been used in this field for the non-destructive testing of external tendons on post-tensioned bridges. these structures are filled with steel cables and protective grouting or grease. in this application, a mobilized, remotely-controlled ecvt device is placed around the external tendon and scans the interior of the tendon. the ecvt device can then decipher information about the quality of the grouting or grease within the tendon in real time. it can also determine the size and location of any air voids or moisture within the tendon. finding these issues is a critical task for bridge inspectors, as air and moisture pockets within the tendons can lead to corrosion of steel cables and failure of the tendon, which puts the bridge at risk of structural damage.