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1 Introduction
Corrosion of reinforcing steel has been one of the most important factors causing serious degradation of the durability of reinforced concrete (RC) structures. The decrease in durability has resulted in substantial damage to property and fatalities all over the world ([2] Bentur et al. , 1997; [1] Elsener, 2000). In general, concrete provides a high degree of protection against corrosion to the reinforcing steel, by virtue of the high alkalinity (PH>13.5) of the pore solution. The reinforcing steel remains passive in high alkaline ambience. As sufficient chloride ions penetrate to the reinforcement, or as the pH value of the pore solution drops to low values due to the carbonation, the protective film is destroyed and the reinforcing steel depassivates. Corrosion, in the form of rust formation and/or loss in cross-section of the rebar, occurs in the presence of oxygen and water (humidity) ([3] Broomfield, 1997; [4] González et al. , 1997). Essentially, the corrosion process in most of RC structures is a series of electrochemical reactions ([5] Bertolini et al. , 2004).
In view of the impact of corrosion-induced failures of reinforcing steel, the desire to find effective approaches to prevent and control the initiation and development of the corrosion in new and existing infrastructures is very urgent. Recently, pro-active corrosion prevention measures, including the use of corrosion inhibitors and cathodic protection (CP) ([13] Elsener et al. , 1993; [9] Saricimen et al. , 2002; [8] Tritthart, 2003; [6] Nmai, 2004; [7] Trabanelli et al. , 2005; [10] Söylev and Richardson, 2008; [11] Al-Mehthel et al. , 2009; [12] Tommaselli et al. , 2009), etc. and passive corrosion control methods such as electrochemical realkalisation (ERA) and electrochemical chloride removal (ECR) ([14] Mietz, 1998; [15] Angst, 2005; [16] Fajardo et al. , 2006; [18], [20] Miranda et al. , 2006, 2007; [19] Yeih et al. , 2006; [17] Elsener and Angst, 2007; [21] Pérez et al. , 2010) have been applied to alleviate the corrosion of RC structures. According to previous researches, such techniques are very suitable to prevent the initiation of corrosion in new infrastructures; though interest is focused preferentially on ECR for existing structures as it is much less expensive and is more friendly to the environment and to worker health...