Electrochemical treatment to arrest OH- leaching from cement paste in an aquatic environment

Abstract

The present study concerns a mitigation of OH- leaching in the cement paste immersed in external water by applying the electrochemical treatment, prior to an exposure to external water. The cement paste specimen was fabricated and exposed to an aquatic environment under air-tight condition. The OH- leaching took place significantly for the first 24 h, followed by a further leaching of OH- ions. As for the electrochemical treatment, an increase in the current density and duration of the treatment resulted in a decrease in the OH- leaching. In particular, the OH- leaching was dramatically reduced at 1000 mA/m2 for 4 weeks. The cumulative OHconcentration leached from the cement matrix accounted for only 1.40 x 10-6 mol/l in 100 days monitoring, whilst untreated specimen leached 0.29 mol/l OH- ions in external water. Moreover, the pH profile in the cement paste indicated the higher alkalinity at electrochemical treatment.