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准弹性中子散射(Quasi-elastic neutron scattering,QENS)实验是研究受限水动态的一种重要实验手段。水泥样品中存在有结合水和受限水,各自的含量随着水泥样品的老化时间、环境温度、水和水泥(w/c)质量比、添加剂等因素的不同而变化,处于强受限状态的水的动态特性影响着水泥石的耐久性和力学特性,因此,水泥样品中受限水动态的研究具有重要的意义。本文综述了近年来水泥样品中受限移动水含量比例和受限水动态的QENS实验研究,着重介绍采用弛豫盒子模型(Relaxing cage model,RCM),对QENS谱实验数据的拟合分析,得到描述水泥样品中受限水动态相关信息的关键物理参数:受限移动水比例系数1-p,微纳孔中受限水分子在某位置上的诱捕(俘获)时间?0、受限水平均迁移弛豫时间<?>及其自扩散系数D,表征水泥样品微纳孔均匀性的形状因子?等,为QENS实验在受限水动态研究中的应用提供一种合理实用的方法。
Quasi-elastic neutron scattering (QENS) experiment is an important experimental method to study the limited water dynamics. There are bound water and restricted water in the cement samples. The content of each sample varies with the aging time of the cement sample, the ambient temperature, the mass ratio of water to cement (w / c), additives and other factors, The dynamic properties of water influence the durability and mechanical properties of cement stone. Therefore, the research on the limited water dynamic in cement samples is of great significance. In this paper, the QENS experimental studies on the ratio of restricted mobile water and the limited water dynamics in cement samples in recent years are reviewed. Emphasis is given on the fitting analysis of experimental data of QENS spectra using the Relaxing cage model (RCM) The key physical parameters describing the information on the dynamics of restricted water in cement samples are the limited mobility of water proportional coefficient 1-p, the trap (capture) time of a restricted water molecule in a micro-nanohole at a location 0, Migration relaxation time <?> And its self-diffusion coefficient D, the shape factor characterizing the uniformity of micro / nano-pores in cement samples, etc., provide a reasonable and practical method for the application of QENS experiment in the study of restricted water dynamics.