Long-term creep of encased polymer liners

Due to increasing costs and inconveniences in replacing deteriorated sewer pipelines by conventional excavation methods, the trenchless or \u27no-dig\u27 technology is being extensively used. In trenchless technology, a polymer or reinforced polymer is applied to the inside of the deteriorated host pipe to prevent ground water from seeping into the sewer pipelines. In this work, a testing method was developed to determine the long-term creep behavior of encased polymer liners.;Short-term tests, following the ASTM D790 procedure, were conducted on pipe liner samples to determine the initial elastic modulus and compare it to the elastic modulus obtained from long-term testing of the encased liner.;Long-term tests were conducted on 6 ft length, 12 in diameter polymer liner samples encased in steel pipes. Several viscoelastic models were investigated in order to fit the data. The data is used to predict the long-term modulus used in design. (Abstract shortened by UMI.)