Fiber-Reinforced Polymer Wrapping of Deteriorated Concrete Columns

Abstract

The New York State Department of Transportation initiated a fiber-reinforced polymer (FRP) Column Wrap Demonstration Project in March 1998. The purpose of this project is to investigate the effectiveness and efficiency of preserving deteriorated concrete with FRP, its possible detrimental effects, and its viability as an alternative for concrete column repair and rehabilitation without regard to seismic considerations. To the authors’ knowledge, this is the first FRP column wrap demonstration project of its kind to involve most of the FRP wrap suppliers in the United States. A 5-year condition-monitoring program was established to monitor the performance of FRP wrapping in preserving the concrete columns. A baseline condition of the piers was established through testing, including concrete cores for compressive strength, chlorides, pH, and freeze-thaw resistance; hammer soundings; and a tight-grid survey of electric potentials. Concrete spalls were repaired; however, delaminations were not. To monitor corrosion of the column reinforcing steel, corrosion probes using linear polarization technology were embedded in the concrete. Initial corrosion readings were collected before wrapping, enhancing the observed baseline condition data. In addition, concrete humidity and temperature probes were installed through the FRP wraps, and strain gauges were mounted on the FRP wraps. Data will be collected at 3-month intervals for 4 or 5 years. The wraps will be removed after monitoring, and a complete column testing program will be implemented at that time.

Advances in the application of FRP for repairing corrosion damage

“…Precured laminates are in the form of cured FRP shells or plates that can be directly bonded to the concrete surface6. Table 1 provides data on six different unidirectional carbon and glass fibres used in a demonstration project7 in New York. Results are reported on the basis of the dry fibre area (gives a higher value since the fibre area is smaller) or the gross cross‐sectional area of the laminate.…”

“…Since the Vermont project, a significant amount of research4,12–30 has been carried out. More importantly, several state agencies have used FRP to conduct contact‐critical repairs of corrosion‐damaged structures7,31–41. Many of these were heavily instrumented and their performance provide a wealth of critical data that is invaluable to decision makers.…”

“…This was the first demonstration study of its kind in the USA7,35 to evaluate the use of FRP for corrosion mitigation in which most of the FRP wrap suppliers participated. A total of six, 1.5‐m‐square corroded reinforced columns were wrapped with carbon and glass supplied by six different vendors.…”

A laboratory and field investigation utilizing FRP as a chloride protection system

“…The wrap effectively prevents visual inspections of the corrosion behind the wraps which makes this situation even more precarious. The New York DOT launched a similar program in 1998 that looked into the effectiveness of FRP for preserving deteriorated concrete (25) A second study by Bisby and Green (27) utilized the same cycling test with both carbon and glass FRP sheets attached to the concrete beams instead of the carbon FRP plates utilized in their earlier experiment. The results were similar revealing that the flexural fourpoint test indicated no significant damage to the anchorage of the FRP sheets to the beams.…”