Organic corrosion inhibitor mixtures for reinforcing steel embedded in carbonated alkali-activated fly ash mortar

This paper evaluates the inhibitive effect of two mixtures of organic compounds, disodium β-glycerol phosphate (GPH) with sodium 3-aminobenzoate (3AMB) and GPH with sodium N-phenylanthranilate (PhAMB), on the corrosion of carbon steel reinforcement bars embedded in carbonated chloride-polluted ordinary Portland cement (OPC) and alkali-activated fly ash (FA) mortars. Mortar carbonation was achieved by maintaining the specimens in a carbon dioxide (CO2) atmosphere for 60 days at room temperature and 65% relative humidity. The OPC and FA mortars were partially immersed in a water solution containing 1% (by binder weight) chlorides (as NaCl), both in the absence and in the presence of the inhibitors.A carbonated synthetic solution containing 0.1 M NaCl simulating the pore chemistry in carbonated chloride-polluted mortars was used to obtain preliminary results on the efficiency of the corrosion inhibitors. Inhibitor efficiency was assessed in the solution by polarization curve recording and in the mortars by electrochemical impedance spectroscopy (EIS) analysis. The mixture of GPH with PhAMB showed the best protective properties.

► Inhibitive effect (IE) of two mixtures of organic compounds in carbonated SCP containing 0.1 M NaCl was investigated.
► IE of these mixtures in carbonated fly ash and cement mortars partially immersed in a solution containing 1% Cl− was studied.
► Inhibitor efficiency was assessed in the solution by polarization curve recording and in the mortars by EIS analysis.
► The mixture of GPH with PhAMB showed the best protective properties in solution.
► The efficiencies were higher in the fly ash mortars than in the cement mortars.