Effect of potassium-chromate and sodium-nitrite on concrete steel-rebar degradation in sulphate and saline media

• 0.145 M K2CrO4 inhibitor admixture exhibited optimal performance in H2SO4 medium.
• 0.679 M NaNO2 inhibitor admixture exhibited optimal performance in NaCl medium.
• NaNO2 inhibitor admixture exhibited poor corrosion inhibition performance in H2SO4.
• Compressive tests showed that H2SO4 had adverse effect on the strength of concrete.
• Compressive tests showed that NaCl had no adverse effect on concrete strength.

In this paper, effect of potassium-chromate (K2CrO4) and sodium-nitrite (NaNO2) on concrete steel-rebar degradation in sulphuric-acid and in sodium-chloride media were studied. Electrochemical monitoring of open circuit potential and compressive strength effect of the different concentrations of these admixtures in steel-reinforced concretes immersed in the acidic/marine-simulating environments were analysed for detailing admixture performance. Results subjected to ASTM C876 interpretations showed that concrete admixed with 0.145 M potassium-chromate exhibited optimum inhibition effectiveness with good compressive strength improvement in the acidic medium. In the saline medium, the concrete admixed with 0.679 M sodium-nitrite exhibited optimal inhibition performance, but with reduction in concrete compressive strength.