Innovative Approach to Repair Corroded Steel Piles using Ultra-High Performance Concrete

Abstract

Steel H-piles are a common structural system in existing bridges. Many steel H-piles have been corroded as a result of severe weather and acid/alkaline salt exposures, causing a reduction in the axial load capacity. This paper experimentally investigates the use of ultra-high performance concrete (UHPC) encasement as a novel repair method for corroded steel H-pile. UHPC displays better tensile strength, early compressive strength, workability, and durability compared with conventional concrete. The proposed repair is used to bridge the corroded section in H-pile using either a cast-in-place or precast UHPC elements. A series of push-out tests was conducted on eight full-scale piles to assess the axial force that can be transferred through shear studs and bond between the UHPC and steel piles. The test parameters include the type of casting of the UHPC, that is, cast-in-place versus precast elements, thickness and shape of the UHPC elements, an inclusion of carbon fiber reinforced polymer (CFRP) grid, number and grade of bolts, an inclusion of washer, and applying torque on the bolts. The experimental work demonstrated that the UHPC precast repair can be easily implemented. Moreover, using 57 mm (2.25 in.) thick UHPC plates reinforced by two layers of the CFRP grid was capable of transferring up to 81% of the squash load of the H-pile.