align="left">A limited survey was made tc gather as much data as possible on incidents of corrosion of prestressing steel which may have occurred in the United States during the past 5 years. From the authors? experience? and information gathered from close to 100 responses to the survey, 50 structures were found in which tendon corrosion has occurred. Corrosion incidents were usually found to be associated? with poor details and/or execution, generally in the presence of an aggressive environment. Considering the fact that about 200,000 tons (approx. 180,000 metric tons) of prestressing steel per year are? used in the United States, the number of incidents reported is small, particularly since about 40 percent of them have occurred in post-tensioned parking structures exposed to high concentrations of chlorides from deicing salts. Of the 50 corrosion incidents reported, 10 cases of probable brittle failures related to stress corrosion or hydrogen embrittlement were cited. It is likely that a few more may have occurred. In most cases, the exposure of the prestressing steel to an aggressive environment, particularly with sulphides present, has triggered the loss in ductility. Those incidents involving embrittlement, in which more details were available, are described herein.? Recommendations are put forth whereby corrosion embrittlement failures of prestressing steels can be avoided.?
展开▼
