Utilization of CO2 in direct aqueous carbonation of concrete fines generated from aggregate recycling: Influences of the solid-liquid ratio and CO2 concentration

JOURNAL OF CLEANER PRODUCTION

卷:312

Article

Ho, Hsing-Jung¹  Iizuka, Atsushi²  Shibata, Etsuro²  Tomita, Hisashi³  Takano, Kenji³  Endo, Takumi³ 

[1] Tohoku Univ, Grad Sch Environm Studies, Dept Environm Studies Adv Soc, Aoba Ku, Aoba 468-1 Aramaki, Sendai, Miyagi 9800845, Japan

[2] Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Ctr Mineral Proc & Met, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi 9808577, Japan

[3] IHI Corp, Ctr Engn, Carbon Solut Business Unit, Resources Energy & Environm Business Area, 1-1 Toyosu 3 Chome Koto Ku, Tokyo 1358710, Japan

关键词: CO2 utilization;    Direct aqueous carbonation;    Concrete fines;    Aggregate recycling waste;    Atmospheric pressure;    Low purity CO2;   

DOI  :  10.1016/j.jclepro.2021.127832

来源: Elsevier

【 摘 要 】

Development of an effective aggregate recycling process for concrete waste is an important issue. During aggregate recycling, the hydrated cement fraction in concrete that decreases the quality of recycled aggregate is removed, and this yields concrete fines as a by-product. Appropriate treatment of the concrete fines is needed to improve the feasibility of aggregate recycling. In this study, concrete fines from aggregate recycling were used for CO2 utilization through direct aqueous carbonation with a low energy input using low-purity CO2 at atmospheric pressure. Two samples of actual concrete fines and one of synthetic concrete fines were compared in these experiments. The differences between CO2 uptake efficiencies were explained according to the characteristics of the different concrete fines. Solid-liquid ratio and concentration of introduced CO2 were studied and their effects on the reaction were determined and explained according to the three main steps of direct aqueous carbonation, Ca extraction, CO2 dissolution, and CaCO3 precipitation. The results are supported by and compared to the literature based on the carbonation mechanism and kinetics. Additionally, the mechanisms of particle collision and solidification were observed, and their effect was determined by several characterization analyses. The CO2 uptake efficiency was compared with those from other studies, which proves concrete fines are a promising candidate for direct aqueous carbonation. The present method under atmospheric pressure with a low CO2 concentration was effective for CO2 utilization with concrete fines and had a CO2 uptake capacity of 0.13 g-CO2/g-concrete fines.

【 授权许可】

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