Performance of CFRP-Lined PCCP with Continuing Wire Breakage

Washington Suburban Sanitary Commission (WSSC) has been using carbon fiber reinforced polymer (CFRP) liners for repair of prestressed concrete cylinder pipe (PCCP) since mid-2000s. As part of its repair program, WSSC also performs investigations of PCCP previously lined with CFRP to help improve the understanding of CFRP liner behavior. CFRP liner is typically installed in partially deteriorated pipes such that upon installation, both the host pipe and the CFRP liner share in carrying the internal pressure and external loads. With time, host pipe continues to deteriorate and CFRP eventually ends up carrying all loads on the pipe. WSSC monitored the progression of distress in one of its critical transmission mains (54 in. diameter Rock Creek pipeline installed in the late 1970s) for a period of six years after it was lined with CFRP in 2010. The pipe was monitored using acoustic fiber optic (AFO) cable installed in the pipeline that indicated continuing wire breakage after the CFRP repair, to an extent that practically all wires were predicted to be broken by 2016. In 2016, despite lack of any leakage or other anomalies, WSSC removed this pipe from the ground to investigate the condition of the host PCCP and the CFRP liner, and plan for future repairs as needed. Investigations included analytical evaluation of the existing CFRP liner with respect to the new AWWA Standard C305”CFRP Renewal and Strengthening of PCCP, performing field tests and dissection on CFRP-lined pipe, and laboratory examinations of samples removed the CFRP liner. This paper presents the results of this investigation and provides data regarding performance of a CFRP liner in a pipe with continuing degradation.

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