Made available in DSpace on 2014-12-17T14:07:20Z (GMT). No. of bitstreams: 1 ElvioAG_TESE.pdf: 3444604 bytes, checksum: d60cf497e4c263de969e02bb2eefe56f (MD5) Previous issue date: 2013-12-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This research was motivated by the requirement of asbestos s replacement in building systems and the need to generate jobs and income in the country side of the state of Bahia, Brazil. The project aimed at using fibers from licuri leaves (syagrus coronata), an abundant palm in the region, to produce composites appropriate for the sustainable production of cement fibre reinforced products in small plants. The composites were produced in laboratory using Portland cement CP-II-F32, sand, water, licuri palm fiber contents of 1.0, 1.5 and 2.0% by weight of binder (two different fiber length) and metakaolin. The latter was chosen as an additional binder for its efficiency to reduce the alkalinity of cementitious matrixes therefore preventing the degradation of vegetable fibers. The characterization of the composite components was carried out by sieving and laser particle size analyses, thermal analysis, fluorescence and X-ray diffraction. The composites performance was evaluated by 3- point-bending tests, compressive strength, ultrasound module of elasticity, free and restrained shrinkage, water capillarity absorption and apparent specific gravity. It has been found that the addition of fibers increased the time to onset of cracking over 200.00% and a 25% reduction in cracks opening in the restrained shrinkage test. The capillary absorption reduced about 25% when compared to fiber-free composites. It was also observed with regard to flexural strength, compressive strength and specific gravity, that the addiction of fibers did not affect the composite performance presenting similar results for compounds with and without fibers. In general it can be stated that the reinforced composite fibers of palm licuri presents physical and mechanical characteristics which enable them to be used in the intended proposals of this research / A exig?ncia da substitui??o do amianto em sistemas construtivos em conjunto com a necessidade de gera??o de renda no sert?o da Bahia fez nascer o projeto do aproveitamento da fibra da palma do licuri (syagrus coronata), palmeira abundante na regi?o, na produ??o de comp?sitos para a fabrica??o artefatos de cimento refor?ados com fibras para a constru??o civil de maneira sustent?vel, em pequenas unidades fabris. Os comp?sitos foram produzidos em laborat?rio utilizando cimento Portland CP II-F32, areia, ?gua, metacaulinita e fibra da palma do licuri. As fibras foram adicionadas em teores de 1,0, 1,5 e 2,0% da massa do aglomerante e com dois comprimentos de fibra diferentes. A metacaulinita foi selecionada como aglomerante suplementar de forma a agir na redu??o da alcalinidade da matriz ciment?cia na perspectiva de diminuir ou at? mesmo eliminar a degrada??o das fibras vegetais em meio alcalino. Foram realizados ensaios de caracteriza??o dos componentes do comp?sito, incluindo granulometria, an?lise t?rmica, fluoresc?ncia e difratometria de Raios-X. A verifica??o do desempenho dos comp?sitos foi feita com ensaios de flex?o em tr?s pontos, resist?ncia ? compress?o axial, m?dulo de elasticidade por ultrassom, retra??o livre e restringida, absor??o de ?gua por capilaridade e massa espec?fica aparente. Verificou-se que a presen?a das fibras de licuri aumentou o tempo para o surgimento da fissura??o acima de 200,00% e redu??o de 25% na abertura das fissuras no ensaio de retra??o restringida. Com rela??o ? absor??o capilar ocorreu uma redu??o de 25%, quando comparados com os materiais sem fibras. Observou-se que, com rela??o ? resist?ncia a flex?o, compress?o axial e massa espec?fica aparente, a adi??o de fibras n?o afeta o desempenho dos materiais, apresentando resultados similares para materiais com e sem fibras. De uma maneira geral pode-se afirmar que os comp?sitos refor?ados com fibras da palma do licuri apresentam caracter?sticas f?sicas e mec?nicas que viabilizam sua aplica??o dentro das condi??es estabelecidas neste trabalho

O Engineered Cementitious Composite ou ECC é um compósito cimentício de elevada capacidade de deformação, concebido na Universidade de Michigan. Constituído por agregados miúdos, cimento e fibras, o compósito apresenta elevada ductilidade associada com a capacidade de gerar microfissuras quando submetido a carregamentos, num comportamento conhecido como strain-hardening. As pesquisas previamente desenvolvidas no Laboratório de Ensaios e Modelos Estruturais (LEME) da UFRGS objetivaram caracterizar um ECC adaptado aos materiais do Brasil, adicionando-se fibras de polipropileno na elaboração do compósito, e estudando-se alternativas para a substituição parcial de cimento. Na pesquisa aqui relatada, adotou-se o traço de referência definido previamente (ECCRef) e também foi utilizado um traço alternativo com 30% (em volume) de cinza de casca de arroz moída por 4 horas, em substituição parcial do cimento (ECCCCA). A pesquisa foi dividida em duas abordagens. A primeira consistiu na caracterização das propriedades mecânica dos traços em laboratório com a realização de ensaios de resistência à tração na flexão, à compressão simples, avaliação da aderência por cisalhamento direto e da trabalhabilidade, bem como ensaios de fadiga em viga quatro pontos. Em ensaios monotônicos o ECCCCA apresentou uma resistência à tração na flexão média (ft,f) de 8,2 MPa e resistência à compressão simples média (fc) de 50 MPa; já o ECCRef teve valores médios de 6,8 MPa e 36 MPa, respetivamente. Nos ensaios de aderência obtiveram-se resistências ao cisalhamento de 2050 kPa (ECCCCA) e 1900 kPa (ECCRef) A avaliação da trabalhabilidade permitiu estabelecer critérios para aprimorar o processo de mistura e manuseio do material em estado fresco, desta forma obteve-se adequada trabalhabilidade no ensaio de flow table, que aumentou de 44 para 90, possibilitando a utilização de betoneiras de tombo e obter os volumes de material necessários. Com os resultados dos ensaios dinâmicos foram estabelecidos modelos de fadiga em termos da deformação específica de extensão inicial (εti), deformação específica de extensão inicial normalizada (ti/εtP) e tração inicial (σti), assim como da energia dissipada (DE), igualmente foi possível estudar o processo de degradação dos compósitos. A segunda abordagem da pesquisa consistiu na realização de ensaios em verdadeira grandeza, com a utilização do simulador de tráfego do Laboratório de Pavimentação (LAPAV). Foram construídos dois recapeamentos (de 50 e 30 mm de espessura) sobre pavimentos flexíveis que apresentavam idêntico padrão de trincamento. Em cada recapeamento foram aplicados 100 mil ciclos da carga de semi-eixo de 5,5 toneladas. Foram acompanhados, visualmente, o surgimento e evolução de fissuras e outras manifestações patológicas, bem como o desgaste superficial, por meio dos ensaios de Pêndulo Britânico e Altura de Mancha de Areia. Após o fim do tráfego, foram serradas placas das seções trafegadas para verificar a propagação das fissuras e a aderência entre o compósito e o pavimento. Concluiu-se que o controle de qualidade na mistura é fundamental