Mechanical activation (MA) resulted in a rapid decrease in γ-
C2S amount to 49±8wt.%, and an increase of amorphous phase
to 37±8wt.%, Table 1. The amount of the β polymorph (13±1wt.%)
seemed not to be affected significantly by high energy milling. The
amorphisation of material during milling reflects the structural disorder
formed as a result of this treatment [35]. Moreover, Rietveld analysis
revealed a drop of crystallite size for both C2S polymorphs. This was
more pronounced for the γ phase, where the size decreased from 133
nm to 49nm. The size of the β grains decreased from 68 nm to 45 nm.
The different amorphisation of various minerals during high energy
milling has been reported in other research as well, e.g. Kriskova et al.
[31]. Themechanical activation also resulted in a decrease in the particle
size, Fig. 2. In detail, the d50 and d90 of sintered powder were 7 μm and
18 μm, respectively, and were reduced to 1 μm and 6μm, respectively,
after the mechanical activation. Concurrently, the BET specific surface
increased from 3.1m2/g to 6.2m2/g after mechanical activation.