In general, when metals and alloys

In general, when metals and alloys interact with their environ- ment chemically, biochemically or electrochemically, sur- face loss occurs, and they convert to their oxides, hydroxides, or carbonates which are more thermodynamically stable. This process is termed as corrosion [1]. Along the surface of an embedded steel bar, when there is a difference in electrical potential, the concrete acts as an electrochemical cell which consists of anodic and cathodic regions on the steel, with the pore water in the hardened cement paste acting as an electrolyte [3]. This generates a flow of current through the system, causing an attack on the metal with the more negative electrode potential, i.e. the anode while the cathode remains undamaged [4]. Thus, cor- rosion of rebar is initiated.