para garantir a qualidade da superfície. Além disso, percebeu-se que a aparição de fissuras está associada com possíveis problemas de aderência ECC-pavimento asfáltico, e em menor escala reflexão de fissuras. Globalmente, constatou-se que é possível produzir ECC’s com materiais disponíveis no estado e que este material pode ser aplicado na restauração de pavimentos. / Engineered Cementitious Composite or ECC is a material with a high deformation capacity, designed at the University of Michigan. Composed of fine aggregates, cement and fibres, the composite presents high ductility associated with the ability to generate microcracks when loaded, in a behavior known as strain-hardening. The research previously developed in the Laboratory of Structural Models and Tests (LEME) of UFRGS aimed to characterize an ECC adapted to the materials of Brazil, adding polypropylene fibres in the preparation of the composite, and studying alternatives for the partial replacement of cement. In the research reported here, the previously defined reference mix proportion (ECCRef) was adopted and an alternative mix proportion was used with 30% (by volume) of unprocessed rice-husk ash grinded for 4 hours, in partial replacement of the cement (ECCCCA). The research was divided into two approaches. The first one consisted in the characterization of the mechanical properties of the ECC’s in the laboratory with the execution of tests of flexural behavior and compressive strength, evaluation of adhesion by direct shear tests and the workability, as well as fatigue tests in four point configuration. In monotonic tests ECCCCA showed a resistance to flexural strength of 8.2 MPa and average compression strength of 50 MPa; ECCRef had mean values of 6.8 MPa and 36 MPa, respectively. In the adhesion tests, shear strengths of 2050 kPa (ECCCCA) and 1900 kPa (ECCRef) were obtained The evaluation of the workability allowed for the determination of criteria to improve the process of mixing and handling of the material in fresh state, in this way, adequate workability was obtained in the flow table test, which increased from 44 to 90, permitting the use of concrete mixer machines and to obtain the required volumes of material. With the results of the dynamic tests, fatigue models were stipulated in terms of initial tensile strain (εti), normalized initial tensile strain (ti/εtP) and initial traction (σti), as well as the dissipated energy (DE), it was also possible to study the process of degradation of the composites. The second approach of the research consisted in the accomplishment of tests in true greatness, with the use of the Accelerated Loading Facility of the Laboratory of Pavements (LAPAV). Two overlays (50 and 30 mm thick) were built over flexible pavements that had the same cracking pattern. At each overlay, 100 thousand cycles of the semi-axle load of 5.5 tons were applied. The appearance and evolution of cracks and other pathologies were monitored visually, as well as surface wear through the British Pendulum and Sand Patch tests. After the end of the traffic simulator, plates of the trafficked sections were sawn to verify the propagation of the cracks and the adhesion between the composite and the pavement. It was concluded that the quality control in the mixture is fundamental to guarantee the quality of the surface. In addition, it was noticed that the appearance of cracks is associated with possible problems of adhesion ECC-asphalt pavement, and to a lesser extent reflective cracking. Overall, it has been found that it is possible to produce ECC's with Brazilian materials and the ECC can be applied in the restoration of pavements. / El ECC (Engineered Cementitious Composites) es un compósito cementicio de elevada capacidad de deformación desarrollado en la Universidad de Michigan. Conformado por agregados finos, cemento y fibras poliméricas, presenta una alta ductilidad asociada con la capacidad de generar microfisuras durante la aplicación de cargas, comportamiento conocido como strain-hardening. Las investigaciones previamente desarrolladas en el Laboratório de Ensaios e Modelos Estruturais (LEME) de la UFRGS se direccionaron para caracterizar un ECC adaptado a los materiales brasileros, utilizando fibras de polipropileno y estudiando alternativas para la sustitución parcial del cemento. En la presente investigación se adoptó el trazo de referencia definido previamente (ECCRef), también fue utilizado un trazo alternativo con 30% (en volumen) de ceniza de cáscara de arroz molida por 4 horas como substituto parcial del cemento (ECCCCA). La investigación fue dividida en dos abordajes. La primera consistió en la caracterización de las propiedades mecánicas en laboratorio con la realización de ensayos de resistencia a tracción por flexión e compresión simple, evaluación de la adherencia por corte directo y de la trabajabilidad, además de ensayos de fatiga en viga cuatro puntos. En ensayos monotónicos el ECCCCA presentó una resistencia a la tracción por flexión media (ft,f) de 8,2 MPa y resistencia a la compresión simple media (fc) de 50 MPa; ya el ECCRef tuvo valores medios de 6,8 MPa y 36 MPa, respectivamente. En los ensayos de adherencia se obtuvieron resistencias al corte de 2050 kPa (ECCCCA) y 1900 kPa (ECCRef). La evaluación de la trabajabilidad permitió establecer criterios para mejorar el proceso de mezcla y manipulación del material en estado fresco, de esa forma se obtuvo una adecuada trabajabilidad en el ensayo de flow table, que aumentó de 44 para 90, posibilitando la utilización de mezcladoras de tambor y la obtención de los volúmenes de material necesarios. Con los resultados de los ensayos dinámicos fueron establecidos modelos de fatiga en términos de la deformación específica de extensión inicial (εti), de la deformación específica de extensión inicial normalizada (ti/εtP), de la tracción inicial (σti) y de la energía disipada (DE), igualmente fue posible estudiar el proceso de degradación de los compósitos El segundo abordaje de la investigación consistió en la realización de ensayos en verdadera grandeza con la utilización del simulador de tráfico del Laboratório de Pavimentação (LAPAV). Fueron construidos dos recapeamentos (de 50 y 30 mm de altura) sobre pavimentos flexibles que presentaban idéntico patrón de fisuración. En cada recapeamento fueron aplicados 100 mil ciclos da carga de semi-eje de 5,5 toneladas. Fueron acompañados, visualmente, la aparición y evolución de fisuras y otras patologías, así como el desgaste superficial por medio de los ensayos de Péndulo Británico y Altura de Mancha de Arena. Una vez terminados los ciclos de carga, fueron extraídas placas de las secciones ensayadas para verificar la propagación de las fisuras y la adherencia entre el compósito y el pavimento. Se concluyó que el control de calidad durante el proceso de mezcla es fundamental para garantizar la calidad superficial. Además, fue percibido que la aparición de fisuras está asociada con posibles problemas de adherencia ECC-pavimento asfáltico y en menor escala reflexión de fisuras. Globalmente, se constató que es posible producir ECC’s con materiales disponibles a nivel local y que este material puede ser aplicado en la restauración de pavimentos.

