Licorice (Glycyrrhiza glabra) as corrosion inhibitor of carbon steel reinforcing bars in mortar and its synergic effect with nitrite

Nitrites are effective corrosion inhibitors for concrete structures, but their toxicity leads to their total or partial substitution. Licorice and its synergic effect with nitrites are studied both in simulated pore solutions and in mortars with chlorides. EIS and polarization studies show that a 50% licorice + 50% Na₂NO₂ mix can reduce the corroding surface and the corrosion rate in solution. Moreover, the efficiency of this mix is higher than that of Na₂NO₂ when it is added to mortars with 0.8% Cl^-. The tested inhibitors, in the amount considered (0.2%), do not affect the mechanical properties of the mortars.