Corrosion behavior of low alloy steel bars containing Cr and Al in coral concrete for ocean construction

Abstract

The corrosion resistance of carbon steel is poor in a harsh marine environment, and thus it is necessary to improve the durability of the structure. Coral concrete is a new cement-based composite material that exhibits excellent properties including local availability, high efficiency, good economy, and prospects for broad application in the construction of ocean-structures such as islands and reefs. Based on the corrosion mechanism of rebar, a low amount of Cr and Al are added to quantitatively analyse the corrosion time-varying performance of a low-alloy rebar in coral aggregate concrete. Based on XPS analysis, the corrosion resistance mechanism of Cr and Al low-alloy steel bars is determined, and the improvement value of steel bars' maintenance of passivity properties is quantitatively analysed. The polarization curves of reinforcement in coral aggregate concrete are obtained via the linear polarization method and electrochemical impedance spectroscopy to analyse the corrosion potential and corrosion current of low alloy reinforcement in coral aggregate concrete. A rebar performance improvement coefficient is defined to characterize the reinforcement durability improvement of alloy with Cr and Al elements. There is considerable scientific value and application significance attainable from the examination of the corrosion mechanism and behavior of corrosion-resistant steel bars in a harsh marine environment. It is essential to develop high strength corrosion-resistant low-alloy steel bars that are suitable for service in a harsh marine environment and to establish a rapid method to evaluate the corrosion resistance of steel bars.