STRENGTH AND MECHANISM OF PORTLAND CEMENT PREPARED FROM STONE COAL
VANADIUM SLAG
ZHANG Pengyu, OU Leming, LIU Kun*
(School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
*Corresponding author E-mail: LIU Kun ([email protected])
ABSTRACT
The strength and mechanism of Portland cement prepared from stone coal vanadium slag were studied in
this paper. Initially, the slag was used as silicon raw material to prepare clinker. By blending the prepared
clinker with gypsum, waste and fly ash, series grades of cement were prepared. All of performances of the
cements were up to the requirements of national standard of China. The hydration products and
microstructure of cement were identified and analyzed by X-ray diffraction and scanning electron
microscopy. With the comparison of cement hydration characteristics at different ages, the strength
formation mechanism of cements was clarified. The experimental results suggested that adding the fine
materials (mainly waste and fly ash) to replace part of clinker would accelerate cement hydration, as it
provided additional surface for the nucleation and growth of hydration products. And the hydration
products were familiar to ordinary Portland cement, mainly containing the amorphous calcium silicate
hydrates (C-S-H), acicular ettringite (AFt) and portlandite (CH). With hydration time increasing, the
hydration products continuously covered the cement particles, resulting in a thicker surface layer. As a
result, it gradually condensed into a dense structure block with small pores and smooth surface, which led
to higher strength. In a conclusion, using the vanadium slag to prepare Portland cement can realize the
utilization of solid mineral waste, which will bring huge ecological and economic benefits.
Figure 1 – Flexural and compressive strength of cement at different hydration ages
KEYWORDS
Stone coal vanadium slag, Cement, Strength, Hydration, Utilization