Cross-section sector positioning of steel tendon in grouting duct based on mutual-capacitance analysis

Ensuring that the position of prestressed tendon complies with engineering construction standards is a fundamental requirement for reliably evaluating the integrity of duct grouting in post-tensioned concrete structures. Hence, a novel bi-electrode co-surface capacitive sensor employing mutual-capacitance sensing method has been developed. The capacitance distribution obtained through rotational acquisition is utilised to detect the position of the tendon. The performance of the sensor is assessed through comprehensive evaluation comprising numerical simulations and experimental investigations. The results indicate that the method can effectively locate a single 16 mm diameter prestressed tendon within the positioning active zone of an 80 mm inner-diameter duct. Furthermore, the disparities observed between the simulation and experiment are also elucidated. The results indicate that the proposed mutual-capacitance sensing method exhibits considerable potential as a non-destructive testing (NDT) approach for locating prestressed tendon in post-tensioned concrete structures.