O principal impacto ambiental do processo de beneficiamento da casca de coco verde é a geração de resíduo líquido com elevada carga orgânica. Este trabalho teve como objetivo aplicar o sistema convencional de lodos ativados para o tratamento biológico do líquido gerado no beneficiamento da casca de coco verde, além de utilizar o teste de taxa de consumo de oxigênio (TCO) para avaliar a toxicidade do efluente ao lodo aeróbio. O reator de escala laboratorial foi inoculado com lodo proveniente de uma estação de tratamento de esgoto em escala plena. Inicialmente o sistema foi alimentado com efluente sintético contendo sacarose e nutrientes para posterior adição progressiva do resíduo líquido proveniente da reciclagem da casca de coco verde. Para o ensaio de respirometria, as composições testadas foram 25, 50, 75 e 100% de resíduo líquido em termos de carga orgânica e o teste se baseou na medição manual da TCO ao longo do tempo. Para cada composição de efluente se verificou o valor máximo de TCO, o nível de toxicidade devido ao líquido da casca de coco verde (LCCV) e a indicação de inibição permanente. O parâmetro usado nos cálculos de toxicidade e de inibição permanente foi a taxa de consumo de oxigênio específica (TCOe) máxima. Para o monitoramento do sistema de fluxo contínuo, foram empregados os parâmetros pH, índice volumétrico de lodo (IVL), oxigênio dissolvido (OD), demanda química de oxigênio (DQO), taninos totais e sólidos suspensos. O reator foi operado com carga orgânica volumétrica (COV) de 0,8 a 2,9 gDQO/L.d e tempo de detenção hidráulica (TDH) de 26,7 d. Devido à presença natural de leveduras no resíduo líquido, os testes de respirometria foram realizados com o efluente tanto esterilizado quanto in natura. Como os resultados preliminares de respirometria não foram conclusivos, optou-se por começar a adaptação do reator de fluxo contínuo com a menor porcentagem testada: 25% de resíduo líquido. Nos testes adicionais de respirometria não houve toxicidade ao lodo e a TCOe foi diretamente proporcional à concentração de resíduo líquido. A remoção média de DQO obtida durante a operação (LCCV a 100%) foi de 81% com amostra filtrada e 82% com amostra bruta. Houve diminuição significativa da concentração de taninos, de 5332 para 1206 mg/L, em média. No início da operação ocorreu o decaimento da concentração de oxigênio dissolvido (OD) no reator para valores menores que 1 mg/L em decorrência do aumento da concentração de biomassa, mas esta situação não afetou a remoção de matéria orgânica e nem a sedimentabilidade do lodo. A remoção de matéria orgânica obtida com o tratamento em escala laboratorial do LCCV mostra que o sistema convencional de lodos ativados pode ser aplicado como alternativa no tratamento biológico dos resíduos líquidos do beneficiamento da casca de coco verde, porém a demanda elevada de oxigênio pode ser um entrave na operação em escala plena. / The main disadvantage of coconut recycling is the highly pollutant wastewater generated during the process. The objectives of this study were to treat the coconut husk liquor (CHL) using a conventional activated sludge system (AS) and to use the oxygen uptake rate (OUR) test for determining the initial effluent composition of reactor feeding and for wastewater toxicity assessment. The laboratory-scale reactor was inoculated with sludge from a full-scale sewage treatment plant. Firtly the system was fed with synthetic effluent containing saccarose and nutrients which was substituted by CHL. For the OUR test the substrate compositions were 25, 50, 75 and 100% of CHL. For each substrate composition, it was verified the maximum OUR value, the toxicity level and permanent inhibition caused by CHL. The maximal specific oxygen uptake rate (SOUR) was the parameter applied for the toxicity assessment and permanent inhibition calculation. The lab-scale reactor was monitored on the basis of pH, sludge volume index, dissolved oxygen, chemical oxygen demand (COD), total tannins and suspended solids. The respirometry assays were carried out with sterilized and natural effluent because of yeast contamination in CRW. Because of the lack of conclusive results in the first respirometry test, it was chosen the lower composition for reactor adaptation beginning: CRW 25%. In the additional OUR tests it was not detected toxicity and the SOUR values were as higher as CRW concentration. After initializing the reactor adaptation with CRW 25%, the percentage changed to 30% and than increased by 10% each 2 or 3 days until the operation beginning. The mean COD removal values were 81% (filtered sample) and 82% (raw sample). The mean tannin concentration decreased from 5332 to 1206 mg/L. The organic removal and sludge settleability were not affected by the DO concentration decrease to less than 1 mg/L due to biomass increase. The organic removal obtained in the lab-scale AS treatment shows that this system can be an alternative for CHL biological treatment, even though the high oxygen demand could be a disadvantage at full-scale treatment.

