Design of A Interdigital Capacitive Sensor for Detecting Corrosion of Reinforcement in Concrete

Corrosion of reinforcement is one of the main reasons for the deterioration of durability of reinforced concrete structures. In view of the shortcomings of traditional capacitive corrosion sensor, a design of interdigital capacitive corrosion detection sensor for steel bar in concrete is proposed. Taking Q235 carbon steel as an example, this paper introduces the structure and working principle of the corrosion sensor, and analyzes the influence of material size and sectional area loss. The corrosion sensor consists of two comb-shaped electrodes made of, an acrylic substrate and an outer package made of hot glue. In order to verify its feasibility and stability, four corrosion sensors were embedded in the concrete and four concrete samples were prepared. The electrochemical accelerated corrosion test was carried out on four concrete specimens, and the relationship between the capacitance change of the corrosion sensor and the corrosion degree of the comb electrode was quantitatively analyzed by the weight-loss method. The experimental results show that the capacitive corrosion sensor designed in this paper adopts interdigital structure, which can greatly improve the sensitivity of the steel corrosion sensor and more effectively detect the corrosion state of Q235 carbon steel. In addition, the corrosion sensor is highly sensitive to the early corrosion and corrosion transition of Q235 carbon steel, which provides a reliable basis for timely and effective maintenance.