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Description: Bleeding of grouts used in post-tensioned concrete construction is problematic because the bleed water tends to migrate to the tendon high points and form a void in the grout. The water may be reabsorbed by the grout, evaporate, or remain in place. In any case, a void is formed in the duct where the tendon is susceptible to corrosion. The assumption traditionally has been that bleed water remaining in the duct will, like the grout, provide a protective environment for the steel unless chlorides enter the system. Recent examples of corroded bridge tendons in the absence of chlorides have led to speculation about the mechanism of corrosion in this system. This report details a study investigating the corrosive nature of bleed water from grouts with certain cement-admixture combinations. Research findings showed significant corrosion in most of the specimens. A suspected corrosion mechanism is discussed and recommendations for avoiding this type of corrosion are presented. This report is also found on DVD021.
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