O principal impacto ambiental do processo de beneficiamento da casca de coco verde é a geração de resíduo líquido com elevada carga orgânica. Este trabalho teve como objetivo aplicar o sistema convencional de lodos ativados para o tratamento biológico do líquido gerado no beneficiamento da casca de coco verde, além de utilizar o teste de taxa de consumo de oxigênio (TCO) para avaliar a toxicidade do efluente ao lodo aeróbio. O reator de escala laboratorial foi inoculado com lodo proveniente de uma estação de tratamento de esgoto em escala plena. Inicialmente o sistema foi alimentado com efluente sintético contendo sacarose e nutrientes para posterior adição progressiva do resíduo líquido proveniente da reciclagem da casca de coco verde. Para o ensaio de respirometria, as composições testadas foram 25, 50, 75 e 100% de resíduo líquido em termos de carga orgânica e o teste se baseou na medição manual da TCO ao longo do tempo. Para cada composição de efluente se verificou o valor máximo de TCO, o nível de toxicidade devido ao líquido da casca de coco verde (LCCV) e a indicação de inibição permanente. O parâmetro usado nos cálculos de toxicidade e de inibição permanente foi a taxa de consumo de oxigênio específica (TCOe) máxima. Para o monitoramento do sistema de fluxo contínuo, foram empregados os parâmetros pH, índice volumétrico de lodo (IVL), oxigênio dissolvido (OD), demanda química de oxigênio (DQO), taninos totais e sólidos suspensos. O reator foi operado com carga orgânica volumétrica (COV) de 0,8 a 2,9 gDQO/L.d e tempo de detenção hidráulica (TDH) de 26,7 d. Devido à presença natural de leveduras no resíduo líquido, os testes de respirometria foram realizados com o efluente tanto esterilizado quanto in natura. Como os resultados preliminares de respirometria não foram conclusivos, optou-se por começar a adaptação do reator de fluxo contínuo com a menor porcentagem testada: 25% de resíduo líquido. Nos testes adicionais de respirometria não houve toxicidade ao lodo e a TCOe foi diretamente proporcional à concentração de resíduo líquido. A remoção média de DQO obtida durante a operação (LCCV a 100%) foi de 81% com amostra filtrada e 82% com amostra bruta. Houve diminuição significativa da concentração de taninos, de 5332 para 1206 mg/L, em média. No início da operação ocorreu o decaimento da concentração de oxigênio dissolvido (OD) no reator para valores menores que 1 mg/L em decorrência do aumento da concentração de biomassa, mas esta situação não afetou a remoção de matéria orgânica e nem a sedimentabilidade do lodo. A remoção de matéria orgânica obtida com o tratamento em escala laboratorial do LCCV mostra que o sistema convencional de lodos ativados pode ser aplicado como alternativa no tratamento biológico dos resíduos líquidos do beneficiamento da casca de coco verde, porém a demanda elevada de oxigênio pode ser um entrave na operação em escala plena. / The main disadvantage of coconut recycling is the highly pollutant wastewater generated during the process. The objectives of this study were to treat the coconut husk liquor (CHL) using a conventional activated sludge system (AS) and to use the oxygen uptake rate (OUR) test for determining the initial effluent composition of reactor feeding and for wastewater toxicity assessment. The laboratory-scale reactor was inoculated with sludge from a full-scale sewage treatment plant. Firtly the system was fed with synthetic effluent containing saccarose and nutrients which was substituted by CHL. For the OUR test the substrate compositions were 25, 50, 75 and 100% of CHL. For each substrate composition, it was verified the maximum OUR value, the toxicity level and permanent inhibition caused by CHL. The maximal specific oxygen uptake rate (SOUR) was the parameter applied for the toxicity assessment and permanent inhibition calculation. The lab-scale reactor was monitored on the basis of pH, sludge volume index, dissolved oxygen, chemical oxygen demand (COD), total tannins and suspended solids. The respirometry assays were carried out with sterilized and natural effluent because of yeast contamination in CRW. Because of the lack of conclusive results in the first respirometry test, it was chosen the lower composition for reactor adaptation beginning: CRW 25%. In the additional OUR tests it was not detected toxicity and the SOUR values were as higher as CRW concentration. After initializing the reactor adaptation with CRW 25%, the percentage changed to 30% and than increased by 10% each 2 or 3 days until the operation beginning. The mean COD removal values were 81% (filtered sample) and 82% (raw sample). The mean tannin concentration decreased from 5332 to 1206 mg/L. The organic removal and sludge settleability were not affected by the DO concentration decrease to less than 1 mg/L due to biomass increase. The organic removal obtained in the lab-scale AS treatment shows that this system can be an alternative for CHL biological treatment, even though the high oxygen demand could be a disadvantage at full-scale treatment.

