INSITU STRENGTH AND CONDITION ASSESSMENT OF PCCP PIPE

摘要

Weaknesses in the core concrete and/or delamination of the core layers and the mortar coating provide data to determine the current condition, instillation and use history of PCCP pipes. A combination of measured wave velocity and thickness resonate frequency values are used to identify and categorize weak areas in PCCP pipe concrete. The velocity/speed that sonic/ultrasonic waves propagate through the core concrete is used to determine the elastic moduli and strength characteristics of PCCP core concrete. These velocity values are primarily affected by the severity and density of cracking and the compressive force exerted by the wire wrap. Resonate frequency data, obtained simultaneously with velocity data, are used to assess for delamination/ loss of bonding between core layers and the mortar protective coating. The combination of the velocity and resonant frequency data and specific location where anomalous readings occur are indicators of pipe conditions such as overloading, broken wires, pipes manufactured with low or no prestressing, loss of mortar coating etc.This paper will discuss the sonic/ultrasonic testing method and comparison of results with excavated pipe conditions and reported pipe operation incidences.