Effects of Na: Al and water: solid ratios on the mechanical properties of fly ash based geopolymer

Abstract

Every segment industry infrastructure like onshore/offshore setup, power generation and water management is part of a complex system which involves large investment. Unfortunately, these infrastructures easily susceptible to be attacked by corrosion, resulting in hundreds of millions of dollars in losses. Conventionally, steel is protected by anticorrosive chromate coatings. But these coatings contain carcinogenic hexavalent chromium compound which may cause to environment and health related issues. To reduce those impacts, conventional coatings are replaced by water-based alternatives and inorganic coatings. Geopolymer as a green inorganic material with superior properties is in great research to be explored as a new coating material. The present paper outlines briefly the potential of geopolymer as a coating material through the mechanical performance test of adhesion and flexural strength. Scanning electron microscopy (SEM) was used to examine the morphology of geopolymer and unreacted fly ash matrix. The test was conducted by varying two aspects of Na: Al and water: solid ratios. The findings show both the alkali and water content plays a asignificant role in geopolymerization. The increase in water content at low Na/Al ratio causes dilution of activator thus resulted in decreased of adhesion and flexural strength.