CONDITION ASSESSMENT OF FRP-STRENGTHENED CONCRETE BRIDGE DIAPHRAGMS USING NON-DESTRUCTIVE TESTING

Carbon fibre-reinforced polymer (CFRP) materials are lightweight, corrosion-resistant composite materials extensively used to strengthen or retrofit deteriorated concrete bridge components. The retrofitting process is usually a multi-stage manual process with the inherent capability of introducing defects at the various stages of work. In this paper, a methodological approach involving various nondestructive testing (NDT) techniques has been developed for a detailed condition assessment of the state of damage in deteriorated concrete bridge diaphragms. These three diaphragms from a major Canadian bridge were externally retrofitted with multiple layers of CFRP materials and subjected to years of environmental exposure. In addition, a detailed comparison of results obtained from the NDTs and visual inspection is presented. Several issues were identified, including CFRP delamination, material incompatibility, discolouration due to corrosion, inter-fibre cracks, and fundamental problems arising from the construction of the bridge diaphragms and installation of the CFRP.