Okeniyi J.O., Oladele I.O., Omoniyi O.M., Loto C.A., Popoola A.P.I.
Mechanical Engineering Department, Covenant University, Ota, Nigeria; Chemical and Metallurgical Engineering Department, Tshwane University of Technology, Pretoria, South Africa
Okeniyi, J.O., Mechanical Engineering Department, Covenant University, Ota, Nigeria; Oladele, I.O., Mechanical Engineering Department, Covenant University, Ota, Nigeria; Omoniyi, O.M., Mechanical Engineering Department, Covenant University, Ota, Nigeria; Loto, C.A., Mechanical Engineering Department, Covenant University, Ota, Nigeria, Chemical and Metallurgical Engineering Department, Tshwane University of Technology, Pretoria, South Africa; Popoola, A.P.I., Chemical and Metallurgical Engineering Department, Tshwane University of Technology, Pretoria, South Africa
This paper studied corrosion-inhibition and compressive-strength performances of Na<inf>2</inf>Cr<inf>2</inf>O<inf>7</inf> (sodium dichromate) and C<inf>10</inf>H<inf>14</inf>N<inf>2</inf>Na<inf>2</inf>O<inf>8</inf>·2H<inf>2</inf>O (ethylenediaminetetraacetic disodium salt: EDTA-Na2) admixtures in steel-reinforced concrete immersed in NaCl and in H<inf>2</inf>SO<inf>4</inf> corrosive environments. Electrochemical methods were used for studying corrosion responses of different concentrations of the individual admixtures and their synergies, in the model that partially replace the toxic Na<inf>2</inf>Cr<inf>2</inf>O<inf>7</inf> by the environmentally-friendly C<inf>10</inf>H<inf>14</inf>N<inf>2</inf>Na<inf>2</inf>O<inf>8</inf>·2H<inf>2</inf>O, in steel-reinforced concretes. After the electrochemical experiment, the steel-reinforced concrete samples were subjected to the compressive-strength testing and analyses of ASTM C39/C39M-03 and ASTM C267-01(2012). Results showed that the use of environmentally-friendly EDTA-Na<inf>2</inf> for partially replacing toxic Na2Cr2O7 chemical exhibited better corrosion-inhibition and compressive-strength improvement in the NaCl-immersed concretes, than in the H2SO4-immersed concretes. The 2 g Na<inf>2</inf>Cr<inf>2</inf>O<inf>7</inf> + 6 g EDTA-Na<inf>2</inf> admixture (representing partial replacement model of 6 g Na<inf>2</inf>Cr<inf>2</inf>O<inf>7</inf> by 6 g EDTA-Na<inf>2</inf>) exhibited optimal corrosion inhibition efficiency (η = 99.0%) and very good compressive-strength improvement advantage in the NaCl-immersed concretes. In contrast, comparatively low compressive-strength reduction tradeoff with the good inhibition effectiveness of η = 79.9% support use of 6 g EDTA-Na<inf>2</inf> admixture only (i.e., without Na<inf>2</inf>Cr<inf>2</inf>O<inf>7</inf> addition) for inhibiting reinforcing-steel corrosion in the H<inf>2</inf>SO<inf>4</inf>-immersed concretes.
Columns (structural); Composite structures; Concrete additives; Concrete testing; Concretes; Corrosion; Corrosion inhibitors; Reinforced concrete; Steel testing; Compressive strength testing; Corrosion inhibition; Corrosion inhibition efficiency; Corrosive environment; Electrochemical experiments; Low compressive strengths; Statistical distribution; Steel reinforcements; Compressive strength; compressive strength; concentration (composition); corrosion; reinforced concrete; sodium chloride