CORROSION CONDITION EVALUATION AND CORROSION PROTECTION OF UNBONDED POST-TENSION CABLES IN CONCRETE STRUCTURES

摘要

There is disclosed a method and apparatus for thecorrosion condition evaluation of unbonded prestressing elementsin post-tension concrete structures. The method involves locatinga prestressing element in the structure and providing at least twoopenings in the structure at positions along the length of theelement. One of the openings is an inlet port and the other is anoutlet port, each of the ports permitting communication with thegaseous environment within a conduit surrounding the prestressingelement. The gaseous environment is accessed through the outletport by extracting a sample of gas therethrough. The sample isthen measured to determine its humidity and thereby evaluate thecorrosion condition of the prestressing element between the inletport and the outlet port. A method and apparatus is also providedfor the on-site corrosion protection of unbonded prestressingelements whereby the gaseous environments within the conduits arecyclically pressurized with a dry gas. The protection method mayalso include programmable control of the dry gas pressurizationand feedback of the humidity levels in the conduits for adjustingthe parameters of cyclical pressurization so as to maintain apredetermined maximum humidity value in the gaseous environmentsassociated with the prestressing elements of the structure.