Abstract

Limestone-calcined clay cements (LC3) reduce the environmental impact of cement production and accelerate the industry transition toward carbon neutrality. While conventional LC3 with 50% clinker replacement (LC3-50) demonstrate long-term performance comparable to ordinary Portland cement (OPC) in concrete, early-age performance is generally compromised. This study explores for the first time, joint thermal treatment—that is, co-calcination—of limestone (LS) and bulk kaolinitic clay in mass ratios of 1:1 to 1:4 under a calcination regime specifically designed to ensure activation of the clay mineral. The co-calcination converts a small fraction of LS to metastable CaO, thus providing an additional reactive calcium source during hydration. Microstructural, kinetic, and thermodynamic studies on systems with 50% clinker replacement are used to quantify enhanced early-stage in situ formation of portlandite, which promotes the precipitation of C−A−S−H and carboaluminate hydrates, that refine the pore structure and improve early-age strength—even in systems with low calcined clay content. A performance-efficiency index is used to indicate the improved mechanical and environmental performance of co-calcined blends as compared to traditional LC3. The approach offers a potential pathway to achieving higher clinker substitution levels.

Department(s)

Materials Science and Engineering

Second Department

Civil, Architectural and Environmental Engineering

Publication Status

Full Text Access

Comments

Arizona State University, Grant DMR 2228782

Keywords and Phrases

Carboaluminates; Co-calcination; Hydration; Limestone-calcined clay cement (LC3); Strength; Thermodynamic modeling

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 Feb 2026

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