Pozzolan Obtained by Mechanochemical Treatment of Kaolinite Clay

Abstract

Pozzolans are supplementary materials added to Portland cement in order to increase the mechanical strength and durability of concrete structures. A number of thermal, mechanical and chemical methods have been used to activate the reactive potential of pozzolanic materials. The aim of the study is to obtain pozzolana, from Serbian kaolinite clay by mechanochemical treatment. Kaolinite clay Garaši was subjected to mechanical treatment during different times of milling. The changes were monitored using particle size distribution (PSD) analyses, thermal methods [thermogravimetric analysis (TGA), and differential thermal analysis (DTA)] and X‐ray diffraction methods (XRD). The pozzolanic activity was determined using Chapelle method. Milling withing 20 min influences particle size decrease and after that time continuous increase. XDR analysis indicates gradual decrease of cristallinity with prolonged milling time. The higher values for pozzolanic activitie, expressed through consumption of gCa(OH)2 per gPozzolana are 0.78 and 0.77, and they were obtained for milling times 20 and 40 min, respectively. The values are comparable with commercial pozzolan—metakaolin. The results indicates that milling has caused the disintegration of particles and the consequent formation of new active surfaces in addition to changes in its physico‐chemical properties that decrease its crystallinity (through amorphization) and increase it reactivity.