Development of Fly Ash Based Geopolymer as Erosion Mitigation Coating

Abstract

Loss of durability of concrete materials in sewage and chemical treatment facilities exposed to acidic environments is a key issue that affects the life cycle performance. Applications of organic coating such as epoxy and acrylic usually covers the concrete surface by physical addition normally failed to act as an effective coating due to debonding when the organic coating absorbs water. In this work, geopolymer was used as alternative material for concrete coating. Preparation of geopolymer involved fly ash, a materials containing high aluminosilicate and calcium mixed with various concentrations (6, 8 and 12M) of sodium hydroxide (NaOH). Subsequently, all samples were tested and analysed through compressive strength test and gel time. Geopolymers synthesised from 12M NaOH concentration exhibited high compressive strength and low gel time, hence was chosen as a coating for the concretes for the erosion evaluation. Results show that, concretes coated with geopolymers yielded low percentage of mass loss compared to the uncoated concretes. This suggest that geopolymers has high potential to be used as erosion mitigation coating to prevent the concretes from degrading due to the acidic environment.