陰極防蝕技術應用於含氯鋼筋混凝土之研究

The Application of Cathodic Protection on the Chlorine Reinforced Concrete

在海洋環境下，鋼筋混凝土構造物受氯離子之侵蝕常會導致鋼筋的銹蝕，進而促使構造物崩裂毀壞。為使構造物之維護及使用年限得以延長，針對已遭受氯離子侵襲之鋼筋混凝土試體，應用陰極防蝕技術，依據鋼筋極化現象之量測及氯離子滴定的結果，探討含氯鋼筋混凝土構造物防蝕所需之最佳外加電流密度及所達成的去氯成效。試驗結果顯示：隨著外加電流密度的增加及通電時間的增長，鋼筋混凝土試體內剩餘之氯離子含量會明顯下降，下降量以在鋼筋附近最為顯著，惟最終的去氯成效仍有其一定的限度。此外，若試體之水灰比愈高，則其去氯成效愈佳。綜合評估可得：為防護鋼筋免於腐蝕發生，其所需施加之最佳電流密度應為10 mA/m2 ~ 20 mA/m2。

Failure of reinforced concrete structures exposing to marine environments occur frequently due to steel corrosions induced by intrusion of chlorides. To find the physical solutions of protecting such kinds of structures from aggravation corrosions and extending its lifetime, specimens of reinforce concrete containing with chlorides are prepared and a series of laboratory experiments are performed in this study. Adopting the cathodic protection technique, both of the optimization density of the impressed current and effects of steel polarization are measured and chloride ion titrate, the de-chloride efficiency is evaluated as well. Tested results show that the residual content of chloride in specimens decreasing and converging to a certain limitation as increasing both of the impressed current density and the desalination time. The regions where appeared with the most significant de-chloride effects are found neighboring to the steel. Moreover, it is found that the higher ratio of water/cement in specimens, the better the de-chloride effects are.Synthetically speaking, for steel corrosion control the impressed optimum current density of about 10 mA/m2 ~ 20 mA/m2 is proposed.