Corrosion inhibition and adsorption behavior of (3-aminopropyl)-triethoxysilane on steel surface in the simulated concrete pore solution contaminated with chloride

Predicted Corrosion Performance of Organofunctional Silane Coated Steel Reinforcement for Concrete Structures: An Overview

“…Organofunctional silane (3-aminopropyl)-triethoxysilane or similarly named gammaaminopropyltriethoxysilane (APS, APTS) was successfully tested as a corrosion inhibitor of mild steel in simulated concrete pore solutions and against the action of chloride anions (admixed inhibitor) [264,265]. It was found that the inhibition efficiency of this organosi-lane in a simulated concrete pore solution of pH 12.5 with the addition of 3.5% NaCl is better than that of N,N'-dimethylethanolamine (DMEA) by approximately 27%.…”

“…Compared to this alkanolamine inhibitor, APS inhibitor has a stronger adsorption ability and has a higher inhibition effect on the anodic dissolution of iron and cathodic reduction of oxygen. Compared to DMEA adsorption (adsorption to the surface takes place with a lone pair of electrons of nitrogen and/or oxygen atoms donate to the vacant d-orbital of an iron atom-i.e., coordination bond or in other words donor-acceptor relationship), silane adsorption is based on promoted hydrolysis by alkaline media and stable Si-O-Me bonds are formed (the detailed mechanism will be described below) [264][265][266][267]. Adsorbed molecules of both substances are shown on the mild steel surface in Figure 11.…”

“…It turns out that the inhibitory effect of APS is more significant in carbonated concrete pore solution (lower pH solution-content of e.g., NaHCO 3 /Na 2 CO 3 ) than in the usual simulated concrete pore solution (saturated Ca(OH) 2 sometimes with additions of NaOH/KOH). In the case of carbonated concrete pore solution, there is physical adsorption and at the same time chemical adsorption of APS on steel surface (adsorption energy is relatively high), while in simulated concrete pore solution there is only physical adsorption such as van der Waals force and electrostatic force (adsorption energy is low) [265]. APS functional solutions can also be used as an electro-migrating (EM) inhibitor (cationic inhibitory chemicals) in the form of protection of concrete reinforcement [268,269] as part of electrochemical treatments, both in the ERA method (electrochemical re-alkalization, i.e., re-increasing alkalinity of the pore solution of carbonated concrete at the phase interface of reinforcing rebars and cement paste) [270,271] and the ECE method (electrochemical chloride extraction, i.e., removal of chloride anions in contaminated concrete at the phase interface of reinforcing rebars and cement paste) [272,273].…”

Effect of Immersion Time in Chloride Solution on the Properties of Structural Rebar Embedded in Alkali-Activated Slag Concrete

“…The values of these parameters have been obtained using a complex least-square nonlinear program (CNLS) [19]. In addition, the EIS test allows the diffusion coefficient to be calculated and the degree of porosity of the material to be related [20]. Finally, the Bode plots have been simulated using the equivalent electrical circuit in Figure 3.…”