O Engineered Cementitious Composite ou ECC é um compósito cimentício de elevada capacidade de deformação, concebido na Universidade de Michigan. Constituído por agregados miúdos, cimento e fibras, o compósito apresenta elevada ductilidade associada com a capacidade de gerar microfissuras quando submetido a carregamentos, num comportamento conhecido como strain-hardening. As pesquisas previamente desenvolvidas no Laboratório de Ensaios e Modelos Estruturais (LEME) da UFRGS objetivaram caracterizar um ECC adaptado aos materiais do Brasil, adicionando-se fibras de polipropileno na elaboração do compósito, e estudando-se alternativas para a substituição parcial de cimento. Na pesquisa aqui relatada, adotou-se o traço de referência definido previamente (ECCRef) e também foi utilizado um traço alternativo com 30% (em volume) de cinza de casca de arroz moída por 4 horas, em substituição parcial do cimento (ECCCCA). A pesquisa foi dividida em duas abordagens. A primeira consistiu na caracterização das propriedades mecânica dos traços em laboratório com a realização de ensaios de resistência à tração na flexão, à compressão simples, avaliação da aderência por cisalhamento direto e da trabalhabilidade, bem como ensaios de fadiga em viga quatro pontos. Em ensaios monotônicos o ECCCCA apresentou uma resistência à tração na flexão média (ft,f) de 8,2 MPa e resistência à compressão simples média (fc) de 50 MPa; já o ECCRef teve valores médios de 6,8 MPa e 36 MPa, respetivamente. Nos ensaios de aderência obtiveram-se resistências ao cisalhamento de 2050 kPa (ECCCCA) e 1900 kPa (ECCRef) A avaliação da trabalhabilidade permitiu estabelecer critérios para aprimorar o processo de mistura e manuseio do material em estado fresco, desta forma obteve-se adequada trabalhabilidade no ensaio de flow table, que aumentou de 44 para 90, possibilitando a utilização de betoneiras de tombo e obter os volumes de material necessários. Com os resultados dos ensaios dinâmicos foram estabelecidos modelos de fadiga em termos da deformação específica de extensão inicial (εti), deformação específica de extensão inicial normalizada (ti/εtP) e tração inicial (σti), assim como da energia dissipada (DE), igualmente foi possível estudar o processo de degradação dos compósitos. A segunda abordagem da pesquisa consistiu na realização de ensaios em verdadeira grandeza, com a utilização do simulador de tráfego do Laboratório de Pavimentação (LAPAV). Foram construídos dois recapeamentos (de 50 e 30 mm de espessura) sobre pavimentos flexíveis que apresentavam idêntico padrão de trincamento. Em cada recapeamento foram aplicados 100 mil ciclos da carga de semi-eixo de 5,5 toneladas. Foram acompanhados, visualmente, o surgimento e evolução de fissuras e outras manifestações patológicas, bem como o desgaste superficial, por meio dos ensaios de Pêndulo Britânico e Altura de Mancha de Areia. Após o fim do tráfego, foram serradas placas das seções trafegadas para verificar a propagação das fissuras e a aderência entre o compósito e o pavimento. Concluiu-se que o controle de qualidade na mistura é fundamental para garantir a qualidade da superfície. Além disso, percebeu-se que a aparição de fissuras está associada com possíveis problemas de aderência ECC-pavimento asfáltico, e em menor escala reflexão de fissuras. Globalmente, constatou-se que é possível produzir ECC’s com materiais disponíveis no estado e que este material pode ser aplicado na restauração de pavimentos. / Engineered Cementitious Composite or ECC is a material with a high deformation capacity, designed at the University of Michigan. Composed of fine aggregates, cement and fibres, the composite presents high ductility associated with the ability to generate microcracks when loaded, in a behavior known as strain-hardening. The research previously developed in the Laboratory of Structural Models and Tests (LEME) of UFRGS aimed to characterize an ECC adapted to the materials of Brazil, adding polypropylene fibres in the preparation of the composite, and studying alternatives for the partial replacement of cement. In the research reported here, the previously defined reference mix proportion (ECCRef) was adopted and an alternative mix proportion was used with 30% (by volume) of unprocessed rice-husk ash grinded for 4 hours, in partial replacement of the cement (ECCCCA). The research was divided into two approaches. The first one consisted in the characterization of the mechanical properties of the ECC’s in the laboratory with the execution of tests of flexural behavior and compressive strength, evaluation of adhesion by direct shear tests and the workability, as well as fatigue tests in four point configuration. In monotonic tests ECCCCA showed a resistance to flexural strength of 8.2 MPa and average compression strength of 50 MPa; ECCRef had mean values of 6.8 MPa and 36 MPa, respectively. In the adhesion tests, shear strengths of 2050 kPa (ECCCCA) and 1900 kPa (ECCRef) were obtained The evaluation of the workability allowed for the determination of criteria to improve the process of mixing and handling of the material in fresh state, in this way, adequate workability was obtained in the flow table test, which increased from 44 to 90, permitting the use of concrete mixer machines and to obtain the required volumes of material. With the results of the dynamic tests, fatigue models were stipulated in terms of initial tensile strain (εti), normalized initial tensile strain (ti/εtP) and initial traction (σti), as well as the dissipated energy (DE), it was also possible to study the process of degradation of the composites. The second approach of the research consisted in the accomplishment of tests in true greatness, with the use of the Accelerated Loading Facility of the Laboratory of Pavements (LAPAV). Two overlays (50 and 30 mm thick) were built over flexible pavements that had the same cracking pattern. At each overlay, 100 thousand cycles of the semi-axle load of 5.5 tons were applied. The appearance and evolution of cracks and other pathologies were monitored visually, as well as surface wear through the British Pendulum and Sand Patch tests. After the end of the traffic simulator, plates of the trafficked sections were sawn to verify the propagation of the cracks and the adhesion between the composite and the pavement. It was concluded that the quality control in the mixture is fundamental to guarantee the quality of the surface. In addition, it was noticed that the appearance of cracks is associated with possible problems of adhesion ECC-asphalt pavement, and to a lesser extent reflective cracking. Overall, it has been found that it is possible to produce ECC's with Brazilian materials and the ECC can be applied in the restoration of pavements. / El ECC (Engineered Cementitious Composites) es un compósito cementicio de elevada capacidad de deformación desarrollado en la Universidad de Michigan. Conformado por agregados finos, cemento y fibras poliméricas, presenta una alta ductilidad asociada con la capacidad de generar microfisuras durante la aplicación de cargas, comportamiento conocido como strain-hardening. Las investigaciones previamente desarrolladas en el Laboratório de Ensaios e Modelos Estruturais (LEME) de la UFRGS se direccionaron para caracterizar un ECC adaptado a los materiales