Multi-technique Approaches to Evaluate the Pozzolanic Properties of Alkali-Rich Calcined Kaolinite and Bentonite Clay Blends

Abstract This study presents an investigation of the reactivity of three clay blends containing kaolinite and bentonite using various experimental techniques. Two of the clay blends were fused with alkali hydroxides via co-calcination to achieve better reactivity. The reactivities of thermally activated clays were evaluated using inductively coupled plasma-optical emission spectrometry (ICP-OES), in situ attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and the rapid, relevant, and reliable (R3) test. The ICP-OES test was used to measure the solubility rate of silicon and aluminum from the clay blends with and without alkali addition. In situ ATR-FTIR was used to monitor the portlandite and calcium silicate hydrate peak changes at the early stage of the reaction. Eventually, both ICP-OES and ATR-FTIR test results were analyzed in comparison to that of the standard R3 test. It was observed that silicon and aluminum solubility measurement using ICP-OES can be an effective method for quick screening of the reactivity of a large number of samples with minimal sample preparation.