Banca de DEFESA: THIAGO VIEIRA FONSECA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : THIAGO VIEIRA FONSECA
DATA : 15/12/2016
HORA: 15:00
LOCAL: A definir
TÍTULO:

Evaluation of self-compacting concretes with low content of cement incorporating metakaolin, pozzolan of rice husk, limestone filler, and addition of hydrated lime.


PALAVRAS-CHAVES:

self-compacting concrete, hydrated lime, mineral additions, carbonation, durability.


PÁGINAS: 119
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
SUBÁREA: Construção Civil
ESPECIALIDADE: Materiais e Componentes de Construção
RESUMO:

The concrete industry is a major consumer of natural resources from aggregate extraction to Portland cement production, when a large amount of limestone is extracted. In addition, the cement industry has great utility in greenhouse gas emissions. However, it is possible to reduce the environmental impact caused through the concrete industry by using waste from other industries as components of the fine materials, considerably reducing the consumption of cement and maintaining or improving the mechanical properties and durability. The self-compacting concrete (SCC) has a high content of fine materials and has been widely used due to its characteristics of high fluidity and cohesion. In this way, the present work investigated the feasibility of the development of SCC's made with high levels of mineral additions and hydrated lime. For this, cement was replaced in 60% by mineral additions (pozzolan of rice husk, metakaolin and limestone filler) based on the reference admixture with consumption of 451.1 kg/m³ of cement. So, new admixtures with cement consumption were originated between 167.7 kg/m³ and 173.3 kg/m³. The hydrated lime was incorporated as an addition in three admixtures in the content of 5% on the total mass of the fine materials. The SCC's were characterized in the fresh state by the slump flow test, T500, J-ring, V-funnel and L-box. In order to evaluate the mechanical performance of the SCC's, tests of compressive strength, ultrasonic pulse velocity and modulus of elasticity were carried out, and for the evaluation of the durability, capillary absorption, chloride ion diffusion, electrical resistivity and carbonation were analyzed. The SCC's with mineral additions presented satisfactory mechanical performance, although inferior to the reference admixture. The compressive strength at 28 days of the concretes with mineral additions showed a reduction of 15 to 60% in relation to the reference admixture, but all the results were compatible with structural concretes according to the requirements of NBR 6118 (ABNT, 2014). Regarding the durability, the concrete with mineral additions showed a reduction in the diffusion coefficient of chloride ions that varied 25.4% and 74.8%. The electrical resistivities of the reference concrete were much lower than those of concrete with mineral additions, but all the admixtures were classified as probable negligible corrosion rates. The electrical resistivities suffered great reduction when analyzed in carbonated samples. The analysis of the accelerated carbonation showed that the substitution of cement by mineral additions at high levels makes the SCC's very susceptible to carbonation. As for the addition of hydrated lime, it was verified that its effect was not positive in the mechanical performance of the SCC's studied, but it had a positive effect in reducing the carbonation depth.


MEMBROS DA BANCA:
Externo à Instituição - ANA CECILIA VIEIRA DA NOBREGA - UFPE
Presidente - 022.621.844-96 - MARCOS ALYSSANDRO SOARES DOS ANJOS - IFRN
Interno - 1507841 - MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA
Notícia cadastrada em: 29/11/2016 16:56
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