Experimental study on rehabilitation of corrosion-damaged reinforced concrete beams with carbon fiber reinforced polymer
TL;DR: In this paper, a modified retrofit method based on substrate repairs was developed, which is bonding CFRP after replacing V-notch of substrate concrete with polymer mortar, and four-point bending experiments were conducted on a series of corrosion-damaged RC beams with CFRP.
About: This article is published in Construction and Building Materials.The article was published on 2013-01-01. It has received 72 citations till now. The article focuses on the topics: Carbon fiber reinforced polymer.
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TL;DR: In this article, a modified concrete damaged plasticity model (CDPM) based on ABAQUS is presented to accurately simulate the mechanical responses of steel-polypropylene hybrid fiber reinforced concrete (HFRC).
118 citations
TL;DR: In this paper, the experimental and analytical behavior of four reinforced concrete beams with corroded steel reinforcements with low mass loss (around 7.5%), yet in need of removal of cracked concrete cover, treatment of steel bars, application of cement-based repair patch and of externally bonded EBR or NSM FRP laminates.
Abstract: This paper presents the experimental and analytical behavior of four reinforced concrete beams with corroded steel reinforcements with low mass loss (around 7.5%), yet in need of removal of cracked concrete cover, treatment of steel bars, application of cement-based repair patch and of externally bonded EBR or NSM FRP laminates. It comes out the assessment of residual flexural capacity of the as-built corroded beams and the suitable strengthening measures depend largely on the concrete cover crack pattern and width, as accelerated corrosion-related cracks were measured just wider than 0.3 mm (failing to fulfill serviceability limit state requirements marginally). This study also demonstrates that assessment of contribution of corroded steel and treatment in the above cases requires partial uncovering in order to apply inhibitors and better calibrate the actual mass loss with corresponding cover concrete damage. All the above may be fulfilled at the characteristic limit state of initiation of concrete cover separation. The observed failure modes, the recorded force – deflection curves and strains on steel and FRP laminates, validate for the strengthened corroded beams the full force transfer through old concrete – patch interface and through patch and FRP laminate interface, as predicted in the case of non-patched beams. The beam strengthened with two NSM FRP strips of equivalent axial rigidity with EBR FRP laminate presented 18.2% higher load and 41.6% higher deflection than the latter. The P-d behavior of all beams was modeled with advanced 3D Finite Elements (FE) that enabled further analytical investigation of the observed modes of failures and patch repair effects.
94 citations
TL;DR: In this paper, the performance of FRP-concrete bond systems subjected to chloride exposure is investigated and a lower bound of the tensile property retention of epoxy resin and FRP composites is compared with the published specifications.
77 citations
TL;DR: In this paper, the experimental results of damaged/repaired reinforced concrete beams were presented, which showed that using externally bonded U-shaped CFRP sheets restored the ductility of corroded beams without stirrups and prevented bond failure at the steel concrete interface due to the absence of internal Stirrups.
Abstract: Strengthening/repair of existing reinforced concrete structures has become one of the important issues in the field of civil engineering. In reinforced concrete structures located in hot and humid areas, steel reinforcement is generally vulnerable to deterioration due to corrosion. Corrosion of reinforcement in many cases is considered the main cause of concrete structures deterioration which in turn requires large budgets for repair and maintenance. This paper presents the experimental results of damaged/repaired reinforced concrete beams. The experimental program consisted of testing 12 reinforced concrete rectangular beam specimens with/without shear reinforcement and exposed to accelerated corrosion. The corrosion level was varied between 5 and 7.5 % which represents mass loss of the longitudinal steel reinforcement on the tension side. Corroded beams without shear reinforcement were repaired by bonding longitudinal carbon fiber reinforced polymer (CFRP) sheets to the tension side in addition to external U-shaped CFRP sheets to restore the strength loss due to corrosion. Corroded beams with stirrups were repaired by bonding longitudinal CFRP sheets to the tension side only. The test results showed that using externally bonded U-shaped CFRP sheets restored the ductility of corroded beams without stirrups and prevented bond failure at the steel concrete interface due to the absence of internal stirrups. In addition, combining U-shaped and longitudinal CFRP sheets enhanced the ultimate load by 37 % and the stiffness by 25 % in corroded beams without stirrups. For corroded beams with stirrups ductile failure was observed. Corroded beams with stirrups strengthened with CFRP sustained higher failure loads; however, the stiffness was unchanged.
