Abstract

This study investigates the physicochemical and mechanical performance of cementitious composites incorporating fluidized bed combustion (FBC) ash under accelerated carbon dioxide (CO2) curing. FBC ash, due to its high contents of free calcium oxide (CaO) and sulfate (SO3), has been reported to cause challenges, such as volume instability and lower early-age strength. To address these limitations, CO2 curing was applied to promote accelerated carbonation and stabilize the hydration products. Cement paste and mortar samples, made with up to 40 % by cement weight replacement with FBC ash (labelled CF), were subjected to either CO2 curing or conventional water curing for 28 d. Compressive strength results indicated that CO2 curing significantly improved the mechanical performance at both early and later ages, especially for the CF (CaO-rich) series, due to the formation of calcium carbonate (CaCO3). Carbonation depth analysis and thermogravimetric analysis (TGA) confirmed extensive conversion of calcium hydroxide (Ca(OH)2) to CaCO3 in fully carbonated zones. X-ray diffraction (XRD) supported the disappearance of portlandite and intensified calcite peaks in CO2-cured samples. Nanoindentation measurements for CO2-cured cementitious materials incorporating CF demonstrated that carbonated regions exhibited 80 % higher compared to non-carbonated zones.

Department(s)

Civil, Architectural and Environmental Engineering

Publication Status

Full Text Access

Keywords and Phrases

CO2 curing; Fluidized bed combustion ash; Mineral carbonation; Nanoindentation; Thermogravimetric analysis (TGA); X-ray diffraction (XRD)

International Standard Serial Number (ISSN)

0950-0618

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 Elsevier, All rights reserved.

Publication Date

13 Jan 2026

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