Utilization potential of silica fume in fired clay bricks

Silica fume (SF) is an inorganic waste material which is generated during the elemental silicon and ferro-silicon alloy production. Due to the unique properties, it is utilized in several industries. However, very little information is available on the utilization potential of SF in traditional clay brick industry. In this study, the effect of different quantities of SF addition on the properties of fired clay brick was investigated. Test samples were produced by uniaxial pressing and fired at 800, 900, 1000 and 1100 degrees C. The microstructures of the samples were investigated by Scanning Electron Microscopy (SEM). The strength of the fired samples at 1000 and 1100 degrees C were significantly improved with SF addition. It was concluded that the reactive amorphous nature of SF particles enhances the sintering action locally and this gives better strength behaviour. SF addition also improved the efflorescence behaviour of the bricks. It was concluded that the effect of SF addition on the fired clay brick mainly depends on the firing temperature. At low firing temperatures, SF addition has a tendency to decrease the bulk density. However at higher firing temperatures, SF addition allows better sintering action with a drastic increase in bulk density.