[en] The corrosion protection provided prestressing steel by portland cement-based grout in the presence of sulfide, nitrate, and chloride ion environments was evaluated. Results were compared to those obtained from selected, commercially available petroleum-microcrystalline waxes (petrolatums) compounded with organic corrosion inhibitors. The investigation was conducted in two phases: (1) a review of literature to establish the mechanisms of prestressing steel corrosion, techniques available for protection of prestressing steel in hostile environments, and the performance of structures that have utilized either nongrouted- or grouted-tendon prestressing systems; and (2) a laboratory study to develop relative performance data for portland cement grout and selected commercial petroleum-based greases and waxes containing inhibitors. Conclusions derived from the investigation indicate that (1) sulfide, nitrate, and chloride salts must be excluded from prestressing materials; (2) prestressing materials must be continuously protected from inimical environments; (3) the effectiveness of the protection provided by both the organic- and cement-based corrosion inhibitors is reduced unless the steel is completely covered; and (4) both cement- and organic-based corrosion inhibitors completely protect prestressing materials when properly applied