Quantification and Modelling of the Saturation Behaviour of Hardened Cement Paste During Frost Attack By Means of Innovative NMR Imaging

通过创新核磁共振成像对霜冻期间硬化水泥浆体的饱和行为进行量化和建模

• 批准号: 239295528
• 负责人: Privatdozent Dr.-Ing. Edme Horst Hardy
• 金额: --
• 依托单位: Abteilung Baustoffe und Betonbau
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/239295528?language=en
• 关键词: Quantification; Modelling; Saturation; Behaviour; Hardened

Frost resistance of concrete is significantly influenced by water transport in the matrix of hardened cement paste as a consequence of freezing and thawing action. The intensity of exposure is a direct function of degree of saturation of the pore system. Every freeze-thaw-cycle leads to an increased saturation. Upon reaching a critical value of saturation structural damage occurs. The presented project aims at a quantification of this so called frost-suction process as a function of hardened cement-pasted quality and prevalent environmental conditions considering the underlying physical mechanisms. Frost suction will be analyzed non-destructively using methods of one-dimensional NMR imaging. Thereby for the first time a basis for the derivation of an engineering model for the prediction of saturation process as a function of frost exposure will be provided. Investigations will be conducted in situ in a low-field NMR apparatus equipped with single-sided temperature control. Using two-dimensional NMR methods, a good spatial resolution as well as a monitoring of fast signal decay is to be achieved. Signal decay is governed by state of aggregation as well as surface interaction of the observed water molecules. Advancements of NMR methodology will be of general interest for research on porous media.

混凝土的抗冻性受冻融作用引起的水在硬化水泥浆体基质中的迁移影响很大。暴露强度是孔隙系统饱和度的直接函数。每次冻融循环都会导致饱和度增加。当达到饱和临界值时，结构发生破坏。本项目的目的是量化这种所谓的霜吸过程作为硬化水泥浆质量和普遍的环境条件下，考虑到潜在的物理机制的功能。将使用一维核磁共振成像方法对霜吸力进行非破坏性分析。因此，第一次的基础上推导的工程模型预测的饱和过程作为霜冻暴露的函数将提供。调查将在现场进行，在低场核磁共振设备配备了单面温度控制。使用二维NMR方法，将实现良好的空间分辨率以及对快速信号衰减的监测。信号衰减受聚集状态以及所观察到的水分子的表面相互作用的支配。核磁共振方法学的发展将是多孔介质研究的热点。