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Design of recycled concrete under ultimate limit state by normal stresses

Title: Design of recycled concrete under ultimate limit state by normal stresses
Author(s): B. González-Fonteboa, F. Martínez-Abella, D. Carro-López and I. Martínez-Lage
Paper category : conference
Book title: 2nd International RILEM Conference on Progress of Recycling in the Built Environment
Editor(s): V.M. John, E. Vazquez, S.C. Angulo, C. Ulsen
e-ISBN: 978-2-35158-122-3
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 275 - 285
Total Pages: 11
Nb references: 14
Language: English

Abstract: This work deals with different aspects of the behaviour and design of structural recycled concrete. The aim of this research was to determine whether the classical method used for limit state design in flexure and compression can be applied when recycled concrete is being used. This method uses a parabolic-rectangular stress block to simplify the stress-strain curve of the concrete.

Within this frame, two different tests were developed:
First of all, a test to know the behaviour under sustained load was arranged. Thus, using concretes with 100% of recycled coarse aggregate, a test under very slow speed was carried out. The results indicated that the coefficients (strength under standard speed- strength under very slow speed) in compression and in tensile are very similar in conventional and recycled concretes.

Secondly, a test to know the full stress-strain diagram was carried out. For the non-linear analysis of structural members of concrete, it is necessary to determine their real stress-strain curves in compression. The curves proposed in different codes for the conventional concretes are based on experimental results obtained by testing cylinders under axial compression. After that, for the design of cross sections under ultimate limit state, the codes (EHE, Eurocode 2) propose the use of simplified stress - strain relationships, adopting the usual parabola-rectangle diagram consisting of a parabola up to the abscissa corresponding to the peak strain of 2 ‰ (at the maximum stress) and a rectangle, up to the ultimate strain of 3.5 ‰ (strain at which failure is defined). To know the stress-strain curve of recycled concretes, recycled concretes with different percentages of replacement of the coarse aggregate (20, 50, 100 %) were used. The results allowed to establish the differences of the curve with respect to that of the conventional concrete regarding the percentage of replacement.

Online publication: 2012-02-08
Publication type : full_text
Public price (Euros): 0.00

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