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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Estudos exploratórios da produção de concreto celular autoclavado com o emprego de finos oriundos da reciclagem de concreto como agregados / Exploratory study of the production of autoclaved a erated concrete with fines grains from recycled concrete agreggate

Rostirola, Ângelo Cezar Fumagalli 24 October 2013 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-05-29T18:30:06Z No. of bitstreams: 1 Ângelo Cezar Fumagalli Rostirola.pdf: 4315210 bytes, checksum: ff48e5f928774ac2545c3ae6774d5dcf (MD5) / Made available in DSpace on 2015-05-29T18:30:06Z (GMT). No. of bitstreams: 1 Ângelo Cezar Fumagalli Rostirola.pdf: 4315210 bytes, checksum: ff48e5f928774ac2545c3ae6774d5dcf (MD5) Previous issue date: 2013-10-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / SINDUSCON-NH - Sindicato das Indústrias da Construção Civil Novo Hamburgo / A construção civil atualmente é a indústria com maior crescimento no Brasil, fomentada por financiamentos e programas do governo federal. É também uma das indústrias que mais consome recursos naturais e energia, além de ser a principal geradora de resíduos sólidos urbanos. Grande parcela destes recursos naturais consumidos pela construção é formada pelos agregados. Uma alternativa econômica e ambientalmente correta, para diminuir a extração deste material, é a sua substituição por algum outro material, se possível por um resíduo, como apontam várias pesquisas. A busca por materiais e produtos ecologicamente corretos está em uma crescente, assim como os estudos para a reciclagem de diversos resíduos. A união entre produtos que consomem um volume menor de matéria-prima com o emprego de resíduos na sua produção parece uma saída viável para um desenvolvimento mais sustentável. Artefatos para a construção civil produzidos com concreto celular autoclavado (CCA) utilizam até quatro vezes menos materiais quando comparados a produtos com características semelhantes, produzidos com concreto convencional, cerâmico, entre outros. Além do menor consumo dos materiais constituintes, o concreto celular possui outras propriedades interessantes, como: suficiente resistência à compressão; isolamento térmico e acústico; baixa densidade; resistência ao fogo. Esta pesquisa teve como objetivo principal avaliar a influência da substituição parcial do agregado natural por agregado reciclado de concreto (ARC) na produção de concreto celular autoclavado. Após realização de estudos-piloto, optou-se pelo emprego da proporção de Cimento e Agregado Natural (AN) de 67% e 33% e sobre estes 0,45% de Cal e 0,3% de Alumínio com relação água/sólidos igual a 0,32. Foram empregados Cimento Portland CP-V ARI, Cal calcítica, areia natural e agregado fino reciclado de concreto, em teores de 0%, 25% e 50%. A dimensão máxima do agregado empregado na produção de CCA é de 150 µm. A cura foi realizada em autoclave após um tempo de espera de 24 horas a partir do início da mistura, por um período de 6 horas. Foram avaliadas a resistência à compressão, a absorção de água capilar, a massa específica e a porosidade. Os ensaios de resistência à compressão foram realizados em 48 e 72 horas, e a absorção de água, em corpos de prova preparados e acompanhados pelo período de 96 horas. A microestrutura dos CCA produzidos foi caracterizada por microscopia eletrônica de varredura (MEV). Verificou-se que existem expressivas alterações nas propriedades do CCA produzidos com ARC em substituição do AN, com a tendência de aumentar a densidade de massa aparente, bem com a resistência à compressão, a medida que aumenta-se o teor de ARC. Na análise dos resultados, percebeu-se que o uso de ARC alterou as propriedades dos concretos produzidos neste estudo exploratório, sem, entretanto, inviabilizar o seu emprego. Com um ajuste da dosagem, pode ser obtido um CCA produzido com ARC, cujo comportamento seja compatível com o comportamento de CCA produzido somente com o AN. / In the last years, the Brazilian construction industry is among those of national production sectors that have been having a great growing, mostly due to the incentive from the government and due to financed resources by private and public agents. This industry is also one of the major consumers of natural resources and energy, besides being the main generator of solid waste. One of these natural resources used in the constructions is sand. An environmentally friendly and economical alternative to reduce the extraction of natural resources is the use of recycled waste. The associated use of low volume of raw materials with alternative materials, like waste, is one of the ways to get more sustainability in the construction sector. Construction and building components made with autoclaved cellular concrete (ACC) employ four times less material than others with the same function. Other advantage of ACC is the performance of its properties like compressive strength, thermal and acoustic behavior, lower density, fire resistance. The aim of this research was to investigate the use of fine grains from recycled concrete aggregate (ARC) as partial sand replacement in the production of autoclaved aerated concrete. With the goal to find the mix proportion some pilot studies were made. After this, it was chosen a relation of 67% of cement and 33% of natural fine aggregate (sand). The lime was used in the amount of 0.45% of total cement and sand, and 0.3% of aluminium. The water to total solids ratio was 0.32. It was employed Portland cement type V according to Brazilian standards, calcitic lime, natural sand and ARC passing in sieve with 150 micron opening. The replacement rate of sand by ARC was 0%, 25% and 50%. From 24 hours after the mixing of materials, the samples were submitted to steam curing in an autoclave chamber for 6 hours. It was evaluated the compressive strength, the density, the capillary water absorption and porosity. The compression strength tests were performed at 48 and 72 hours. Water absorption tests were conducted for 96 hours after samples preparing. The capillary porosity was calculated with the capillary water absorption data. ACC's microstructure analysis was done by scanning electron microscopy (SEM). The results showed in general that the behavior of ACC produced with ARC differs significantly from the ACC produced with natural aggregate. When the ARC rate increases the apparent specific gravity also increases as well as the compressive strength. The observed increase in the apparent specific gravity is not desired. However this behavior of ACC done with RCA does not prevent the use of this recycled aggregate. An optimized study of pre-wetting of RCA could improve its performance as aggregate for use in ACC, once its grain size showed to be appropriated for this kind of use.
12

