Experimental and numerical evaluations of corrugated steel pipe and rehabilitation using a geosynthetic cementitious composite MAT

Abstract

Corrugated steel pipes (CSPs) are widely used in transportation infrastructure but are vulnerable to corrosion and structural deterioration. Geosynthetic Cementitious Composite Mats (GCCMs) are increasingly used for corrugated steel pipe (CSP) rehabilitation; however, their structural performance and interaction with the host pipe remain inadequately investigated. Parallel-plate loading tests are commonly used to evaluate CSP structural performance, yet existing standards provide limited guidance for testing corrugated pipes. This thesis investigates the behavior of CSPs under parallel-plate loading and evaluates the effectiveness of GCCM-based rehabilitation systems through numerical analyses and laboratory experiments. Finite element analyses were first conducted to examine the influence of longitudinal constraints on pipe response and to establish guidelines for selecting appropriate length-to-diameter (L/D) ratios for cost-effective laboratory testing. Comparisons with experiments indicate that previous test data were underestimated by approximately 7%–16% under the new analysis. For subsequent parallel loading tests, a CSP with a length of 1826 mm and a diameter of 900 mm was selected. This pipe was expected to exhibit a vertical stiffness 95% of that predicted by thin ring theory. Bending tests were then performed on a GCCM product using several configurations with different span lengths and loading arrangements. Bending tests with the span increased to 300 mm from 100 mm provided consistent measurements and enabled reliable determination of the material’s flexural properties, informing improved testing protocols for GCCMs. Parallel-plate loading tests were conducted on a corroded CSP before and after rehabilitation using two methods: GCCM liners installed directly on the corrugations and GCCM liners combined with grout-filled corrugations. Under laboratory conditions examined, when the GCCM liner was installed directly on the CSP corrugations, the liner–pipe system did not form a composite section and likely behaved as a zero-bond interface with maintained contact. As a result, this method primarily provides hydraulic remediation with only limited structural enhancement. In contrast, the grout–GCCM system provided measurable structural improvement. The CSP and grout exhibited near-full bond, whereas the GCCM generally behaved under a zero-bond contact condition. This system may therefore serve as a viable structural rehabilitation method for corroded CSPs.