Abstract

Aluminosilicate resources from unconventional sources offer promising potential for developing low-carbon supplementary cementitious materials (SCMs), yet their activation typically requires energy-intensive thermal processing. Kaolinite is a geographically abundant and highly attractive precursor clay mineral to reduce the clinker factor in concrete. By integrating mechano- and thermo- chemistry sequentially in a novel hybrid mechano-thermal activation (MTA) strategy for clay mineral activation, the dehydroxylation of pure kaolinite polymorphs KGa-1b and KGa-2 for enhanced pozzolanic reactivity is unlocked at temperatures that are lower than those needed for conventional thermal activation (TA). The mechano-chemical activation (MCA) step that induces significant structural defects and disorder facilitates further structural transformations under milder imposed temperatures, thus enhancing the reactivity of the final product. For the first time, the mechano-chemically amorphized material is quantitatively characterized by isoconversional kinetic analysis to rationally inform the design of post-milling calcination regime. Solid-state NMR reveals the trend of progressive increase in the population of reactive AlV and AlIV coordination sites, along with soluble Q4mAl species, across the MCA, MTA, and TA pathways. Additionally, XRD patterns, thermogravimetry, and FTIR spectroscopy provide further unique insights into the mechanisms and extent of mineralogical evolution induced by the MTA process, which yields ∼[jls-end-space/]25% higher reactivity relative to the precursor MCA materials under the applied post-milling thermal treatment. These findings highlight the critical influence of adopted thermal regime following MCA on the reactivity of the activated kaolinite and demonstrate the potential for process optimization in the synthesis of high-performance pozzolans.

Department(s)

Materials Science and Engineering

Second Department

Civil, Architectural and Environmental Engineering

Publication Status

Full Text Access

Keywords and Phrases

Calcination; Kaolinite; Mechano-chemical activation; Mechano-thermal activation; Supplementary cementitious materials; Sustainability

International Standard Serial Number (ISSN)

0008-8846

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 Elsevier, All rights reserved.

Publication Date

01 Jun 2026

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