Study on improvement of durability for reinforced concrete by surface-painting migrating corrosion inhibitor and engineering application

The corrosion currents of steel bar in concrete with three W/B and four chloride contents after surface-painting two migrating corrosion inhibitors (PCI-2015 and MCI-A) 14d to 150d in atmospheric condition were measured. The results showed that the corrosion current density (I-corr) of steel bar reduced to 0.1 mu A. cm(-2) from the initial highest 3.833 mu A. cm(-2) (W/B= 0.65, NaCl-1%) after surface-painting PCI-2015 14 d, and the I-corr was still lower than 0.1 mu A. cm(-2) until 150d. The compressive strength and chloride migration coefficient of concrete specimens were tested. The possible reasons of the mechanisms of durability improvement for reinforced concrete by applying PCI-2015 inhibitor were PCI-2015 may be reacted with calcium hydroxide in cement concrete and lots of inhibitor particles may be adsorbed on the active sites first and then a stable protective layer may be formed. The Icorr of steel bars in a hydraulic aqueduct concrete structure after painting PCI-2015, MCI-A (the United States) and MCI-B (Europe) during 6 months was monitored by Gecor 8 tester. The results showed that the average values of Icorr of steel bars after painting the PCI-2015 150d fulfilled the specification requirements in "Design code for concrete structure strengthening (E. 3)"(GB50367-2013).