brasileros, utilizando fibras de polipropileno y estudiando alternativas para la sustitución parcial del cemento. En la presente investigación se adoptó el trazo de referencia definido previamente (ECCRef), también fue utilizado un trazo alternativo con 30% (en volumen) de ceniza de cáscara de arroz molida por 4 horas como substituto parcial del cemento (ECCCCA). La investigación fue dividida en dos abordajes. La primera consistió en la caracterización de las propiedades mecánicas en laboratorio con la realización de ensayos de resistencia a tracción por flexión e compresión simple, evaluación de la adherencia por corte directo y de la trabajabilidad, además de ensayos de fatiga en viga cuatro puntos. En ensayos monotónicos el ECCCCA presentó una resistencia a la tracción por flexión media (ft,f) de 8,2 MPa y resistencia a la compresión simple media (fc) de 50 MPa; ya el ECCRef tuvo valores medios de 6,8 MPa y 36 MPa, respectivamente. En los ensayos de adherencia se obtuvieron resistencias al corte de 2050 kPa (ECCCCA) y 1900 kPa (ECCRef). La evaluación de la trabajabilidad permitió establecer criterios para mejorar el proceso de mezcla y manipulación del material en estado fresco, de esa forma se obtuvo una adecuada trabajabilidad en el ensayo de flow table, que aumentó de 44 para 90, posibilitando la utilización de mezcladoras de tambor y la obtención de los volúmenes de material necesarios. Con los resultados de los ensayos dinámicos fueron establecidos modelos de fatiga en términos de la deformación específica de extensión inicial (εti), de la deformación específica de extensión inicial normalizada (ti/εtP), de la tracción inicial (σti) y de la energía disipada (DE), igualmente fue posible estudiar el proceso de degradación de los compósitos El segundo abordaje de la investigación consistió en la realización de ensayos en verdadera grandeza con la utilización del simulador de tráfico del Laboratório de Pavimentação (LAPAV). Fueron construidos dos recapeamentos (de 50 y 30 mm de altura) sobre pavimentos flexibles que presentaban idéntico patrón de fisuración. En cada recapeamento fueron aplicados 100 mil ciclos da carga de semi-eje de 5,5 toneladas. Fueron acompañados, visualmente, la aparición y evolución de fisuras y otras patologías, así como el desgaste superficial por medio de los ensayos de Péndulo Británico y Altura de Mancha de Arena. Una vez terminados los ciclos de carga, fueron extraídas placas de las secciones ensayadas para verificar la propagación de las fisuras y la adherencia entre el compósito y el pavimento. Se concluyó que el control de calidad durante el proceso de mezcla es fundamental para garantizar la calidad superficial. Además, fue percibido que la aparición de fisuras está asociada con posibles problemas de adherencia ECC-pavimento asfáltico y en menor escala reflexión de fisuras. Globalmente, se constató que es posible producir ECC’s con materiales disponibles a nivel local y que este material puede ser aplicado en la restauración de pavimentos.

Esta pesquisa trata da estabilização de misturas de agregados reciclados por meio da ativação de seus finos, cujas composições possibilitam a ocorrência de reações químicas de cimentação. Para o desenvolvimento da pesquisa foram utilizados dois tipos de agregados reciclados: um proveniente de resíduo de demolição de natureza cimentícia e outro da indústria de cerâmica vermelha. O uso dos materiais foi feito por meio de dosagens para obtenção de misturas cujas combinações de materiais pudessem, quimicamente, potencializar a ocorrência de hidratação do cimento anidro existente nos finos do agregado reciclado cimentício e de reação pozolânica pela pozolanicidade da cerâmica vermelha. Com isso foram obtidas cinco misturas, compostas pelos agregados reciclados em estudo misturados entre si e com a adição de aglomerantes hidráulicos, sobre as quais foram realizados ensaios em laboratório para verificação da ocorrência das reações químicas esperadas com consequente estabilização das misturas, de modo a influenciar nos respectivos comportamentos mecânicos. Também foi realizada a avaliação de características do empacotamento dos grãos como forma de verificar se o arranjo físico, neste caso, exerce influência significativa na melhora do comportamento mecânico das misturas estudadas. Os resultados obtidos indicaram que, de fato, ocorreram as reações químicas esperadas, comprovadas pelos resultados dos ensaios de termogravimetria e difração de raios x, realizados em três diferentes idades de cura. Verificou-se, também, a melhora no comportamento mecânico das misturas por meio do aumento da resistência à compressão simples e do módulo de resiliência com a evolução da cura, além de baixa deformabilidade aos 91 dias de cura. Com isso foi comprovada a estabilização das misturas em estudo, com a consequente melhora de seus desempenhos, sendo devida, principalmente, à ocorrência das reações químicas de hidratação do cimento anidro e pozolânica. A pesquisa demonstrou a possibilidade de se estabilizar misturas de agregados reciclados cimentícios e de cerâmica vermelha por meio da ocorrência de reações químicas de cimentação promovidas pela combinação destes materiais. / This research deals with the stabilization of mixtures constituted by recycled aggregates through the activation of its fines portions, whose components enable the occurrence of chemical cementation reactions. In order to develop this research, two types of recycled aggregates were used: one from demolition waste with cementitious origin, and the other one from the red ceramic industry. The use of these materials was done through mix designs to obtain mixtures whose combinations of materials could chemically increase the occurrence of hydration of the anhydrous existing in fine portion of the recycled cementitious aggregates, and pozzolanic reactions due to the pozzolanicity of red ceramics. Thus, five mixtures were obtained, and they were composed by the studied recycled aggregates, mixed together and with the addition of hydraulic binders, on which laboratory tests were performed in order to verify the occurrence of the expected chemical reactions with consequent stabilization of the mixtures, in order to influence their mechanical behavior. Furthermore, it was performed the evaluation of packing characteristics of the particles to verify if the physical arrangement, in this case, has any significant influence on improving the mechanical behavior of the mixtures studied. The results obtained indicated that in fact the expected chemical reactions occurred, which was verified by the results from thermogravimetry and X-ray diffraction tests performed at three different times of curing. The improvement of the mixtures mechanical behavior by increasing of their compressive strength and their resilient modulus was also verified as the mixtures were cured, in addition to low deformability at 91 days of curing. Thus, the stabilization of the mixtures studied was confirmed, which was mainly due to the occurrence of chemical hydration reactions of the anhydrous cement and pozzolanic reactions. The study demonstrated the possibility of stabilizing mixtures of recycled aggregates cementitious waste and red ceramic by the occurrence of cementing chemical reactions promoted by combination of these materials.

