This study presents the results from a preliminary investigation on the corrosion behavior of carbon steel in cement extract (CE) in the presence of very low concentration (0.0024 wt. %) polymeric nano-aggregates (PEO113-b-PS780 vesicles). Two types of vesicles were studied: vesicles with a CaO-containing core and vesicles with an “empty” core. The results from the electrochemical measurements (Electrochemical Impedance Spectroscopy (EIS) and Potentio-dynamic Polarization (PDP)) indicate that the presence of the CaO-containing vesicles lead to a significantly increased corrosion resistance of the steel, but no pronounced effect was observed for the “empty” vesicles. However, steel surface analysis indicates that the presence of both vesicles type results in a more homogeneous and compact product layer.