コンクリート中の鉄筋の腐食 (第1報)

海水および硫酸塩溶液による腐食

抄録

The mortar, containing none or 1% CaCl₂, was coated with tar, asphalt, silicofluoride or zinc powder-water glass mixture. These mortar blocks were soaked in sea water or 10% Na₂SO₄ solution, and, after leaving to stand for a certain period, the mechanical strength of each mortar was determined. All the mortar blocks, except asphalt-coating, soaked in sea water, showed good strength. In sulfate solution, the mortar containing CaCl₂ showed a good strength, while the strength of other mortars were very poor. Asphalt or tar lowered the strength of mortar.
Corrosion of steel in the mortar, which was soaked in sea water or 10% Na₂SO₄ solution, was examined by RGY test (the measurement of voltage-current curve). The effect of addition of CaCl₂ on corrosion of steel in mortar is not very large but it seems, in absence of stray current corrosion, that the use of CaCl₂ may be preferable for prevention of corrosion of steel in concrete soaked in sea water or sulfate solution. This result also is confirmed by the weight-loss test.