Change in Toughness Parameters of Sewer Pipes Rehabilitated with Two Types of Epoxy CIPP Liners

Abstract

The main objective of the investigation was to evaluate the influence of the installation of two kinds of epoxy cured-in-place pipe (CIPP) liners (adhesive and independent) on the change in load capacity of concrete and vitrified clay pipes, and ring stiffness of polyvinyl chloride pipes. Adhesive liners stick to internal surfaces of the pipes, whereas independent liners do not stick to those. Load capacity and ring stiffness tests were carried out on samples made of pipes without liners (control samples) and those with liners. Pipe surface roughness was measured for control samples. Pull-off tests were performed on samples with adhesive liners. Mean liner thickness was determined for every sample with a liner. Results of the investigation show that change in load capacity or ring stiffness of the pipes with liners is positively correlated with adhesion strength between the pipe and the liner. Adhesion strength depends on the pipe internal surface roughness. The same load capacity or ring stiffness increase of the sewer pipes may be obtained by the installation of thinner adhesive or thicker independent liner. The results made it possible to determine adhesive liner thickness reducing coefficients.