Utilisation of Fly Ash in Geobricks Produced By Pressure Forming Process

Abstract

In this experimental investigation, various geobricks were produced from F and C-type fly ash. A combination of sodium hydroxide (NaOH) and sodium silicate solution was used as alkaline activator. The fly ash based geobricks were treated at various heat treatment temperatures for different heat treatment hours. Following the compressive strength tests, density and water absorption measurements were conducted on the geobricks. Microstructures of the F-type fly ash based geobricks were also analysed by Scanning Electron Microscopy (SEM) technique. The effects of heat treatment temperature and duration on the physical and mechanical properties of geobricks were extensively investigated. The compressive strength of C-type fly ash based geobricks varied between 8 and 13 MPa. The strength of F-type fly ash based geobricks increased generally with increase in heat-treatment duration. It has been found that the effect of heat treatment temperature and heat treatment duration on the density of F-type and C-type fly ash based geobricks was not remarkable. The water absorptions of F-type fly ash based geobricks somewhat increased as the heat-treatment temperature increased. It was observed that geobricks have contained large amount of unreacted fly ash particles bound together by geopolymeric gel.