The mechanism of corrosion of reinforcing steel in concrete was investigated by the measurements of local cell polarization curve, X-ray diffraction and electron diffraction.
The formation of the protective cement film on the surface of the reinforcing steel in wet concrete is faster than that in dry concrete, and it is accelerated by existence of CO₂ gas, and is delayed by existence of Cl^- ion.
It seems, therefore, the cement film is a complex compound containing CaCO₃. But the epitaxic relation between the cement film and the surface of the reinforcing steel could not be provided.

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In 1959 Yokkaichi Plant of Japan Synthetic Rubber Co., Ltd. laid a total of 35, 250m of hydrocarbon gas lines for butadiene production, from its 3 combine plants and the wharf, the maximum distance being 5, 070m. These pipe lines (2″, 3″, 6″) were coated with asphalt enamel and thin glass cloth, tested afterwards by Holiday detector at 10, 000V, and protected by 297 pieces of Mg anode. As an electric railroad is running near by, and crossing at 3 points, the pipe lines were equipped with drainage equipment.
Corrosion test specimens, made from the same pipe, which were coated identically or uncoated partially, were either connected or disconnected as control to the pipe lines. 144 pieces of such specimens, laid at 2 selected line terminals, were scheduled to be dug up for checking 1, 2, 3, 5, 7, 10, 13, 16 and 20 years after being laid.
2 years' record of the specimens and pipe to soil potential measurement all over the lines and gas analysis at 148 testing holes showed good corrosion protection of these pipe lines.

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