Dans le domaine de l’isolation thermique du bâtiment, les évolutions réglementaires (RT2012)et normatives (NF BPE : Béton à Propriétés Thermiques, septembre 2016) incitent à évoluer vers des bétons isolants et structurels (BIS). La maîtrise de leur conductivité thermique est primordiale. Il est possible, en plus de faire appel à un squelette granulaire léger, de jouer sur la nature de la pâte en utilisant des inclusions qui apporteraient un pouvoir isolant supplémentaire : les cénosphères. Dans un contexte de facilité de mise en oeuvre, à ces propriétés est rajouté le critère auto plaçant des bétons. On parle alors de Bétons Isolants Structurels Autoplaçants (BISAP). La maitrise et la validation de ces nouvelles formules dans le respect d’une approche prescriptive a nécessité la caractérisation des matériaux à différentes échelles (de l’inclusion à l’échelle de l’ouvrage) en développant des approches expérimentales et numériques. Leur comportement à l’état frais et à l’état durci a été analysé. Les conductivités thermiques mesurées placent ces nouveaux bétons dans la catégorie Bétons Isolants Structurels au sens du nouveau référentiel. Le modèle numérique développé permet d’approcher correctement les valeurs expérimentales. D’autre part, la sensibilité des BISAP incorporant des cénosphères à plusieurs indicateurs de durabilité (porosité accessible à l’eau, perméabilité,carbonatation et retrait) a également été étudiée. L’influence des microsphères est plus ou moins notable en fonction du mécanisme abordé. / In the field of building thermal insulation, regulatory (RT2012) and standards (NF BPE: Béton à Propriétés Thermiques, September 2016) evolutions are encouraging the use of insulating structural concrete (BIS). The control of their thermal conductivity is essential. It is possible, in addition to using lightweight aggregates, to modify the composition of the cement paste by using hollow inclusions (fly ash cenospheres) to bring an additional thermal insulating potential. In a context of improved workability, to these properties is added the criterion of self-compacting concrete. The validation of these new formulas required the characterization of materials at different scales (from inclusion scale to building scale) by implementing experimental and numerical approaches. Their properties at fresh and hardened state were analyzed. The measured thermal conductivities place these new concretes in the Category of Structural Insulating Concrete in the sense of the new standard. The developed numerical model allowed approaching the experimental measurements correctly. The effect of cenospheres’ incorporation into cement paste on several durability indicators was also characterized.

Land-based turbine engines are currently used to burn heavy fuel oil (HFO), which is a lower cost fuel. HFO contains inorganic material that forms deposits on turbine blades reducing output and efficiency. Magnesium based additives are used to inhibit vanadium pentoxide deposition and reduce the corrosive nature of the gas and deposits in the hot gas path of the gas turbine. The focus of this study was to determine particle morphology and elemental composition of ash when firing HFO in an atmospheric combustor at various fuel injector atomization pressures. Prior to firing, the HFO was washed with water to remove sodium and potassium. A commercially available magnesium based additive was used to inhibit the vanadium in the HFO. Fuel was injected using an air-blast atomizer at air blast atomization gage pressures of 117, 186, and 255 kPa. Ash was collected from three locations downstream of combustion: immediately following combustion (pre-cyclone), from a cyclone separator (cyclone), and finally from a position located after the cyclone separator (post-cyclone). A Philips XL30 Scanning Electron Microscope (SEM) provided images, weight percent of elements of the ash, and element maps. Images taken from the SEM clearly show two particle types: 1) hollow spherical particles, or cenospheres, and 2) submicron agglomerated spherical particles. The cenospheres contained high carbon concentrations and were found primarily in the cyclone and probe bag filter. Element maps show that cenospheres, regardless of size, predominately contain carbon, oxygen, and sulfur with lesser amounts of sodium, magnesium, aluminum, and silicon. Particles collected downstream of the cyclone were primarily sub-micron in size and inorganic in composition. It is postulated that the cenospheres are the result of incomplete combustion of fuel oil droplets while the submicron spheres are nucleated inorganic material that initially evaporated from the liquid droplets. Particle size analysis was performed for each sample location. As the injection pressure was increased; the pre-cyclone and cyclone locations had similar number mean diameters that would decrease with increasing pressure. The diameter of the post-cyclone location did not change significantly with increasing air atomization. While increasing atomization pressure decreased the carbon content of the ash at all measurement locations, the atomization had little influence on the inorganic composition of the particles. The fine condensed phase particles and the larger cenosphere particles both produced similar compositions of inorganic material.

