Influence of Physical and Chemical Stress on the Properties of CIPP Pipes Based on Vinyl Ester

Cured-in-place pipe (CIPP) is one of the trenchless sewer rehabilitation methods for repairing sewer pipe using different types of resin, curing technology and reinforced polymer fiber. In the research described in this article, the chemical and temperature resistance of CIPP pipes based on vinyl ester resin, cured with hot water, were tested. The specimens of the CIPP pipes were exposed to a chemically aggressive environment and an elevated temperature, namely 20% sulfuric acid (pH = 1) and a temperature of 50°C. The samples were tested every month for short-term flexural properties as well as hardness. Changes of the flexural properties and hardness were compared with reference samples that were stored under laboratory conditions (23±0,5°C, relative humidity 50% ±10%). It was found out that the applied aggressive environment does not have a negative impact on the mechanical properties of the CIPP pipes based on vinyl ester resin even after long-term exposure. Furthermore, the influence of the aggressive environment on the microstructure of CIPP samples was monitored by digital optical microscopy.