CORROSION OF STEEL IN CABONATED CONCRETE OR CONCRETE CONTAINING CHALORIDEION

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The paper reports the corrosion claracteristic of 38mm anodes of mild steel embeded in cracked section or uncracked concrete specimens, which were reinforced by deformed bars coated with thin epoxy film. The macrocells were set up by electrically connecting between the mild steel (anode part) and the stainless steels (cathodic part) embedded separately in the same specimens. First. the specimens were kept in air containig 10% CO_2. Concrete were partially or completely carbonated. Then the specimens were sujected to the proposed accelerated corrosion test of automatically repeated cycles of one day wetting in 65℃±3, 3.2% NaCl solution and one day drying in the empty tank. The corrosion current was measured continuously by a computer measuring system. The total period of exposure test was 35 cycles or 70 days. The results indicate that (1) the weight loss of steel increased as the crack width and the water by cement ratio increased. The cover thickness did not has effect on. (2)In the carbonated concrete speeimens that crack did not occurred, corrosion current flowed in W/C=50, 70% concrete. On the whole, the weight loss of steel in carbonated concrete in larger than that in noncarbonated concrete specimens before.