Critical conditions and life prediction of reinforcement corrosion in coral aggregate concrete

Abstract

As a new type of cement-based composite material, coral aggregate concrete exhibits excellent performance in terms of using local materials, high efficiency and economy, and broad application prospects in the construction of ocean-going island reef projects. In this study, based on the corrosion mechanism of steel bars, the critical chloride concentration in coral aggregate concrete was obtained, and the model of the rebar corrosion initiation conditions was established. Combined with electrochemical test and power loading device, the stainless steel bar replaces an electrode in energized devices and it is the counter electrode in electrochemical test. A rapid determination method was proposed for chloride ions accelerated by the electric field by improving the anode energization acceleration method. The linear polarization resistance method and electrochemical impedance spectroscopy were used to analyze the time-dependent denaturation of the corrosion potential and corrosion current in the coral aggregate concrete. The corroded layer on the steel reinforcement surface was observed using scanning electron microscopy. The rebar corrosion rate in the coral aggregate concrete was 0.25 µA/cm2 at the beginning of steel corrosion, and the corrosion rate ratio in the coral aggregate concrete and common aggregate concrete was 1.67. Based on the similarity theory of life test, an accelerated life test was used to predict the durability life of the coral aggregate concrete structures.