Detection of bond deterioration in reinforced concrete using active sensing technique

The detection of bond damage in steel-reinforced concrete, which are largely hidden from traditional techniques of inspection, could help prevent structural catastrophes and avoid the loss of human lives. An active sensing technique using piezoceramic elements has been proposed to detect and monitor bond damage within steel-reinforced concrete.; This research work focused on identifying a suitable sensor design that will enable measurements to be made reliably and efficiently. Parametric studies done as part of the sensor design led to the choice of steel clips to hold the piezoceramic sensors. The sensor design chosen was used for the construction of pullout test specimens that were designed to fail with 2 distinctive bond failure modes. The results of the tests showed that bond damage could be detected and monitored using the active sensing technique.; A bond deterioration index (BDI) is defined to quantify the amount bond damage occurring within the concrete specimens during the static pullout tests. The results showed a linear change of the BDI for unconfined concrete test specimens as the applied loading increases gradually until failure occurs. Whereas for the confined concrete test specimens, the BDI measured by the piezoceramic sensors showed that not only it could detect bond damage with increase loading, it also showed that the BDI at slip failure indicated and confirmed the remains of some bond strength between the steel bar and concrete.; Some basic issues of implementation concerning maximum sensor spacing and minimum number of sensors needed for detection of bond deterioration in reinforced concrete were also addressed. An approach to determine these basic design parameters was subsequently defined.