This article reports on a field demonstration study by the University of Florida using a unique f... more This article reports on a field demonstration study by the University of Florida using a unique fiber-reinforced polymer (FRP) which was wrapped around corroding reinforced concrete piles to evaluate the feasibility of making underwater pile repairs. Results show a water-activated resin matrix allows for the possibility of installing FRP wrap for the repair of piles, even in open-water conditions. Long-term performance monitoring of this system is being continued by the authors.
Experimental corrosion damage and dynamic behavior of nine 3 meter concrete beams (15x15 cm cross... more Experimental corrosion damage and dynamic behavior of nine 3 meter concrete beams (15x15 cm cross section) pre-stressed with four strands (6-wire, 0.8 cm in diameter) were evaluated by visual inspection (crack morphology) and vibration testing. Corrosion was induced in ...
24th World Road CongressWorld Road Association (PIARC), 2011
Fiber reinforced polymers (FRPs) were first used for repairing corrosion damage in a prestressed ... more Fiber reinforced polymers (FRPs) were first used for repairing corrosion damage in a prestressed concrete bridge spanning the Bay of Tokyo, Japan in the 1970’s. Twenty years later when the bridge was replaced and selected girders examined it was discovered that FRP had prevented further intrusion of chlorides. Subsequently, research studies were undertaken to quantify the benefits of using FRP in chloride-induced corrosion repair. This paper provides an overview of the findings from long term laboratory studies and several field demonstration projects undertaken by the University of South Florida over the past decade to explore the use of FRP for repairing corroding piles in tidal waters. The findings are presented in the form of answers to questions that are of interest to highway authorities considering using FRP for corrosion repair.
Journal of Composites for Construction, Aug 1, 2010
This paper presents results from a multiyear study to evaluate the role of prewrap substrate prep... more This paper presents results from a multiyear study to evaluate the role of prewrap substrate preparation on corrosion mitigation in a marine environment. Seventeen one-third scale prestressed piles were corroded to 20% metal loss to simulate severe corrosion. Subsequently, two types of prewrap substrate preparation were carried out: (1) full repair in which the delaminated concrete was removed and the section reformed and (2) epoxy injection repair in which the cracks were sealed and the surface cleaned. Specimens were then wrapped using carbon fiber-reinforced polymer (CFRP) and exposed to simulated tidal cycles at 60°C for 28 months. The postexposure wrap performance was evaluated from gravimetric testing in which the metal loss in all specimens was measured. Results showed that the performance of the full repair and the epoxy injection were comparable with relatively minor increased steel loss despite the severity of the exposure. In contrast, the steel in unwrapped controls exposed to the same environ...
Journal of Composites for Construction, Oct 1, 2018
AbstractThe Friendship Trail Bridge linking St. Petersburg to Tampa, Florida, was demolished in 2... more AbstractThe Friendship Trail Bridge linking St. Petersburg to Tampa, Florida, was demolished in 2016. This was the site of 13 fiber-reinforced polymers (FRP) repairs of corroding reinforced concret...
The lightweight, high strength and corrosion resistance of fiber reinforced polymers (FRP) make t... more The lightweight, high strength and corrosion resistance of fiber reinforced polymers (FRP) make them ideally suited for quick and effective structural repairs. As a result, they have been favoured for conducting emergency bridge repairs where speed is of essence. The availability of resins that can cure under water has made it possible to similarly extend its application to substructure elements such as partially submerged damaged piles. Such repairs can be carried out using the same strategies that were successfully used in recent demonstration projects in which FRP was used to repair and rehabilitate corrosion-damaged piles. In the projects two disparate FRP systems-a pre-preg and a wet layup-were used and both carbon and glass evaluated. Access to the piles in the deep waters was provided by a custom-designed, lightweight modular scaffolding system that was assembled around the piles. An overview of the project is provided with particular emphasis on changes that would allow its adoption for emergency repairs.
