Experirental Studies on Corrosion of Steel Bars in Concrete -Experiments 5, In Case of Over-dosage of Corrosion Inhibitors, 2-

摘要

The paper is the 2nd report of the 5th series of experiments on corrosion tests of steel bars embedded in concrete specimens. The concrete of specimens in this series of experiments has contained salt and corrosion inhibitors, and its water-cement ratio is 50%. The cover concrete depth over steel bars is constant through all the specimens and 2cm. The experiments has been planned and undertaken in accordance with the L_9 (3^4) Table of the Experimental Design. Salt concentration and dosage of corrosion inhibitor are main factors of the experiments, and their levels are 0.03, 0.15, and 0.75% of concrete by weight in salt concentration and two, three, and four times of the standard dosage of the maker specified in corrosion inhibitor content. The main feature of this series of experiments is high dosage of corrosion inhibitor into concrete to clarify the effect of inhibitor under high salt concentration in concrete. The following results are obtained at the time when one and half year has passed after embedding steel bars into concrets specimens. 1. Two times dosage of the inhibitor has been enough to inhibite corrosion of steel bars in the concrete which contain 0.03 and 0.15% of salt by weight. 2. Where salt content of concrete specimens amounts to as much as 0.75% by weight, the high dosages of inhibitor of this series of experiments could not restrain the rusting of steel bars, and almost steel bars in the specimens of 0.75% salt concentration have had some corrosion. 3. The effect due to differences of dosages of inhibitor are observed where the specimen concrete contain 0.75% salt by weight. The two times dosage of inhibitor is most effective for inhibiting corrosion of steel bars, the three times dosage seemed to have adverse effect on corrosion inhibitation. 4. The interaction of main factor effects between salt concentration in concrete and dosage of inhibitor has been established in this series of experiments, and we could not talk about the effect of inhibitors on corrosion protection without mentioning the salt concentration at the same time.