Effectiveness of corrosion inhibitors in simulated concrete pore solution

Abstract

Steel embedded in concrete is normally in a passive state against corrosion due to a thin iron oxide layer that forms on the steel surface and remains stable in the high alkaline environment of the concrete. This protective film must be destroyed (depassivation) and this can be mainly done in two ways: by the attack of chlorides on the steel (seawater, de-icing salt, unwashed sea sand, admixtures etc.) or by carbonation. Corrosion inhibitors may be a good alternative to protection steel against corrosion due to its lower cost and easy application. Many researchers are inclined to use surface applied corrosion inhibitors and prefer to use the Cl-/inhibitor parameter as an indication of chloride inhibitor threshold level. The objective of this study was to fill the gap left by public research in developing methods of corrosion control of reinforcement in concrete by synthetic solutions to emulate concrete environment. Three inhibitors were distinguished as passivation inhibitors in real solution extract and synthetic. In this study the tests with calcium nitrite (CNI), sodium monoflurophosphate (MFP) and ethanolamine based inhibitors showed reductions in the overall rates of corrosion after the inhibitive treatments.

Novel green plants extract as corrosion inhibiting coating for steel embedded in concrete

“…The impedance spectra for different Nyquist plots were analyzed by fitting the experimental data to a simple equivalent circuit model Rel + Cf/Rf + Cdl/ R ct for steel treated with inhibitors (Simescu and Idrissi, 2009; Elshami et al , 2018). The impedance spectra for different Nyquist plots were analyzed by fitting the experimental data to simple equivalent circuit (Figure 7) which includes the medium resistance (Rel) and the double layer capacitance (Cdl) which is placed in parallel to Aubepine and Molokhia coating resistance R ct , Rf (Eddy and Odiongenyi, 2010).…”

“…The electrochemical impedance spectroscopy (EIS) technique was used to investigate the change in the electrochemical properties of the passive film formed on the metal surface when steel is immersed in solutions. The electrochemical measurements were carried out after six days of immersion (Elshami et al , 2017).…”

“…The stability was set to be zero mV/sec. This means that the test will be terminated only when the total time ends. Sample area : The sample surface area in (cm 2 ) that is immersed in the solution (Kavitha et al , 2014; Elshami et al , 2017). …”

“…Sample area : The sample surface area in (cm 2 ) that is immersed in the solution (Kavitha et al , 2014; Elshami et al , 2017).…”

“…Very high scan rates lead to unreliable data; however, very low scan rate elongate the test period. The applied scan rate was 0.1 mV/s (Sankara Narayanan et al , 2006; Elshami et al , 2018).…”