Atualmente, o aproveitamento de resíduos na construção civil tem sido estimulado devido essa atividade ser um dos maiores consumidores de materiais naturais em seus processos e produtos. As cinzas agroindustriais ocupam lugar de destaque dentre os resíduos com possibilidades de aplicação em materiais cimentícios, pois algumas, como a cinza da casca do arroz, apresentam propriedades pozolânicas, contribuindo para a redução do consumo de cimento Portland. Nesse sentido, esta pesquisa teve como objetivo principal a avaliação da viabilidade técnica do uso de cinza agroindustriais em matrizes de cimento Portland, tendo como estudo de caso a cinza da casca da castanha de caju (CCCC). As cascas das castanhas de caju, resíduos da produção das castanhas, são incorporadas novamente ao processo, e, nas caldeiras, irão gerar calor para a decorticação de novas castanhas. A CCCC é o resíduo colhido no fundo da grelha das caldeiras, resultante da queima das cascas de castanhas. Atualmente, esse resíduo é utilizado como adubo em plantações de caju, sendo uma pequena parte destinada à aterros sanitários comuns. Foram realizados ensaios para avaliar a composição físico-química da CCCC; analisar o potencial pozolânico; analisar a retração por secagem e da profundidade de carbonatação de argamassas confeccionados com CCCC; e determinar a capacidade de estabilização/solidificação da CCCC pela matriz cimentícia. A partir dos resultados, pode-se apontar como características principais da CCCC: i) não apresentar potencial pozolânico; ii) favorecer a incorporação de ar em matrizes cimentícias; iii) ocasionar solubilidade de metais pesados e Fenol quando no estado in natura; iv) contribuir para o aumento da retração por secagem e da carbonatação em argamassas; v) liberar Cromo e Sódio mesmo quando estabilizada/solidificada em pastas em teores de até 10% de substituição. Por essas considerações, a CCCC não apresentou viabilidade técnica para uso em matrizes cimentícias. / Nowadays, the use of wastes on civil building has been stimulated for it to be one of most consumers of raw materials in their processes and products. The agroindustrial ashes have a prominent place among the wastes with possibilities of application in cementitious materials, because some ashes, such rice husk ash, have pozzolanic activity, and they contribute to reduce the Portland cement consumption. This work aimed to study the evaluation of technical feasibility of the agroindustrial ashes for use in Portland cement matrices, using the ash of the rind of the cashew nut (ARCN) as case study. The rinds of cashew nut (wastes of nuts\' production) are burned again during the heating process, and in boilers, they will generate heat for shelling other nuts. The ARCN is the waste collected from the boiler grid, resulted from burning of the rind of nuts. This waste is used as compostes in plantings of cashew and a little part of it is dumped in landfill sites. Tests were made for evaluation of physico-chemical composition of ARCN; for analyse of pozzolanic activity; for analyse of drying shrinkage and carbonation in mortars made with ARCN; and the analyse of the stabilization/solidification of ARCN in pastes. After the analyse of results, it may be pointed as main features of ARCN: i) not show pozzolanic activity; ii) to promote air entrainment in cementitious matrices; iii) to cause heavy metals and Phenol solubilization as in raw state; iv) to increase the drying shrinkage and carbonation in mortars; and, v) to let out Chrome and Sodium when stabilizated/solidificated in pastes in levels of replacement until 10%. For all these considerations, the ARCN haven\'t showed technical feasibility for use in cementitious matrices.

