Long-Term Design Life Assessment of a Corrugated Steel Pipe Culvert Rehabilitated with Geopolymer Liner

Metal culverts exist throughout North America and are by nature prone to deterioration. A number of rehabilitation techniques have been developed to prolong the service life of deteriorated metal culverts. One such technique, and the focus of this article, is the use of spray-applied geopolymer mortar as a structural liner. The concept of using spray-applied geopolymer liner for culvert rehabilitation has received attention in recent years among researchers and practitioners; however, a number of uncertainties remain with regards to the performance of the culvert-liner system, particularly in the long term when the possibility of host culvert completely deteriorating exists. In this article, numerical modeling techniques have been employed to assess the performance of a deteriorated corrugated metal pipe culvert rehabilitated with spray-applied geopolymer liner. Modeling is performed with Abaqus finite element software employing a series of steps to simulate the extended service life of a lined culvert, with steps including: culvert installation and fill placement, culvert deterioration, liner application, further deterioration of the host metal culvert, and finally, complete deterioration of the host metal culvert. It is shown that loads initially carried by the host culvert are progressively transferred to the liner; the liner caries zero load upon installation and load is subsequently transferred to the liner as the host culvert experiences further deterioration. The novelty of this study is in capturing the entire construction and loading history of the culvert, as these two factors are known to predominantly influence the short-and-long-term soil-structure-interaction behavior. Results of the numerical study suggest that the performance of the structure is acceptable even when the host pipe is completely deteriorated, as axial stresses and bending moments fall well below the typical limiting values of the geopolymer liner material. This study helps advance the state of knowledge by evaluating existing uncertainties on the long-term performance.