(259p) Design of Corrosion Inhibitors in Concrete Pore Solution: Modelling and Experimentation

Concrete, a complex composite material, is the single most widely-used material in the world. Its strength decreases when loaded in tension and, therefore, it is a common practice to reinforce concrete with steel to improve the tensile mechanical properties. Generally, all concrete structures contain reinforcing steel and degradation of this reinforced steel i.e., corrosion, is a major problem of worldwide significance. This steel degradation leads to plant shutdowns, resource waste, loss/contamination of product, reduction in efficiency and maintenance issues. Several corrosion inhibitors have been developed to address the problem of corrosion in different working environments. Usually, development of a corrosion inhibitor is an experimental approach where one uses prior knowledge to suggest potentially effective compounds. This development approach is normally time consuming and expensive. In order to accelerate the process of developing new, novel and (potentially) more effective corrosion inhibitors, we propose the use of a computer aided molecular design (CAMD) algorithm based on the Signature molecular descriptor (J. V. Faulon). In CAMD, we make use of computer-implemented algorithms to design molecule with optimal desired properties. A quantitative structure-property relationship (QSPR) model is created for the property of interest and it is employed to generate structures that have the desired properties (J. M. Faulon). We use this in developing corrosion inhibitors that can effectively inhibit corrosion of carbon steel (CS 1018) in a solution that mimics the environment inside a concrete pore.

Previously, CAMD has been used for designing chemical admixtures: shrinkage-reducing admixtures (SRAs) (Kayello HM). For SRAs the property of interest is the surface tension of compounds in aqueous solutions as this relates to the shrinkage in concrete. Five new compounds were identified, which performed similar to the commercial admixtures but had different chemical functionalities and better strength development.

Our property of interest in this work is corrosion inhibition efficiency (Soylev) and this tells us the percent that a compound inhibits the degradation of the carbon steel in a concrete pore solution. Our training set consists of ten commonly used and commercially available corrosion inhibitor compounds. We run electrochemical impendence spectroscopy (EIS) and poteniodynamic cyclic polarization for our concrete pore solution loaded with the different corrosion inhibitors to determine their respective efficiencies. Then we apply our CAMD algorithm to identify and, ultimately, confirm new corrosion inhibitors. References

Faulon, J.L.,Brown,W.M.,& Martin,S. "Reverse engineering chemical structres from molecular descriptors: How many solution?" Journal of Computer-Aided Molecular Design (2005): 637-650.

Faulon, J.L.,Churchwell,C.J.,& Visco,D.P.,Jr. "The signature molecular descriptor.2.Enumerating molecules from their extended valence sequences." Journal of Chemical Information and Computer Sciences (2003): 721-734.

Kayello HM, Tadisina, NKR, Shlonimskaya N, Biernacki JJ, Visco DP. "Application of Computer-Aided Molecular Design (CAMD) Using the Signature Molecular Descriptor-Part 1. Identification of Surface Tension Reducing Agents and the Search for Shrinkage Reducing Admixtures." Jornal of the American Ceramic Society (2013): 1-13.

Soylev, T.A., & Richardson, M.G. "Corroson Inhibitors for steel in concrete: State-of-the-art report." Construction and Building materials (2008): 609-622.