Simultaneous effect of nano and micro silica on corrosion behaviour of reinforcement in concrete containing cement strength grade of C-525

The present study investigated the changes in the effect of additive nano-silica replacing micro-silica to reduce corrosion rate of steel in the concrete made of C-525 cement in a corrosive environment, and also the optimum combination of these additives in reinforced concrete for the production of reinforced concrete with high resistance to corrosion of the reinforcement. To this end, 7 series of cylindrical corrosion samples were prepared, which comprised a base design and 6 designs of various combinations of micro and nano silica, weighing a constant 11% in total of the weight of cement used in each sample. Samples were placed in a 3.5% salt-water solution and underwent various electrochemical tests, including corrosion potential (OCP), linear polarization (LPR), impedance spectroscopy (EIS), and Tafel polarization test. The results obtained suggested combined use of 1.6% nano and 9.4% micro-silica for achieving the most appropriate cost considering the increased useful life of concrete structures and the optimum reduction in rate of corrosion of concrete.