Long-term performance of water repellants on rendered autoclaved aerated concrete

Kus, Hülya January 2002 (has links)
Many failures of external walls made of porous buildingmaterials are caused by excessive moisture content,particularly after driving rain and under long duration ofmoist conditions. Lack of sufficient protection againstexposure conditions is one of the reasons for external wallsprematurely demonstrating failures, i.e. properties andperformance above/below critical levels. Silicon-based waterrepellants are increasingly used in order to improve theperformance of both old and new buildings. Water repellants areexpected to prolong the service life and improve the durabilityof wall components by preventing or minimising water ingressinto the structure and thus delaying the deteriorating effectsof the atmosphere. To date, various kinds of water repellantshave been developed. However, only limited research has beencarried out, particularly on the long-term field exposuretesting. Existing research is mainly focused on the performanceof surface treatments of concrete structures and the protectionof historical buildings built of stone, brick and wood, and isprimarily based on short-term laboratory testing. The aim ofthis research work is to study the long-term performance,degradation processes and ageing characteristics of renderedautoclaved aerated concrete (AAC) with and without waterrepellants. Investigations are carried out by physical andchemical analysis of fresh samples, samples naturally weatheredby long-term field exposure and samples artificially aged byshort-term accelerated laboratory tests. Two differentapplication of water repellants are employed: impregnation ofrendering surface with an aqueous product and as additive inpowder form mixed into the fresh rendering mortar. Continuousmoisture and temperature monitoring of naturally exposed testsamples are also included in the study. Wetcorr sensors andresistance-type nail electrodes are used to measure the surfacemoisture and the moisture content in the material,respectively. This thesis describes the experimental set-upand presents the results from site monitoring and laboratorytests of unexposed, naturally and artificially exposed samples(freeze-thaw and UV+water). The results from the continuousmoisture measurements are compared with the results obtainedfrom the full-scale test cabin built within the EUREKA-projectE 2116 DurAAC. The test cabin has the same basic measurementinstruments for continuous monitoring of moisture andtemperature. An attempt has been made to develop methods forlong-term performance assessment of water repellants to be usedin service life prediction. The combination of data obtainedfrom the field measurements with data obtained from thelaboratory tests and analysis may also meet practical needs ofthe end-users.
13

A Study On Material Properties Of Autoclaved Aerated Concrete (aac) And Its Complementary Wall Elements: Their Compatibility In Comtemporary And Historical Wall Sections

