Environmental cracking of prestressing steel in calcium-hydroxide solutions

Failure of prestressed steel tendon in concrete due to corrosion or environmental cracking (or both) has become a major technological concern because of increased utilization of this form of construction in corrosive exposure such as coastal bridge deck structures. At the same time cathodic protection has evolved as the most practical means for arresting corrosion of reinforcing steel in existing structures. This technology also applies to pretensioned tendons. However, concerns have been raised that cathodic protection might cause embrittlement, since yield stress of these materials is relatively high. For the purpose of analyzing this embrittlement tendency a series of constant load and slow strain rate experiments were performed and the data evaluated. Influence of potential, chloride concentration, pH and precharging on the cracking susceptibility have been evaluated. The cracking process has been explained based on test results and SEM analysis.