Effect of high temperature exposure on Kaolin geopolymer

Abstract

The geopolymer material is a green material which produce less emission of CO2 and less energy consuming material compare to Portland Cement (PC) materials. An experimental study the effect of high temperature exposure on kaolin geopolymers is carried out. The kaolin powder form was mixed with alkali activator to produce geopolymers paste then moulding into the steel mould. The sample molded will undergoes curing at temperature 60˚C for 3 days to become solid cube then sample will demould and samples were exposure to high temperature from 200oC to 800oC. The samples were then tested and characterized on their physical observation, density, compressive strength, chemical composition analysis, microstructural analysis, functional group identification and thermogravimetric analysis. Samples were unexposed to high temperature shows no cracking appear while samples were exposed to high temperature shows increasing of crack. The compressive strength and density of unexposed samples was highest and its density and strength decreased with increasing temperature exposure. From the chemical composition analysis shows the raw material which is kaolin present of high percentage of silica oxide and aluminium oxide. From microstructural analysis, compact structure and more geopolymeric gel form at unexposed samples while samples exposed to high temperature seem shows loosely pack structure and larger precipitate. Based on functional group analysis, geopolymers bonding at peak range of 900 to 1000 cm-1 shows the greater bonding of geopolymer. Thermogravimetric analysis shows all samples undergoes loss water at temperature below 100˚C and samples stables up to temperature 700˚C to 800˚C. This study shows that kaolin geopolymer can sustain the high temperature environment and overcome weakness of Ordinary Portland Cement (OPC).