Journal of Advanced Concrete Technology
Online ISSN : 1347-3913
ISSN-L : 1346-8014
Scientific paper
Cold-sintered Carbonated Concrete Waste Fines: A Calcium Carbonate Concrete Block
Ippei MaruyamaNgoc Kien BuiAmr MeawadRyo KuriharaYuji MitaniHikotsugu HyodoManabu KanematsuTakafumi Noguchi
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2024 Volume 22 Issue 7 Pages 406-418

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Abstract

Cementitious materials generally have large carbon footprints because of the high CO2 emitted during Portland cement production. This is because limestone is used as an essential CaO resource, and its decomposition by calcination emits CO2. From this perspective, the concrete in urban buildings can be considered an urban mine of CaO resources. In this study, we propose obtaining a solidified product by crushing all the waste concrete, carbonating it, pressurizing it with a calcium bicarbonate solution, and drying it. The experimental results show that the bicarbonate solution, high-temperature conditions, and extended loading period produce a higher strength. In addition, neck growth at the contact surfaces of the carbonated concrete fines was confirmed using scanning electron microscopy. Consequently, the proposed method indicates that the hardening mechanism is the cold sintering of calcium carbonate on the surface of fine-carbonated concrete particles. This method allows the developed blocks to be used semi-permanently with relatively low energy consumption through repeated crushing and re-pressurization.

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© 2024 by Japan Concrete Institute
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