CATHODIC PROTECTION OF PRE-TENSIONED CONCRETE: Part I - Brittle Fracture Propensity of Corrosion Damaged Prestressing Tendon Wire

摘要

Constant extension rate tests were performed upon prestressing wire specimens in air and in saturated Ca(OH)_2 solution at -0.90 and -1.30 v (SCE) i n order to investigate the influence of various levels of precorrosion upon mechanical properties and fracture behavior. It was determined that ultimate tensile strength (UTS) was reduced to a greater extent in the case of specimens which exhibited layer corrosion compared to those with simulated pits. The UTS of layer corroded specimens was not significantly influenced by corrosion morphology acuity but, instead, correlated with the magnitude of cross sectional area reduction. The results are discussed within the context of the previously proposed negative potential limit of -0.90 v (SCE) for cathodic protection of prestressing steel, and a modified qualification criterion is introduced based upon a relationship between fracture load (alternatively, prestress level) and the magnitude of cross section reduction by corrosion.