Yusuke KITAOKA

Study on Effectiveness of Chloride Ion Removal by Desalinaiton

SupervisorFKyuichi MARUYAMA

The objective of this study is to evaluate the influence of desalination on prestressed RC member both qualitatively and quantitatively. Influence of Hydrogen embrittlement on corroded prestressing steel, estimation of ionic migration in concrete, and evaluation of migration behavior of free Chloride ion are focused on. Hence, influence of accumulation of alkali ions near the steel and the effect of desalination against corrosion are examnined.
Defected prestressing steel, which was corroded electrically at first, then set in desalination, was loaded in tension to rupture. The fracture surface was observed by SEM. There's no influence of Hydrogen embrittlement on tensile behavior of PC steel material Besides, the influence of hydrogen embrittlement was not seen from the Scanning Electron Microscope observation.
The estimation of migration mechanism of each ion was examined by the ionic density measurement test. The migration behavior of free Chloride ion was able to be evaluated by utilizing a simple models, that is, relationship between density of free Chloride ion and resistance density, and relationship between density of free Chloride ion and electrophoresis flux of free Chloride ion. These model can be also applied to any other concrete.
After finishing desalination test, outdoor exposure test was executed and the crack was confirmed to concrete. But the corrosion of the steel was not observed.It is thought that Ettringite is one of cause of occurrence of crack.