Andolsun, Simge 01 September 2006 (has links) (PDF)
Examined in this study were some physical, mechanical, compositional and durability properties of AAC, its neighboring plasters and jointing adhesive, all of which were produced in Turkey. The compatibility of these materials inside the contemporary wall section and within historic fabric was discussed in terms of their material properties. In addition to the literature survey, laboratory studies were conducted on two types of AAC as G2 and G4, its jointing adhesive and exterior finishing layers as base coat, under coat, finish coat, water repellent finish coat / and some historical traditional construction materials of Anatolia as timber, masonry and infill brick, lime based exterior and interior plasters. The results were evaluated in terms of material properties of AAC, the compatibility of AAC and its complementary elements with each other and with the historic timber framed structures in Anatolia. It was concluded that the use of AAC in repairs of historical structures could be discussed only if the original infill is lost. In addition, its cement-plasters should be avoided from the historic fabric since they introduce salt problems to the structure. In terms of vapor permeability and modulus of elasticity, water repellent finish coat was proper finishing for AAC, and AAC, especially G4, exhibited similarities with historic infill mud brick. Further studies on other compatibility parameters were, however, necessary to decide on the compatibility of AAC with its neighboring materials. Moreover, the integrity of AAC with the historic fabric needed improvement by increasing its pozzolanicity and/or producing a new intermediary repair mortar/plaster.
14

Long-term performance of water repellants on rendered autoclaved aerated concrete

Kus, Hülya January 2002 (has links)
<p>Many failures of external walls made of porous buildingmaterials are caused by excessive moisture content,particularly after driving rain and under long duration ofmoist conditions. Lack of sufficient protection againstexposure conditions is one of the reasons for external wallsprematurely demonstrating failures, i.e. properties andperformance above/below critical levels. Silicon-based waterrepellants are increasingly used in order to improve theperformance of both old and new buildings. Water repellants areexpected to prolong the service life and improve the durabilityof wall components by preventing or minimising water ingressinto the structure and thus delaying the deteriorating effectsof the atmosphere. To date, various kinds of water repellantshave been developed. However, only limited research has beencarried out, particularly on the long-term field exposuretesting. Existing research is mainly focused on the performanceof surface treatments of concrete structures and the protectionof historical buildings built of stone, brick and wood, and isprimarily based on short-term laboratory testing. The aim ofthis research work is to study the long-term performance,degradation processes and ageing characteristics of renderedautoclaved aerated concrete (AAC) with and without waterrepellants. Investigations are carried out by physical andchemical analysis of fresh samples, samples naturally weatheredby long-term field exposure and samples artificially aged byshort-term accelerated laboratory tests. Two differentapplication of water repellants are employed: impregnation ofrendering surface with an aqueous product and as additive inpowder form mixed into the fresh rendering mortar. Continuousmoisture and temperature monitoring of naturally exposed testsamples are also included in the study. Wetcorr sensors andresistance-type nail electrodes are used to measure the surfacemoisture and the moisture content in the material,respectively. This thesis describes the experimental set-upand presents the results from site monitoring and laboratorytests of unexposed, naturally and artificially exposed samples(freeze-thaw and UV+water). The results from the continuousmoisture measurements are compared with the results obtainedfrom the full-scale test cabin built within the EUREKA-projectE 2116 DurAAC. The test cabin has the same basic measurementinstruments for continuous monitoring of moisture andtemperature. An attempt has been made to develop methods forlong-term performance assessment of water repellants to be usedin service life prediction. The combination of data obtainedfrom the field measurements with data obtained from thelaboratory tests and analysis may also meet practical needs ofthe end-users.</p>
15

Reutilização de dispositivos intravaginais de progesterona autoclavados para a indução e sincronização de estro em cabras da raça Toggenburg / Reutilization of autoclaved intravaginal progesterone device for estrous induction and synchronization in Toggenburg goats