76 citations
TL;DR: In this article, the experimental results on the effectiveness of patch repair and FRP bonded laminates to retrofit reinforced concrete beams with corrosion damage are discussed, and the necessity of the removal of the cracked concrete substrate, treatment of corroded reinforcement and repair by patching with a polymer modified mortar is highlighted.
Abstract: The experimental results on the effectiveness of patch repair and FRP bonded laminates to retrofit reinforced concrete beams with corrosion damage are discussed in this paper. The uncovering of the damaged concrete cover provides a more accurate assessment of the corrosion degree, as the actual mass loss of reinforcement can be better calibrated. The mass loss of the tensile reinforcement varied at approximately 7.5%–24%. The necessity of the removal of the cracked concrete substrate, treatment of corroded reinforcement and repair by patching with a polymer modified mortar is highlighted. Two different strengthening techniques are implemented, of externally bonded EBR or NSM Carbon FRP laminates, having equivalent axial rigidity. CFRP wraps were also applied for shear strengthening to replace corroded stirrups. The load-deflection curves showed that the effect of corrosion on load bearing capacity and bond between the concrete and steel was detrimental for high mass losses. A satisfactory force transfer through the old and patch repaired concrete and through repair mortar and CFRP reinforcement interface was noted. The shear strengthening not only prevented the debonding of the EB laminate at the end but also improved the bond performance between the laminate and concrete, especially for the high corroded beam.
63 citations
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01 Jan 2002
TL;DR: The Emerging Technology Series as mentioned in this paper is a series of information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions of committee members, with a focus on the development and appropriate use of new and emerging technologies.
Abstract: *Co-chairs of the subcommittee that prepared this document. Note: The committee acknowledges the contribution of associate member Paul Kelley. ACI encourages the development and appropriate use of new and emerging technologies through the publication of the Emerging Technology Series. This series presents information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions of committee members. The presented information and recommendations, and their basis, may be less fully developed and tested than those for more mature technologies. This report identifies areas in which information is believed to be less fully developed, and describes research needs. The professional using this document should understand the limitations of this document and exercise judgment as to the appropriate application of this emerging technology.
2,963 citations
TL;DR: In this article, the effect of harsh environmental conditions such as wet/dry cycling using salt water on the performance of FRP-bonded concrete beams and on the interfacial bond between the fiber and the concrete was investigated.
Abstract: The strengthening of concrete structures in situ with externally bonded fiber reinforced plastic (FRP) composite sheets is increasingly being used for repair and rehabilitation of existing structures. This paper provides information in the area of long-term durability of concrete beams externally bonded with FRP sheets. It was intended to study the effect of harsh environmental conditions such as wet/dry cycling using salt water on the performance of FRP-bonded concrete beams and on the interfacial bond between the fiber and the concrete. Concrete beams were strengthened with four different types of FRP sheet: two carbon and two glass. Three different types of two-part epoxy were used. Test variables included (1) the type of fiber, (2) the type of epoxy system, and (3) the environmental exposure condition. The specimens were conditioned in two different environments: (a) room temperature (+20 °C), and (b) 300 wet/dry cycles (salt water was used for the wet cycles and hot air at 35 °C and 90% humidity for the dry). At the end of each exposure, load-deflection curves of the specimens were obtained in order to evaluate their maximum capacity, stiffness, and ductility. The performance of the wet/dry exposed specimens was compared with those kept at room temperature. Results showed that specimens subjected to wet/ dry environmental conditions and those kept at room temperature exhibited significant improvement in flexural strength when FRP sheets were bonded to the tension face of the concrete beams. However, the specimens subjected to wet/dry conditions showed less improvement than those kept at room temperature. None of the specimens failed due to FRP rupture but rather due to the debonding between the FRP sheet and the concrete interface. The selection of epoxy was shown to be very important for using the FRP strengthening technique, especially in a marine environment.
193 citations
"Experimental study on rehabilitatio..." refers background in this paper
...In these studies, some researchers used natural corrosion methods to account for deteriorate material properties, either obtained directly from the field [3] or conditioned in the laboratory [1,4,5]....
