Laboratory investigation to study the corrosion initiation of rebars in fly ash concrete

Abstract

The objective of this study is to detect reliably the onset of corrosion in fly ash concrete using an embedded reference electrode. The half-cell potential of rebars in fly ash concrete subjected to 10% sodium chloride solution is monitored using an embedded reference electrode and an alternating current impedance spectroscope, along with other impedance parameters such as polarisation resistance and specific concrete resistance. At initiation of corrosion, the values of chloride threshold levels are obtained and the effect of long curing for fly ash concrete on chloride threshold values is analysed. The combination of two corrosion monitoring systems allows the estimation of corrosion initiation in fly ash concrete. It is found that chloride threshold values for fly ash concrete given a longer curing period approach the values for Portland cement concrete. Probabilistic analysis of the experimental data is carried out to find a best-fit probability distribution for time to initiate corrosion and chloride threshold values of fly ash concrete.