TY - JOUR
T1 - Strength degradation of seawater-mixed alite pastes
T2 - an explanation from statistical nanoindentation perspective
AU - Sun, Yanjie
AU - Lu, Jian Xin
AU - Poon, Chi Sun
N1 - Funding Information:
The work described in this paper was supported by the Theme-Based Research Scheme of the Research Grants Council of the Hong Kong SAR Government (Project No. T22-502/18-R ).
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2022/2
Y1 - 2022/2
N2 - Interest in investigating seawater concrete has been increasing in recent years, but most studies of the strength degradation of seawater mixed concrete have only been carried out on the macro-scale. In this study, alite, the main phase in ordinary Portland cement, was hydrated with various salt solutions (NaCl, MgCl2, CaCl2 and simulated seawater) with a solution-to-binder ratio of 0.5 to explore the effects of common cations in seawater on the micro-mechanical performance of alite pastes. Nanoindentation-energy dispersive X-ray spectroscopy analysis, porosity analysis, and phase evolution tests were carried out to reveal the microstructure evolution of salt-added alite systems. The results showed that in addition to the acceleration of alite hydration by the salt solutions, more low-density (LD) C-S-H in the hydration products was formed. All the cations used in this study were able to enter the mesopores in the C-S-H particles, which improved the micro-mechanical performance of alite pastes. However, the deleterious effects of simulated seawater on the modulus and hardness of C-S-H were noticed, mainly attributed to the presence of Mg2+ in seawater.
AB - Interest in investigating seawater concrete has been increasing in recent years, but most studies of the strength degradation of seawater mixed concrete have only been carried out on the macro-scale. In this study, alite, the main phase in ordinary Portland cement, was hydrated with various salt solutions (NaCl, MgCl2, CaCl2 and simulated seawater) with a solution-to-binder ratio of 0.5 to explore the effects of common cations in seawater on the micro-mechanical performance of alite pastes. Nanoindentation-energy dispersive X-ray spectroscopy analysis, porosity analysis, and phase evolution tests were carried out to reveal the microstructure evolution of salt-added alite systems. The results showed that in addition to the acceleration of alite hydration by the salt solutions, more low-density (LD) C-S-H in the hydration products was formed. All the cations used in this study were able to enter the mesopores in the C-S-H particles, which improved the micro-mechanical performance of alite pastes. However, the deleterious effects of simulated seawater on the modulus and hardness of C-S-H were noticed, mainly attributed to the presence of Mg2+ in seawater.
KW - Cations
KW - Cement
KW - Hydration
KW - Seawater
KW - Tricalcium silicate
UR - http://www.scopus.com/inward/record.url?scp=85118993696&partnerID=8YFLogxK
U2 - 10.1016/j.cemconres.2021.106669
DO - 10.1016/j.cemconres.2021.106669
M3 - Journal article
AN - SCOPUS:85118993696
SN - 0008-8846
VL - 152
JO - Cement and Concrete Research
JF - Cement and Concrete Research
M1 - 106669
ER -