Souza, Joanna Maria Gonçalves de 21 January 2010 (has links)
Made available in DSpace on 2015-03-26T13:55:07Z (GMT). No. of bitstreams: 1 texto completo.pdf: 401249 bytes, checksum: f3d11e6c4ad3c09c868346f932457256 (MD5) Previous issue date: 2010-01-21 / This study aimed to evaluate the efficacy of reusing autoclaved intravaginal devices on induction of estrus, ovulation and fertility in Toggenburg goats, besides to measure the plasma progesterone (P4) profile in these animals. The study was performed during the seasonal anestrous period (n=42) and in the breeding season (n=67), at the City of Piau-MG (latitude 21°35 S and longitude 43°15 W). Goats received new intravaginal progesterone devices (CN), or devices used previously during six days (C6) or 12 days (C12) and then autoclaved. Dinoprost (5 mg) latero-vulvar was administered on the day of device insertion and eCG (200 IU) latero-vulvar was done 24 h before its removal. The devices were maintained for six days in all treatments. Ten goats from each treatment were evaluated by transrectal ultrasonography (5 MHz). Blood was collected at different moments for plasma P4 analysis. There was no statistical difference (P>0.05) among the goats of three treatments on the following reproductive parameters observed during the anestrous or breeding season, respectively (average for three treatments): mean estrous induction/synchronization rate (94.9; 76.2%), mean interval from device removal to estrus (33.1 ± 11.4; 37.4 ± 16.2 h), mean duration of estrus (28.6 ± 11.8; 31.7 ± 12.8 h), mean conception rate (61.5; 50.7%), mean ovulating female rate (95.2; 66.7%), mean number of ovulations (1.7 ± 0.7; 1.5 ± 0.6), mean interval from removal to ovulation (68.4 ± 13.0; 77.3 ± 13.8 h), interval from estrus to ovulation (36.6 ± 12.6; 36.7 ± 11.2 h), mean diameter of the dominant follicle (7.4 ± 0.6; 6.7 ± 0.5 mm), co-dominant (6.8 ± 0.6; 6.2 ± 0.1 mm) and medium (7.2 ± 0.6; 6.6 ± 0.4 mm). The small initial concentrations of P4 in alltreatments seven days before device insertion (0.12 ± 0.21) or at the time of insertion (0.23 ± 0.20) may be interpreted as a consequence of reproductive seasonality. Six hours after device insertion CN treatment showed higher (P<0.05) concentrations of P4 (7.16 ± 3.64) when compared to C6 (4.66 ± 2.13) or to C12 (4.34 ± 1.85) and these values remained greater in size up to four days after insertion. One day after device removal, plasma P4 concentration was at subluteal levels. Higher P4 concentrations (P<0.05) were detected in nulliparous when compared to lactating goats in different moments. The autoclave process did not affect the efficiency of reutilizing progesterone intravaginal device in reproductive parameters as fertility rate, induction and synchronization of estrus and ovulation in Toggenburg goats. The supraluteal concentration maintained in all treatments during the insertion device period allow inferring that the autoclave process does not influence progesterone concentration, being a viable alternative to reduce costs in a goat herd. / O objetivo deste estudo foi avaliar a eficácia da reutilização de dispositivos intravaginais autoclavados sobre a indução do estro, ovulação e fertilidade em caprinos da raça Toggenburg, além de caracterizar o perfil de progesterona plasmática destes animais. O estudo foi realizado na estação de anestro estacional (n=42) e na estação de acasalamento natural (n=67), no município de Piau-MG (21°35 S de latitude e 43°15 W de longitude). As cabras receberam dispositivos intravaginais de progesterona novos (CN) ou que foram previamente utilizados por seis (C6) ou 12 dias (C12) e autoclavados posteriormente. Dinoprost (5 mg) foi administrado latero-vulvar no dia da colocação do dispositivo e eCG (200 UI), aplicado na mesma região, 24 h antes de sua retirada. Os dispositivos permaneceram por seis dias em todos os tratamentos. Dez cabras de cada tratamento foram avaliadas por ultrassonografia transretal (5 MHz). Foram efetuadas coletas de sangue em diferentes momentos para análise de progesterona (P4) plasmática na estação de anestro estacional. Não houve diferença (P>0,05) entre os três tratamentos nos seguintes parâmetros reprodutivos observados na estação de anestro e de acasalamento natural, respectivamente (valor médio dos três tratamentos): taxa média de indução/sincronização de estro (94,9; 76,2%), intervalo médio da retirada do dispositivo ao estro (33,1 ± 11,4; 37,4 ± 16,2 h), duração média do estro (28,6 ± 11,8; 31,7 ± 12,8 h), taxa média de concepção (61,5; 50,7%), taxa média de fêmeas ovulando (95,2; 66,7%), número médio de ovulações (1,7 ± 0,7;1,5 ± 0,6), intervalo médio da retirada do dispositivo à ovulação (68,4 ± 13,0; 77,3 ± 13,8 h), intervalo médio do início do estro à ovulação (36,6 ± 12,6; 36,7 ± 11,2 h), diâmetro médio do maior folículo (7,4 ± 0,6; 6,7 ± 0,5 mm), segundo maior (6,8 ± 0,6; 6,2 ± 0,1 mm) e médio (7,2 ± 0,6; 6,6 ± 0,4 mm). As baixas concentrações iniciais de P4 em todos os tratamentos sete dias antes da inserção dos dispositivos (0,12 ± 0,21) ou no momento da inserção (0,23 ± 0,20) podem ser interpretadas como reflexo da estacionalidade reprodutiva. Às 6 h após a inserção do dispositivo o tratamento CN apresentou maiores (P<0,05) concentrações de P4 (7,16 ± 3,64) do que C6 (4,66 ± 2,13) ou C12 (4,34 ± 1,85) e estes valores mantiveram-se superiores até quatro dias após a inserção. A partir da retirada dos dispositivos, as concentrações plasmáticas de P4 caíram bruscamente para níveis subluteais. Maiores concentrações (P<0,05) de P4 plasmáticas foram identificadas em cabras nulíparas do que em lactantes em diferentes momentos. O processo de autoclavagem não afetou a eficiência da reutilização de dispositivos intravaginais de progesterona em parâmetros reprodutivos como taxa de concepção, indução e sincronização de estro e ovulação em cabras da raça Toggenburg. Os níveis supraluteais mantidos em todos os tratamentos durante o período de permanência do dispositivo permitem inferir que o processo de autoclavagem não interfere na disponibilidade de progesterona nos dispositivos, constituindo-se em uma alternativa viável para reduzir os custos dentro de um rebanho caprino.
16

[pt] AVALIAÇÃO DO COMPORTAMENTO MECÂNICO DE PAINÉIS SANDUÍCHE COM COMPÓSITOS LAMINADOS REFORÇADOS COM FIBRA DE CURAUÁ E NÚCLEO DE CONCRETO CELULAR AUTOCLAVADO / [en] EVALUATION OF THE MECHANICAL BEHAVIOR OF SANDWICH PANELS WITH CURAUÁ FIBER-CEMENT COMPOSITE LAYERS AND AUTOCLAVED AERATED CONCRETE CORE

ISABELA DE PAULA SALGADO 19 December 2019 (has links)
[pt] O presente trabalho propõe-se a analisar o comportamento mecânico de painéis sanduíche constituídos por duas camadas externas de compósitos cimentícios reforçados com fibras naturais, separadas por um núcleo de concreto celular autoclavado (CCA). Cada placa de material compósito foi moldada diretamente sobre a superfície de um bloco de CCA, por meio da disposição manual de três camadas unidirecionais de fibras longas de curauá. Visando prover maior durabilidade ao compósito, desenvolveu-se uma matriz com baixo teor de hidróxido de cálcio, substituindo uma parcela do cimento por materiais pozolânicos. Ensaios de caracterização da matriz, dos filamentos de curauá e dos blocos de CCA foram realizados para a obtenção de suas propriedades independentes. Os compósitos foram submetidos a ensaios de arrancamento do tecido, tração direta e flexão a quatro pontos para a avaliação de diferentes aspectos de seus mecanismos de fissuração, resistência e capacidade de deformação. Zonas de carregamento foram indicadas em cada caso para demonstrar o comportamento padrão dos compósitos. Os painéis sanduíche, por sua vez, foram analisados em termos de interface, por meio de ensaios de aderência e micrografias da superfície de transição dos materiais, e de desempenho mecânico, por ensaios de flexão a quatro pontos cíclicos e monotônicos. Esses últimos forneceram a rigidez, capacidade de carga e deflexão dos painéis sanduíche, tal como as principais propriedades de seus elementos: para o núcleo, a resistência ao cisalhamento e o módulo de cisalhamento, e para as lâminas, a resistência à compressão e à tração. Os ensaios cíclicos testaram a resistência do material a séries de carregamento-descarregamento, enquanto ensaios de aderência foram utilizados para verificar a interface entre os compósitos laminados e o núcleo de CCA. Os resultados indicaram um desempenho satisfatório dos painéis sanduíche, uma vez que os compósitos foram capazes de lhes fornecer um comportamento de strain/deflection hardening, aumentando sua resistência e tenacidade. A adesão entre lâminas-núcleo mostrou-se eficaz, de maneira que os diferentes materiais compreendidos demonstraram interação adequada entre si, bem como propriedades complementares. Dentre os objetivos desse trabalho, encontra-se o desenvolvimento de um material sustentável, leve, resistente e tenaz, de modo que constitua uma alternativa promissora e de baixo custo a aplicações de Engenharia. / [en] This present work aims to analyze the mechanical behavior of sandwich panels consisting of two outer layers of natural fiber-reinforced cementitious composites separated by a core layer of autoclaved aerated concrete (AAC). The molding of each composite layer was made directly on the surface of an AAC block, by manually arranging three layers of long unidirectional aligned curauá fibers in the mortar. In order to increase the composite durability, a matrix with a low content of calcium hydroxide was developed, where the Portland cement was partially replaced by pozzolanic materials. Characterization tests of the matrix, the curauá filaments and the AAC blocks were performed to obtain their independent properties. The composites were submitted to fabric pull-out tests, direct tensile tests and four-point bending to evaluate different aspects of their cracking mechanisms, strength and deformation capacity. Loading zones were indicated in each case to demonstrate the standard composite behavior. The sandwich panels, on the other hand, were analyzed in terms of interface, through pull-off tests and SEM images of the materials transition surface, and mechanical performance, by means of cyclic and monotonic four-point bending tests. The latter registered the rigidity, load capacity and deflection of the sandwich panels, as well as the main properties of their elements: for the core, shear strength and shear modulus, and for the skin layers, compressive strength and tensile strength. Cyclic tests evaluated the resistance of the material to loading-unloading cycles, while pull-off tests were used to verify the interface between the laminated composites and the AAC core. The results indicated a satisfactory performance of the sandwich panels, since the composite layers provided a strain/deflection hardening behavior to the material, increasing its flexural strength and toughness. The adhesion between the layers and the core proved to be effective, so that the comprised materials displayed adequate interaction between each other, as well as complementary properties. Among the objectives of this work is the development of a sustainable, lightweight, resistant and tough material, in a way that it represents a promising and low-cost alternative to Engineering applications.
17

