Reinforcement corrosion assessment capability of surface bonded and embedded piezo sensors for reinforced concrete structures

Rebar corrosion has become a very common cause of degradation in the reinforced concrete structures. It is most frequently the result of the chloride-induced breakdown of the passive film formed in the highly alkaline environment. This article presents a comparison of the sensing capabilities of surface bonded and embedded piezoceramic (lead zirconate titanate) patches in diagnosing chloride-induced corrosion for reinforced concrete structures. Experiments are conducted with lead zirconate titanate patches surface bonded on rebar as well as embedded in the vicinity of the rebar inside concrete to compare the sensitivity of the two. Accelerated corrosion tests are performed on reinforced concrete specimens, and a comparison of the statistical index and the equivalent parameters is done for the two types of sensor configurations. The experimental results indicate that the embedded sensor is very sensitive in capturing the changes occurring in the concrete during chloride ingress. However, when the passive film is damaged, thereby initiating corrosion, their sensing ability is reduced. At this point, the lead zirconate titanate patch surface bonded on the rebar is more effective. Overall comparison of experimental results shows that both sensor types can complement each other for an effective detection and monitoring of rebar corrosion.