The effect of basic oxygen furnace slag and fly ash additions in triaxial porcelain composition: phase and micro structural evolution

Basic oxygen furnace (BOF) slag generated in iron and steel industries were gradually added in a standard triaxial vitrified porcelain tile composition substituting feldspar. Fly ash, a by product of thermal power plant was used as filler by replacing quartz in part or full. The effect of such additions on the physico-mechanical properties of the samples fabricated by ceramic processing technique and heated in the temperature range of 1,050-1,200 A degrees C have been investigated. Out of seven compositions studied, three were selected for detailed investigation on the basis of their lower vitrification temperature. Among three, two have shown early vitrification at 1,150 A degrees C and resulted in highest flexural strength (> 70 MPa), while another one vitrified at 1,200 A degrees C and resulted in lower strength (similar to 55 MPa). This variation in mechanical properties is correlated with their densification behaviour, XRD and SEM data. X-Ray diffraction studies confirm the presence of anorthite (CaAl2Si2O8), mullite (Al6Si2O13), fayalite(Fe2SiO4), quartz (SiO2), enstatite(MgSiO3). The weight percentages of crystalline and glassy phases have also been calculated form Rietveld analysis of XRD data. The SEM photomicrographs on selected vitrified specimens supported the XRD observation. The paper also discusses the application of such vitrified products in construction industries