Mechanochemical treatment of Serbian kaolin clay was carried out in a
planetary ball mill using two different milling media, hardened steel or
zirconia vials and balls. The samples obtained with various milling times
were characterized by the particle size laser diffraction (PSLD), X-ray
diffraction (XRD), differential scanning calorimetry/thermogravimetry
(DTA/TGA) and Fourier-transform infrared (FTIR) analyses. Mechanochemical
treatment induced amorphization of the kaolinite phase accompanied by
dehydroxylation. It was found that for the given milling parameters,
amorphization mainly took place in the milling period up to 15 min, and was
completed after about 30 min of milling for both milling media used. The
pozzolanic activities were determined by the Chapelle method. Milling in the
hardened steel milling medium had no significant influence on pozzolanic
activity, even though there was accumulated iron contamination. For both
milling media, pozzolanic activity of 0.79 was obtained for the samples
milled for 15 min and it remained almost unchanged with prolonged milling.
The determined pozzolanic activity values are close to these of commercial
metakaolinite or metakaolinite obtained by the calcination of the same clay,
therefore, indicating possibility for obtaining high reactive pozzolana by
mechanochemical treatment of Serbian kaoline clay.
Mechanochemical treatment of Serbian kaolin clay to obtain high reactive pozzolana