Modification of properties of reinforced concrete through nanoalumina electrokinetic treatment

- Nanoalumina particles were drifted into reinforced concrete through electrokinetic treatment.
- Transport of nanoalumina was evidenced up to rebar-concrete interface by microstructural observations.
- Nanoalumina transport into reinforced concrete reduced total porosity at rebar-concrete interface.
- Nanoalumina transport increased bond strength between rebar and concrete.

An attempt was made to drift nanoalumina particles into concrete pores through electrokinetic treatment. An external electric current (current density = 3 A/m2) was applied for 3 and 15 days in reinforced concrete blocks toward steel reinforcement and microstructural characterizations (i.e. morphology observation and porosity analysis) were performed on concrete fragments of different depth from exposure surface. The morphology observation evidenced transport of nanoalumina from the exposure surface even reaching the rebar-concrete interface (up to 25-30 mm, in 15 days treatment). The porosity analysis of treated samples revealed that reduction of porosity of rebar interface was more pronounced as compared to the exposure surface and the treatment for 15 days was more beneficial for porosity refinement than treatment for 3 days. Effects of the electrokinetic NA treatment on strength of rebar-concrete interface were evaluated through pull-out test. The results showed that by increasing current density, bond strength of rebar-concrete interface increased.