Des détériorations importantes sont observées dans les réseaux d’assainissement en béton en raison de la présence d’hydrogène sulfuré (H2S). Différentes études ont montré qu’un environnement riche en hydrogène sulfuré entraîne, au contact de surfaces cimentaires, la sélection de bactéries sulfo-oxydantes (bactéries capables d’oxyder des composés soufrés réduits), menant à la production d’acide sulfurique. Cet acide détériore localement les réseaux par dissolution et recomposition minéralogique de la matrice cimentaire (formation de gypse et d’ettringite). Les réseaux ne collectent alors plus correctement les eaux usées et ce phénomène provoque donc des travaux de rénovation onéreux. Dans ce contexte, des solutions plus performantes que celles mises en place actuellement doivent être étudiées. L’objectif du projet FUI DURANET dans lequel s’inscrit cette thèse vise à proposer un essai accéléré et à développer un modèle.La mise en place d’essais abiotiques a permis de démontrer que cette première étape n’est pas l’étape limitante du phénomène de biodétérioration. En effet, le pH de surface des matériaux cimentaires adapté au développement microbien est rapidement atteint lorsqu’ils sont mis au contact de l’hydrogène sulfuré à une concentration élevée (100 ppm), quel que soit le matériau cimentaire considéré (mortiers à base de ciments CEM I, CEM III, CEM IV, CEM V, CAC et CSS). La modélisation de l’attaque par l’acide sulfurique et la mise en place d’un essai représentatif et accéléré ont ensuite été abordées pour prédire la durabilité des différents matériaux cimentaires de l’étude. Pour l’essai, différentes techniques d’ensemencement des microorganismes à la surface des matériaux cimentaires ont été comparées, afin de déterminer laquelle mène à la meilleure reproduction des conditions d’un réseau d’assainissement et à l’accélération des mécanismes de biodétérioration la plus importante. Ces essais permettent de préconiser l’utilisation de boues activées contenant un consortium de microorganismes, par rapport à l’utilisation de souches de collection, dont l’activité dépend trop fortement de leur adaptabilité aux conditions environnementales. L’ensemble des résultats, obtenus expérimentalement et par modélisation, montre une meilleure résistance des ciments d’aluminate de calcium et une dégradation très importante des ciments Portland face aux mécanismes mis en jeu, en accord avec les essais in-situ / Important deteriorations have been observed in concrete sewers, due to hydrogen sulfide (H2S) presence. H2S is used as nutrients for sulfur-oxidizing bacteria (bacteria able to oxidize the reduced sulfur compounds) and is oxidized into sulfuric acid. This acid attack of concrete leads to cementitious matrix dissolution and expansive products formation (gypsum and ettringite). This phenomenon disturbs the sewer system and conducts to expensive works of rehabilitation. In order to avoid this degradation, a French project named “FUI Duranet” was initiated to propose more efficient solutions. The aim of this thesis is to define a representative and accelerated test as well as a predictive model.Abiotic tests allow stating that this first stage of the biodeterioration mechanisms is not the limiting stage. Indeed, the adapted surface pH of the cementitious materials to bacteria development is quickly reached with a high H2S concentration (100 ppm), whatever the cementitious materials considered (mortars based on CEM I, CEM III, CEM IV, CEM V, CAC, and SSC cements). The chemical-transport modeling of the sulfuric acid attack of cementitious materials and the establishment of a representative and accelerated test have been proposed to predict their service life in these conditions. For the test, different seeding technics have been compared in order to determine which one lead to the better reproduction and acceleration of biodeterioration mechanisms. This test allows recommending the sludge use, which contains a microorganism’s consortium, rather than a collection strain use, whose activity is too dependent on environmental conditions. With the experimental test and the model, the better resistance of the calcium aluminate cement and the important degradation of the Portland cements are quickly confirmed, as highlighted during the field tests

Strain-hardening cement-based composites (SHCC) are a special class of fiber-reinforced concrete which develop multiple, fine cracks when subjected to increasing tensile loading, reaching strain capacities of up to several percent. The tensile behavior of SHCC is a result of a purposeful material design accounting for the mechanical and physical properties of the cementitious matrix, of the reinforcing fibers and of their interaction. The exceptionally high energy dissipation through inelastic deformations before reaching tensile strength makes SHCC suitable for manufacturing or strengthening of structural elements which may be subjected to impact loading. However, the tensile behavior of SHCC is highly strain rate dependent, both in terms of tensile strength and strain capacity. The different strain rate sensitivities of the constitutive phases of SHCC (matrix, fiber and interfacial bond) lead to disproportionate dynamic alteration of their mechanical properties under increasing strain rates and, consequently, to an impairment of the micromechanical balance necessary for strain-hardening and multiple cracking. Thus, high energy dissipation under impact loading can only be ensured through a targeted material design. This work presents a series of mechanical experiments at different strain rates and different scales of investigation with the goal of developing a qualitative and quantitative basis for formulating material design recommendations for impact resistant SHCC. Three different types of SHCC were investigated, consisting of two types of polymer fibers (polyvinyl-alcohol and high-density polyethylene) and cementitious matrices (normal-strength and high-strength). Uniaxial tension experiments were performed on SHCC specimens and on non-reinforced matrix specimens with different testing setups at strain rates ranging from 10-4 to 150 s-1. Besides the measured mechanical properties, special attention was paid to the crack patterns and the condition of fracture surfaces. Additionally, micro-scale investigations were performed to quantify the strain rate dependent changes in the mechanical behavior of individual component phases, i.e., matrix, fibers and fiber-matrix bond. The results obtained from the micromechanical investigations were used in an analytical model for crack bridging. The model links the micromechanical parameters and their strain rate sensitivities to the single-crack opening behavior under increasing displacement rates, making it useful for material design purposes. If given an extensive experimental basis for the fracture mechanical properties of the non-reinforced cementitious matrices, the model can be extended for predicting the strain capacity (multiple cracking) of SHCC under different strain rates. / Die hochduktilen Betone (Engl.: Strain-Hardening Cement-based Composites – SHCC) bilden eine besondere Klasse von Faserbetonen, die eine multiple Rissbildung unter zunehmenden Zugspannungen aufweisen, was zu einer sehr hohen Bruchdehnung führt. Das dehnungsverfestigende, hochduktile Zugverhalten der SHCC wird durch eine gezielte Materialentwicklung erreicht, die die mechanischen und physikalischen Eigenschaften der zementgebundenen Matrizen, der Kurzfasern und deren