentos em laboratório no Centro de Ciências Agrárias da Universidade Federal de Alagoas (CECA/UFAL). No primeiro experimento, as hastes foram colhidas em três diferentes horários, recebendo durante o período pós-colheita cortes periódicos na base da haste. No segundo experimento, foram testadas substâncias biocidas (Sulfato de 8- hidroxiquinolina, Sulfato de alumínio, Ácido salicílico, Hipoclorito de sódio) associadas à redução ou não do pH. No terceiro experimento as hastes receberam tratamento de pulsing com soluções de sacarose entre 2 e 20%, por períodos de 12, 24 e 48 h, seguidas de manutenção em água destilada ou em solução de 8-hidroxiquinolina (HQS) comparando-se com duas testemunhas (água destilada ou solução de HQS). No quarto experimento, foram testados três tempos de exposição (30, 60 e 120 minutos) a STS 1mM, seguido ou não de pulsing em sacarose a 20%, por 12 horas. No quinto experimento, foram verificados os efeitos da adição de Ca (sulfato de cálcio a 50 e 100mM), Si ( silicato de sódio a 1,25 e 2,50 mM) e Ca+Si em solução de manutenção. No sexto experimento, as hastes foram submetidas a soluções de SILVA, A.T.C. 2006 Manejo pós-colheita de alpinia purpurata (Vieill) K. Schum (zingiberaceae)... xv giberelina (GA3), a 10, 30 e 60 μM e citocinina (benziladenina 6-BA), a 10, 20 e 100 μM em pulsing por 24 horas, sob luz contínua. Em todos os experimentos, a massa fresca e a qualidade (com base em notas) das hastes foram determinadas diariamente, ou a cada 2 dias; no final de cada experimento foram também determinados o conteúdo relativo de água das brácteas florais e a massa seca das hastes. O delineamento utilizado foi o inteiramente casualizado sendo os dados submetidos à análise de variância, teste de médias e, quando necessário, à análise de regressão. As hastes cortadas ao final da tarde tiveram maior durabilidade comercial, porém o corte periódico da base das hastes reduziu sua longevidade. O uso de HQS proporcionou maior durabilidade e hidratação das hastes, sendo que os demais biocidas testados não melhoraram a qualidade. A redução do pH, pelo uso do ácido cítrico, não influenciou nas variáveis estudadas. O uso de sacarose em pulsing só foi efetivo quando as hastes foram mantidas em água destilada, sendo melhor o resultado para a concentração de 20% por 12 horas. O tiossulfato de prata em pulsing por 30 minutos, promoveu um aumento de hidratação, mas desidratou as hastes a 60 minutos ou mais ou quando adicionado à sacarose. O uso de sulfato de cálcio em solução de manutenção e quando associado ao silicato de sódio promoveu elevada melhoria de qualidade das hastes. O uso de citocininas e giberelinas embora tenha melhorado as relações hídricas das hastes não afetou a durabilidade comercial das mesmas.