Inspections and maintenance of a structure are essential to maintain design thresholds during its lifetime. In order to obtain qualitative and quantitative information on corrosion processes, it is necessary to implement techniques that require qualified personnel, as a visual inspection is ineffective during the early stages of the process.

The use of systems for monitoring the useful life of structures is of great interest to ACCIONA Construcción S.A., which is why it is of interest to test different sensors available on the market, such as the Corrochip system from Witeklab.

The objective of this study is for ACCIONA to evaluate the Corrochip system for long-term monitoring of the corrosion and service life of reinforced concrete structures for use in its works. To this end, in mid-2022, a battery of tests was implemented on concrete subjected to marine environment conditions in various exposure zones. ACCIONA’s demonstration facility at the Musel Port in Gijón was used for this purpose. This experimental development is carried out in collaboration with the Electrochemistry Laboratory of the ETSIE-Universitat Politècnica de València, which will be responsible for carrying out concrete characterisation tests and providing scientific advice.

The Gijón Port Authority (APG) sees innovation as a key element for improving competitiveness, which is why ACCIONA has rented an area of the port’s North Quay to carry out validation and demonstration work on various innovation projects.

A marine environment has been chosen because seawater contains many dissolved salts, some of which affect the durability of concrete. On the other hand, marine organisms (algae, molluscs, sea urchins, barnacles and bacteria) can interact with concrete structures; both algae and molluscs can be a problem when the concrete surface is porous and can generate a significant loss of alkalinity.

This experimental trial consists of 12 concrete elements, in which more than 70 sensors of various types have been embedded to monitor several parameters related to the corrosion of reinforced concrete structures. The most important parameters that can be obtained with these sensors are:

  • icorr (µA/cm2): corrosion intensity, referring to Spanish standard UNE 112072.
  • Ecorr (mV): corrosion potential, referring to Spanish standard UNE 112083.
  • vcorr (µm/year): corrosion rate, referring to Spanish standard UNE 112072.
  • Temperature (ºC).

Fabrication of concrete elements with embedded Corrochip sensors (left) and data station and connection piping (right).

The CORROCHIP sensors display the information collected via a web application, which shows the location of the sensors, descriptions of the installation and the data provided by the sensors on the condition of the structure. Various graphs showing the corrosion potential, corrosion intensity and corrosion rate are displayed.

CORROCHIP web application.

The current trend in Structural Health Monitoring (SHM) strategies in large and small infrastructures is driven by the interest shown by large companies such as ACCIONA and the support of important public bodies such as the Gijón Port Authority.

This increase in the implementation of SHM is justified because the failure of any infrastructure can not only cause large economic costs, but also have repercussions on the well-being of the users of these assets. In addition, regulations are becoming increasingly stringent with regard to the durability of structures, which together with the increasing ageing of existing structures is driving the growth of this sector.

Therefore, this is another example of the relevance that the CORROCHIP system can have for the durability of structures by monitoring long-term corrosion processes. Its usefulness and uniqueness in the market presents a great advantage in assessing these phenomena in a precise, simple and continuous way, allowing preventive maintenance strategies.