Zusammenwirkung berücksichtigt. Das außergewöhnliche Energieabsorptionsvermögen der SHCC durch plastische Verformungen vor dem Erreichen der Zugfestigkeit qualifiziert diese Verbundwerkstoffe für die Herstellung oder Verstärkung von Bauteilen, die Impaktbeanspruchungen ausgesetzt sein könnten. Jedoch weisen SHCC sowohl bezüglich deren Zugfestigkeit als auch deren Dehnungskapazität ein ausgeprägtes dehnratenabhängiges Verhalten auf. Unter zunehmenden Dehnraten führen die unterschiedlichen Dehnratensensitivitäten der gestaltenden Phasen von SHCC (Matrix, Faser und deren Verbund) zur Beeinträchtigung des mikromechanischen Gleichgewichts, welches für die Dehnungsverfestigung und multiple Rissbildung erforderlich ist. Eine hohe Energiedissipation unter Impaktbeanspruchungen kann deshalb nur durch eine gezielte Materialentwicklung der SHCC hinsichtlich deren Verhaltens unter hohen Dehnraten gewährleistet werden. Die vorliegende Arbeit umfasst eine Reihe von experimentellen Untersuchungen mit verschiedenen Dehnraten und an unterschiedlichen Betrachtungsebenen, mit dem Ziel eine qualitative und quantitative Basis für Empfehlungen zur Materialentwicklung von Impakt-resistenten SHCC zu schaffen. Drei verschiedene SHCC-Zusammensetzungen wurden untersucht. Die Referenz-Zusammensetzung aus einer normalfesten zementgebundenen Matrix und Polyvinyl-Alkohol-Kurzfasern wurde mit zwei unterschiedlichen SHCC verglichen (hochfest und normalfest), die mit Kurzfasern aus hochdichtem Polyethylen bewehrt wurden. Einaxiale Zugversuche wurden an SHCC-Proben und unbewehrten Matrix-Proben mit verschiedenen Prüfvorrichtungen bei Dehnraten von 10-4 bis 150 s-1 durchgeführt. Zusätzlich zu den gemessenen mechanischen Eigenschaften wurden die Rissbildung und die Bruchflächen detailliert untersucht. Darüber hinaus wurden mikromechanische Untersuchungen durchgeführt, um die Dehnratensensitivität der einzelnen Phasen, d.h. Matrix, Faser und deren Verbund zu beschreiben. Die aus den mikromechanischen Untersuchungen erzielten Ergebnisse wurden als Eingangswerte in einem analytischen Einzelriss-Modell verwendet. Das entwickelte Modell verbindet die mikromechanischen Parameter und deren Dehnratenabhängigkeit mit dem Rissöffnungsverhalten von SHCC bei zunehmenden Verschiebungsraten. Das macht es vorteilhaft für Materialentwicklungszwecke. Das Modell kann für die Vorhersage der Dehnungskapazität von SHCC bei diversen Dehnraten weiterentwickelt werden, wenn eine umfassende experimentelle Basis für die bruchmechanischen Eigenschaften der Matrizen vorliegt.

Le manque de granulats de qualité dans certaines régions françaises tend à devenir un problème majeur pour les entreprises de travaux publics. En effet, avec une consommation annuelle de 200 millions de tonnes de granulats, la route se doit de faire face en imaginant de nouvelles solutions comme la valorisation de certains matériaux.La craie, située entre roche et sol, possède une place particulière dans le monde des travaux publics. En effet, si son usage est relativement bien maîtrisé en vue de la réalisation de remblais ou de couches de forme, il en est tout autrement des couches d’assise de chaussées.Ce type de matériau est usuellement rejeté de la conception des assises de chaussées car il ne s’insère pas dans les guides normatifs utilisés par les professionnels de la route. Les performances mécaniques et la grande sensibilité à l’eau de ce matériau ne lui permettent pas d’entrer dans les spécifications requises par les normes. Cependant, il est tout à fait envisageable que la craie trouve sa place de manière totale ou partielle en assise de chaussée.Ce matériau que l’on trouve en abondance dans certaines régions françaises pauvres en granulats "haut de gamme" (Nord-Pas de Calais, Champagne-Ardenne…), pourrait ainsi palier un certain manque, participer à la préservation de ressources naturelles et économiser frais et pollution générés par un approvisionnement lointain.Ces travaux menés en partenariat entre le Laboratoire de Génie Civil de l’Ecole Centrale de Lille et le Laboratoire Routier Eurovia de Loos ont donc pour but de proposer des pistes d’amélioration des performances mécaniques de la craie en vue de sa valorisation en assise de chaussée routière / The lack of high quality aggregates in some French regions seems to become a main issue for road work firms. With an annual consumption of 200 millions tonnes of aggregates, road professionals must square up finding new solutions like the valorisation of some forgotten materials. Between rock and soil, chalk has a particular position in road work. While its use is relatively well managed for the realisation of fills and subgrade courses, the same certainly cannot be said for base courses. This kind of material is usually rejected for the design of road base courses because it is not approved within the current standards used by road professionals. Indeed, the low mechanical performances and the high water sensibility of chalk do not allow this material to be used. However, it seems possible to find some pre-treatments to harden chalk for a use in road base courses.This material is found profusely in some French regions otherwise limited in upscale aggregates (Nord-Pas de Calais, Champagne-Ardenne…). Therefore, valorising chalk may overcome the lack of aggregates, contribute to the preservation of natural resources, save up money and avoid pollution due to distant supplying.The study presented here is conducted in partnership between the Ecole Centrale de Lille Civil Engineering Laboratory and the Eurovia Roadworks Laboratory of Loos. We provide several trails aimed at improving the mechanical properties of chalk for its use in road base courses

La prédiction du comportement à long terme des matériaux cimentaires est un enjeu majeur pour contribuer à l'étude de la durabilité des structures précontraintes. Le présent travail porte sur l'utilisation de la méthode de l'inclusion équivalente, approche d'homogénéisation multi-échelle simplifiée, pour la prédiction du fluage dans ces matériaux. Le fluage est modélisé par la viscoélasticité linéaire sans vieillissement. La méthode de l'inclusion équivalente permet de contourner certaines difficultés et limitations que présentent les approches classiques. Pour les matériaux cimentaires, fortement hétérogènes, les approches multiéchelles classiques sont ou bien numériquement lourdes et très complexes à mettre en œuvre, ou bien pas suffisamment détaillées pour prendre en compte les spécificités d'une microstructure. La méthode de l'inclusion équivalente présente un juste-milieu et permet de calculer des microstructures simplifiées de type matrice-inclusions et de fournir des estimations ou des bornes sur le comportement homogénéisé. Sous sa forme variationnelle, la méthode de l'inclusion équivalente n'a jusqu'alors été mise en œuvre que pour des inclusions de forme sphérique. Le présent travail propose d'étendre cette méthode à des inclusions de forme ellipsoïdale dont la variation de l'élancement permet de modéliser de nouveaux éléments asphériques tels que les fissures, les fibres et les cristaux de portlandite. Cette complexification de la géométrie a un impact sur le temps de calcul, qui est amplifié dans le cadre du fluage. Le second volet du travail porte alors sur l'extension de la méthode de l'inclusion équivalente à la viscoélasticité linéaire sans vieillissement par l'intermédiaire de la transformée de Laplace-Carson. Une méthodologie efficace (tant du point de vue de la précision que de celui du temps de