Abstract: There is disclosed a method and apparatus for the corrosion condition evaluation of unbonded prestressing elements in post-tension concrete structures. The method involves locating a prestressing element in the structure and providing at least two openings in the structure at positions along the length of the element. One of the openings is an inlet port and the other is an outlet port, each of the ports permitting communication with the gaseous environment within a conduit surrounding the prostressing element. The gaseous environment is accessed through the outlet port by extracting a sample of gas therethrough. The sample is then measured to determine its humidity and thereby evaluate the corrosion condition of the prestressing element between the inlet port and the outlet port. A method and apparatus is also provided for the on-site corrosion protection of unbonded prestressing elements whereby the gaseous environments within the conduits are cyclically pressurized with a dry gas.

Abstract: A compact, inexpensive, and lightweight pressure calibrator and a method for calibrating pressure monitoring devices. The pressure calibrator (10) comprises a plunger (14) sized to slide snugly within a hypodermic syringe barrel (12). Included within the plunger are pressure transducer (56), a microprocessor (54) and other electronic components (62). A digital display (30) disposed within the side of the plunger is operative to display the pressure developed within the syringe barrel (12) as the operator moves the plunger. "O" rings (28) provide a hermetic seal between the plunger and the internal bore (16) of the syringe barrel. A tube (22) is connected to the output port (20) of the syringe and provides fluid communication between the syringe and a pressure monitoring device (26) being calibrated.

Abstract: An apparatus for electrically and thermally "burning in" a plurality of integrated circuits mounted on a carrier tape includes a printed circuit board base and a pair of covers. The printed circuit board base includes a plurality of contact arrays arranged and constructed to contact the leads from the integrated circuits mounted on the tape. The pair of covers are pivotally connected to the printed circuit board base. The covers include a corresponding number of pressure pads which force contact between integrated circuit leads and a contact array when a cover is in its closed position. A locking assembly is provided to keep the covers locked in their closed positions. The printed circuit board base also carries circuitry for electrically exercising the integrated circuits during burn-in.