Role of Grout Strength and Liners on the Performance of Slip-Lined Pipes

Abstract

As infrastructure built during the 20th century reaches the end of its service life, engineers and managers are increasingly turning to rehabilitation rather than replacement to potentially reduce costs. For corrugated steel pipes and culverts, one such rehabilitation alternative is to use slip lining where a liner (new pipe) is placed inside the existing deteriorated pipe and the space between them is grouted. The current research seeks to better understand the performance of slip-lined systems by (1) characterizing the properties of a low-strength and a high-strength grout; (2) conducting a series of pipe tests to determine the load-carrying capacity and stiffness of a corrugated steel pipe and pipes that have been rehabilitated with slip liners; (3) understand the impact of grout strength and the liner on pipe stiffness and strength; and (4) determine the level of composite action in the pipe system by using a plasticity approach to estimate the load-carrying capacity of the system. The pipes rehabilitated with low-strength grout had increased strength (three times greater) and stiffness (eight times greater) versus an unrehabilitated pipe, whereas the specimens rehabilitated with high-strength grout showed higher increases in both load-carrying capacity (ten times greater) and stiffness (50 times greater) over the unrehabilitated pipe. The high density polyethylene (HDPE) liner had no impact on the load-carrying capacity of the specimens with high-strength grout and required large diameter changes to enhance the load-carrying capacity of low-strength grout specimens. A plasticity approach was used to estimate the load-carrying capacity of the specimens and indicated that for these tests, composite behavior between the grout and the corrugated steel pipe was developed.