| 1. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Corrosion-induced cracking and bond behaviour of corroded reinforcement bars in SFRC
- 2017
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Ingår i: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368. ; 113, s. 123-137
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates, experimentally and numerically, the effect of fibre reinforcement on the initiation of corrosion-induced cracks in concrete and the bond behaviour of corroded reinforcement bars in fibre reinforced concrete. The fibres, due to their confining effect, contributed to delay crack initiation, improve the post-peak bond behaviour and retain the initial splitting strength for corrosion levels of up to 8%. The mechanisms for delayed crack initiation were explained through 3D finite element analyses of the experiments whereas a 1D model, using experimental bond-slip curves as an input, was employed to quantify the beneficial effect of fibres on the reinforcement anchorage length.
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| 2. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
-
Corrosion-induced cracking and bond behaviour of corroding reinforcement bars in SFRC
- 2017
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Ingår i: Nordic Concrete Research. - 0800-6377. - 9788282080569 ; , s. 123-126
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Konferensbidrag (refereegranskat)abstract
- In this study, an experimental programme has been carried out to investigate the influence of fibres on the onset of corrosion-induced splitting cracks. Cylindrical lollipop specimens with a centrally positioned Ø16 mm bar and varying cover depths from 40 to 64 mm were subjected to accelerated corrosion. A constant current of 100 μA/cm2 was impressed through the specimens and the electrical resistance between each rebar and an external copper mesh acting as cathode was monitored. The fibres, due to their confining effect, contributed to delay crack initiation, improve the post-peak bond behaviour and retain the initial splitting strength for corrosion levels of up to 8%.
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| 3. |
- Berrocal, Carlos Gil, 1986
(författare)
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Corrosion of steel bars in fibre reinforced concrete: corrosion mechanisms and structural performance
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The viability of employing fibre reinforcement to improve the durability performance of RC structures by delaying and/or reducing rebar corrosion and by mitigating the structural impact of corrosion-induced damage have been investigated. Given the enhanced crack control of FRC, it could be advantageous to use fibres in civil engineering structures to decrease the ingress of corrosion-initiation substances. However, the combined use of both types of reinforcement in chloride environments raises questions regarding the potential influence that fibres may have on the corrosion process of conventional rebar.Long-term experiments were carried out featuring naturally corroded RC elements subjected to different loading conditions and varying crack widths. Complementary short-term experiments were carried out to isolate the influence of fibres on individual parameters governing the process of reinforcement corrosion, such as chloride diffusion, internal cracking and electrical resistivity, as well as on corrosion-induced damage, such as cracking and spalling of the cover.From the experiments it was found that the ingress of chloride ions into concrete, assessed through migration and bulk diffusion tests, was not significantly affected by the presence of fibres. The internal crack pattern of conventionally RC beams subjected to bending loads revealed a tendency for crack branching and increased tortuosity when fibres were present, which can potentially decrease the permeation of concrete and promote crack self-healing. The time to corrosion initiation, evaluated through half-cell potential monitoring, for fibre reinforced beams were similar or longer than the plain concrete ones. However, the effect of fibres was minor compared to the difference between cracked and uncracked specimens, thus highlighting the importance of cracks for the initiation of corrosion. The DC resistivity was found to be unaffected by steel fibres, indicating that they do not pose a risk for increased corrosion rates. Gravimetric steel loss measurements showed that the corrosion level of reinforcement bars embedded in FRC beams was similar or even lower than for plain concrete beams. Moreover, the examination of the corrosion patterns and a detailed analysis of individual corrosion pits revealed a tendency for more distributed corrosion with reduced cross-sectional loss in FRC. Corrosion-induced cracking of the cover was somewhat delayed by fibre reinforcement, particularly for small cover thicknesses, which was attributed to the additional source of passive confinement provided by the fibres. Thereafter, corrosion-induced cracks were effectively arrested by fibres, which resulted in an enhanced bond behaviour of SFRC with no apparent loss of bond strength and high residual bond-stresses. Fibres also had a positive effect on the residual flexural capacity of corroded beams, which generally displayed a slightly increased load-carrying capacity and rotation capacity compared to plain concrete beams with corroded reinforcement. The promising results obtained in this study indicate that FRC may be effectively used to extend the service life of civil engineering structures by delaying and reducing reinforcement corrosion as well as by mitigating the structural effects of corrosion-induced damage.
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| 4. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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FIbrer i anläggningskonstruktioner
- 2017
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Ingår i: Bygg och Teknik. - 0281-658X. ; 7:Betong, s. 30-33
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- I ett doktorandprojekt som genomförts i samarbete mellan Chalmers tekniska högskola och Thomas Concrete Group har experiment utförts för att undersöka hur fibrer påverkar korrosion av konventionell armering. Resultaten visar att kombinationen av fibrer och konventionell armering kan effektivt förlänga livslängden hos anläggningskonstruktioner, dels genom att armeringskorrosion fördröjs och minskas, och dels genom att effekten på bärförmågan av korrosionsskador begränsas. I den här artikeln sammanfattas projektets huvudresultat.
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| 5. |
- Fahimi, Shayan, et al.
(författare)
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Replication of Crack Pattern in FE Analysis Based on Discretization of Tension Softening Curves
- 2017
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Ingår i: Nordic Concrete Research. - 0800-6377. ; 56:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Today, there is an increasing need for reliable methods for condition assessment and service-life evaluation of existing structures. Although advanced 3D Nonlinear Finite Element (3D NLFE) analysis has proven to be capable of describing the behavior of reinforced concrete in a comprehensive way, the analysis results are difficult to couple with visual inspection data such as cracking and spalling. Moreover, 3D NLFE programs are numerically expensive and incomprehensible for full-scale practical applications. Thus, the present study aims to couple 3D NLFE analysis with condition assessment data, and consequently to increase the accuracy, to optimize the computation time and to improve robustness of such analyses.
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