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Title: Kaolinite Clay for Enhancing the Properties of Alkali-Activated Slag and Fly Ash Binders

Author(s): Chathurani Chandrasiri, Zihui Li and Sulapha Peethamparan

Publication: Symposium Paper

Volume: 349


Appears on pages(s): 711-724

Keywords: acid leaching resistivity, alkali-activated slag/fly ash, compressive strength, kaolinite clay, nano-Silica

DOI: 10.14359/51732783

Date: 4/22/2021

The potential of using naturally occurring kaolinite clay as a low embodied energy fine material additive to enhance the performance of alkali-activated slag and fly ash binders are evaluated. The behavior of kaolinite clay (KC) containing systems was compared to that of the most popular nanoparticle, nao-silica (NS), incorporated binders. Kaolinite clay was added at 2 and 6 % by mass of the slag and fly ash to modify the early age hydration kinetics, strength development, and acid leaching resistance of alkali-activated binders. Sodium silicate solutions with a 1.5 silica modulus (SiO2 /Na2O) and a 2.5 or 5% Na2O% (by mass of the binder) respectively for slag and fly ash mixtures were used. Similarly to the nano-silica containing systems, higher dosages of kaolinite clay significantly improved the compressive strength of alkali-activated binder systems. Kaolinite clay fine particles accelerated the early age hydration kinetics and modified the microstructure developments. The clay incorporated alkali-activated binders outperformed that of nano-silica incorporated binders in the acidic environment.