-
研究水化硅酸钙(C-S-H)中受限水动态的一种重要手段是准弹性中子散射(quasi-elastic neutron scattering, QENS)实验. C-S-H样品的QENS谱数据可通过跳跃扩散和转动扩散模型进行分析拟合, 进而导出C-S-H样品微纳孔中水动态的相关物理参数: 不动水指数C、转动扩散系数Dr、均方位移 u2 、自扩散系数Dt及平均停留时间0. 本文对水与水泥质量比为30%的C-S-H样品, 测量温度为230-280 K的QENS谱进行了分析, 得到的拟合参数可定量描述C-S-H样品内不同尺度的微纳孔中受限水随温度变化的动态过程. 转动扩散系数Dr随散射矢量Q的变化可知, Q值较大时, 水分子的转动对QENS谱影响较大. 均方位移 u2 随Q值的不同而变化, 其拟合值可区分C-S-H样品中的不动水、强受限水和受限水. 在Q较小时, Dt 和0 的拟合值随温度而变化, 并分别在230和240 K突然增大, 由此揭示温度为230-240 K 时, C-S-H 样品中受限水分子的动态特性发生了转变.
-
关键词:
- 受限水动态 /
- 准弹性中子散射谱 /
- 跳跃扩散和转动扩散模型 /
- 水化硅酸钙样品
Cement is a widely used construction material in the world. Calcium-silicate-hydrate (C-S-H) is the main component of aged cement (concrete). The quality and durability of concrete are strongly affected by the dynamics of water confined in it. Dynamics of the confined water can be studied experimentally by the quasi-elastic neutron scattering (QENS). In this paper, the jump-diffusion and rotation-diffusion model (JRM) is used to fit the QENS spectra of C-S-H paste samples at different measured temperatures for the whole scattering vector Q-range from 0.3 to 1.7 -1. Five important parameters are extracted to describe the dynamics of water confined in C-S-H samples: the index of immobile water C, the rotational diffusion constant Dr, the mean square displacement (MSD) u2 , the self-diffusion coefficient Dt, and the average residence time between jumps 0. Here, all the C-S-H samples, each with a 30% weight ratio of water to cement, are measured at temperatures ranging from 230 to 280 K. The fitted parameters can quantitatively describe the dynamics of water confined on different scales of C-S-H gel pores. The results show that the QENS spectra are fitted very well not only for small Q (Q 1 -1) but also for large Q (Q 1 -1). The obtained rotational diffusion constant is Q dependent. Thus the contribution of the water molecule rotation to a QENS spectrum increases with the value of Q increasing. The mean square displacement (MSD) u2 decreases with the increase of Q, which can be used to distinguish the confined water, ultra-confined water, and bound water contained in C-S-H samples. When Q is small, the fitted Dt and 0 vary with the measured temperature. Dt has a maximum value at 230 K and 0 has a peak at 240 K. These indicate that the dynamics of the confined water shows different behaviors at 230 K and 240 K. There are crossover or critical phenomena for water confined in C-S-H sample at low temperature.-
Keywords:
- dynamics of confined water /
- quasi-elastic neutron scattering spectra /
- jump-diffusion and rotation-diffusion model /
- calcium-silicate-hydrated
[1] Li H, Fratini E, Chiang W S, Baglioni P, Mamonto E, Chen S H 2012 Phys. Rev. E 86 061505
[2] Bordallo H N, Aldridge L P, Desmedt A 2006 J. Phys. Chem. B 110 17966
[3] Ridi F, Luciani P, Fratini E, Baglioni P 2009 J. Phys. Chem. B 113 3080
[4] Ridi F, Dei L, Fratini E, Chen S H, Baglioni P 2003 J. Phys. Chem. B 107 1056
[5] Nestle N, Galvosas P, Krger J 2007 Cem. Concr. Res. 37 398
[6] Skinner L B, Chae S R, Benmore C J, Wenk H R, Monteiro P J M 2010 Phys. Rev. Lett. 104 195502
