2000-2003: Use of fibre reinforced self compacting concrete for improving the strength and ductility of masonry constructions

Masonry compression failure mode governed by the mortar bond strength

POCTI/36035/ECM/2000 (2000-2003)

Summary: The scientific and technological objective of this research project was to improve the knowledge about the fibres concrete infill mechanical behaviour avoiding the steel bars reduction or replacement in the masonry constructions. In the infill and consolidation composites domain its applications concern the masonry structures built in according the Eurocode 6 and also the historical masonry stability rehabilitation. The attainability to these applications has a strong dependence of the fibres reinforced concrete infill properties; its adequacy will improve the tensile strength and the ductility to the good service performance of masonry constructions.
The main particularity in this case is the fact of the voids in the masonry (stone, brick, clay, concrete masonry, etc.) is constituted of the porous media or subtracts that can modify the initial water-cement ratio improving a very plastic shrinkage. This phenomenon is responsible of the bond weakness among the concrete infill, masonry units and the steel bars. Additional problems to assure the concrete infill workability come from the necessary increasing of the bars size and the limited voids area to fill; this particularity needs a self-compactability capacity of the concrete infill.
In a first phase, mix design procedures were performed to give the possibility to choice an optimal mixture with self-compactability properties. In a second phase, it was appreciated the fibres reinforced concrete contribution on the compressive and flexural masonry strength and its ductility. Mathematical models to predict the fibres concrete infill fresh and hardened behaviour and a study about the global plastic behaviour in reinforced masonry walls filled with steel fibres self-consolidating concrete was developed.

Results outline: A satisfactory control parameter of the self-compactability like the mortar ratio was proposed to mix design a steel fibres self-compacting concrete. With the proposed methodology is possible to obtain the desired self-compacting properties of the masonry reinforced concrete infill till 1.5% fibres volume. The increase of fibres volume is responsible of important augmentation in the flexural capacity of the SFRSCC.
It was preview that the contribution carried by the each 0,5% volume fibres addition is very significant and can be appreciate as an equivalent reinforcement bar area.
The characterization of the global plastic behaviour for the walls analyzed in this work it is not possible to apply the same criterion, generally used on the current elements of reinforced concrete with one-dimensional behaviour, assuming a plasticizing length of tensile re-bars equal to useful effective depth of the cross section. The results of this work show that such length is sufficiently more restricted (not very superior to the thickness of the mortar joints).

International journal papers:

Oliveira, L.A.P. (2004), Evaluation of early shrinkage of structural masonry concrete infill, Masonry International, UK, Vol.17, Nº2, pp 66-70.

National journal papers:

Oliveira, L.A.P e Bernardo, L.F.A, (2004), A construção racional de edifícios em alvenaria armada, Construção Magazine, Portugal, 4º trim, Nº11, pp-22-29.

Articles in international conferences:

Oliveira L.A.P. and Rocha, M. F P., (2002), Masonry compression failure mode governed by the mortar bond strength, 4th International Conference Analytical Models and New Concepts in Concrete and Masonry Structures, Kraków, Poland, June 5 – 8 2002.

Oliveira, L.A.P., Carreiro, P.S. and Pericão, M.S, (2003) “The steel fibers self-compacting concrete infill contribution on the ductility of concrete masonry wall”, International Conference Composites in Construction 2003, September 16-19, University of Calabria, Italy.

Oliveira, L.A.P., Carreiro, P.S. and Pericão, M.S, (2003) Development of steel fibers self-compacting masonry concrete infill. In: Composites in Construction 2003, Edited by Domenico Bruno, Giuseppe Spadea and Narayan Swamy, p. 145-149.

L. A. Pereira de Oliveira, J.P. Castro Gomes e C.N. Gonilho Pereira (2004), Influence of mineral additions in the capillary absorption of self-compacting concrete. Proceedings of 8th International Conference of Modern Building Materials, Structures and Techniques, Vilnius GediminasTechnical University,Vilnius, Lithuania.

Oliveira, L.A.P and Bernardo, L.F.A, (2005), Global plastic behaviour of structural masonry reinforced with steel fibers self-consolidating concrete, In: Composites in Construction 2005, Vol.2, Edited by P. Hamelin, D.Bigaud, E. Ferrier and E. Jacquelin, Lyon, France, pp 1181-1188.

Articles in national conferences:

Oliveira L.A.P. (2000), Optimização da composição do betão auto-compactável, Encontro Nacional Betão Estrutural 2000, 22-24 Novembro 2000, Porto, Editores: Comissão Organizadora BE2000, pp 65 – 74

Oliveira L.A.P. (2001), A viabilidade técnico-económica da construção racional de edifícios em alvenaria armada, ENGENHARIA’2001 – Inovação e Desenvolvimento, Universidade da Beira Interior, Novembro 2001, pp 73-78

Oliveira L.A.P., Gomes J.P.C. (2001), A Influência do Teor de Argamassa na Viscosidade do Betão auto-compactável Reforçado com Fibras de Aço, ENGENHARIA’2001 – Inovação e Desenvolvimento, Universidade da Beira Interior, Novembro 2001, pp 309-313

Oliveira L.A.P. (2001), A Formulação do Betão auto-compactável Reforçado com Fibras de Aço, Construção 2001 – Congresso Nacional da Construção, Lisboa, Dezembro 2001, pp 463-470

L. A. Pereira de Oliveira, J.P. Castro Gomes e C.N. Gonilho Pereira, (2003) Influência de adições minerais na absorção capilar de betões auto-compactáveis, Engenharia2003 – Inovação e Desenvolvimento, Universidade da Beira Interior, Novembro 2003, p. 291-296

Oliveira L.A.P, Bernardo L.F.A, (2004), Resistência e ductilidade em flexão de paredes de alvenaria armadas e preenchidas com betão autocompactável reforçado com fibras de aço, In: Actas Encontro Nacional Betão Estrutural 2004, Ed. Joaquim A. Figueiras, Porto, Vol 1, p 669-678

Oliveira, L.A.P, Ramos M, Castro Gomes J.P, (2005), Dosagem de concreto auto-adensável reforçado com fibras de aço, In: Proccedings of 47º Congresso Brasileiro do Concreto, Vol 5, Editores: Jacinto A. E. P. G. A, Monteiro E, Bittencourt T. N., Brasil pp 568 -581.

Invited Lectures:

Oliveira L.A.P, Concreto Auto Compactável, conferência apresentada na Faculdade de Tecnologia de São Paulo CEETEPS/UNESP, em 05 de Setembro de 2000.

Oliveira L.A.P., The Rheology of Self-Compacting Concrete, Seminar at Bialystok Technical University, Poland, September, 2001

Oliveira L.A.P., Betão Auto Compactável: tecnologia e aplicações, Conferência apresentada em 18/04/2001, Ciclo de Conferências NECUBI – DECA, Universidade da Beira Interior

Oliveira L.A.P., From mortar rheology to self-compacting concrete, SIABE/INCOS 06, II International Conference on Concrete for Structures, Rio de Janeiro, Brasil, 2006, (Keynote Lecture)

Scientific Report:

L. A. Pereira de Oliveira, J.P. Castro Gomes, M.C. S. Nepomuceno, M. S.G. Pericão, Relatório final 02 Nov 03- POCTI36035/ECM/2000, Utilização de betões auto-compactáveis reforçados com fibras para melhorar a resistência mecânica e a ductilidade de construções de alvenaria, Universidade da Beira Interior, 2003, 50p.

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