Latest revision as of 10:44, 21 May 2020

Asbtract

The corrosion behaviour of galvanized bars was studied in ${\displaystyle 0\cdot 1-3g}$ ${\displaystyle Ca(OH)_{2}}$ (pH ${\displaystyle 11\cdot 1-12\cdot 6}$) solutions designed to simulate the aqueous phase found in concrete pores. Corrosion potential and current density were monitored over the course of the 33 day tests and the corrosion products were examined by light and electron microscopy, X-ray diffraction, and IR absorption spectroscopy. Most specimens showed high initial corrosion rates which fell to a lower, nearly constant level after ${\displaystyle ~6}$ days. The corrosion kinetics were found to depend only on solution pH. ${\displaystyle Ca^{2+}}$ concentration had no effect other than on the nature of the corrosion products: ${\displaystyle Ca(Zn(OH)_{3})_{2}\cdot 2H_{2}O}$ is the passivation product in the presence of calcium ions, ${\displaystyle Zn(OH)_{2}}$ in their absence. Localized corrosion was observed at pH ${\displaystyle <11\cdot 5}$.