The diploma thesis focuses on new possibilities to reduce raw materials costs in production of heat-resistant cordierite ceramics. Cordierite is very often used as furnace wagon lining and for production of blazing utilities for its high resistance against temperature changes. The thesis gives complete overview of cordierite material. It includes description of different production technologies for form-pieces preparation, raw materials for their production and their applications. The goal of performed laboratory measuring in an experimental part was to verify and prove a possibility of reducing raw-material costs in production of cordierite ceramics by using cheaper preferably secondary raw materials.

Submitted by Milena Rubi (milenarubi@ufscar.br) on 2017-08-08T18:02:30Z No. of bitstreams: 1 CACURO_Thiago_2016.pdf: 32188052 bytes, checksum: 4ea1d6b1518db8bbf23e24ea2e2a94d7 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2017-08-08T18:03:10Z (GMT) No. of bitstreams: 1 CACURO_Thiago_2016.pdf: 32188052 bytes, checksum: 4ea1d6b1518db8bbf23e24ea2e2a94d7 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2017-08-08T18:03:16Z (GMT) No. of bitstreams: 1 CACURO_Thiago_2016.pdf: 32188052 bytes, checksum: 4ea1d6b1518db8bbf23e24ea2e2a94d7 (MD5) / Made available in DSpace on 2017-08-08T18:03:21Z (GMT). No. of bitstreams: 1 CACURO_Thiago_2016.pdf: 32188052 bytes, checksum: 4ea1d6b1518db8bbf23e24ea2e2a94d7 (MD5) Previous issue date: 2016-03-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The ashes resulting from the burning of sugarcane bagasse is a heterogeneous material and has various applications as an adsorbent. To enhance and assist in prospecting new applications is critical to better understand the properties of the material. In this work, its morphological, spectroscopic and elemental characterization of the ashes of sugarcane bagasse from three different plants and two different harvests and the prospect of its use as an adsorbent. The particles of the ash were separated according to their density and in order to characterize, FTIR was used in the investigation of chemical groups present in the samples, additionally to the SEM and EDS elemental and morphological characterization of the particles present in the samples. Cenospheres, spherical particles present in ash, were identified as coreshell structure, where the core is a mixed metal oxide and the shell is a layer of silicon dioxide. The correlation between the ratio of the relative abundance between the carbonyl and hydroxyl groups and the mass distribution of the granulometric extracts were used as indirect measure of the level of oxidation of the samples. The ashes’ adsorption capacity showed affinity for the methylene blue dye with an adsorption capacity of 39 mg of dye per gram of ash used, in contrast to the low adsorption of potassium chromate solution, 1.2 mg per gram of ash. / As cinzas oriundas do processo de queima do bagaço de cana-de-açúcar são um material heterogêneo e com diversas aplicações, como a adsorção. Para potencializar e auxiliar na prospecção de novas aplicações é fundamental conhecer melhor as propriedades do material. Neste trabalho foi feita esta caracterização morfológica, espectroscópica e elementar das cinzas do bagaço da cana-de-açúcar provenientes de três diferentes usinas e duas diferentes safras e a prospecção de seu uso como adsorvente. As partículas das cinzas foram separadas de acordo com sua densidade e para a caracterização foi utilizada a técnica de FTIR na investigação dos grupos químicos presentes nas amostras e MEV juntamente com o EDS para a caracterização morfológica e elementar. As cenosferas, partículas esféricas presentes nas cinzas, foram identificadas como estruturas coreshell onde o core é composto por um misto de óxidos metálicos e o shell composto por dióxido de silício. A correlação entre a razão da abundância relativa entre os grupos de carbonila e hidroxila e a distribuição mássica dos extratos granulométricos, foi usada como medida indireta do nível de oxidação das diferentes amostras. Quanto à sua capacidade de adsorção, as cinzas mostraram afinidade na adsorção do corante azul de metileno com uma capacidade de adsorção de 39mg de corante por grama de cinza usada em contraste com a baixa adsorção apresentada para a solução de cromato de potássio com 1,2 mg por grama de cinza.