Test Methods to Identify Robustness of Grout Materials to Resist Corrosion

Abstract The application of prestressed concrete including post-tension construction technology has seen wide acceptance for highway bridges as it provides structural engineers greater options for bridge design with certain advantages in construction and economy. Although there is increased use of PT bridge construction, challenges with the application of grout as exhibited by documented corrosion of steel tendons in several bridges in the past three decades persist. In the early 2000s, thixotropic grouts that prevent grout bleeding were developed and specified in bridge construction. However, isolated cases of corrosion of tendons with a prepackaged thixotropic grout product were observed. In consideration of the grout product in field application that exhibited tendency to segregate, current research is ongoing to identify test methodologies to assess the robustness of grouts by the corrosion performance when cast in non-ideal conditions. The preliminary testing using a modified accelerated corrosion test and rapid-macrocell test explored the idea of assessing the robustness of grouts subjected to non-ideal conditioning. These tests incorporated testing of grout subjected to adverse conditioning and mixing to promote grout deficiencies. Preliminary results show that methodologies prescribed in existing test guidelines may be applicable to assess grout robustness and corrosion propensity in deficient grout. A grout with the most adverse grout segregation showed results that would be considered not meeting acceptance criteria. Further test developments should consider test configurations that would provide reasonable grout conditioning and handling yet still appropriately assess robustness.