There are many studies about how the addition of lime and rice husk ash (RHA) gives the soil a better mechanical behavior, particularly on clayey soils, where usually fine particles reach more than 75%. However, the soils with a small presence of fine particles (59-60%) do not have much research. This analysis evaluates the influence that RHA has on this kind of soil stabilized with 3% of lime. After the initial mix of soil-lime, CBR increased 11.2 times its initial value; within the addition of the ash, the CBR averaged between 45-50% up until 28% of RHA was added, where the results decreased considerably. Soil workability improved and the specimens with more ash resulted in a more granular material, with a group index value 0 following the AASHTO standards. The greatest CBR record was obtained with the specimen of 16% RHA, 3% lime and soil, reaching a 51.3% CBR, 1.58g/cm3 of MDD and 16.5% of OMC. Yet, it only showed a 1.55% more resistance than the lime-soil specimen. The CBR with more presence of RHA tends to decrease its value, therefore for silica-rich clayey soils, the addition of lime by itself should be enough for an adequate performance.

Em cerâmicas refratárias, a formação de mulita (3Al2O3.2SiO2) \"in situ\", a partir da reação entre alumina e sílicas amorfas sintéticas (SAS´s) aumenta a resistência ao choque térmico e à corrosão destes materiais. Essa reação é fortemente afetada pelas características físico-químicas e morfológicas das SAS´s. Este estudo comparou a formação de mulita\"in situ\" a partir da combinação de alumina calcinada ultrafina (α-Al2O3) com quatro tipos de SAS´s obtidas por diferentes processos de sínteses (precipitação de silicato de sódio, extração da cinza da casca do arroz, extração da casca do arroz e precipitação de vapor de silício elementar) e com características variadas. Inicialmente, esses quatros tipos de SASs foram caracterizados em relação às suas propriedades físico-químicas, microestrutura e morfologia. Em seguida, após mistura com alumina, compactação e sinterização (1100-1500°C) assistida por dilatometria, as amostras foram caracterizadas em relação à sua porosidade, densidade, módulo elástico, resistência à flexão, microestrutura e fases presentes. Verificou-se que as propriedades das estruturas finais foram fortemente afetadas pela mudança de SAS´s. De forma geral e em comparação com as amostras de referência (100% alumina ou 100% mulita pré-formada por eletrofusão), houve significativo ganho de rigidez e tensão de ruptura em menores temperaturas e grande redução de porosidade final. Valores de tensão de ruptura e módulo elástico da ordem de 114 MPa e 308 GPa foram obtidos, respectivamente. A correlação das propriedades obtidas com as características prévias das sílicas mostrou que a área superficial e o volume de poros internos das partículas afetaram mais o ganho de rigidez e redução de porosidade do que o tamanho médio das partículas. Além desse aspecto, a presença de fases de baixo ponto de fusão (em especial nas amostras com microssílica) também contribuiu fortemente para densificação. / In refractories ceramics, the formation of mullite (3Al2O3.2SiO2) \"in situ\", from the reaction between alumina and synthetic amorphous silica (SAS\'s) increases the resistance to thermal shock and corrosion of these materials. This reaction is strongly affected by the physic-chemical and morphological features of SAS\'s. This study compared the mullite formation \"in situ\" from the combination of calcined alumina with four kinds of ultrafine\'s SASs obtained by various synthesis processes (precipitation of sodium silicate, from rice husk, extraction of rice husk ash and steam precipitation of silicon metal) and with varying characteristics. Initially, these four kinds of SAS´s were characterized in relation to their physicochemical properties, microstructure and morphology. After compaction and sintering (1100-1500°C) assisted by dilatometry, samples were characterized regarding their porosity, density, elastic modulus, flexural strength, microstructure and phases present. The properties of the final structure were strongly affected by the change of SAS\'s. In general, and in comparison with reference samples (100% alumina or 100% mullite preform for electrofusion), a significant stiffness gain of strength at low temperature and lower final porosity, respectively. Value of rupture and elastic modulus of the order of 114 MPa and 308 GPa were obtained. The correlation of properties obtained with the prior characterization of SAS´s showed that surface area and the volume of the internal poros of the particles affect the gain more stiffness and lower porosity than the average particle size. Aparts from this, the presence of phases of low melting point (especially in samples with microssilica) also contributed strongly to densification.

