Development of testing protocol to assess the reinforcing steel-to-concrete bond strength of in-service marine concrete structures

Marine steel reinforced concrete (RC) structures in Canada are exposed to severe degradation including freeze-thaw damage, corrosion of steel, and often alkali silica reactivity (ASR). Degradation of RC structures causes the bond strength between the reinforcing steel and the concrete to reduce, which adversely affects the capacity of structures (i.e., reduced ultimate capacity), and increase the uncertainty around code prediction of resistance (i.e., reduced confidence of capacity prediction). Survey of existing national and international testing standards indicates the lack of standardized testing procedures to determine the bond strength for in-service concrete structures in general, and marine structures specifically. In this research, a testing procedure for evaluating the bond strength of existing marine infrastructure will be developed and utilized to assess the bond strength of in-service RC structures at the Fairview terminal of the port of Halifax in partnership with the Halifax Port Authority (HPA). The goals of this partnership are to assist HPA in developing tools to predict the remaining service life of their RC structures, foster relevant R&D projects in the marine sector, and train highly qualified personnel (HQP) specialized in marine structural assessment. The project consists of three phases. In Phase 1, the testing protocol will be developed along with fabricating an apparatus to perform the testing. In Phase 2, the developed testing procedure will be utilized to assess the bond strength of select RC specimens extracted from in-service RC structures operated by HPA. In Phase 3, a parametric experimental program will be developed to calibrate formulas to predict the impact of Nova Scotia environmental exposure on the bond strength using accelerated testing on replica specimens. Benefits to Canada include optimizing the decision making regarding the remaining service life of marine RC structures based on predicting the degradation in bond strength (economic) and assisting owners to make informed decisions regarding repair versus replacement of structures, where repair typically yields reduced carbon footprint (environmental).