Evaluation of steel corrosion in fly ash concrete using electrochemical techniques

It is generally considered that the admixing of fly ash improves various properties of concrete including durability. However, the admixing of fly ash also reduces the resistance against carbonation of concrete due to consuming Ca(OH)2 by pozzolan reaction. Then, it is important to evaluate the corrosion behavior of reinforcing steel embedded in concrete using fly ash. In this study, the influence of fly ash admixed into concrete as the substitute for cement or fine aggregate on corrosion behavior of reinforcement due to both chloride attack and carbonation, was evaluated by means of electrochemical techniques. The results showed that when fly ash was admixed as the substitute for fine aggregate, restrained permeation of CO2 or Cl- into concrete resulted in small corrosion loss of steel. However, when fly ash was admixed as the substitute for cement, corrosion loss of reinforcing steel was not restrained under the severe corrosion condition in this study.