| 1. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Characterisation of bending cracks in R/FRC using image analysis
- 2016
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 90, s. 104-116
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Tidskriftsartikel (refereegranskat)abstract
- In this study, experiments were conducted to induce bending cracks of specific surface crack width to reinforced concrete beams made of plain concrete (RC) and reinforced concrete beams made of fibre reinforced concrete (R/FRC). After injecting and impregnating the cracks with dyed epoxy resin, image processing and analysis were employed to investigate the internal crack morphology. Several crack features including crack width (accumulated, effective and maximum), branching and tortuosity were defined and quantified. The results showed that in addition to arrested crack development, the presence of fibres yielded a distinctive change in the internal crack pattern, including increased branching and tortuosity, both of which have positive implications regarding concrete permeation. Likewise, specimens with fibres exhibited reduced maximum individual crack widths near the rebar, potentially increasing the ability of autogenous crack healing and reducing the risk of corrosion initiation.
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| 2. |
- 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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| 3. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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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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| 4. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Corrosion initiation in cracked fibre reinforced concrete: Influence of crack width, fibre type and loading conditions
- 2015
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 98, s. 128-139
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports results from an ongoing project aimed at investigating the influence of fibre reinforcement on corrosion of rebar in chloride environments. Material tests showed that the resistivity of concrete decreased with the addition of fibres, whereas the chloride migration coefficient remained unaffected. Fibres at low dosages (
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| 5. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Corrosion of Steel Bars Embedded in Fibre Reinforced Concrete under Chloride Attack: State-of-the-Art
- 2016
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 80, s. 69-85
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Forskningsöversikt (refereegranskat)abstract
- This literature review summarises the influence of fibres on the main parameters governing corrosion of conventional reinforcement. The ability of fibres to suppress crack growth has proven to decrease permeation in cracked concrete while chloride diffusion, in uncracked concrete, seems to remain unaffected by the addition of fibres. Steel fibres in concrete are considered to be insulated owing to the high impedance of the passive layer. However, they will become conductive if they are depassivated. Although low carbon steel fibres may suffer severe corrosion when located near the concrete surface or bridging the cracks, embedded fibres will remain free of corrosion despite high chloride contents. Published experimental observations indicate that fibres had little influence on the corrosion rate of rebars. Steel fibres improved corrosion resistance of rebars moderately; this is mainly attributed to a reduced ingress of chlorides due to arrested crack growth.
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| 6. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Effect of fibre reinforcement on the crack width profile and internal crack pattern of conventionally reinforced concrete beams
- 2016
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Ingår i: Proceedings of the 9th RILEM International Symposium on Fiber Reinforced Concrete. - 9782351581872 ; , s. 355-366
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Konferensbidrag (refereegranskat)abstract
- Although fibre reinforcement is known to reduce the crack width and crack spacing of conventionally reinforced concrete elements, the impact of fibres on the crack width profile and crack morphology has not received as much attention. This paper presents experimental results of the crack width profile and internal crack pattern obtained from three-point bending test of conventionally reinforced concrete notched beams made of plain concrete and fibre reinforced concrete at low fibre dosages. The induced cracks were, under loaded conditions, injected with a fluorescent epoxy-resin. From each beam, two pieces were extracted and subjected to a second impregnation. Digital images were taken using a microscope and were then processed and analysed to extract quantitative information. The results revealed that the accumulated crack width was similar for all mixes. However, in the samples with fibres the main crack branched off into several narrower cracks compared to plain concrete, which generally exhibited a single and wider crack. Based on the known relation between permeation and crack width, this finding describes a mechanism through which fibre reinforcement can improve the water tightness of reinforced concrete structures and potentially extent their service life reducing the ingress of detrimental agents.
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| 7. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Electrical resistivity measurements in steel fibre reinforced cementitious materials
- 2018
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Ingår i: Cement and Concrete Composites. - : Elsevier BV. - 0958-9465. ; 89, s. 216-229
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports results from experiments aimed at better understanding the influence of fibre dosage and fibre geometry on the AC frequency needed to determine the DC resistivity of cementitious materials containing steel fibres. Impedance spectroscopy and DC galvanodynamic measurements were performed on mortar prisms with varying fibre reinforcement to determine the matrix resistivity (related to ionic current within the pore solution) and composite resistivity (accounting for both ionic current and electronic current through the fibres). The results showed that adding steel fibres did not significantly affect the DC nor the AC matrix resistivity of the mortar prisms. However, the steel fibres yielded a drastic reduction of the frequency associated to the AC matrix resistivity from ∼1 kHz in plain mortar to ∼1 Hz in steel fibre reinforced mortar. These findings revealed the need to adequately adjust the frequency in AC resistivity measurements of steel fibre reinforced cementitious materials.
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| 8. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Experimental Investigation on Rebar Corrosion in Combination with Fibres
- 2014
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Ingår i: Proceedings of the XXII Nordic Concrete Research Symposium. - 9788282080439 ; , s. 532-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, early results from an on-going project aimed at investigating the influence of fibre reinforcement on corrosion of rebar are presented. Resistivity of mixes containing fibres was reduced when compared with plain concrete while chloride migration seemed to remain unaffected. On the mechanical properties, results showed that while the flexural behaviour was greatly enhanced by addition of fibres up to 0.5% vol., the variation in compressive strength was negligible regardless of the fibre type. Early results from the main experiments indicated atendency of earlier corrosion initiation with increasing crack width, and that the initiation time was somewhat delayed for the fibre reinforced specimens.
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| 9. |
- 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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| 10. |
- Berrocal, Carlos Gil, 1986, et al.
(författare)
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Influence of fibre reinforcement on the initiation of corrosion-induced cracks
- 2016
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Ingår i: Materials, Systems and Structures in Civil Engineering 2016 - Segment on Service Life. - 9782351581704 ; 1, s. 231-240
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Konferensbidrag (refereegranskat)abstract
- The initiation of corrosion-induced cracks, often running parallel to the reinforcement, becomes a turning point in the service life of a reinforced concrete (RC) structure as they promote increased corrosion rates, thus accelerating the degradation process of the structure. Compared to plain concrete, fibre reinforced concrete (FRC) provides additional confinement to the reinforcement, which has been reported to delay or even prevent the appearance of mechanically induced splitting cracks. 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. Crack initiation, determined from a drop in electrical resistance, and confirmed by visual inspection, revealed that fibre reinforcement may delay corrosion-induced cracks, an effect that was more noticeable for reduced c/Ø ratios, featuring up to 50% higher corrosion levels at crack initiation compared to plain concrete.
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