Calcined Clays as Supplementary Cementitious Materials for Sustainable Construction: A Systematic Comparative Review of Mineralogy, Calcination Conditions, and Performance Outcomes
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Authors
Kalatehjari, Roohollah
Rotimi, Funmilayo Ebun
Bihari, Renuka
Moshood, Taofeeq Durojaye
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Journal Article
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MDPI AG
Abstract
Cement production accounts for approximately 8% of global CO2 emissions, and while calcined clays have attracted growing attention as supplementary cementitious materials, the literature remains fragmented across clay types and performance metrics, with no unified comparative framework examining how mineralogical composition and calcination conditions jointly govern pozzolanic reactivity and downstream performance outcomes. This study addresses that gap through a PRISMA-guided systematic review of 32 peer-reviewed studies, validated by structured expert interviews, and a comparative assessment of five calcined clay categories: metakaolin (MK), limestone-calcined clay blends (LC3), illite-rich clays, montmorillonite (MM)- based clays, and ceramic waste (CW)- derived clays. Findings establish clear performance hierarchies with direct implications for the construction sector. MK at 10–15% cement replacement delivers compressive strength gains of 8–36%, chloride permeability reductions of 61–87%, and sulphate expansion reductions of up to 89%, confirming its suitability for high-performance, chemically aggressive-environment structural concrete. LC3 systems enable 30–50% clinker substitution, yielding an estimated 30–40% embodied CO2 reduction alongside 6–10% strength gains and 64–90% reductions in chloride migration, representing the most significant decarbonisation opportunity reviewed. Illite-rich clays reduce compressive strength by 6–25%, limiting application to non-structural uses despite moderate durability gains. MM-based clays exhibit highly variable performance, ranging from a 60% strength loss to an 8% gain, with workability penalties of up to a 90% slump reduction, constraining adoption. CW-derived clays achieve 50–69% reductions in chloride diffusion while valorising industrial waste, though strength reductions of 11–20% limit structural applications. Across all clay types, superplasticiser demand increases by 1.5–3.6 times, posing a universal cost and logistics challenge for practitioners in mix design.Description
Keywords
1201 Architecture, 1202 Building, 1203 Design Practice and Management, 3301 Architecture, 3302 Building, 4005 Civil engineering, calcined clay, metakaolin, LC³, supplementary cementitious materials, sustainable concrete, pozzolanic reactivity, concrete durability, construction decarbonisation
Source
Buildings, ISSN: 2075-5309 (Online), MDPI AG, 16(8), 1608-1608. doi: 10.3390/buildings16081608
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Copyright: © 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.