Contribution to the study of shrinkage and creep and their low ages performing mechanisms in structural concretes / Contribuição ao estudo da retração e da fluência e seus mecanismos de atuação a baixas idades em concretos estruturais

AUTOR(ES)

Giana Sousa Sena Rodrigues

DATA DE PUBLICAÇÃO

2010

RESUMO

This work aimed to study the development of shrinkage and creep in commercial concretes with resistance varying about 20, 35 and 50 MPa. Determination tests of shrinkage and creep in sealed and not sealed specimens were carried out by applying a variation of parameters that influence the deformation development. From the results, the differentiation of specific regimes for the shrinkage development speeds and for the relative variation of water mass in lower ages of the concrete was verified. Rates for the differentiation of variable development were estimated and those rates were used to explain the material behaviour along the age. The obtained results enabled to verify that the conditions of material exposition and the period of time processed between the mixture and the exposition of the specimens to moisture gradients exerted significant influence, by altering values of total deformations, with or without load application. In relation to the creep determined for sealed prisms, the concrete with characteristic resistance of 50 MPa presented the highest deformation values, both intermediate and final. For unsealed prisms, from the age of 20 days, the concrete with characteristic resistance of 20 MPa presents higher values of creep. From the results, the differentiation of specific regimes for the shrinkage development speeds and for the relative variation of water mass in lower ages of the concrete was verified. Rates for the differentiation of variable development were estimated and those rates were used to explain the material behaviour along the age. Besides, it was verified that the specific shrinkage behavior was the inverse of the resistance behavior, once lower resistance concretes presented higher values of specific creep. Independently of specimens covering conditions, the results indicated that creep represented a significant part of deformation under constant loading development.

ASSUNTO(S)

commercial concretes shrinkage retração fluência deformações concretos comerciais estruturas creep deformations

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