| Summary: | 碩士 === 國立屏東科技大學 === 土木工程系碩士班 === 93 === The study employed an electrochemical nondestructive test to measure the corrosion potential, the concrete resistivity and the corrosion current density of steel bar in reinforced concrete, where a Gecor 8 corrosion rate meter was used. The strength of concrete specimens were 210 kg/cm2. Variables of the test included chloride ion contents of 0, 5, 10, 15 and 20 kg/m3, and concrete ages of 7, 14, 21, 28 and 60 days. The least volume of pre-wetting water and the least required waiting time for obtaining a stable measurement value by one sprinkling were also studied.
The results showed that, the least volume of pre-wetting water with an average flow of 0.468 kg/sec was a volume of sprinkling for 50 seconds, in which the measurements of corrosion potential, the concrete resistivity and the corrosion current density were able to obtain a stable value at three to four minutes after sprinkling. Several regression equations of corrosion potential, concrete resistivity and corrosion current density respect to concrete age were developed for different chloride ion contents of specimens. The results showed that, when chloride ion content were higher, corrosion potential and concrete resistivity became lower, but the corrosion current density went higher. That meant higher chloride ion content would cause more serious corrosion and higher corrosion rate. Except the specimen of chloride ion contents of 10 kg/m3, the concrete resistivity increased and the corrosion current density decreased with concrete age. In the other words, the corrosion rate decreased with concrete age for most of the specimens.
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