Corrosion effects on the bond behaviour of steel bars in self-compacting concrete

<p>The bond behaviour of concrete specimens with carbon textile reinforcement was investigated in the presented research programme. Pull-out specimens were cast from self-compacting concrete with expansive admixtures and in this way chemical prestress was introduced. The aim of the research was to compare bond behaviour between prestressed specimens and non-prestressed control specimens. During pull-out tests, the pull-out force and notch opening were measured with a load cell and laser sensors. Further, bond - slip and pull-out force - crack width relationships were drawn and compared for prestressed and non-prestressed specimens. Chemically prestressed specimens reached 24% higher bond strength than non-prestressed ones. It can be therefore concluded, that chemical prestressing positively influences the bond behaviour of concrete with textile reinforcement and thus better utilisation of its properties can be provided.</p>

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Experimental analysis of reinforced concrete columns strengthened with self-compacting concrete and connectors

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952012000300004 ◽

2012 ◽

Vol 5 (3) ◽

pp. 305-315

Author(s):

P. P. Nascimento ◽

R. B. Gomes ◽

L. L. J. Borges ◽

D. L. David

Keyword(s):

Reinforced Concrete ◽

Failure Mode ◽

Experimental Analysis ◽

Thick Layer ◽

Concrete Columns ◽

The Other ◽

Experimental Phase ◽

Self Compacting Concrete ◽

Reinforced Concrete Columns ◽

Steel Bars

There are many problems involving cases of destruction of buildings and other structures. The columns can deteriorate for several reasons such as the evolution and changing habits of the loads. The experimental phase of this work was based on a test involving nine reinforced concrete columns under combined bending and axial compression, at an initial eccentricity of 60 mm. Two columns were used as reference, one having the original dimensions of the column and the other, monolithic, had been cast along the thickness of the strengthened piece. The remaining columns received a 35 mm thick layer of self-compacting concrete on their compressed face. For the preparation of the interface between the two materials, this surface was scarified and furrowed and connectors were inserted onto the columns' shear reinforcement in various positions and amounts.As connectors, 5 mm diameter steel bars were used (the same as for stirrups), bent in the shape of a "C" with 25 mm coatings. >As a conclusion, not only the quantity, but mainly, the location of the connectors used in the link between substrate and reinforcement is crucial to increase strength and to change failure mode.

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Experimental analysis of reinforced concrete columns strengthened with Self-Compacting concrete

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952010000300002 ◽

2010 ◽

Vol 3 (3) ◽

pp. 271-283 ◽

Cited By ~ 2

Author(s):

M. Y. M. Omar ◽

R. B. Gomes ◽

A. P. A. Reis

Keyword(s):

Reinforced Concrete ◽

Ultimate Load ◽

Rectangular Cross Section ◽

Concrete Columns ◽

Loading Capacity ◽

Longitudinal Reinforcement ◽

Self Compacting Concrete ◽

Reinforced Concrete Columns ◽

Subsequent Test ◽

Steel Bars

This paper presents the results of reinforced concrete columns strengthened by addition of a self-compacting concrete overlay at the compressed and at the tensioned face of the member, with and without addition of longitudinal steel bars. Eight columns were submit- ted to loading with an initial eccentricity of 60 mm . These columns had 120 mm x 250 mm of rectangular cross section, 2000 mm in length and four longitudinal reinforcement steel bars with 10 mm in diameter. Reference columns P1 and P2 were tested to failure without any type of rehabilitation. Columns P3 to P8 were loaded to a predefined load (close to the initial yield point of tension reinforce- ment), then unloaded and strengthened for a subsequent test until failure. Results showed that the method of rehabilitation used was effective, increasing the loading capacity of the strengthened pieces by 2 to 5 times the ultimate load of the reference column.

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