EPOXY BARRIER COATINGS REINFORCED WITH SOLIDIFIED-WASTE MICROFILLERS FOR AGGRESSIVE ACIDS

Abstract

This paper designs and evaluates three-layer epoxy protective systems for concrete and metal substrates that incor- porate microfillers derived from solidified neutralization sludge alongside quartz flour and glass flakes to achieve high chemi- cal resistance with circular-materials benefits. Formulations are spray-applied and assessed by pull-off adhesion per EN ISO  4624, 28-day exposures to HCl, H2SO4, CH3COOH, and HNO3, and SEM of matrix–filler interfaces to confirm dispersion and interfacial cohesion. The coatings retain  adhesion  after  HCl  and H2SO4 immersion, show severe degradation in acetic acid, and exhibit marked adhesion loss in nitric acid, with failure typically in the concrete substrate except under the harshest oxidizing conditions. SEM reveals effective encapsulation of treated sludge particles within the epoxy matrix and strong interlayer bonding, indicating low risk of pollutant release during service. Critically, substituting primary fillers with solidification by-products does not diminish adhesion or chemical resistance relative to a reference epoxy system, demonstrating a viable  route to sustainable polymer coatings for chemically aggressive environments.