Pure monoclinic C3S phase used in this study was prepared by a
high-temperature calcination method. i.e., by the reaction of
calcium carbonate with silicon dioxide. To avoid carbonation, the
reaction was conducted under nitrogen environment. The reaction
mixture was kept at 1500 C for 2 h, followed by cooling down and
grinding the C3S product. The obtained product was re-calcined
until X-ray diffraction indicates that no other phases were present.
The XRD pattern of synthesized C3S samples is shown in Fig. 1. The
content of f-CaO was approximately 0.15 wt.%. The obtained C3S
powder had a nitrogen BET surface area of about 0.22 m2
/g.
(