Corrosion of self-curing waterborne zinc oxide-potassium silicate coating modified with aluminium powder

To protect the steel bars against the corrosion in autoclaved aerated concrete (AAC), a new approach of preparing the self-curing waterborne zinc-oxide-potassium silicate coating modified with aluminium powder was proposed. In addition to the mechanical properties, the corrosion behavior of coatings were characterized by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to investigate the phase component, chemical structure and micrograph of the coatings, respectively. With the addition of aluminium powder, the adhesion strength, impact toughness and alkali resistance of coating increased. Moreover, potassium silicate reacted with calcium hydroxide and strengthened the bonding between steel bar and AAC matrix. Furthermore, EIS and PDP results revealed that the coating modified with aluminium powder had the better anticorrosive performance depending on the combined effect of physical shielding and cathodic protection. (C) 2019 Elsevier B.V. All rights reserved.