Effects of dissolved oxygen on marine biofilm formation and its on microstructure and chloride ion permeability of concrete

To explore the role of dissolved oxygen (DO) in the corrosion process of marine biofilms on concrete structures, we investigated the evolution of biofilms on concrete surfaces in seawater with different DO and the influence of biofilms on concrete microstructure and resistance to chloride ion permeability. The results show that DO in seawater contributes to the attachment and expansion of biofilm on the concrete surface. The main product of bio-corrosion is gypsum, and DO promotes the metabolism of SO42- by bacteria within the biofilm, so more gypsum and greater mass loss of concrete. Furthermore, compared with concrete in sterile seawater, biofilm can block SO42- and Cl- in seawater, enhancing the durability of reinforced concrete. The biofilm regulation technology can be foreseen as one of the measures to effectively mitigate concrete corrosion in the future.