TY - JOUR
T1 - Effect of seawater on the morphology, structure, and properties of synthetic ettringite
AU - Cai, Yamei
AU - Tao, Yong
AU - Xuan, Dongxing
AU - Sun, Yanjie
AU - Poon, Chi Sun
N1 - Funding Information:
The authors would like to acknowledge the financial support by the Research Grants Council of the Hong Kong SAR Government (Project No. T22-502/18-R ), the Research Centre for Resources Engineering towards Carbon Neutrality (RCRE) and The Hong Kong Polytechnic University . The first author is also grateful to Dr. Yongqiang Li and Dr. Xiaohong Zhu for their help with the calculation of crystal size and TG test.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2023/1
Y1 - 2023/1
N2 - This work investigated the influence of seawater on the growth rate, morphology, and properties of ettringite (AFt). The results showed that, in the absence of calcium hydroxide (CH), a part of the Mg ions in seawater preferentially formed Mg–Al layered double hydroxide containing Cl− (Mg-Al-Cl LDH), which could accelerate the subsequent precipitation of AFt in seawater. However, in the presence of CH, some of the Mg ions in seawater formed brucite, and there was no significant acceleration for the precipitation of AFt in the seawater-CH solution, compared with the AFt formed in seawater without CH. Besides, in both cases with and without CH, some Mg ions in seawater could enter the sites of Ca in the AFt structure, leading to an unstable structure. This would cause a relatively lower packing density compared with the corresponding AFt samples synthesized in deionized (DI) water, further leading to a relatively lower mechanical property. When the Mg ions were excluded from seawater, the AFt samples synthesized seemed to have a relatively higher packing density compared with the corresponding AFt formed in DI water, resulting in a relatively higher mechanical property. This finding could lead to a better understanding of the degradation of the micromechanical properties of AFt in seawater-mixed cementitious materials caused by the Mg ions.
AB - This work investigated the influence of seawater on the growth rate, morphology, and properties of ettringite (AFt). The results showed that, in the absence of calcium hydroxide (CH), a part of the Mg ions in seawater preferentially formed Mg–Al layered double hydroxide containing Cl− (Mg-Al-Cl LDH), which could accelerate the subsequent precipitation of AFt in seawater. However, in the presence of CH, some of the Mg ions in seawater formed brucite, and there was no significant acceleration for the precipitation of AFt in the seawater-CH solution, compared with the AFt formed in seawater without CH. Besides, in both cases with and without CH, some Mg ions in seawater could enter the sites of Ca in the AFt structure, leading to an unstable structure. This would cause a relatively lower packing density compared with the corresponding AFt samples synthesized in deionized (DI) water, further leading to a relatively lower mechanical property. When the Mg ions were excluded from seawater, the AFt samples synthesized seemed to have a relatively higher packing density compared with the corresponding AFt formed in DI water, resulting in a relatively higher mechanical property. This finding could lead to a better understanding of the degradation of the micromechanical properties of AFt in seawater-mixed cementitious materials caused by the Mg ions.
KW - Atomistic simulations
KW - Ettringite
KW - Hydration
KW - Mechanical property
KW - Seawater
UR - http://www.scopus.com/inward/record.url?scp=85142205720&partnerID=8YFLogxK
U2 - 10.1016/j.cemconres.2022.107034
DO - 10.1016/j.cemconres.2022.107034
M3 - Journal article
AN - SCOPUS:85142205720
SN - 0008-8846
VL - 163
JO - Cement and Concrete Research
JF - Cement and Concrete Research
M1 - 107034
ER -