Corrosion rate models of reinforcement in modified coral aggregate concrete

Abstract

As a valuable product in the reef environment, coral waste can be used as recycled material in concrete. The purpose of this research is to produce green marine concrete using coral waste and industrial waste, such as fly ash (FA), silica fume (SF), and ground-granulated blast-furnace slag (GGBS). The durability of reinforced concrete members produced with coral waste and different industrial waste in the tropical marine environment were compared. The corrosion behaviour of the reinforcement in the modified coral aggregate concrete (CAC) was analyzed using the electrochemical test method, and the CAC resistivity was measured using an improved alternating current (AC) method. The potentiodynamic polarisation, capacitance–reactance, and impedance modulus curves for the reinforcement in the MCAC were plotted through linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS). The feasibility conclusions for the application of green marine concrete are drawn. (1) Compared to the CAC without admixtures, the chloride resistance of the CAC containing 10% SF, 20% GGBS, and 20% FA increased by 87.0%, 68.73%, and 50.15%, respectively. (2) An improved AC method was applied to determine the CAC resistivity for different admixtures, and the quantitative relationship between the admixtures and the resistivity of the CAC was established to develop a model for predicting the MCAC resistivity. (3) The regression analysis functions between the admixtures dosage and corrosion rate of the reinforcement in the MCAC were established, and the correction coefficient of the admixtures to the corrosion rate of the CAC was obtained. (4) Based on the resistance control of the reinforcement corrosion process, a predicting model for the corrosion rate of reinforcement in the MCAC was developed.