This report presents results from a two-year experimental study to evaluate the interface bond be... more This report presents results from a two-year experimental study to evaluate the interface bond between a cast-in-place seal slab and prestressed concrete or steel piles. Both scale model and full-scale tests were conducted and several cofferdam conditions were simulated. These were (1) marine environment, (2) fresh water conditions, and (3) drilling fluid condition. Normal pile surfaces were investigated. Additionally, the situation of "soil-caked" piles was also investigated. In the model tests, a total of 36 one-third scale specimens were tested - 28 prestressed concrete and 8 steel. Bonded embedment depth in the seal slab was varied between d to 2d where d was the size of the pile. The results of these tests indicated that shear stress variation was non-uniform leading to larger computed bond stresses with shallower embedment. Values were least for drilling fluid. Concrete piles had better bond with the seal concrete than steel piles. "Soil-caked" condition was found to be relevant for the drilling fluid situation only. In other cases, it was washed away from the pile surface. In the full-scale tests, a total of 32 specimens were tested divided equally between steel and concrete. The prestressed piles were 14 in. square and the steel piles were 14 in. deep wide flange sections. Embedment depth was varied between 0.5d to 2d, i.e., 7 to 28 in., with the larger depth reserved for the drilling fluid condition. Four of the 16 prestressed piles were cast with embedded gages located at the top, middle and bottom of the interface region. The results of the full-scale tests were similar to those from the one-third scale tests. The most important findings were (1) loads were transferred over a distance equal to the depth of the pile, (2) scale effects were present - the average calculated bond stresses were lower for the full-scale tests than from the corresponding scale model tests, (3) prestressed piles cracked prior to bond failure, and (4) the seal slab cracked prior to bond failure. Based on the test results it is proposed that the interface bond between piles and the seal slab be restricted to an effective area in contact with the cast-in-place seal slab. The effective area is calculated using the actual embedment depth or the size of the pile, whichever is smaller. The average bond stress over this region is limited to 300 psi for concrete piles and 150 psi for steel piles. These values are reduced by a third in cases where drilling fluid is used. Application of the proposed values to the conditions related to the full-scale tests led to average factors of safety in excess of two for both the prestressed and steel piles. However, tension loads taken by the piles should not lead to cracking (concrete) or exceed the allowable tension load (steel) of the piles. Nor should the seal slab crack.
This report presents results of laboratory and field studies to evaluate the role of fiber reinfo... more This report presents results of laboratory and field studies to evaluate the role of fiber reinforced polymers (FRPs) in repairing corrosion damaged piles in a marine environment. Both carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) were evaluated in laboratory testing and in field demonstration studies using instrumented piles. The focal point of the laboratory study was to determine whether a FRP wrap reduced corrosion in prestressed specimens when the chloride threshold level was exceeded. Results from exposure tests under ambient and accelerated conditions convincingly showed that the FRP was effective in slowing down the corrosion rate. In both exposures, identical wrapped and unwrapped specimens were subjected to simulated tidal cycles under ambient or nominal 140 deg F temperature. For ambient exposure, the reduction in strand weight loss in newly fabricated CFRP and GFRP wrapped specimens was only 50% that in unwrapped controls. In the hot water exposure the increase in strand metal loss in unwrapped specimens initially pre-corroded to a target 25% and then exposed for nearly 2 years was 64.1% compared to 12.1% in the worst performing FRP wrapped specimen. Gravimetric and ultimate strength tests from this study also showed that the effect of the type of repair prior to wrapping was relatively unimportant. Results for full and epoxy repair were comparable. Two field demonstration projects were conducted using both dry (cofferdam) and wet wrap systems. In both studies, a significant number of piles were instrumented to allow corrosion assessment. Corrosion rate in the wrapped piles was found to be lower in comparison to unwrapped controls and CFRP had lower rates than GFRP. On-site bond tests carried out showed that the bond from one of the two wet wrap systems evaluated was comparable to that from the dry system using cofferdam construction. Overall, findings suggest that FRP wrap is a viable method for repairing corrosion-damaged piles.
Corrosion damaged piles are commonly repaired by jacketing the pile. These jackets consist of rem... more Corrosion damaged piles are commonly repaired by jacketing the pile. These jackets consist of removable or stay-in-place forms that are installed around the pile and subsequently filled with concrete, mortar or epoxy. Jackets can be flexible (constructed of industrial strength fabric) or rigid, although semi-rigid fiberglass jackets have become popular because of their light weight. Pile jackets are widely used in Florida: a survey completed in 1996 showed that the state had 279 bridges with jacketed piles with a cumulative jacket length of 83,068 feet. The Florida Department of Transportation (FDOT) uses six different fiberglass jackets designated as Type I through Type VI. Use by type varies with extent and position of damage. Types I-IV are non-structural and are used to repair minor damage. Types V and VI are structural and are used in cases of severe damage where there is a need to provide reinforcing steel to replace prestressing strands that have corroded. The vast majority of the repairs carried out, however, are minor repairs. Structural repairs constitute a tiny fraction of the total number. Although much information is available on the manner in which repairs are to be carried out and on the performance of repair materials, relatively little information is available on the structural efficiency of the repaired piles. Without information on the strength of repaired piles, rational decisions that potentially could lead to savings are more difficult to justify.