calcul) est finalement proposée pour effectuer l'inversion numérique de cette transformée / The prediction of long-term behaviour of cementitious materials is a major concern which contributs to the study of the durability of prestressed structures. This work focuses on the use of the equivalent inclusion method, simplified multi-scale homogenization approach, for the prediction of creep in these materials. Creep is modelled by the non-ageing linear viscoelasticity. The equivalent inclusion method overcomes certain difficulties and limitations posed by conventional approaches. For cementitious materials (highly heterogeneous), conventional multi-scale approaches are, either digitally heavy and complex to implement, or not sufficiently detailed to take into account the specificities of a microstructure. The equivalent inclusion method presents a middle way and allows the calculation of simplified matrix-inclusion type microstructures and to provide estimates or bounds on the homogenized behaviour.Under its variational form, the equivalent inclusion method has, up to now, been implemented only for spherical inclusions. This work proposes to extend this method to ellipsoidal inclusions whose variation of slenderness allows the modelling of new aspheric elements such as cracks, fibers and portlandite crystals. Such enrichment of the geometry has an impact on the computation time, that is amplified in the context of creep. The second aspect of the work then applies to the extension of the equivalent inclusion method to the non-ageing linear viscoelasticity by means of the Laplace-Carson transform. An effective methodology (both from the viewpoint of precision and calculation time) is finally proposed to perform the numerical inversion of this transform

La durabilité des structures en béton armé ainsi que leur durée de vie sont étroitement liées à la mise en œuvre simultanée de nombreux phénomènes physiques et chimiques. Ceux-ci sont de diverses natures mais restent, en général, fonction des propriétés hydriques des matériaux étudiés. Ainsi, la prédiction des dégradations potentielles d'un matériau cimentaire requiert l'étude du transport de l'eau liquide et des phases gazeuses à travers ce dernier, considéré comme un milieu poreux. En milieu naturel, les structures subissent des variations périodiques de l'humidité relative extérieure (HR). Cependant, la plupart des modèles de transfert hydrique préexistants dans la littérature, s'intéresse uniquement au processus de séchage. Il existe peu de modèles décrivant à la fois l'humidification et le séchage du matériau (ces deux phénomènes se produisent dans le matériau en condition naturelle d'humidité relative (HR)). Tenir compte des phénomènes d'hystérésis dans les transferts hydriques réduit à nouveau le nombre de modèles à disposition. Ainsi, cette thèse s'attache à proposer une meilleure compréhension de l'état hydrique du béton en fonction des variations d'humidité relative extérieure, sur la base d'une nouvelle campagne expérimentale et de modélisations numériques. Un soin sera apporté afin de tenir compte dans les modèles numériques des effets d'hystérésis. Dans ce travail, nous détaillerons, tout d'abord, un modèle multi-phasiques complet. Un modèle simplifié est obtenu, sur la base de considérations théoriques et de vérifications expérimentales dans le cas où la perméabilité intrinsèque à l'eau liquide reste très inférieure à la perméabilité intrinsèque au gaz. Une étude comparative des modèles d'hystérésis couramment utilisés permet d'obtenir un jeu de modèles proposant les meilleures prédictions d'isothermes de sorption d'eau et de leurs hystérésis. Par la suite, le modèle de transport simplifié est couplé avec les modèles d'hystérésis sélectionnés afin de simuler les transferts hydriques dans des bétons soumis à des cycles d'humidification-séchage. La comparaison avec des données expérimentales révèle que la prise en compte de l'hystérésis de l'isotherme de sorption d'eau ne peut pas être négligé. De plus, il est montré que les prédictions obtenues avec des modèles d'hystérésis théoriques, sont les plus cohérentes avec les résultats expérimentaux, en particulier, pour des chemins secondaires d'hystérésis. Plusieurs scénarios (conditions environnementales, bétons différents) sont également simulés. Les résultats obtenus pointent à nouveau la nécessité de tenir compte de l'hystérésis lors de la modélisation des transferts hydriques à travers des matériaux cimentaires soumis à des variations d'humidité relative. La définition d'une profondeur pour laquelle le profil hydrique du béton est modifié par les variations périodiques d'humidité relative permet de mieux comprendre comment la modélisation de la pénétration des espèces ioniques est influencée par les cycles d'humidification-séchage. Par ailleurs, notre analyse révèle qu'il est pertinent de considérer l'effet de Knudsen pour la diffusion de la vapeur afin d'améliorer la prédiction de la diffusivité apparente / The durability of reinforced concrete structures and their service life are closely related to the simultaneous occurrence of many physical and chemical phenomena. These phenomena are diverse in nature, but in common they are dependent on the moisture properties of the material. Therefore, the prediction of the potential degradation of cementitious materials requires the study of the movement of liquid-water and gas-phase transport in the material which is considered as a porous medium. In natural environment, structures are always affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on the drying process. There are few researches considering both drying and wetting, although these conditions represent natural RH variations. Even few studies take into account hysteresis in moisture transport. Thus, this work is devoted to better understand how the moisture behaviour within cementitious materials responds to the ambient RH changes through both experimental investigations and numerical modelling. In particular, hysteretic effects will be included in numerical modelling. In this thesis, we first recalled a complicate multi-phase continuum model. By theoretical analysis and experimental verification, a simplified model can be obtained for the case of that the intrinsic permeability to liquid-water is smaller than the intrinsic permeability to gas-phase. The review of commonly-used hysteresis models enabled to conclude a set of best models for the prediction of water vapour sorption isotherms and their hysteresis. After that, the simplified model was coupled with selected hysteresis models to simulate moisture transport under drying and wetting cycles. Compared with experimental data, numerical simulations revealed that modelling with hysteretic effects can provide much better results than non-hysteresis modelling. Among different hysteresis models, results showed that the use of the conceptual hysteresis model, which presents closed form scanning loops, can provide more accuracy predictions. Further simulations for different scenarios were also performed. All comparisons and investigations enhanced the necessity of considering hysteresis to model moisture transport for varying relative humidity at the boundary. The investigation of moisture penetration depth could provide a better understanding of how deep moisture as well as ions can move into the material. Furthermore, the analysis revealed that the consideration of Knudsen effects for diffusion of vapour can improve the prediction of the apparent diffusivity