Made available in DSpace on 2014-06-11T19:25:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-04-13Bitstream added on 2014-06-13T19:12:01Z : No. of bitstreams: 1 silva_ej_me_ilha.pdf: 3783689 bytes, checksum: 33016836c826eae75c76a0b521c81b78 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A presente pesquisa contribui para a utilização de cinza de casca de arroz (CCA) na construção civil abordando dois aspectos importantes ainda em discussão na literatura. O primeiro aspecto compreende uma análise da influência que a forma de plantio, clima, solo, cultivares e fonte/quantidade de fertilizantes à base de nitrogênio, utilizados na cultura do arroz, exercem na composição química e nas propriedades cristalográficas da CCA. O segundo aspecto foi aplicar em pastas, argamassas e concretos de alto desempenho uma CCA com baixo teor de carbono, de elevado caráter pozolânico, na condição natural (sem moagem), produzida de uma maneira simples e sem controle de temperatura. De acordo com os resultados obtidos neste trabalho, verifica-se a importância de efetuar ensaios rotineiros de análises químicas e de Difração de Raio-X para manter o controle de qualidade das CCAs produzidas, pois em situação de produção de CCA em larga escala, poderiam ser utilizadas cascas de diferentes origens. Neste trabalho, também ficou comprovada a viabilidade técnica e científica do método de produção de CCA utilizado. O método produz CCA que, dependendo da forma de amassamento dos compósitos, pode dispensar o emprego de moinhos para aumentar a finura e/ou reatividade de CCAs. / This research contributes to the use of rice husk ash (RHA) in the civil building covering two important aspects that still under discussion in the literature. The first one includes an analysis of the influence that the form of planting, climate, soil, rice and source/amount of nitrogen-based fertilizers used in rice cultivation in performing crystallographic properties and chemical composition of the rice husk ash. The second one was to aplicate to the pastes, mortar and concrete of high performance a RHA with low carbon, high pozzolanic character, in the natural physical state (without grinding), produced in a simple way and without control of temperature. According to the results obtained in this research, it is important to do routine testing of chemical analysis and X-ray Diffraction to keep quality control of RHAs produced, because at industrial production in large scale it can be used husks of different origins. This research was also demonstrated the feasibility technical and scientific method of production of RHA used. The method produces RHA that depending on the form of production of the composite may eliminate the use of grinders to increase the fineness and/or reactivity of RHAs.

