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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Matériaux de construction en zone tropicale humide : Potentialités de sous-produits ou de matériaux naturels locaux en substitution ou addition à la matrice cimentaire / Construction materials in tropical humid zone : Potential by-products or local natural materials in substitution or addition to the cementitious matrix

Rodier, Loïc 01 December 2014 (has links)
L’incorporation de sous-produits agricoles ou de matériaux naturels dans la matrice cimentaire confère des propriétés intéressantes aux composites élaborés. L’objectif de cette thèse est d’élaborer un matériau pouvant répondre aux exigences mécaniques, thermiques et de durabilité des matériaux de construction en zone tropicale humide. Dans un premier temps, l’activité pouzzolanique d’une pouzzolane naturelle, de cendres de tronc de bambou et de cendres de bagasse de canne à sucre ont été évaluées. L’influence de leur incorporation a été ensuite étudiée sur les propriétés mécaniques et la durabilité des mortiers exposés à des ions chlorures et sulfates. Dans un second temps, l’influence de l’ajout de fibres de bagasse sur les propriétés thermiques et mécaniques des composites a été étudiée en fonction de différents paramètres (teneur en fibres, environnement de vieillissement, type de matrice cimentaire).Les résultats obtenus ont permis de montrer que les matériaux étudiés possèdent une activité pouzzolanique et qu’il est possible de les incorporer au ciment afin de lutter contre la corrosion. De plus, les composites élaborés avec des fibres de bagasse sont plus isolants que ceux élaborés sans fibres. Cependant, du point de vue des propriétés mécaniques, l’incorporation de fibres de bagasse diminue les contraintes à la flexion des composites. / The incorporation of crop wastes or natural materials in the cement matrix confers interesting properties to composites prepared. The aim of this thesis is to develop a material that can reach the mechanical, thermal and durability requirements for building materials in the humid tropical zone. Firstly, pozzolanic activity of a natural pozzolan, bamboo stem and sugar cane bagasse ashes has been determined. Influence of their incorporation on mechanical properties and durability of mortars exposed to chloride and sulphate ions was studied. Secondly, influence of addition of bagasse fibers on thermal and mechanical properties of composites was studied as a function of various parameters (fibers content, curing, type of cement matrix).These results has shown that the materials studied have pozzolanic activity and it is possible to incorporate them into the cement to fight against corrosion. Moreover, composites elaborated with bagasse fibers are more insulating than those elaborated without fibers. However, from the viewpoint of mechanical properties, incorporation of bagasse fibers decreases flexural strength of composites in the present work and under the conditions producing procedures that were adopted.
52

Estudo da incorporação de altos teores de argila calcinada no concreto compactado com rolo / Study of the incorporation of high amounts of calcined clay in roller compacted concrete

RIBEIRO, Adriano Mendes 28 September 2010 (has links)
Made available in DSpace on 2014-07-29T15:03:31Z (GMT). No. of bitstreams: 1 adriano mendes.pdf: 4708776 bytes, checksum: 4bc099a31f3941241f5dd5294da28bba (MD5) Previous issue date: 2010-09-28 / The rolled compacted concrete (RCC) is a still relatively new technique, but with growing volume of use, a fact generated by its technical and economical advantages, requiring more studies in order to use with greater efficiency, safety and economy. This work deals with the RCC with high levels of replacement and addition of part of the Portland cement by calcined clay pozzolan, aiming to analyze and quantify the improvements of the concrete properties and reach a satisfactory level of use, which allows for improvement or maintenance of the properties with a lower consumption of cement per cubic meter. So its impacts on the properties of RCC for this type of mineral addition were studied for the substitution levels adopted, checking the influence on the properties of the fresh concrete in the consistency and the density. For the hardened concrete some mechanical properties and durability were evaluated by compressive and tensile strength, capillarity and immersion by water absorption, test of permeability by water and ultrasound test. The use of calcined clay come together with the needs of the cement production for the construction of dams in the north of the country, as the case of Santo Antônio / RO, because its place is far removed from major industries and cement production slag, fly ash and silica fume, requiring the study of materials to enhance the production of cement. As an important result obtained with this research, it was found that substitution ranging from 27% to 50% achieved the best results, regarding the applicability of this material on the surveyed properties. / O Concreto Compactado com Rolo (CCR) é uma técnica ainda relativamente nova, porém com volume de utilização crescente, fato gerado pelas suas vantagens econômicas e técnicas, requerendo assim mais estudos para embasar o seu uso com maior eficiência, segurança e economia. O presente trabalho trata do CCR com elevados teores de substituição e de adição de parte do volume de cimento Portland por pozolana de argila calcinada, objetivando analisar e quantificar as melhorias das suas propriedades e chegar a um teor satisfatório de utilização, o qual possibilite melhoria ou manutenção das propriedades avaliadas com um menor consumo de cimento por metro cúbico. Desta forma foram avaliados os impactos nas propriedades do CCR para este tipo de adição mineral, nos teores adotados, aferindo a influencia nas propriedades do concreto no estado fresco quanto à consistência e massa específica. No estado endurecido algumas propriedades mecânicas e de durabilidade foram analisadas através da resistência à compressão e à tração por compressão diametral, a absorção de água por capilaridade e por imersão, a permeabilidade à água e ensaio de ultrassom. O uso da argila calcinada vem ao encontro das necessidades da produção de cimento para as usinas em construção na Região Norte do país, como é o caso de Santo Antônio / RO, pois se trata de uma obra muito distante das grandes indústrias cimenteiras e da produção de escória, cinza volante e sílica ativa, o que requer a investigação de materiais para aperfeiçoar a produção de cimento. Como resultado importante obtido na pesquisa em questão, verificou-se que a substituição oscilando entre 27% a 50% atingiu os melhores resultados quanto à aplicabilidade desse material nas propriedades pesquisadas.
53

