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The reinforced concrete structures have been considered durable for a long time. But recently, it has been reported that they are deteriorated by reinforcement corrosion to be suffered from chloride attack. Desalination, which is an electrochemical treatment of chloride extraction from concrete, has been developed as an essential repair method. Steel bar embedded in concrete acts as a cathodic electrode through desalination process and sodium ions are gathered about the steel bar.In this study, expansion of concrete due to alkali silica reaction during and after desalination was examined in concrete having reactive aggregates.

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This study tried the application of electrochemical realkalization using Li3BO3 solution as the electrolyte, compaired with the case of usual Na2CO3 solution. The results obtained from this study are shown as follows: (1) The rate of concrete expansion by alkali-silica reaction (ASR) after realkalization using Li3BO3 solution was smaller than the case of Na2CO3 solution. (2) The realkalization effect obtained just after treatment was enough even when Li3BO3 solution was applied like as the case of Na2CO3 solution. (3) The pH value of cover concrete at 1 year after finishing realkalization using Li3BO3 maintained the same level as the case of Na2CO3 solution. Further more, the pH value obtained by realkalization using Li3BO3 solution maintained acceptable level under the accelerated condition of carbonation for 30 days.

This paper mainly describes corrosion behavior of the steel bars in concrete specimens using fly ash or blast-furnace slag, deteriorated by chloride attack, carbonation of concrete, or complex of both mechanisms. Furthermore, chloride removal effect due to applying desalination to such deteriorated specimens is investigated. Results obtained from this study can be summarized as follows: (1) Carbonation depth of concrete using fly ash or blast-furnace slag was larger than that of normal concrete and the larger replacement rate of them became, the more carbonation depth of concrete increased. (2) As the result of measurement of CI" content in concrete before desalination, in the case of carbonated specimens, soluble chloride percentage to total chloride near the exposed surface was increased with the influence of carbonation of concrete. (3) Chloride removal percentage due to applying desalination to non-carbonated specimens was 15-30% as a whole cover concrete. On the other hand, in the case of carbonated specimens, CI" ion near the exposed surface was decreased by desalination and chloride removal percentage reached 50-80%.