Em cerâmicas refratárias, a formação de mulita (3Al2O3.2SiO2) \"in situ\", a partir da reação entre alumina e sílicas amorfas sintéticas (SAS´s) aumenta a resistência ao choque térmico e à corrosão destes materiais. Essa reação é fortemente afetada pelas características físico-químicas e morfológicas das SAS´s. Este estudo comparou a formação de mulita\"in situ\" a partir da combinação de alumina calcinada ultrafina (α-Al2O3) com quatro tipos de SAS´s obtidas por diferentes processos de sínteses (precipitação de silicato de sódio, extração da cinza da casca do arroz, extração da casca do arroz e precipitação de vapor de silício elementar) e com características variadas. Inicialmente, esses quatros tipos de SASs foram caracterizados em relação às suas propriedades físico-químicas, microestrutura e morfologia. Em seguida, após mistura com alumina, compactação e sinterização (1100-1500°C) assistida por dilatometria, as amostras foram caracterizadas em relação à sua porosidade, densidade, módulo elástico, resistência à flexão, microestrutura e fases presentes. Verificou-se que as propriedades das estruturas finais foram fortemente afetadas pela mudança de SAS´s. De forma geral e em comparação com as amostras de referência (100% alumina ou 100% mulita pré-formada por eletrofusão), houve significativo ganho de rigidez e tensão de ruptura em menores temperaturas e grande redução de porosidade final. Valores de tensão de ruptura e módulo elástico da ordem de 114 MPa e 308 GPa foram obtidos, respectivamente. A correlação das propriedades obtidas com as características prévias das sílicas mostrou que a área superficial e o volume de poros internos das partículas afetaram mais o ganho de rigidez e redução de porosidade do que o tamanho médio das partículas. Além desse aspecto, a presença de fases de baixo ponto de fusão (em especial nas amostras com microssílica) também contribuiu fortemente para densificação. / In refractories ceramics, the formation of mullite (3Al2O3.2SiO2) \"in situ\", from the reaction between alumina and synthetic amorphous silica (SAS\'s) increases the resistance to thermal shock and corrosion of these materials. This reaction is strongly affected by the physic-chemical and morphological features of SAS\'s. This study compared the mullite formation \"in situ\" from the combination of calcined alumina with four kinds of ultrafine\'s SASs obtained by various synthesis processes (precipitation of sodium silicate, from rice husk, extraction of rice husk ash and steam precipitation of silicon metal) and with varying characteristics. Initially, these four kinds of SAS´s were characterized in relation to their physicochemical properties, microstructure and morphology. After compaction and sintering (1100-1500°C) assisted by dilatometry, samples were characterized regarding their porosity, density, elastic modulus, flexural strength, microstructure and phases present. The properties of the final structure were strongly affected by the change of SAS\'s. In general, and in comparison with reference samples (100% alumina or 100% mullite preform for electrofusion), a significant stiffness gain of strength at low temperature and lower final porosity, respectively. Value of rupture and elastic modulus of the order of 114 MPa and 308 GPa were obtained. The correlation of properties obtained with the prior characterization of SAS´s showed that surface area and the volume of the internal poros of the particles affect the gain more stiffness and lower porosity than the average particle size. Aparts from this, the presence of phases of low melting point (especially in samples with microssilica) also contributed strongly to densification.

O presente trabalho teve como proposta a preparação de amidos termoplásticos (TPS) e compósitos a partir de amido de arroz e subprodutos do processo de beneficiamento do arroz, no qual resulta em 20% de palha e 14% de grãos quebrados. Estudou-se o amido de arroz como nova fonte para preparação de termoplásticos, avaliou-se o efeito da incorporação de palha de arroz aos TPS a fim de superar as limitações apresentadas por estes tais como baixo desempenho mecânico e alta absorção de umidade, avaliou-se a possibilidade de preparação de termoplásticos diretamente dos grãos de arroz e quirera e investigou-se a influência das condições de processamento (tempo e temperatura) na preparação dos termoplásticos. O amido de arroz foi plasticizado com glicerol em proporções que variaram de 20 a 40%. Para os compósitos, o teor de reforço (palha) variou de 1 a 5% e o teor de glicerol foi fixado em 30%. Tanto os materiais de partida quanto os termoplásticos e compósitos obtidos foram caracterizados por MEV e difração de raios-X; quanto às propriedades térmicas por TG, DSC e DMTA; quanto às propriedades mecânicas por ensaio mecânico de tração. O comportamento frente à absorção de água também foi investigado. O estudo das condições de processamento foi feito com base nos resultados obtidos a partir da reometria de torque, difração de raios-X e MEV e demonstrou que a utilização de apenas uma das técnicas é insuficiente para determinação das condições de processamento que melhor contribuem para desestruturação do grânulo, mistura e homogeneização do TPS. Os TPS preparados a partir de amido de arroz e glicerol seguiram a mesma tendência de variação de suas propriedades em função do teor de plasticizante que os TPS preparados a partir de outras fontes de