Laboratory Study on Effect of Grout Choice on Culvert Rehabilitation Using Sliplining

Two corrugated steel pipes were repaired with grouted high-density polyethylene (HDPE) slipliners, one with low-density (i.e., low-modulus and low-strength) grout, and the other with high-density (i.e., high-modulus and high-strength) grout. The responses of the rehabilitated culverts were measured under service loads and fully factored design loads, as well as even higher load levels, to establish the ultimate limit states. Finally, the test culverts were exhumed and the damage was observed. Sliplining increased the stiffness of both culverts, and their strength then exceeded the required load carrying capacity by more than a factor of 2. Although the lined pipe with low-density grout behaved like a rigid pipe during service loading, it began to behave more flexibly at higher loads. At very high loads, the liner deflections exceeded levels permitted for HDPE pipes. Extensive shear failure and crushing of the grout were observed after the test. The sliplined pipe with high-density grout behaved like a rigid pipe during both service load and ultimate load experiments. Distributions of hoop strain through the liner–grout–steel pipe system demonstrated bonded, composite behavior at some sections of the system repaired using high-density grout, and noncomposite behavior for the system repaired using low-density grout.