Influence of Grout Strength and Residual Deformation on Performance of Rehabilitated RC Pipes

Abstract

Inserting a corrugated steel pipe (CSP) into an existing reinforced concrete pipe (RCP) is a common culvert rehabilitation technique in China. However, few studies have focused on the influence of grout strength and residual deformation on rehabilitated RCPs. Against this background, six specimens were used in experiments to investigate the mechanical behavior of RCPs rehabilitated with grouted CSPs and the influences of grout strength and residual deformation. The rehabilitated RCP had much higher test loading capacity and stiffness than the pre-rehabilitated (pre-rehab) RCP. The test loading capacity of the RCP with large residual deformation and rehabilitated with the grouted CSP was lower than that of the RCP without residual deformation and rehabilitated with grouted CSP, whereas the test loading capacities of the RCP without residual deformation and the RCP with small residual deformation and rehabilitated with grouted CSP were nearly the same. The specimens with high-strength grouts exhibited significant increases in test loading capacity and stiffness; the greater the grout strength, the higher the test loading capacity of the post-rehab RCP. A method for calculating test loading capacity based on a “pipe-in-pipe” system is proposed, and the estimated value of the test loading capacity of post-rehab RCPs is provided within 30%. If a pre-rehab RCP fails to reach its ultimate test loading capacity or reaches its ultimate test loading capacity without large residual deformation, its ultimate test loading capacity can be used to calculate the ultimate test loading capacity of the post-rehab RCP.