CORROSION OF STEEL IN CABONATED CONCRETE OR CONCRETE CONTAINING CHALORIDEION

本文报道了在裂缝截面和未裂缝混凝土试件中嵌入38mm低碳钢阳极的腐蚀特性，并对其进行了涂覆薄环氧膜的变形钢筋加固。在同一试样中分别嵌入低碳钢（阳极部分）和不锈钢（阴极部分），通过电连接建立了大细胞。第一。样品保存在含有10% CO_2的空气中。混凝土部分或完全碳化。在65℃±3.3.2% NaCl溶液中湿化1天，空槽干燥1天，自动重复进行加速腐蚀试验。用计算机测量系统连续测量腐蚀电流。暴露试验的总周期为35个周期，即70天。结果表明：(1)随着裂缝宽度和水灰比的增大，钢的失重量增大；盖层厚度对其无影响。(2)在未发生裂缝的碳化混凝土试件中，腐蚀电流在W/C= 50%、70%的混凝土中流动。总体而言，碳化混凝土中钢材的减重幅度大于未碳化混凝土。

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.