## 1 Introduction
A constant current from a direct current source is applied to the steel in order to accelerate the chloride ion diffusion in the concrete cover during the corrosion initiation phase until the depassivation of the steel bar and thus induce significant corrosion in a short period of time during the following corrosion phase. Furthermore, the addition of chloride ions into the concrete mixture further accelerates the process [7; 17; 18; 19; 20; 21; 22]. These two common methods can be applied to any RC specimen. To investigate the effects of the corrosion products on the cracking process and/or the relationship between the corrosion level and the corrosion-induced crack pattern and its widths, many researchers have paid particular attention to the possibility of linking the rebar section loss to the corrosion-induced crack pattern and its widths [21; 25; 26; 27; 28]. Nevertheless, it is more relevant to analyse and determine the thickness of the corrosion products directly rather than from the rebar section loss in order to obtain a more accurate distribution of the corrosion product thickness [29; 30]. Generally, the corrosion product layer is not constant at the steel/concrete interface, and previous studies have reported that its distribution strongly and intricately affects the crack pattern [27; 31; 32; 33; 34]. It is therefore insufficient to solely consider the amount of corrosion products (rebar section loss) when studying the damage process of a corroded RC element; only a clear analysis of the distribution of corrosion products around the rebar cross-section can help to extend the current understanding of cracking mechanisms in reinforced concrete [29; 30]. This is the reason why the authors have selected this approach. It can also be noted that although some published studies have focused on the corrosion products' thickness at the steel/concrete interface [15; 35; 36], very few have in vestigated the relationship between the actual thickness of corrosion products and the cracking [16; 37]. In light of the findings of the literature review carried out in the preceding paragraphs, the aim of the present paper is to generate a steel rebar corrosion in a short time in order to analyse the relationship between the distribution of corrosion products around the rebar, the evolution of concrete cover cracking (internal cracking) and the concrete surface crack patterns (external cracking) of RC specimens. The particularity of this study also lies in some geometrical features, such as a corner rebar and a concrete strength representative of old RC structures and a ribbed steel rebar as commonly implemented in the field. Additionally, the natural corrosion process in concrete can take place gradually over a very long period of time before visible damage in the structure is observed. For this reason, techniques such as impressed current methods are often considered by many authors to induce an artificial steel corrosion to simulate real corroded conditions in laboratory [4; 6; 7; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22]. Although there are some differences between natural corrosion and artificial corrosion (for example, the anode and cathode locations are predefined or the chemical composition of corrosion products), the use of these accelerated corrosion methods is one of the most popular ways to study the behaviour of corroded structures and obtain results that come close to those obtained from natural corrosion in a short time [17; 38; 39; 40]. Given the benefits offered by this technique, the authors decided to use it for their experimental tests. At the present time, analysis of the surface corrosion-induced crack patterns (their orientations, widths and lengths) does not allow an assessment of the internal damage state caused by corrosion (distribution and thickness of the corrosion products and internal corrosion-induced cracking) [4; 5]. The reverse is also not as straightforward to accomplish [4; 5].