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TL;DR: In this paper, the authors report the results of an experimental program designed to provide a realistic assessment of the potential of using fiber-reinforced polymer (FRP) materials in the repair and strengthening of reinforced concrete (RC) flexural members.
Abstract: This paper reports the results of an experimental program designed to provide a realistic assessment of the potential of using fiber-reinforced polymer (FRP) materials in the repair and strengthening of reinforced concrete (RC) flexural members. The experimental program included seven RC flexural beams, 270-by-400 mm in cross section and 4,350 mm in length. Four of the seven RC beams were reinforced externally with one or two layers of carbon FRP (CFRP) composite. Variables considered included state of damage (damaged versus undamaged) and loading condition during bonding (loaded versus unloaded). Damage was introduced in four of the seven RC beams using an accelerated corrosion technique developed at the University of Toronto. Test results revealed that it is necessary to consider the effects of corrosion- and load-induced damage as well as sustained load on the load-carrying and deflection capacities of externally reinforced flexural members. Furthermore, it is concluded that it is possible to achieve adequate corrosion repair with externally bonded CFRP and minimal intervention. In particular, results showed that it is important to optimize CFRP layout to balance strength recovery with control of faulting and splitting, which could lead to premature member failure.
132 citations
"Experimental study on rehabilitatio..." refers background or methods in this paper
...[2], Bonacci and Maalej [7], Masoud and Soudki [10] experimentally studied the short-term performance of corrosiondamaged RC beams retrofitted with CFRP, Masoud and Soudki [11], Al-Hammoud et al....
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...To accelerate the aging process, others researchers used the application of induced electrical current [2,6–15]....
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TL;DR: In this paper, the authors investigated the feasibility of using externally bonded carbon-fiber-reinforced polymer (CFRP) laminates to extend the service life of corroded reinforced concrete (RC) beams.
Abstract: This paper presents the results of an experimental study designed to investigate the viability of using externally bonded carbon-fiber-reinforced polymer (CFRP) laminates to extend the service life of corroded reinforced concrete (RC) beams. A total of 14 beams, 152×254×3,200 mm each, were tested. Three beams were not corroded; two of them were strengthened by CFRP laminates, while one specimen was kept as a virgin. The remaining 11 beams were subjected to different levels of corrosion damage up to a 31% steel mass loss using an impressed current technique. Six of the corroded beams were repaired with CFRP laminates, whereas the remaining five beams were not repaired. Eventually, all specimens were tested to failure under four-point bending. Corrosion of the steel reinforcement significantly reduced the load-carrying capacity of RC beams. At all levels of corrosion damage, CFRP repair increased the ultimate strengths of the corroded beams to levels higher than the strength of the virgin beam but significa...
84 citations
"Experimental study on rehabilitatio..." refers methods in this paper
...To accelerate the aging process, others researchers used the application of induced electrical current [2,6–15]....
[...]
TL;DR: This paper investigated the flexural behavior of corroded steel reinforced concrete beams repaired with carbon-fiber-reinforced polymer (CFRP) sheets under repeated loading and found that CFRP sheets increased the fatigue capacity of the beams with corroded reinforced steel reinforcement beyond that of the control unrepaired beams with uncorroded steel reinforcement.
Abstract: This study investigated the flexural behavior of corroded steel reinforced concrete beams repaired with carbon-fiber-reinforced polymer (CFRP) sheets under repeated loading. Thirty beams ( 152×254×2,000 mm ) were constructed and tested. Fatigue flexural failure occurred in 29 of these beams. The study showed that pitting of the steel reinforcement due to corrosion occurred only after about a 7% actual mass loss which coincided with a decrease in the fatigue performance of the beam. The controlling factor for the fatigue strength of the beams is the fatigue strength of the steel bars. Repairing with CFRP sheets increased the fatigue capacity of the beams with corroded steel reinforcement beyond that of the control unrepaired beams with uncorroded steel reinforcement. Beams repaired with CFRP at a medium corrosion level and then further corroded to a high corrosion level before testing had a comparable fatigue performance to those that were repaired and tested after corroding directly to a high corrosion level.
82 citations
"Experimental study on rehabilitatio..." refers methods in this paper
...To accelerate the aging process, others researchers used the application of induced electrical current [2,6–15]....
[...]
...[13] investigated the fatigue behavior of corroded RC beams with CFRP, and Al-Hammoud et al....
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