amido. Levando em consideração TPS preparados a partir de amido de mandioca, milho e batata, observa-se que os TPS preparados a partir de amido de arroz apresentaram a menor absorção de água. Em relação aos compósitos, a palha contribuiu para melhorar o desempenho mecânico, no entanto favoreceu o aumento da absorção de água. Foi possível obter termoplásticos preparados diretamente dos grãos de arroz (polido e integral) e da quirera. Em comparação com o TPS amido/glicerol, os TPS obtidos a partir dos grãos apresentaram maior cristalinidade, rigidez e temperatura de transição vítrea. No entanto, apresentaram menor estabilidade térmica, menor ductilidade e maior absorção de água. / This work aimed at preparation of thermoplastic starch (TPS) and composites from rice starch and byproducts of the beneficiation process of rice, which results in 20% of husk and 14% of broken grains. The rice starch was studied as a new source for preparing thermoplastics. The effect of incorporation of rice husk to the TPS was evaluated aiming to overcome the limitations presented by pure TPS such as poor mechanical properties and high moisture absorption. The preparation of thermoplastic directly from grain and broken rice was also studied. The rice starch was plasticized with glycerol in proportions ranging from 20 to 40%. For composites, the amount of husk ranged from 1 to 5% and glycerol content was 30%. The effect of processing conditions (time and temperature) in the preparation of thermoplastics were investigated. Starting materials, thermoplastics and composites were characterized by SEM and X-ray diffraction; the thermal properties by TG, DSC and DMTA; and mechanical properties by mechanical tests. The behavior in the water uptake was also investigated. The processing conditions study was based on the results obtained from the torque rheometry, X-ray diffraction and scanning electron microscopy and demonstrated that the use of only one technique is inadequate to determine the best processing conditions. The TPS prepared from rice starch and glycerol followed the same trend of variation of its properties as a function of plasticizer content when compared to TPS prepared from other starch sources. Considering TPS prepared from cassava starch, corn and potato, it was observed that the TPS prepared from rice starch presented a lower water uptake. For composites, husk has improved mechanical performance, but favors the increase in water uptake. It was possible to obtain thermoplastic prepared directly from grain rice (polished and integral) and broken grain. Compared to the starch/glycerol TPS, TPS obtained from the grains had higher crystallinity, and stiffness and glass transition temperature. However, had lower thermal stability, lower ductility and increased absorption of water.

The work presented in this thesis deals with the development of self-consolidating high performance concrete (SCHPC) incorporating rice husk ash (RHA) as a supplementary cementing material. Various SCHPCs were produced using the water-binder (W/B) ratios of 0.30, 0.35, 0.40 and 0.50, and RHA content in the range of 0 to 30% of cement by weight. In addition, a number of pastes and mortars formulated from the concretes were prepared and tested for the filling ability. The paste and mortar filling abilities were tested with respect to flow time and flow spread, respectively, at various dosages of high-range water reducer (HRWR). Also, the mortars were tested for the air content at various dosages of air-entraining admixture (AEA). It was observed that the flow time of the pastes increased with lower W/B ratio and higher RHA content, whereas the flow spread of the mortars decreased with higher W/B ratio and greater RHA content. Both paste and mortar filling abilities increased with higher HRWR dosages. In addition, the air content of the mortars decreased with lower W/B ratio and higher RHA content for given AEA dosages. The fresh SCHPCs were tested for filling ability, passing ability, air-void stability, segregation resistance, unit weight and air content. The filling ability was determined with respect to slump and slump flow, inverted slump cone flow time and spread, and orimet flow time and spread. The passing ability was measured with regard to slump and slump flow with J-ring, inverted slump cone flow spread with J-ring, and orimet flow spread with J-ring. The air-void stability in several fresh SCHPC mixtures was investigated with respect to re-mixing of concrete and subsequent measurement of air content at different test stages. The test results obtained for the fresh properties showed that the inverted slump cone and orimet flow times increased with lower W/B ratio and greater RHA content. In addition, the slump flow, inverted slump cone flow spread, and orimet flow spread with and without J-ring increased considerably with lower W/B ratio and greater RHA content. However, the increases in slump with and without J-ring at lower W/B ratio and higher RHA content were not significant. The unit weight of concrete slightly decreased with higher W/B ratio and greater RHA content, and with higher air content. Achieving the target air content required greater AEA dosages for lower W/B ratio and higher RHA content. However, the presence of RHA had no adverse effect on the air-void stability of concrete. The segregation resistance of various SCHPCs was investigated by visual inspection of concrete in mixer pan, and