Prestressed Concrete Cylinder Pipe Decay

Prestressed Concrete Cylinder Pipe (PCCP), as any other pipe material, decays over time. The rate of decay is influenced by the quality of materials and workmanship used during manufacturing, construction methods, operational parameters and environmental conditions. PCCP pipe does not go from a perfect condition to failure instantly, but rather it is a deterioration/aging process that can be measured and tracked with sonic/ultrasonic nondestructive testing. Often the mortar coating is carbonated due to environmental conditions. The reduction in coating thickness can reduce the structural capacity of the pipe and compromises the passivation of the prestressing wire. The coating thickness can be precisely determined by sonic/ultrasonic method. The concrete core can experience cracking due to low wire prestressing, inadequate bedding, earth overload, over pressurization, or aging. Depending on the level of core cracking, the cracking can extend to the mortar coating and allow prestressing wire corrosion. Sonic/ultrasonic testing can detect the level of core cracking and the longitudinal extent. A subsequent sonic/ultrasonic survey provides the data needed to develop a pipe decay curve vs. time.