TY - JOUR N2 - Two kaolin ores with the almost same fineness and purity of original kaolinite but possessing different kaolinite crystallinity (Hinckley Index) were selected to study the influence of crystallinity and calcination conditions on the pozzolanic activity of metakaolin after dehydroxylation. The different calcination conditions were conducted by altering the calcination temperature and holding time to obtain different metakaolin samples with different degrees of dehydroxylation. Then pozzolanic activities of metakaolin samples were tested by the modified Chapelle test, Frattini test and strength evaluations. Additionally, the apparent activation energies of two kaolin ores were calculated to study the thermal properties of kaolinite by isoconversional methods followed by iterative computations. The results showed that pozzolanic activities were dependent on the degree of dehydroxylation, except for the metakaolins calcined at 900℃ due to the fact that recrystallization and high pozzolanic activity was conducted by complete dehydroxylation (degree of dehydroxylation ≥ 90%). Moreover, the lower crystallinity of original kaolinite favored the removal of the structural hydroxyls, leading to a reduction of apparent activation energy and increase of pozzolanic activity, indicating that the higher calcination temperature or longer holding time was required during calcination to reach the same degree of dehydroxylation and finally highly ordered kaolinite converted into the less active metakaolinite, which was confirmed by the lower Ca(OH)2 consumption in the modified Chapelle test, higher [CaO] and [OH] in the Frattini test and weaker compressive strength. L1 - http://www.czasopisma.pan.pl/Content/119173/PDF/Liu-i-inni.pdf L2 - http://www.czasopisma.pan.pl/Content/119173 PY - 2021 IS - No 1 EP - 56 DO - 10.24425/gsm.2021.136295 KW - kaolin KW - crystallinity KW - calcination conditions KW - pozzolanic activity A1 - Liu, Yuanyuan A1 - Huang, Qian A1 - Zhao, Liang A1 - Lei, Shaomin PB - Komitet Zrównoważonej Gospodarki Surowcami Mineralnymi PAN PB - Instytut Gospodarki Surowcami Mineralnymi i Energią PAN VL - vol. 37 DA - 2021.03.28 T1 - Influence of kaolinite crystallinity and calcination conditions on the pozzolanic activity of metakaolin SP - 39 UR - http://www.czasopisma.pan.pl/dlibra/publication/edition/119173 T2 - Gospodarka Surowcami Mineralnymi - Mineral Resources Management ER -