## 3 Method Proposed for Corrosion Evaluation
### Experimental Tests Regarding the Corrosion Detection in a Bridge of The United Arab Emirates, UAE  
To evaluate the reliability of the non-invasive method for the detection of the concrete degradation, the Ghalilah bridge was tested.  
This bridge (Figure 12), belonging to the highway E11 in the Emirate of Ras Al Khaima (on the north side of the city of Dubai, UAE), is a multi-span reinforced concrete bridge with five internal supports, while both ends of the bridge can be depicted as simply supported.  
Figure 11: (**A**) OCP tests at different sulfate concentrations; (**B**) calibration line obtained from OCP tests.  
As can be seen in Figure 13, each span, 9 m high, is approximately 11 m long, for a total length of 69 m.  
Furthermore, a trellis system, consisting of five longitudinal transverse beams, supports a 9-m-wide roadway, including two cantilevered sidewalks of approximately 2 m.  
Temlab stations (Figure 14) are equipped with a local acquisition and processing system (Edge Computing) and data transmission via IOT protocols (such as MQTT and/or OPC-UA). The architecture of the platform makes managing both electrochemical and physical-mechanical sensor data (in static and/or dynamic mode) possible if the structure is properly instrumented, following the philosophy of the \"Smart City\" and the \"Smart Road\".  
Figure 14: TEM monitoring station positioned in the Ghalilah bridge.  
Figure 12: Ghalilah bridge.  
Figure 13: Front elevation and section of Ghalilah bridge.  
Temlab, in collaboration with researchers from the University of Palermo and researchers from the Ministry of Energy Infrastructure of the United Arab Emirates (UAE), conducted a pilot project for the remote monitoring of the corrosion risk of the Wadi Ghalilah bridge. The monitoring station was equipped with three Cl and pH sensors, connected both to the copper sulfate counter electrode (liquid junction) and to the activated carbon pseudo-reference electrode.  
Remote monitoring is facilitated by the use of a dashboard (Figure 15), in this case, Grafana, which allows the user to view the values of the current parameters at a glance and to acquire the historical data. In addition, it is possible to set alarms when the threshold values, as determined by the user, are exceeded. In this regard, Figure 16 shows the detection of the mV data of the sensors read by the Grafana software.  
Figures 17 and 18 show the trend of variation in the pH and in the chloride ion concentration, respectively. The data are detected by the sensors embedded in the concrete of the structure. The sensors are inserted at different depths (1 cm, 2 cm and 3 cm). This choice was made in order to estimate the penetration gradient of the carbon dioxide, responsible, as known, for carbonation, and to evaluate the possible decrease in both the pH and the chloride values. Specifically, the low level of pH reported in Figure 14 demonstrates that the concrete cover of the Wadi Ghalilah bridge is carbonated.  
Figure 16: Graphana dashboard for real-time data visualization: chloride concentration in the monitored concrete abutment.  
Figure 15: Graphana dashboard for real-time data visualization: pH concentration in the monitored concrete abutment.  
It is worth specifying that the chemical monitoring is obviously not capable of providing indications of the damage to the structure, as it is focused on the detection of vulnerability conditions of the concrete's structural elements. Nonetheless, the assessment of the condition of the concrete cover is a strategic step in undertaking actions in order to protect the reinforcements against the risk of corrosion. It is also useful for estimating the residual life of a structure (residual life predictions).