Molecular Dynamics Simulations of Mechanical Properties of C-S-H Structures with Varying Calcium-to-Silicon Ratios
LIN Weihui1, FU Jia2, WANG Zhihua1, XIN Hao1
1 Shanxi Key Lab. of Material Strength & Structural Impact, Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024; 2 Laboratoire de Génie Civil et Génie Mécanique, INSA de Rennes, Rennes 35708
Abstract: The atomic structures of calcium silicate hydrate (C-S-H) with varying calcium-to-silicon (C/S) ratios were constructed by the cCSH models of Pellenq et al., and the mechanical properties of C-S-H structures under tensile loading were investigated using molecular dynamics (MD) method. The results from the molecular dynamics simulations showed that the tensile strength was decreased significantly when the C/S ratio was greater than 1.0, compared to the case of C/S=1.0. The interaction between calcium atoms and oxygen atoms played an important role under loading, which made up the shortfall caused by the lack of SiO2, and the decrease of the strength of C-S-H in the case of C/S>1.0 became slow. The water molecules helped to cut off the interaction between calcium atoms and oxygen atoms at a certain deformation degree, which reduced the strength of C-S-H till to the failure mode.
1 Ye Jiayuan, Zhang Wensheng, Wang Hongxia, et al. Structure of calcium silicate hydrate Ca4Si6O14-(OH)4·2H2O simulated by the molecular dynamics[J]. J Chin Ceram Soc, 2010,38(12):2346(in Chinese).
叶家元,张文生,王宏霞,等.分子动力学模拟水化硅酸钙 Ca4Si6O14-(OH)4·2H2O的结构[J]. 硅酸盐学报, 2010,38(12):2346.
2 Hamid S A. The crystal structure of the 11Å natural tobermorite Ca2.25[Si3O7.5(OH)1.5]·1H2O [J]. Zeitschrift fur Kristallographie, 1981,154(3-4):189.
3 Murray S J, Subramani V J, Selvam R P, et al. Molecular dynamics to understand the mechanical behavior of cement paste[J]. Transportation Res Record J Transportation Res Board, 2010,2142(2142):75.
4 D′espinose De La Caillerie J, Lequeux N. Lecture on the structure of CSH, AFm and AFt phases[J]. Physique, Chimie et Mécanique des Matériaux Cimentaire, 2008,106(38):16102.
5 Allen A J, Thomas J J, Jennings H M. Composition and density of nanoscale calcium-silicate-hydrate in cement[J]. Nat Mater, 2007,6(4):311.
6 Pellenq R J, Kushima A, Shahsavari R, et al. A realistic molecular model of cement hydrates[J]. PNAS, 2009,106(38):16102.
7 Abdolhosseini Qomi M J, Krakowiak K J, Bauchy M, et al. Combinatorial molecular optimization of cement hydrates[J]. Nat Commun, 2014,5(4960):4960.
8 Manzano H, Moeini S, Marinelli F, et al. Confined water dissociation in microporous defective silicates:Mechanism, dipole distribution, and impact on substrate properties[J]. J Am Chem Soc, 2012,134(4):2208.
9 Cygan R T, Liang J J, Kalinichev A G. Molecular models of hydroxide, oxyhydroxide, and clay phases and the development of a general force field[J]. J Phys Chem B, 2004,108(4):1255.
10Hou D, Zhu Y, Lu Y, et al. Mechanical properties of calcium silicate hydrate (C-S-H) at nano-scale:A molecular dynamics study[J]. Mater Chem Phys, 2014,146(3):503.
11Shahsavari R, Pellenq J M, Ulm F J. Empirical force fields for complex hydrated calcio-silicate layered materials[J]. Phys Chem Chem Phys, 2010,13(3):1002.12Hou D, Ma H, Zhu Y, et al. Calcium silicate hydrate from dry to saturated state:Structure, dynamics and mechanical properties[J]. Acta Mater, 2014,67(15):81.
13Hou D, Zhao T, Wang P, et al. Molecular dynamics study on the mode I fracture of calcium silicate hydrate under tensile loading[J]. Eng Fracture Mech, 2014,131:557.
14Janakiram Subramani V, Murray S, Panneer Selvam R, et al. Atomic structure of calcium silicate hydrates using Molecular Mechanics[C] ∥ Transportation Research Board 88th Annual Mee-ting. Washington D.C.,2009
15Klessig R, Polak E. Efficient implementations of the polak-ribière conjugate gradient algorithm[J]. SIAM J Control, 1972,10(3):524.
16Berendsen H, Grigera J, Straatsma T. The missing term in effective pair potentials[J]. J Phys Chem, 1987,91(24):6269.
17Plimpton S. Fast parallel algorithms for short-range molecular dynamics[J]. J Comput Phys, 1995,117(1):1.
18Taylor H F W. Cement chemistry[J]. 2nd Edition. London:Tho-mas Telford,2007.
19Hewlett P. Lea′s chemistry of cement and concrete[M].4th Edition.Oxford: Elsevier Butterworth-Heinemann, 2003.
渝公网安备50019002502923号 版权所有：《材料导报》编辑部
2017, Vol. 31 
