Stainless Steel Voltammetric Sensor to Monitor Variations in Oxygen and Humidity Availability in Reinforcement Concrete Structures

Abstract

The present work presents the results obtained with a stainless steel (SS) voltammetric sensor to detect variations in humidity (H2O) and oxygen (O2) availability in concretes. First, studies in solution were run by preparing several solutions to represent the different conditions that can be found in concrete pores. Second, the sensor’s response was studied by varying O2 availability by argon or synthetic air bubbling. Then concrete conditions with different degrees of carbonation were simulated using solutions with a pH between 13 and 8.45. After characterization in solution, a study by means of concrete probes with several water/cement ratios (0.6, 0.5 and 0.4) was performed, in which sensors were embedded and studied under different O2 and H2O saturation conditions. The obtained results revealed that with the voltagram, it is possible to evaluate O2 availability variation from the slopes of the lines identified logarithmically in the voltagram for the obtained cathodic sweeping. All the results obtained with the sensor were correlated/validated by standard assays to characterize porosity in hardened concretes.

Estimation of Humidity Variation and Electric Resistivity in Hardened Concrete by Means of a Stainless Steel Voltammetric Sensor

“…The employed voltammetric sensors systems were the SS type, whose response has already been studied by the researcher group in previously published studies [ 22 , 23 ].…”

“…The average sensor effective surface area was 2.99 ± 0.05 cm 2 ( Figure 2 ). The sensor’s design effectiveness has been evaluated in former works [ 23 , 26 ].…”

“…In order to develop a network of smart sensors, setting up stainless steel (SS) voltammetric sensors in such a network is very interesting, as demonstrated in former studies [ 22 , 23 , 24 , 25 ]. Moreover, SS is an economic and resistant material that allows sensors to be manufactured with bigger effective surface areas and at a lower cost than with other noble metals such as Au and Pt, which have been traditionally used to manufacture voltammetric sensors [ 26 , 27 ].…”

Effect of macrocell currents on rebar corrosion in reinforced concrete structures exposed to a marine environment

“…In recent years, much progress has been made in developing embedded sensors capable of detecting the depassivation of reinforcement (Andrade, 2020;Daniyal and Akhtar, 2020;Rodrigues et al, 2021), and of measuring the electrochemical potential of adjacent rebars (Karthick et al, 2018; or the resistivity of concrete cover (Ramón et al, 2021). Other authors have designed sensors to determine the presence of chlorides or concrete carbonation (Gandía-Romero et al, 2016a;2016b;Ramani and Kuang, 2020), as well as to quantify other corrosion kinetic-related parameters; for example, humidity or oxygen concentration (Martínez-Ibernón et al, 2021). Nonetheless, the most interesting parameter to properly evaluate and control a structure's durability is the corrosion rate because it provides quantitative information about steel section loss owing to corrosion.…”

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

“…In these sensors an excitation potential sweep is applied, as response the sensors emit an electric current at each potential which is associated with a specific reaction. Analysing the response in the potential range where the interest reaction takes place by Principal Components Analysis allows to develop a more robust and reliable detection models than with other sensors technologies [7] . Furthermore, the system is configured by Au voltammetric sensor, being the use of gold as voltammetric sensor for the RCS monitoring very interesting because:  Over the metal surface is favoured the O2 reduction without overlapping of the reaction stages [8][9][10][11],  and the potential peaks related to the adsorption/desorption of OHand O2 change with the variations in pH [12,13].…”