SGER-Nanoscale Study of Cement Hydration by Nuclear Resonant Reaction Analysis

SGER-通过核共振反应分析进行水泥水化的纳米级研究

• 批准号: 0350322
• 负责人: Jeffrey Schweitzer
• 金额: $ 8.66万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-15 至 2006-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0350322&HistoricalAwards=false
• 关键词: SGER; Nanoscale; Study; Cement; Hydration

Nanoscale Investigation of Cement Hydration by Nuclear Resonant Reaction Analysis Nuclear Resonant Reaction Analysis (NRRA) has been applied 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. Initial results have demonstrated that the surface layer formed during the induction period on the tricalcium silicate grains (used in this 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. The use of a very narrow nuclear resonant reaction (in this case the 1 H (15 N?) 12 Creaction at 6.4 MeV), when performed with a beam of nitrogen ions that has excellent energy resolution, is capable of measuring the hydrogen concentration of a thin 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. By raising the beam energy, progressively deeper layers can be investigated. Thus, by using nitrogen beams of successively higher energies from the 6.4 MeV resonance, a profile of the hydrogen concentration as a function of time in the hydration process can be determined. 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. A study of the hydration process of tricalcium silicate at 20 o C determined an induction time of 4.25 hours with a statistical precision of 0.07 hours. Temperature dependent results form an Arrhenius plot yielding and activation energy of 69 kJ/mol.

水泥水化的核共振反应分析纳米尺度研究核共振反应分析（NRRA）已被应用于水泥水化研究。通过使用这种技术，在几个纳米尺度上（对应于几个单元电池）的氢浓度的变化可以研究作为诱导期期间的时间的函数。初步结果表明，在诱导期的硅酸三钙颗粒（用于本研究）形成的表面层是一致的托贝莫来石状材料，根据观察到的氢浓度的绝对值和测量的表面层的厚度。使用一个非常狭窄的核共振反应（在这种情况下，1 H（15 N？）12 C反应在6.4 MeV），当与具有优异的能量分辨率的氮离子束进行时，能够测量薄层的氢浓度。最佳束能量分辨率是关键参数，因为测量的空间分辨率主要由入射离子束的能量分辨率限定。因此，德国波鸿鲁尔大学的Dynamitron串列加速器被用于实验研究，因为该机器在过去15年中进行了大量工作，以产生最佳的离子束能量分辨率。通过提高光束能量，可以研究逐渐更深的层。因此，通过使用来自6.4MeV共振的能量连续更高的氮束，可以确定在水合过程中氢浓度作为时间的函数的分布。氢浓度在晶粒表面几纳米的深度上获得，并且可以连续测量到晶粒中约2微米的深度。对硅酸三钙在20 ° C下的水化过程的研究确定了4.25小时的诱导时间，统计精度为0.07小时。温度依赖性结果形成Arrhenius图，产生69 kJ/mol的活化能。