Conclusions and Recommendations

As municipalities that previously adopted lined concrete sewer pipe engage in their respective inspection programs, it is critical that secondary inspection technologies be utilized to provide validation of the pipe wall condition “behind” the liner. This paper provides a description of the development and use of in­pipe ground penetrating radar (GPR) deployed on a robotic unit for the evaluation of PVC lined concrete pipe. The third generation unit employs multiple GPR units on two arms to facilitate the capture of data from any location above the pipe’s spring line. This improved on the limitations of previous generation, which were restricted to only capturing information at the 12 o’clock position within a pipe.

Furthermore, coring samples were conducted to validate the results obtained from the GPR unit. Samples were extracted from two different pipe locations. For each location, two 75 mm diameter core samples were taken. One sample was at a suspected defect location, while the other was in an unaffected section of the concrete pipe wall for comparison. The samples from the defect section had lower compressive strength measures compared to the unaffected samples.


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