Carbon Fiber Rehabilitation of Prestressed Concrete Pipe
* What are the proper procedures, standards, and design guidelines for repairing prestressed concrete pipelines using fiber reinforced polymer (FRP) (e.g. carbon fiber) reinforcement?
Need and Benefit
Reclamation has many miles of prestressed concrete pipeline in various projects. Over time, some of the prestressed concrete pipeline degrades, requiring repair or replacement of the pipeline section. The goal in repairing the pipeline is to restore the original strength of the pipe. Prestressed concrete pipe is a pipe which has been precompressed during manufacture. The compression is obtained by wrapping the core, with wires which are under high tensile stress. The induced compressive stress in the core is dependent upon the cross-sectional area of wire and the amount of tension in the wire. As the wire corrodes and breaks repairs are required. Traditional repair consisted of lining the interior of the pipe with a steel pipe or wrapping the exterior of the pipe with tendons composed of strands of steel wire. In both cases, these repairs themselves will need maintenance due to corrosion of the steel.
In recent years, FRP reinforcement has been used to strengthen concrete structures to accommodate tensile and shear stresses. These products have received much attention over the last few years as an attractive and cost effective alternative for restoring, protecting and strengthening certain structures. However, there are many unanswered questions concerning proper guidelines, standards, or procedures to repair prestressed concrete pipes using this type of reinforcement. Presently, there is a dearth of guidelines, standards and procedures within the industry. Reclamation should investigate the possible variables during installation of the FRP reinforcement to optimize the repair. Reclamation needs to play a strong role in this and work with industry to help establish the guidelines, standards, and procedures for repairing prestressed concrete pipelines.
Reclamation will benefit from having a repair method that will restore a pipe unit to its original strength or increase its strength and having cost savings compared to replacing sections of pipeline. Also, the FRP reinforcement will not corrode like the other methods of repair.
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