Vápenné malty modifikované jemně mletým cihelným střepem / Lime Mortars Modified by Fine Ground Brick Body

Šmerdová, Ludmila January 2013 (has links)
Natural pozzolanic materials played an important role in Ancient architecture. In the last decades and nowadays it is artifical pozzolan which especially finds its use as an additive to mortar and concrete to improve some, especially the mechanical properties. This master thesis deals with study of pozzolan type of fine brick powder which is a by-product of the production of calibrated bricks. Along with studying pozzolanic activity of brick powder, lime mortar with different proportions of brick powder as an additive or replacement of lime dust are investigated. What is observed is its impact on the consistency of these mortar, water absorption, strength in time or fracture-mechanical parameters of mortar. The results may indicate the possible potential use of this source of pozzolanic admixture in lime mortar and plaster which are nowadays mainly used for the restoration of facades of historic buildings.
54

Análisis comparativo del concreto lanzado con cemento tipo IP y tipo HE en el revestimiento de túneles de la mina Orcopampa – Arequipa

Cervantes Abarca, Betsy Pierina, Villa Meza, Liz Katherine January 2015 (has links)
Se viene buscando optimizar la elaboración del concreto lanzado, pero en el proceso se deja de lado el control de calidad por lo cual es indispensable comparar la influencia de un componente primario como el cemento tipo IP y HE. La presente tesis tiene por objetivo realizar el estudio comparativo de concreto lanzado con cemento portland puzolanico tipo IP vs tipo HE en el revestimiento del túnel de la mina Orcopampa–Arequipa. Nos ha impulsado a investigar la necesidad de obtener la relevancia en el desempeño y las implicancias del cemento para shotcrete desde una visión técnica, a través de ensayos de campo y laboratorio. Considerando el enfoque técnico al determinar las diferencias entre el concreto lanzado con cemento Tipo IP y Tipo HE desde el análisis de resistencia a tenacidad y resistencia a la compresión. Realizando un tipo de Investigación básica, cuantitativa, descriptivo, aplicada, de campo con un diseño experimental, según el estudio es cuasi experimental, prospectivo por la cronología de observación, transversal según el número de mediciones, descriptiva, comparativa y explicativa. Los resultados estadísticos nos demuestran que si existen diferencias significativas de 62 % entre los resultados de la resistencia a la compresión del concreto lanzado cemento Tipo HE sobre el concreto lanzado con cemento Tipo IP en su totalidad de edades ensayadas. En el análisis estadístico de los ensayos de tenacidad se observa que el cemento Tipo HE tiene una mejor capacidad para absorber energía ya que tiene la característica de desarrollar resistencias a edades tempranas. It has sought to optimize the development of the shotcrete, but in the process neglects quality control so it is essential to compare the influence of a primary component such as cement type IP and HE. This thesis aims to conduct a comparative study of shotcrete with IP pozzolanic Portland cement type HE vs kind in the lining of the tunnel Arequipa Orcopampa mine. It has prompted us to investigate the need for relevance in the performance and the implications of cement shotcrete from a technical view, through field and laboratory tests. Whereas the technical approach to determine the differences between the shotcrete cement type HE type IP and from the analysis of toughness and resistance to compression. He made a type of Basic, quantitative, descriptive research, applied field with an experimental design, the study is quasi-experimental, prospective timeline for observation cross as the number of measurements, descriptive, comparative and explanatory. The statistical results show that if there are significant differences between the results 62% of the compressive strength of cement Type HE shotcrete shotcrete on cement type IP fully tested age. In the statistical analysis of toughness tests it shows that the cement type HE has a better ability to absorb energy and which has the characteristic of developing resistance at early ages.

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