This article reports on a field demonstration study by the University of Florida using a unique f... more This article reports on a field demonstration study by the University of Florida using a unique fiber-reinforced polymer (FRP) which was wrapped around corroding reinforced concrete piles to evaluate the feasibility of making underwater pile repairs. Results show a water-activated resin matrix allows for the possibility of installing FRP wrap for the repair of piles, even in open-water conditions. Long-term performance monitoring of this system is being continued by the authors.
Experimental corrosion damage and dynamic behavior of nine 3 meter concrete beams (15x15 cm cross... more Experimental corrosion damage and dynamic behavior of nine 3 meter concrete beams (15x15 cm cross section) pre-stressed with four strands (6-wire, 0.8 cm in diameter) were evaluated by visual inspection (crack morphology) and vibration testing. Corrosion was induced in ...
24th World Road CongressWorld Road Association (PIARC), 2011
Fiber reinforced polymers (FRPs) were first used for repairing corrosion damage in a prestressed ... more Fiber reinforced polymers (FRPs) were first used for repairing corrosion damage in a prestressed concrete bridge spanning the Bay of Tokyo, Japan in the 1970’s. Twenty years later when the bridge was replaced and selected girders examined it was discovered that FRP had prevented further intrusion of chlorides. Subsequently, research studies were undertaken to quantify the benefits of using FRP in chloride-induced corrosion repair. This paper provides an overview of the findings from long term laboratory studies and several field demonstration projects undertaken by the University of South Florida over the past decade to explore the use of FRP for repairing corroding piles in tidal waters. The findings are presented in the form of answers to questions that are of interest to highway authorities considering using FRP for corrosion repair.
Journal of Composites for Construction, Aug 1, 2010
This paper presents results from a multiyear study to evaluate the role of prewrap substrate prep... more This paper presents results from a multiyear study to evaluate the role of prewrap substrate preparation on corrosion mitigation in a marine environment. Seventeen one-third scale prestressed piles were corroded to 20% metal loss to simulate severe corrosion. Subsequently, two types of prewrap substrate preparation were carried out: (1) full repair in which the delaminated concrete was removed and the section reformed and (2) epoxy injection repair in which the cracks were sealed and the surface cleaned. Specimens were then wrapped using carbon fiber-reinforced polymer (CFRP) and exposed to simulated tidal cycles at 60°C for 28 months. The postexposure wrap performance was evaluated from gravimetric testing in which the metal loss in all specimens was measured. Results showed that the performance of the full repair and the epoxy injection were comparable with relatively minor increased steel loss despite the severity of the exposure. In contrast, the steel in unwrapped controls exposed to the same environ...
Journal of Composites for Construction, Oct 1, 2018
AbstractThe Friendship Trail Bridge linking St. Petersburg to Tampa, Florida, was demolished in 2... more AbstractThe Friendship Trail Bridge linking St. Petersburg to Tampa, Florida, was demolished in 2016. This was the site of 13 fiber-reinforced polymers (FRP) repairs of corroding reinforced concret...
The lightweight, high strength and corrosion resistance of fiber reinforced polymers (FRP) make t... more The lightweight, high strength and corrosion resistance of fiber reinforced polymers (FRP) make them ideally suited for quick and effective structural repairs. As a result, they have been favoured for conducting emergency bridge repairs where speed is of essence. The availability of resins that can cure under water has made it possible to similarly extend its application to substructure elements such as partially submerged damaged piles. Such repairs can be carried out using the same strategies that were successfully used in recent demonstration projects in which FRP was used to repair and rehabilitate corrosion-damaged piles. In the projects two disparate FRP systems-a pre-preg and a wet layup-were used and both carbon and glass evaluated. Access to the piles in the deep waters was provided by a custom-designed, lightweight modular scaffolding system that was assembled around the piles. An overview of the project is provided with particular emphasis on changes that would allow its adoption for emergency repairs.
