Characterization and evaluation of the hydraulic activity of water-cooled slag and air-cooled slag

Abstract

Water-cooled slag (WS) and air-cooled slag (AS) were characterized chemically and mineralogically and a comparative study of their reactivities with 10% and 20% lime was conducted using an accelerated chemical method. Both types of slag have the same chemical composition, but WS is completely vitreous materials and the main mineral composition of AS is gehlenite. The kinetics of the WS–lime and AS–lime reactions were investigated in suspension by the determination of the proportions of unreacted lime and the combined water up to 28 days. Both slags underwent hydration at room temperature. The rates of hydration were rapid in the first 3 days, but subsequently it depressed due to the formation of dense layer of hydration products on the unhydrated slag grains. The hydration products were identified by X-ray diffraction (XRD) and SEM combined with EDX. The hydration products formed depend on the lime contents. The results obtained suggest that AS may be used in the production of low strength building units or may be used with WS in the production of slag cement.