Možnosti využití kameniva na bázi odpadní skleněné moučky v novodobých stavebních materiálech / Possibilities of utilization of aggregate based on glass powder in new building materials

Novák, Jakub January 2018 (has links)
The diploma thesis deals with the use of waste glass powder as an aggregate in thermal insulation plasters for AAC. In the theoretical part, the problem of thermal protection of buildings is discussed first. The production and properties of foamed glass are described. Then the research of plasters, their composition and properties was made. Thermal-insulating plasters are specified and their use has been proposed for thermal insulation of building structures. In the practical part, suitable formulations have been proposed in the form of dry plaster and mortar mixtures (SOMS). Test samples were prepared from them. The physical and mechanical properties were measured. These were compared with the requirements set by standards and technical regulations. To get closer to the behavior of plasters on real buildings an AAC wall was built. The individual recipes were applied on it. It was monitored working with plaster and how it held on the masonry. During ripening crack development was observed. Optimization calculation inculded these aspects and it determined the optimal recipe. All designed recipes can be used as a thermal-insulating plasters.
18

Vývoj nové technologie pískového pórobetonu s využitím druhotných surovin / Development of new technology of sand autoclaved aerated concrete with using of secondary raw materials

Ondříčková, Pavlína January 2018 (has links)
Autoclaved sand aerated concrete is a modern building material with high thermal insulation properties. Only sand is used as the primary silicate component of aerated concrete in the Czech Republic. For the more favourable economic and ecological properties of aerated concrete, the use of secondary raw materials is used in this work. The secondary raw materials examined included fluidized bed and fly ash, slag and glass recycled. The aerated concrete composite with secondary admixtures was developed under hydrothermal conditions of a laboratory autoclave for 7 and 12 hours at 190°C. From the secondary raw materials tested, a 10% glass recycler additive yielded the highest strength. Other additives that have a positive effect on mechanical properties include SAKO and Oslavany. From the results of the work it is evident that the use of secondary raw materials increases the strength, improves the rheology of the mixture and supports the formation of tobermorite.
19

Studium mikrostruktury autoklávovaného pórobetonu s využitím druhotných surovin / Study of microstructure of autoclaved aerated concrete with using of secondary raw materials

Martanová, Jana January 2018 (has links)
Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.
20

Vliv technologie výroby popílkového pórobetonu na vznik tobermoritických fází / The effect of fly ash aerated concrete production technology to formation of tobermoritic phases

Fleischhacker, Ján January 2016 (has links)
Autoclaved aerated concrete is long-time ecological building material with usefull properties. There needs to be done research of its mineralogical compound for reengineering the production. The main mineral compound of AAC is tobermorite, it increases its mechanical properties. In the presence study, we examine the usage of nature and artificial silicious materials. Also, we investigate the influence of sulfate and alumina admixtures, as well as fluidized bed combustion ash, which can be used as the lime and gypsum replacement. Closure of the study is design of the optimal raw material composition, also hydrothermal treatment of autoclaved aerated concrete. In relation to its mechanical properties, mineralogical composition and cost.

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