Effect of potassium-chromate and sodium-nitrite on concrete steel-rebar degradation in sulphate and saline media
- a Mechanical Engineering Department, Covenant University, P.M.B.1023, Ota, Nigeria
- b Chemical and Metallurgical Engineering Department, Tshwane University of Technology, Pretoria, South Africa
- Received 15 July 2011, Revised 28 September 2013, Accepted 29 September 2013, Available online 19 October 2013
Highlights
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0.145 M K2CrO4 inhibitor admixture exhibited optimal performance in H2SO4 medium.
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0.679 M NaNO2 inhibitor admixture exhibited optimal performance in NaCl medium.
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NaNO2 inhibitor admixture exhibited poor corrosion inhibition performance in H2SO4.
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Compressive tests showed that H2SO4 had adverse effect on the strength of concrete.
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Compressive tests showed that NaCl had no adverse effect on concrete strength.
Abstract
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.
Keywords
- Concrete steel-rebar;
- Potassium-chromate and sodium-nitrite inhibitors;
- Microbial/marine-simulating environments;
- Normal and Weibull distributions;
- Kolmogorov–Smirnov statistics;
- Compressive strength of concrete
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