Mechanical performance of corroded reinforced concrete pipelines rehabilitated with sprayed-on cementitious liners subjected to combined loads

Abstract More and more trenchless repair technologies are used to improve the structural performance of existing corroded pipelines so as to extend their service life. Spray-on liners method have become the preferred method for the trenchless repair of pipelines due to enjoying the advantages of convenient construction, environmental protection, and high flexibility. However, their application to concrete pipelines has not been examined through full-scale testing yet. Thus, to provide the necessary foundations for the development of spray-on liners design methods, the objective of the present paper is to examine the mechanical performance of buried corroded concrete pipelines rehabilitated with sprayed-on cementitious liners when it is subjected to combined loads. To achieve these objectives, four connected pipes were buried in the ground under the conditions of different soil cover, traffic loads, and fluid loads. Furthermore, the impacts of combined the traffic load and water flow on the mechanical properties of the rehabilitated pipeline were taken into account. The pipeline was subsequently repaired with a spray-on liner, and the rehabilitated pipelines were then tested again under the same burial and loading conditions to assess the influence of the spray-on liner on the performance of the pipeline. The results demonstrate that the deformation characteristics of the rehabilitated pipeline are similar to those of the original pipeline. Both pre or post the rehabilitated, the circumferential strain on the joint of the pipes is obviously larger than that on the pipe barrel. In addition, normalizing the sensitivity coefficients of the three parameters demonstrates that the traffic load, the soil pressure, and the fluid load respectively account for 47%, 43%, and 11% of the total influence on the circumferential strain on the pipeline. Therefore, the application of the spray-on liners enhances the structural performance of the corroded pipes to become equal to or even higher than the structural performance of the original pipes.