Reinforcement corrosion due to chloride attack is of major economic significance for reinforced concrete structures. Pozzolans are known to inhibit corrosion initiation mainly by reducing concrete permeability. However, there is evidence in the literature that changes in the chemical environment in the concrete due to the pozzolans may be creating improved corrosion resistance, by themselves. In this study, the composition of a pore solution of mature hydrated cement paste containing silica-fume at different ratios was analyzed. The electrochemical behavior of reinforcing steel was studied in simulated pore solutions with silicate concentrations ranging from 0 to 35.6 mM, which are within the concentration range found by pore solution extraction to be up to 49 mM. Polished reinforcing steel specimens were used for cyclic voltammetry in simulated pore solutions with chloride concentrations of 10-20%. Better corrosion protection was found with increasing silicate concentration up to 3.56 mM. This was indicated by lower corrosion currents both in the passive state and after anodic activation. Anodic activation of steel in a 35.6 mM silicate solution with 20% NaCl yielded a higher potential than the anterior potential.
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Subject: Chemistry and Materials Science - Biomaterials
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