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原文传递 Quantitative Studies of Chloride Penneability of Concrete

题名：	Quantitative Studies of Chloride Penneability of Concrete
作者：	John Walsh. Michael Sock, Jose Lima, Steve Quintin, and Joseph Fera
关键词：	Chloride, concrete, permeability, bridge deck, corrosion, rebar, chloride analysis
摘要：	Studies were undertaken to develop a quantitative determination of chloride ion permeability in concrete based upon measuring the chloride ion migration in the concrete. The intent as to modify AASHTO standard method T-277 to measure the amount of chloride ion which completely passed through a concrete specimen while simultaneously measuring total charge as normally performed by the method. Studies showed that more than 99% of the chloride ion does not pass completely through the concrete disk specimen, but instead, remains within the concrete disk. Evaluation of permeability by measurement of complete passage of chloride ion was therefore not feasible. However, measurement of the test cell chloride ion transferred into the concrete disk was found to be a means to evaluate chloride permeability of the concrete specimen. This enables the measurement of chloride ion permeability n grams of chloride rather than in colulombs of total charge. The studies showed that total charge as measured in the T-277 method is not due solely to chloride ion, but that the total charge is an accumulation of charges contributed to by a water electrolysis background charge, and charges due to presence of other ions in the test cell solutions. It was shown that based upon the amount of chloride ion transferred into the concrete disk, the total charge measured was always much greater than that possibly due to chloride ion alone. Based upon these findings, total charge is not a specific measure of chloride ion permeability. Measurement of chloride ion transferred into the concrete specimen appears to be a direct evaluation of chloride ion permeability of the concrete. It is actually a measure of the absorbance of chloride ion by concrete, and specifically defines the amount (by weight) of chloride ion taken-up by, or permeating into a concrete specimen.
报告类型：	科技报告