Calcium Silicate Materials: Substitution of Hydrated Lime by Ground Granulated Blast Furnace Slag in Autoclaving Conditions

This paper deals with progressive substitution of hydrated lime by granulated blast furnace slag to produce new calcium silicate materials obtained by autoclaving, representing an alternative economic raw material. The slag grain-size grinding and the heat treatment in saturated vapor pressure autoclave conditions were investigated to study the compressive strength behavior of the new material. The results showed a decrease in compressive strength from the substitution. The microstructure analysis showed that reaction products consist mainly of 11 Å tobermorite and xonotlite. When increasing the autoclave temperature, it results in an increase in xonotlite relative to tobermorite. It is also observed that the amorphous composition of granulated blast furnace slag does not release new distinct phases of hydrates. The autoclaved products were characterized using X-ray diffraction (XRD) technique and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDX).