Insights into mechanothermal activation of kaolinite: A novel multistep process for cement precursors

Abstract

This study introduces a novel method for activating kaolinitic clays through mechanothermal activation (MTA), combining mechanical activation (MA) and thermal treatment to enhance kaolin’s pozzolanic reactivity at lower temperatures than traditional thermal activation (TA). MA effectively lowers kaolin’s dehydroxylation temperature, releasing significant hydroxyl groups at just 300 ◦C. Thermogravimetric analysis data confirms that implementing MTA unlocks the kaolinite dehydroxylation at 300 ◦C and 400 ◦C to a great extent and allows almost complete dehydroxylation at 500 ◦C. X-ray diffraction, surface area analysis, and particle size measurements revealed kaolin’s structural changes under MA, TA, and MTA treatments. The pozzolanic values achieved through MTA are significantly higher than those obtained with MA and TA at 300 ◦C, 400 ◦C, and 500 ◦C, as evidenced by reactivity tests. By enabling kaolinite activation at lower temperatures, MTA fosters a promising approach for developing sustainable building materials with a reduced carbon footprint.