Evaluation of corrosion protective properties of fly ash-red mud based geopolymer coating material for mild steel

Abstract

Geopolymeric materials are fabricated via alkali activation of aluminosilicate materials by utilizing waste materials containing amorphous silica and alumina. Fly ash, red mud, metakaolin and blast furnace slag are the most common choices for the preparation of geopolymer. Among various well known applications of geopolymer, protective coating application has received increasing attention in recent years. The present work aimed to develop corrosion protective geopolymer coating for mild steel utilizing fly ash, red mud, alkali activators and additives. Coating material was prepared by addition of water and organic additives to nano sized geopolymer precursor which was prepared through solid state chemistry route. Developed coating was coated on cleaned and treated mild steel using spray coating technique. Coated plates were evaluated for adhesion strength, scratch test, impact test, water absorption and corrosion resistance by accelerated salt fog test as per ASTM/IS standards. Based on the results it is found that the developed coating material provides excellent corrosion protection and helps to enhance the service life of mild steel based structures.