TY - JOUR
T1 - Phase assemblance evolution during wet carbonation of recycled concrete fines
AU - Shen, Peiliang
AU - Zhang, Yangyang
AU - Jiang, Yi
AU - Zhan, Baojian
AU - Lu, Jianxin
AU - Zhang, Shipeng
AU - Xuan, Dongxing
AU - Poon, Chi Sun
N1 - Funding Information:
The authors wish to acknowledge the financial supports of the Research Grant Council (GRF), the Construction Industry Council and the Strategic Public Policy Research (SPPR) Funding Scheme for financial support. We also gratefully acknowledge the equipment support of the University Research Facility on Chemical and Environmental Analysis (URFCE) of PolyU.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/4
Y1 - 2022/4
N2 - In this work, recycled concrete fine (RCF), one of the major products generated from waste concrete recycling process, was carbonated in water. The carbonation mechanism of RCF is investigated, aiming to bring forward the basic understanding of carbonation mechanism and develop value-added products. It was found that the CO2 dissolution and calcite precipitation limited the carbonation process for the initial stage. Afterwards, the kinetics was dominated by the dissolution of RCF. Portlandite was firstly consumed and the decalcification of C-S-H involved three steps associated with pH development of the aqueous environment. The main carbonation products were calcite, amorphous calcium carbonate (CC), alumina-silica gel, silica gel and alumina gel. The formed CC was turned from a poorly-crystalline layer into aggregated calcite grains. Meanwhile, a silica-rich layer was still located at the outermost surface of carbonated RCF. The carbonated RCF had a significantly high pozzolanic reactivity, being reused as supplementary cementitious materials.
AB - In this work, recycled concrete fine (RCF), one of the major products generated from waste concrete recycling process, was carbonated in water. The carbonation mechanism of RCF is investigated, aiming to bring forward the basic understanding of carbonation mechanism and develop value-added products. It was found that the CO2 dissolution and calcite precipitation limited the carbonation process for the initial stage. Afterwards, the kinetics was dominated by the dissolution of RCF. Portlandite was firstly consumed and the decalcification of C-S-H involved three steps associated with pH development of the aqueous environment. The main carbonation products were calcite, amorphous calcium carbonate (CC), alumina-silica gel, silica gel and alumina gel. The formed CC was turned from a poorly-crystalline layer into aggregated calcite grains. Meanwhile, a silica-rich layer was still located at the outermost surface of carbonated RCF. The carbonated RCF had a significantly high pozzolanic reactivity, being reused as supplementary cementitious materials.
KW - Calcium carbonate
KW - Microstructure
KW - Recycled concrete fines, Carbonation kinetics
KW - Silica gel
UR - http://www.scopus.com/inward/record.url?scp=85123601799&partnerID=8YFLogxK
U2 - 10.1016/j.cemconres.2022.106733
DO - 10.1016/j.cemconres.2022.106733
M3 - Journal article
AN - SCOPUS:85123601799
SN - 0008-8846
VL - 154
JO - Cement and Concrete Research
JF - Cement and Concrete Research
M1 - 106733
ER -