## 1 Introduction  
The main cause of environmental degradation in existing reinforced concrete (RC) structures is the corrosion of carbon steel reinforcement [1, 2]. This mechanism leads to a reduction of the steel reinforcement bar (rebar) cross-section [3, 4], the cracking of the concrete cover [3, 4] and a decrease of the bond properties between the steel and concrete [3, 4]. Indeed, once the passivation layer around the reinforcement is broken down, corrosion is activated as long as the environmental conditions are favourable (in terms of oxygen, water and temperature) [5, 6]. The resulting accumulation of corrosion products occupies a volume approximately two to seven times larger than that initially taken up by the steel. This leads to an increasing radial pressure at the interface between the rebar and the surrounding concrete, causing tensile stresses in the concrete along the length of the corroded rebar, which develop slowly [5, 6]. If these stresses exceed the concrete tensile strength, cracks appear and spread towards the outer surface, potentially leading to spalling and delamination of the concrete cover and serious damage to the concrete cross-sections [5; 6]. These cracks can become the primary paths for a quicker ingress of aggressive agents into the steel bars, which accelerates the corrosion process [5; 6]. Furthermore, it is increasingly recognised that the performance of existing RC structures can be compromised by the presence of aggressive agents, such as chloride ions. In countries with a long maritime environment (coasts) and winter de-icing periods, it is obvious that the structural safety and serviceability of corroded RC structures and infrastructures can be consequently affected by the corrosion process. This process can subsequently result in a loss of serviceability of the RC structure. In the absence of appropriate maintenance measures, the structural safety of existing structures may be compromised. Consequently, at the structural scale, there is a need to identify cost-effective solutions that can maintain or even enhance the performance of existing structures, ensuring their continued safe load-bearing capacity. Considering that surface cracks are the most visible signs of corrosion progress, their width can be considered as the most reliable indicator to assess the actual corrosion level [4; 7]. Consequently, corrosion-induced cracking appears as one of the most important key parameters to predict the durability of RC structures and therefore to plan their maintenance [4; 7]. Therefore, establishing a well-defined relationship between the corrosion level and the width of the corrosion-induced cracks and their crack patterns would greatly facilitate the assessment of the condition of a structure based on visual inspection. In view of all the aforementioned detrimental effects of corrosion, many researchers have devoted significant effort to developing tools, such as non-destructive evaluation techniques [8; 9], as well as empirical or numerical predictive models, to assess the corrosion evolution of RC structures [10; 11]. However, most of these tools have not yet been applied in the scope of application, thus preventing end users of structures from having access to an efficient maintenance policy. As part of the efforts in this research area, many experimental tests are available in the literature to investigate corrosion-induced crack initiation and propagation in reinforced concrete [12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24]. These tests consider various types of RC specimens and different parameters. For example, some authors have accelerated the corrosion of RC specimens by applying regular wetting (salt water spraying) and drying cycles in an artificial climate room with controlled temperature and relative humidity [12]. In other studies [13; 14; 15; 16], an impressed current mode was used.