[7] Eckold G, Schober H, Nager S E 2010 Studying kinetics with Neutrons-Prospects for Time-Resolve Neutron Scattering (London: Springer) pp19-75
[8] Eisenberg D, Kauzmann W 1969 The Structure and Properties of Water (New York: Oxford University Press) pp1-296
[9] Debenedetti P G 2003 J. Phys.: Condens. Mattter 15 R1669
[10] Bergman R, Swenson J 2000 Nature 403 283
[11] Qomi M J A, Bauchy M, Ulm F J, Pellenq R J M 2014 J. Chem. Phys. 140 054515
[12] Fujii K, Kondo W 1983 J. Am. Ceram. Soc. 66 C-220
[13] Taylor H F W 1986 J. Am. Ceram. Soc. 69 464
[14] Jennings H M 2008 Cem. Coner. Res. 38 275
[15] Li H, zhang L L, Yi Z, Fratini E, Baglioni P, Chen S H 2015 J. Colloid Interface Sci. 45 2
[16] Fratini E, Chen S H, Baglioni P, Bellissent-Funel M 2002 J. Phys. Chem. B 106 158
[17] Faraone A, Fratini E, Baglioni P, Chen S H 2004 J. Chem. Phys. 121 3212
[18] Yi Z, Zhang L L, Li H 2015 Acta Phys. Sin. 64 056101 (in Chinese) [易洲, 张丽丽, 李华 2015 64 056101]
[19] Mamontov E, Herwig K W 2011 Rev. Sci. Instrum. 82 085109
[20] Bee M 1988 Quasi-elastic Neutron Scattering (Bristol and Philadelphia: Adam Hilger) pp1-437
[21] Sears V F 1966 Can. J. Phys. 44 1299
[22] Singwi K S, Sjlander A 1960 Phys. Rev. 119 863
[23] Li H, Zhang L L, Yi Z 2014 Nuclear Techniques 37 020604 (in Chinese) [李华, 张丽丽, 易洲 2014 核技术 37 020604]
-
[1] Li H, Fratini E, Chiang W S, Baglioni P, Mamonto E, Chen S H 2012 Phys. Rev. E 86 061505
[2] Bordallo H N, Aldridge L P, Desmedt A 2006 J. Phys. Chem. B 110 17966
[3] Ridi F, Luciani P, Fratini E, Baglioni P 2009 J. Phys. Chem. B 113 3080
[4] Ridi F, Dei L, Fratini E, Chen S H, Baglioni P 2003 J. Phys. Chem. B 107 1056
[5] Nestle N, Galvosas P, Krger J 2007 Cem. Concr. Res. 37 398
[6] Skinner L B, Chae S R, Benmore C J, Wenk H R, Monteiro P J M 2010 Phys. Rev. Lett. 104 195502
[7] Eckold G, Schober H, Nager S E 2010 Studying kinetics with Neutrons-Prospects for Time-Resolve Neutron Scattering (London: Springer) pp19-75
[8] Eisenberg D, Kauzmann W 1969 The Structure and Properties of Water (New York: Oxford University Press) pp1-296
[9] Debenedetti P G 2003 J. Phys.: Condens. Mattter 15 R1669
[10] Bergman R, Swenson J 2000 Nature 403 283
[11] Qomi M J A, Bauchy M, Ulm F J, Pellenq R J M 2014 J. Chem. Phys. 140 054515
[12] Fujii K, Kondo W 1983 J. Am. Ceram. Soc. 66 C-220
[13] Taylor H F W 1986 J. Am. Ceram. Soc. 69 464
[14] Jennings H M 2008 Cem. Coner. Res. 38 275
[15] Li H, zhang L L, Yi Z, Fratini E, Baglioni P, Chen S H 2015 J. Colloid Interface Sci. 45 2
[16] Fratini E, Chen S H, Baglioni P, Bellissent-Funel M 2002 J. Phys. Chem. B 106 158
[17] Faraone A, Fratini E, Baglioni P, Chen S H 2004 J. Chem. Phys. 121 3212
[18] Yi Z, Zhang L L, Li H 2015 Acta Phys. Sin. 64 056101 (in Chinese) [易洲, 张丽丽, 李华 2015 64 056101]
[19] Mamontov E, Herwig K W 2011 Rev. Sci. Instrum. 82 085109
[20] Bee M 1988 Quasi-elastic Neutron Scattering (Bristol and Philadelphia: Adam Hilger) pp1-437
[21] Sears V F 1966 Can. J. Phys. 44 1299
[22] Singwi K S, Sjlander A 1960 Phys. Rev. 119 863
[23] Li H, Zhang L L, Yi Z 2014 Nuclear Techniques 37 020604 (in Chinese) [李华, 张丽丽, 易洲 2014 核技术 37 020604]
计量
- 文章访问数: 6871
- PDF下载量: 187
- 被引次数: 0
下载:
