The effect of water aging on Cured-In-Place Pipe (CIPP) samples using non-destructive tests

Pipe rehabilitation and trenchless pipe replacement technologies have been used more than 40 years. Cured-in placepipe (CIPP) is a trenchless method to repair damaged pipelines by inserting a new liner of polymer inside the existing host pipe. Since these liners are exposed to water after installation, the purpose of this study is to investigate the effect of water aging on CIPP samples. The water absorption analyses have been performed by immersion of unsaturated polyester composites reinforced with needle felt samples in distilled water according to ASTM D570/98. The effect of aging is inspected on one hand via comparison of their images obtained through an optic microscope and their weights before and after aging and on the other hand through non-destructive testing using microwaves. The microwaves were used in the frequency range of 75 - 100 GHz in non-contact manner. For this a vectorial network analyser (VNWA) and a frequency-modulated continuous wave radar (FMCW radar) was used to enable an accurate and broadband measurement. In this case the effect of water induced aging appears as a change in run time, which results from a change in permittivity of the material being inspected. The results of the optic microscopic images and weights prove that water absorption is present in the CIPP samples considered.