Electrochemical injection of organic corrosion inhibitors into carbonated cementitious materials: Part 2. Mathematical modelling

A mathematical model is presented for simulation of changes in the pore solution phase chemistry of carbonated hardened cement paste when aqueous solutions of organic base corrosion inhibitors are applied to the surface of the material and constant current densities in the range of 1–5 A/m2 are passed between anodes placed within the inhibitor solutions and steel mesh cathodes embedded within the paste. The model, based on the Nernst–Planck equation, is used to predict the concentration profiles of electrochemically injected inhibitors and the major ionic species present within the pore electrolyte. For two specific organic base inhibitors with widely different pKa values, viz. ethanolamine (pKa 9.5) and guanidine (pKa 13.6), the model predictions are compared with experimental results described in Part 1 of the investigations.