during and after different flow tests. Slight bleeding and a thick layer of paste were noticed in mixer pan for several concretes. The dynamic segregation in the form of discontinuity or blockage of flow did not occur during the orimet and inverted slump cone flow tests for any concrete. No aggregate pile appeared in the slump flow, and orimet and inverted slump cone flow spreads of any concrete. But minor to severe mortar halos were noticed in the periphery of the flow spread of several concretes, particularly in the presence of high RHA content. The results of visual inspection suggest that both lower W/B ratio and greater RHA content improved the dynamic segregation resistance of concrete. In contrast, the higher RHA content resulted in a lower static segregation resistance, which was overcome in the presence of viscosity-enhancing admixture (VEA). The static segregation resistance of several SCHPCs was quantitatively determined by sieve and column apparatus. The segregation index given by the sieve increased with lower W/B ratio and higher RHA content, thus indicating a reduced static segregation resistance. In contrast, the segregation factor given by the column apparatus decreased with lower W/B ratio suggesting an increased static segregation resistance. However, the segregation factor increased with higher RHA content, and thus revealed a reduction in static segregation resistance. In the presence of VEA, both segregation index and segregation factor decreased significantly, indicating an improvement in the static segregation resistance of concrete. The hardened SCHPCs were tested for compressive strength, ultrasonic pulse velocity, water absorption, total porosity and electrical resistivity. Test results revealed that the compressive strength, ultrasonic pulse velocity and true electrical resistivity increased, whereas the water absorption and total porosity decreased with lower W/B ratio and higher RHA content. The entrained air-voids decreased the compressive strength, ultrasonic pulse velocity, water absorption and total porosity, but slightly increased the electrical resistivity of concrete. In general, the hardened properties indicated good durability of the concretes. The empirical models for the filling ability (slump flow) and compressive strength of SCHPC were derived and verified with test data from this study and other data taken from the literature. The slump flow and compressive strength computed from the models were coherent with the measured values. Both filling ability and strength models were useful to develop a mixture design method for SCHPC with and without RHA.

The work presented in this thesis deals with the development of self-consolidating high performance concrete (SCHPC) incorporating rice husk ash (RHA) as a supplementary cementing material. Various SCHPCs were produced using the water-binder (W/B) ratios of 0.30, 0.35, 0.40 and 0.50, and RHA content in the range of 0 to 30% of cement by weight. In addition, a number of pastes and mortars formulated from the concretes were prepared and tested for the filling ability. The paste and mortar filling abilities were tested with respect to flow time and flow spread, respectively, at various dosages of high-range water reducer (HRWR). Also, the mortars were tested for the air content at various dosages of air-entraining admixture (AEA). It was observed that the flow time of the pastes increased with lower W/B ratio and higher RHA content, whereas the flow spread of the mortars decreased with higher W/B ratio and greater RHA content. Both paste and mortar filling abilities increased with higher HRWR dosages. In addition, the air content of the mortars decreased with lower W/B ratio and higher RHA content for given AEA dosages. The fresh SCHPCs were tested for filling ability, passing ability, air-void stability, segregation resistance, unit weight and air content. The filling ability was determined with respect to slump and slump flow, inverted slump cone flow time and spread, and orimet flow time and spread. The passing ability was measured with regard to slump and slump flow with J-ring, inverted slump cone flow spread with J-ring, and orimet flow spread with J-ring. The air-void stability in several fresh SCHPC mixtures was investigated with respect to re-mixing of concrete and subsequent measurement of air content at different test stages. The test results obtained for the fresh properties showed that the inverted slump cone and orimet flow times increased with lower W/B ratio and greater RHA content. In addition, the slump flow, inverted slump cone flow spread, and orimet flow spread with and without J-ring increased considerably with lower W/B ratio and greater RHA content. However, the increases in slump with and without J-ring at lower W/B ratio and higher RHA content were not significant. The unit weight of concrete slightly decreased with higher W/B ratio and greater RHA content, and with higher air content. Achieving the target air content required greater AEA dosages for lower W/B ratio and higher RHA content. However, the presence of RHA had no adverse effect on the air-void stability of concrete. The segregation resistance of various SCHPCs was investigated by visual inspection of concrete in mixer pan, and during and after different flow tests. Slight bleeding and a thick layer of paste were noticed in mixer pan for several concretes. The dynamic segregation in the form of