Rehabilitation of 120 Inch PCCP at a New Mexico Power Plant using CFRP and Strongpipe Hybrid FRP Systems

Abstract

Internally bonded fiber reinforced polymer (FRP) composite liners have been successfully used to rehabilitate damaged and deteriorated prestressed concrete cylinder pipes (PCCP) since early 1990s. These systems consist of multiple layers of longitudinal and circumferential FRP sheets that are saturated on site with epoxy and installed using manual wet lay-up process to produce a cured-in-place composite pipe within the existing pipe. FRP liners have gained popularity as they do not require excavation and can be installed in a relatively short time. However, these systems are relatively expensive and are more suited for individual and short runs of pipes. A more cost effective solution for pipe habilitation can be achieved using a hybrid steelFRP rehabilitation system. The system consists of high strength steel wires continuously wrapped inside the pipe and embedded in a high performance polymeric matrix. The steel wires are placed between two layers of FRP to produce a sandwiched composite structure. The hybrid system combines the stiffness, ductility and low cost of steel with the durability and excellent performance of FRP to produce a structural liner with bidirectional strength that can be used for repair and renewal of both short and long runs of pipes. This paper presents a case study for the rehabilitation of 120 in. (3.05 m) diameter PCCP in a power generation facility located in New Mexico. Both carbon FRP (CFRP) and Hybrid FRP systems were used to upgrade the deteriorated pipe sections. The CFRP system was installed in the discharge line while StrongPIPE Hybrid FRP system was installed in the intake line. The paper highlights the features, limitations, feasibility, quality control requirements and cost of the two rehabilitation systems.