SGER: Nanoscale Investigation of Cement Hydration by Nuclear Resonant Reaction Analysis

核共振反应分析在水泥水化纳米尺度研究中的应用首次将核磁共振反应分析(NRRA)应用于水泥水化研究。通过使用这一技术，可以研究在感应期内氢浓度在几纳米尺度(相当于几个单位电池)上的变化作为时间的函数。初步结果表明，根据观测到的氢浓度的绝对值和测量的表面层厚度，在诱导期形成的硅酸三钙颗粒表面层与类托贝莫来石材料是一致的。最佳束流能量分辨率是一个关键参数，因为测量的空间分辨率在很大程度上取决于入射离子束的能量分辨率。因此，德国波鸿鲁尔大学的Dynamitron串列加速器被用于实验研究，因为这台机器在过去15年里进行了广泛的工作，以产生尽可能好的离子束能量分辨率。氢浓度是在颗粒表面的几个纳米深度上获得的，并且可以连续测量到颗粒中大约2微米的深度。对硅酸三钙在20℃下的水化过程进行了初步研究，确定了诱导时间为4.25小时，统计精度为0.07小时。这项建议将支持应用NRRA技术对水泥水化进行详细研究。一系列实验将考察不同参数对水化过程的影响。对实验数据的分析将为不同参数，如温度、pH和起始成分，如何影响水化过程提供清晰的见解。这些信息最终将用于改进用于建筑和其他目的的水泥配方。

Nanoscale Investigation of Cement Hydration by Nuclear Resonant Reaction Analysis Nuclear Resonant Reaction Analysis (NRRA) has been applied for the first time to study cement hydration. Through the use of this technique, the change in hydrogen concentration on a few nanometer scale (corresponding to a few unit cells) can be studied as a function of time during the induction period. Preliminary results have demonstrated that the surface layer formed during the induction period on the tricalcium silicate grains (used in this initial study) is consistent with a tobermorite-like material, based on the absolute value of the observed hydrogen concentration and the measured thickness of the surface layer. Optimum beam energy resolution is a critical parameter as the spatial resolution of the measurement is defined largely by the energy resolution of the incident ion beam. Therefore, the Dynamitron Tandem accelerator at the Ruhr Universitat, Bochum, Germany is being used for the experimental studies as this machine has had extensive work done over the last fifteen years to generate the best possible energy resolution for ion beams. The hydrogen concentration is obtained over a depth of a few nanometers at the surface of the grains and can be measured continuously to a depth of about 2 microns into the grains. An initial study of the hydration process of tricalcium silicate at 20 oC determined an induction time of 4.25 hours with a statistical precision of 0.07 hours. This proposal will support a detailed investigation of cement hydration by applying the NRRA technique. A series of experiments will investigate the effect of different parameters on the hydration process. The analysis of the experimental data will provide clear insights into the way different parameters, such as temperature, pH, and starting composition, affect the hydration process. This information will ultimately be used to improve the formulation of cements for construction and other purposes.