discontinuity or blockage of flow did not occur during the orimet and inverted slump cone flow tests for any concrete. No aggregate pile appeared in the slump flow, and orimet and inverted slump cone flow spreads of any concrete. But minor to severe mortar halos were noticed in the periphery of the flow spread of several concretes, particularly in the presence of high RHA content. The results of visual inspection suggest that both lower W/B ratio and greater RHA content improved the dynamic segregation resistance of concrete. In contrast, the higher RHA content resulted in a lower static segregation resistance, which was overcome in the presence of viscosity-enhancing admixture (VEA). The static segregation resistance of several SCHPCs was quantitatively determined by sieve and column apparatus. The segregation index given by the sieve increased with lower W/B ratio and higher RHA content, thus indicating a reduced static segregation resistance. In contrast, the segregation factor given by the column apparatus decreased with lower W/B ratio suggesting an increased static segregation resistance. However, the segregation factor increased with higher RHA content, and thus revealed a reduction in static segregation resistance. In the presence of VEA, both segregation index and segregation factor decreased significantly, indicating an improvement in the static segregation resistance of concrete. The hardened SCHPCs were tested for compressive strength, ultrasonic pulse velocity, water absorption, total porosity and electrical resistivity. Test results revealed that the compressive strength, ultrasonic pulse velocity and true electrical resistivity increased, whereas the water absorption and total porosity decreased with lower W/B ratio and higher RHA content. The entrained air-voids decreased the compressive strength, ultrasonic pulse velocity, water absorption and total porosity, but slightly increased the electrical resistivity of concrete. In general, the hardened properties indicated good durability of the concretes. The empirical models for the filling ability (slump flow) and compressive strength of SCHPC were derived and verified with test data from this study and other data taken from the literature. The slump flow and compressive strength computed from the models were coherent with the measured values. Both filling ability and strength models were useful to develop a mixture design method for SCHPC with and without RHA.

Abstract: Hydrogen can be a renewable energy source to replace conventional fossil fuels. Compared to current hydrogen production processes by consuming fossil fuels, biological hydrogen production has the advantage of being environmentally friendly because of the use of renewable and low value biological materials. Some hyperthermophiles, such as Thermotoga species, are capable of producing hydrogen during growth. In this study, Thermotoga maritima, Thermotoga neapolitana DSM 4359 and DSM 5068, were used to investigate their potential in converting selected sugars (glucose and xylose) and complex carbon sources (cellulose, starch, xylan and agricultural residues, such as barley straw, corn stover, soybean straw, wheat straw and corn husk) to hydrogen. In addition, factors which influenced growth and hydrogen production were studied, and optimal conditions for hydrogen production were obtained. All three Thermotoga species could grow in the presence of mono sugars (glucose, xylose) and complex carbohydrates (starch, xylan, milled corn husk). They all could produce hydrogen in the presence of micro-molar level of oxygen without addition of any reducing agents in the growth medium. Compared to the slight inhibition caused by L-lactate accumulation during the growth, gradual pH decreases were the main reasons to inhibit both growth and hydrogen production of T. neapolitana species. Increasing the initial pH of the growth medium to 8.5 and stabilizing the pH by 50 mM Triz buffer resulted in higher growth and hydrogen production of T. neapolitana strains. Adjusting the medium pH at early stationary phase also increased the hydrogen production, and fewer enhancements to the growth. The pH control methods also resulted in higher conversion efficiency (converting glucose to H2) of T. neapolitana strains from 2.2 to 3.6 (H2/glucose), which was approximately 90% of the theoretical efficiency (4 moles H2 produced from 1 mole glucose). The expression of hydrogenases of T. neapolitana strains could also be increased by the pH control methods. Thermotoga species could grow and produce hydrogen using agricultural residues, such as corn husk, achieving 60% growth and hydrogen production as compared to that iii from glucose. With pH control methods, hydrogen production by T. neapolitana strains from corn husk was higher than that from glucose without pH control. These results indicated that the pH was the main factor to affect both hydrogen production and growth of T. neapolitana species, and optimal conditions for hydrogen production could be achieved by using pH control methods. Selected agricultural residues could be utilized for biological hydrogen production by Thermotoga species with minimum pre-treatment, and the pH control methods could result in a higher hydrogen production compared to that from glucose. Further studies on the continuous growth and hydrogenases of Thermotoga species are needed for better understanding of the hydrogen production mechanisms.