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Previous issue date: 2016-09-09 / A fabrica??o do Cimento Portland ? uma atividade que causa grande impacto ambiental devido ? sua elevada taxa de emiss?o de CO2 na atmosfera. Visando reduzir esse impacto, a viabilidade t?cnica de materiais alternativos em substitui??o ao Cimento Portland tem sido cada vez mais analisada. J? s?o conhecidos os benef?cios que as adi??es minerais infere ao concreto convencional (CV), no entanto, existe a necessidade de compreender melhor seus benef?cios quando utilizadas em CAA e verificar o comportamento deste quando curado termicamente. Assim, este trabalho avalia os efeitos da incorpora??o de f?ler calc?rio (Fc) e metacaulim (Mk) na hidrata??o do concreto autoadens?vel, quando submetido ? cura t?rmica. Para tanto, foram produzidos seis composi??es de CAA, sendo uma de refer?ncia, sem adi??o mineral, quatro misturas bin?rias com substitui??o do cimento por 10% de Mk, 10% Fc, 20% de Mk e 20% Fc e uma terci?ria com substitui??o do cimento por 10% de Mk e 10% de Fc. Os concretos foram dosados e realizados os ensaios realizados para os concretos dosados foram: slump flow, T500, L-box, V-test e J-ring para caracteriza??o do CAA no estado fresco. Ap?s iniciada a pega (aproximadamente 3 horas), intervalo chamado de pr?-cura, os corpos de prova moldados foram curados atrav?s de imers?o total em banho aquecido. A taxa de aquecimento utilizada foi de 20 ?C/h, chegando ?s temperaturas m?ximas de 50, 60 e 70 ?C, com posterior resfriamento de 10 ?C/h. O tempo total do ciclo (pr?-cura, aquecimento, patamar isot?rmico e resfriamento), foi de 18 a 20 horas. Tamb?m foram confeccionados corpos de prova de CAA que foram curados por imers?o em ?gua a temperatura ambiente. As propriedades analisadas no estado endurecido de todas as composi??es foram: resist?ncia ? compress?o nas idades de 1, 3, 7 e 28 dias, com m?dulo de elasticidade din?mico, absor??o de ?gua por capilaridade, massa espec?fica e absor??o total aos 28 dias de idade. A an?lise da microestrutura dos diferentes concretos se deu por microscopia eletr?nica de varredura e difra??o de raios X aos 3 e 28 dias de idade. As adi??es de metacaulim e filer calc?rio podem substituir o cimento Portland, nos percentuais de 10% e 20%, de maneira satisfat?ria em misturas bin?rias e terci?rias. Aos 28 dias de idade, os CAA curados termicamente em geral n?o apresentaram resist?ncias ? compress?o inferiores aos curados a 28 ?C. A cura t?rmica ?mida por imers?o propicia um aumento na resist?ncia ? compress?o nas primeiras idades, exceto para os concretos contendo 20% de f?ler calc?rio em substitui??o ao cimento Portland. Para cada tra?o estudado, houve um temperatura que se mostrou mais eficaz, ou seja, uma temperatura patamar mais adequada. Na an?lise da microestrutura dos CAA pode se observar que a elevada resist?ncia obtida a 1 dia de idade, deve-se a r?pida forma??o de CSH para os CAA tratados termicamente. / The manufacture of Portland cement is an activity that causes great environmental impact due to its high CO2 emission rate in the atmosphere. In order to reduce this impact, technical feasibility of alternative materials to replace Portland cement has been increasingly analyzed. It is already known the benefits that mineral additions infers to conventional concrete (CV), however, little is known of their use in self-compacting concrete (SCC) subjected to heat treatment. This work evaluates the effects of the incorporation of limestone fillers (LP) and metakaolin (MK) in the hydration of self-compacting concrete, when subjected to thermal curing. For this purpose six SCC compositions were produced, as a reference without mineral addition, four binary mixtures with replacement of cement with 10% MK, 10% LP, 20% MK and 20% LP and a tertiary with substitution of cement by 10% MK and 10% LP. The concrete were measured and made the tests slump flow, T500, L-box, V-test and J-ring to characterize the SCC fresh. After started the crystallization reactions (about 3 hours), range called pre-curing, the molded specimens were cured through total immersion in a warm bath. The heating rate used was 20 ?C/hr, reaching the maximum temperatures 50, 60 and 70 ?C, with subsequent cooling 10 ?C/hr. The total cycle time (pre-curing, heating, cooling and isothermal level) was 18 to 20 hours. Also, specimens were prepared which were cured by immersion in water at room temperature. The analyzed properties in the hardened state of all compositions were compressive strength at ages of 1, 3, 7 and 28 days at modulus, water absorption by capillarity, density, and total absorption to 28 days of age. The analysis of the microstructure of different concrete was given by scanning electron microscopy and X-ray diffraction at 1 and 28 days of age. The CAA thermally cured obtained a high increase in compressive strength at 1 day old, when compared to CAA cured at room temperature. For each dosage analyzed, there is a maximum temperature within the thermal cycle, which provides better mechanical performance to the CAA. The thermal curing causes changes in the microstructure, including, promote the rapid formation of calcium silicate hydrate (CSH). The additions of metakaolin and lime filer can replace Portland cement in percentages of 10% and 20%, satisfactorily in binary and tertiary mixtures. After 28 days the CAA cured thermally groups showed no resistance to compression to lower cured at 28 ? C. The wet thermal curing dip provides an increase in compressive strength at early ages, except for the concrete containing 20% filler limestone to replace Portland cement. For each studied trait, there was a temperature that was more effective, i.e., a temperature most suitable level. The analysis of the microstructure of the CAA can be seen that the high strength obtained at 1 day old, due to rapid formation of the CSH to the heat-treated CAA.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/22458 |
| Date | 09 September 2016 |
| Creators | Santos, Wesley Feu dos |
| Contributors | 52402444487, N?brega, Andreza Kelly Costa, 02293726436, http://lattes.cnpq.br/9418395015529669, Azeredo, Givanildo Alves de, 64581756472, http://lattes.cnpq.br/0214969078711403, Anjos, Marcos Alyssandro Soares dos, Almeida, Maria das Vit?rias Vieira |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA CIVIL, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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