Initial proposal of a novel voltammetric sensor system for the detection of concrete carbonation by means of PCA model

The monitoring of concrete carbonation takes an important role in the structures maintenance, considering that corrosion induced by this phenomenon is one of the mainly failure causes in the Reinforcement Concrete Structures (RCS) located in industrial zones, roads and cities. Carbonation of concrete is produced by the penetration of the CO2 inside of the porous net, which is mainly combined with the Ca(OH)2 contained in the concrete pore solution producing carbonates with low solubility and eventually causing a pH drop until neutral levels. The pH drop produces the instability and final generalised destruction of the rebars passive layers, which is the step that precedes generalized corrosion. The current existing systems to detect concrete carbonation are based on potentiometric sensors to detect the pH of concrete pore solution. These have some limitations such as the interference of different reactions on the sensor surface. Considering these limitations, in this study a novel system of voltammetric Au sensors embedded in concrete for the detection of concrete carbonation was presented. In the voltammetric sensor, the potential sweep signal applied comprises the potential range where the effect of the pH variations has more influence in the sensor response. Then the response processing by means of the multivariate analysis PCA (principal component analysis) allows to manage a huge quantity of variables and to reduce the effect of the interference with other analytes, increasing the importance of the pH changes effect in the obtained data. Thus, increasing the reliability of the system to detect the concrete carbonation.