This report presents results from a two-year experimental study to evaluate the interface bond be... more This report presents results from a two-year experimental study to evaluate the interface bond between a cast-in-place seal slab and prestressed concrete or steel piles. Both scale model and full-scale tests were conducted and several cofferdam conditions were simulated. These were (1) marine environment, (2) fresh water conditions, and (3) drilling fluid condition. Normal pile surfaces were investigated. Additionally, the situation of "soil-caked" piles was also investigated. In the model tests, a total of 36 one-third scale specimens were tested - 28 prestressed concrete and 8 steel. Bonded embedment depth in the seal slab was varied between d to 2d where d was the size of the pile. The results of these tests indicated that shear stress variation was non-uniform leading to larger computed bond stresses with shallower embedment. Values were least for drilling fluid. Concrete piles had better bond with the seal concrete than steel piles. "Soil-caked" condition was found to be relevant for the drilling fluid situation only. In other cases, it was washed away from the pile surface. In the full-scale tests, a total of 32 specimens were tested divided equally between steel and concrete. The prestressed piles were 14 in. square and the steel piles were 14 in. deep wide flange sections. Embedment depth was varied between 0.5d to 2d, i.e., 7 to 28 in., with the larger depth reserved for the drilling fluid condition. Four of the 16 prestressed piles were cast with embedded gages located at the top, middle and bottom of the interface region. The results of the full-scale tests were similar to those from the one-third scale tests. The most important findings were (1) loads were transferred over a distance equal to the depth of the pile, (2) scale effects were present - the average calculated bond stresses were lower for the full-scale tests than from the corresponding scale model tests, (3) prestressed piles cracked prior to bond failure, and (4) the seal slab cracked prior to bond failure. Based on the test results it is proposed that the interface bond between piles and the seal slab be restricted to an effective area in contact with the cast-in-place seal slab. The effective area is calculated using the actual embedment depth or the size of the pile, whichever is smaller. The average bond stress over this region is limited to 300 psi for concrete piles and 150 psi for steel piles. These values are reduced by a third in cases where drilling fluid is used. Application of the proposed values to the conditions related to the full-scale tests led to average factors of safety in excess of two for both the prestressed and steel piles. However, tension loads taken by the piles should not lead to cracking (concrete) or exceed the allowable tension load (steel) of the piles. Nor should the seal slab crack.
This report presents results of laboratory and field studies to evaluate the role of fiber reinfo... more This report presents results of laboratory and field studies to evaluate the role of fiber reinforced polymers (FRPs) in repairing corrosion damaged piles in a marine environment. Both carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) were evaluated in laboratory testing and in field demonstration studies using instrumented piles. The focal point of the laboratory study was to determine whether a FRP wrap reduced corrosion in prestressed specimens when the chloride threshold level was exceeded. Results from exposure tests under ambient and accelerated conditions convincingly showed that the FRP was effective in slowing down the corrosion rate. In both exposures, identical wrapped and unwrapped specimens were subjected to simulated tidal cycles under ambient or nominal 140 deg F temperature. For ambient exposure, the reduction in strand weight loss in newly fabricated CFRP and GFRP wrapped specimens was only 50% that in unwrapped controls. In the hot water exposure the increase in strand metal loss in unwrapped specimens initially pre-corroded to a target 25% and then exposed for nearly 2 years was 64.1% compared to 12.1% in the worst performing FRP wrapped specimen. Gravimetric and ultimate strength tests from this study also showed that the effect of the type of repair prior to wrapping was relatively unimportant. Results for full and epoxy repair were comparable. Two field demonstration projects were conducted using both dry (cofferdam) and wet wrap systems. In both studies, a significant number of piles were instrumented to allow corrosion assessment. Corrosion rate in the wrapped piles was found to be lower in comparison to unwrapped controls and CFRP had lower rates than GFRP. On-site bond tests carried out showed that the bond from one of the two wet wrap systems evaluated was comparable to that from the dry system using cofferdam construction. Overall, findings suggest that FRP wrap is a viable method for repairing corrosion-damaged piles.
Corrosion damaged piles are commonly repaired by jacketing the pile. These jackets consist of rem... more Corrosion damaged piles are commonly repaired by jacketing the pile. These jackets consist of removable or stay-in-place forms that are installed around the pile and subsequently filled with concrete, mortar or epoxy. Jackets can be flexible (constructed of industrial strength fabric) or rigid, although semi-rigid fiberglass jackets have become popular because of their light weight. Pile jackets are widely used in Florida: a survey completed in 1996 showed that the state had 279 bridges with jacketed piles with a cumulative jacket length of 83,068 feet. The Florida Department of Transportation (FDOT) uses six different fiberglass jackets designated as Type I through Type VI. Use by type varies with extent and position of damage. Types I-IV are non-structural and are used to repair minor damage. Types V and VI are structural and are used in cases of severe damage where there is a need to provide reinforcing steel to replace prestressing strands that have corroded. The vast majority of the repairs carried out, however, are minor repairs. Structural repairs constitute a tiny fraction of the total number. Although much information is available on the manner in which repairs are to be carried out and on the performance of repair materials, relatively little information is available on the structural efficiency of the repaired piles. Without information on the strength of repaired piles, rational decisions that potentially could lead to savings are more difficult to justify.
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