###### Abstract  
The economic cost of repairing corrosion-affected reinforced concrete structures (RCSs) means that reliable and accurate assessment and early detection methods must be sought after. Conventional techniques, such as visual inspections, or measuring either cover layer resistivity or the corrosion potential, are methods that require accessibility and involve personnel having to travel to take in situ measurements. Monitoring by embedded sensors is a much more efficient approach that allows early detection by remote sensing. This work presents the implementation of a new measurement protocol regarding the existing monitoring system called INESSCOM (Integrated Sensor Network for Smart Corrosion Monitoring). Along with the corrosion intensity measurement in embedded sensors, it also proposes monitoring the double layer capacity of the sensors' responses. It aims to determine, along with the rebars' corrosion rate, the triggering agent of the corrosion process. This study was carried out using three reinforced concrete scaled columns that were exposed to different environments. The results demonstrate with this new protocol that the remote INESSCOM monitoring system can establish the corrosion rate and identify the precursor agent of corrosion (carbonation or chlorides), even when the recorded corrosion rates are similar. reinforced concrete structures; corrosion; structural health monitoring; structural management; sensors; remote sensing; corrosion monitoring; multivariate analysis Article  
15 September 2024  
26 September 2024  
30 September 2024  
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process that occurs because of steel metallurgic properties [14]. Under the high alkalinity conditions of concrete's porous solution, corrosion is negligible because a layer of oxides, known as the passive layer, forms on rebars and protects metal [15; 16; 17; 18]. [PERSON] defined this scenario as an initiation stage, a period during which rebar corrosion may be considered negligible [19]. Nonetheless, two typical situations can trigger rebar corrosion [20]: (1) concrete carbonation, which corresponds to inward carbon dioxide penetration and leads the passive layer of rebars to dissolve and then to generalised corrosion [21; 22; 23]; or (2), chloride diffusion to rebars, which will trigger localised corrosion or pitting corrosion [24; 25; 26; 27]. In the second scenario, defined by [PERSON] as the propagation period [19], corrosion can no longer be considered negligible. It is in this second stage when the rebar corrosion rate progressively rises, which dissolves metal and generates products with higher specific volume than the original ones [28; 29]. The accumulation of such oxides will bring about internal stresses in the concrete cover and will trigger the appearance of not only rust stains on the surface, but also cracks and concrete cover spalling once the damage is quite advanced [30; 31]. Today, the assessment and maintenance routines performed in RCSs are based on visual inspections [32]. However, these works involve qualified personnel who have to travel and who are only limited to accessible elements, which, in turn, limits such practises being applied and renders such tasks inefficient. Some authors point out that it is also necessary to include non-destructive methods when assessing the corrosion condition of RCSs, such as corrosion potential measurements or cover layer resistivity analysis [32]. Nonetheless, these are qualitative corrosion measurements that do not actually allow us to know rebar corrosion intensity; instead, they establish a range for the risk of existing corrosion. Moreover, they are only applicable to accessible elements. All these drawbacks demonstrate that they are an inadequate strategy for structural monitoring and management [33]. Conversely, using embedded corrosion sensors for remote sensing is a much more rational approach.