PJCCI - Déconstruction pont Champlain : Bending strengthening of Pont Champlain Bridge slabs using ultra-high-performance fiber reinforced concrete (UHPC)

This paper presents an investigation on the shear behavior of reinforced concrete (RC) and ultra-high performance fiber reinforced concrete (UHPC) repairs applied to slabs from the decommissioned Pont Champlain Bridge. Originally built in 1962, the bridge faced severe deterioration due to harsh environmental conditions, leading to its full deconstruction after 57 years despite multiple RC repair interventions. Two original slabs, two RC-repaired original slabs, and three UHPFRC-repaired slabs produced with different casting methods and with/without rebars in the UHPFRC overlay. The slabs were tested under bending with the repairs under tension. The behavior of slabs was also characterized by digital image correlations (DIC) to accurately measure the crack spacings and crack widths, while fiber density and fiber orientation factors were evaluated in UHPFRC overlays to complement the analysis. Experiments highlight the UHPFRC-repair's superior performance by reducing the crack width by 10 times in service conditions and increasing strength at ultimate conditions by 1.2 to 2 times in comparison to RC repairs. UHPFRC overlays produced with unidirectional (1D) vs bidirectional (2D) casting slightly provide smaller crack spacing and consistently lower crack widths, and enhance ultimate capacity by 1.12 times. The synergic effect of fibers at the mesoscale and rebar at the macroscale further improved crack control and led to smaller crack spacing and crack width. The experiments confirm UHPFRC overlays are a highly effective repair solution for extending service life while reducing maintenance costs. Its application in bridge rehabilitation provides a more durable alternative to conventional RC repairs, supporting the long-term sustainability of infrastructure.