Molecular Dynamics Simulation on Effect of Humidity on Mechanical Properties of Calcium Silicate Hydrate

Abstract

Abstract: Calcium silicate hydrate (C-S-H) is the most important component of cement hydration products, and is the main cementitious phase of cement-based materials. The interlayer water of C-S-H has a significant effect on its nanostructure and mechanical properties. The structure and mechanical properties of C-S-H with different humidity were studied by molecular dynamics method. The influence of humidity on the structure and elastic parameters of C-S-H as well as the mechanical and deformation properties under tension, compression and shear conditions were analyzed by radial distribution function and concentration distribution of atoms, elastic constants and stress-strain relationships. The results show that the increase of humidity leads more O atoms to accumulate around Si and Ca atoms in C-S-H, and makes the distance between layers larger and the stratification more obvious. At the same time, the increase of humidity also reduces the elastic properties of C-S-H. With the increase of humidity, the mechanical and deformation properties of C-S-H under different stress states reduce. The influence degrees on tensile strength and shear strength are greater than that on compressive strength. In terms of deformation properties, humidity has the greatest influence on deformation properties under tension and has the least influence on deformation properties under compression.

Key words: calcium silicate hydrate, molecular dynamics, humidity, interlayer water, mechanical property, stress state

CLC Number:

LIU Shida, LI Zongli, TONG Taotao, LI Yunbo, XIAO Shuaipeng. Molecular Dynamics Simulation on Effect of Humidity on Mechanical Properties of Calcium Silicate Hydrate[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2022, 41(5): 1554-1561.

References

[1] MEHTA P K, MONTEIRO P J M. Concrete: microstructure, properties, and materials[M]. New York: The McGraw-Hill, 2016: 26-27.
[2] 沈春华.水泥基材料水分传输的研究[D].武汉:武汉理工大学,2007:2-3.
SHEN C H. Researches on the moisture transport of cement-based materials[D]. Wuhan: Wuhan University of Technology, 2007: 2-3 (in Chinese).
[3] PINSON M B, MASOERO E, BONNAUD P A, et al. Hysteresis from multiscale porosity: modeling water sorption and shrinkage in cement paste[J]. Physical Review Applied, 2015, 3(6): 064009.
[4] MA H Y, LI Z J. Realistic pore structure of Portland cement paste: experimental study and numerical simulation[J]. Computers & Concrete, 2013, 11(4): 317-336.
[5] 张伟,王攀,王鑫鹏,等.分子动力学理论研究初始缺陷对水泥基材料性能的影响[J].硅酸盐通报,2020,39(3):685-690+695.
ZHANG W, WANG P, WANG X P, et al. Effect of initial defect on performance of cement-based materials by molecular dynamics theory[J]. Bulletin of the Chinese Ceramic Society, 2020, 39(3): 685-690+695 (in Chinese).
[6] HOU D S, MA H Y, ZHU Y, et al. Calcium silicate hydrate from dry to saturated state: structure, dynamics and mechanical properties[J]. Acta Materialia, 2014, 67: 81-94.
[7] ZHOU J K, LIANG Y Z. Effect of water on the dynamic tensile mechanical properties of calcium silicate hydrate: based on molecular dynamics simulation[J]. Materials, 2019, 12(17): 2837.
[8] HOU D S, LI H B, ZHANG L N, et al. Nano-scale mechanical properties investigation of C-S-H from hydrated tri-calcium silicate by nano-indentation and molecular dynamics simulation[J]. Construction and Building Materials, 2018, 189: 265-275.
[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]. The Journal of Physical Chemistry B, 2004, 108(4): 1255-1266.
[10] SHAHSAVARI R, PELLENQ R J M, ULM F J. Empirical force fields for complex hydrated calcio-silicate layered materials[J]. Phys Chem Chem Phys, 2011, 13(3): 1002-1011.
[11] YAPHARY Y L, LAU D, SANCHEZ F, et al. Effects of sodium/calcium cation exchange on the mechanical properties of calcium silicate hydrate (C-S-H)[J]. Construction and Building Materials, 2020, 243: 118283.
[12] SINDU B S, SASMAL S. Molecular dynamics simulations for evaluation of surfactant compatibility and mechanical characteristics of carbon nanotubes incorporated cementitious composite[J]. Construction and Building Materials, 2020, 253: 119190.
[13] PELLENQ R J M, KUSHIMA A, SHAHSAVARI R, et al. A realistic molecular model of cement hydrates[J]. PNAS, 2009, 106(38): 16102-16107.
[14] BONNAUD P A, MANZANO H, MIURA R, et al. Temperature dependence of nanoconfined water properties: application to cementitious materials[J]. The Journal of Physical Chemistry C, 2016, 120(21): 11465-11480.
[15] CHEN J J, THOMAS J J, TAYLOR H F W, et al. Solubility and structure of calcium silicate hydrate[J]. Cement and Concrete Research, 2004, 34(9): 1499-1519.
[16] ALLEN A J, THOMAS J J, JENNINGS H M. Composition and density of nanoscale calcium-silicate-hydrate in cement[J]. Nature Materials, 2007, 6(4): 311-316.
[17] HOU D S, ZHU Y, LU Y Y, et al. Mechanical properties of calcium silicate hydrate (C-S-H) at nano-scale: a molecular dynamics study[J]. Materials Chemistry and Physics, 2014, 146(3): 503-511.
[18] RIVAS MURILLO J S, MOHAMED A, HODO W, et al. Computational modeling of shear deformation and failure of nanoscale hydrated calcium silicate hydrate in cement paste: calcium silicate hydrate Jennite[J]. International Journal of Damage Mechanics, 2016, 25(1): 98-114.
[19] PLIMPTON S. Fast parallel algorithms for short-range molecular dynamics[J]. Journal of Computational Physics, 1995, 117(1): 1-19.
[20] RICHARDSON I G. Model structures for C-(A)-S-H(I)[J]. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials, 2014, 70(6): 903-923.
[21] SOYER-UZUN S, CHAE S R, BENMORE C J, et al. Compositional evolution of calcium silicate hydrate (C-S-H) structures by total X-ray scattering[J]. Journal of the American Ceramic Society, 2012, 95(2): 793-798.
[22] SVENUM I H, RINGDALEN I G, BLEKEN F L, et al. Structure, hydration, and chloride ingress in C-S-H: insight from DFT calculations[J]. Cement and Concrete Research, 2020, 129: 105965.
[23] ABDOLHOSSEINI QOMI M J, KRAKOWIAK K J, BAUCHY M, et al. Combinatorial molecular optimization of cement hydrates[J]. Nature Communications, 2014, 5: 4960.
[24] HAJILAR S, SHAFEI B. Nano-scale investigation of elastic properties of hydrated cement paste constituents using molecular dynamics simulations[J]. Computational Materials Science, 2015, 101: 216-226.