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基于低场核磁共振技术的水泥浆体孔结构与比表面积的原位表征

ISSN号：1671-4431
期刊名称：武汉理工大学学报
时间：2013.10.30
页码：11-15
分类：TU525[建筑科学—建筑技术科学]
作者机构：[1]同济大学先进土木工程材料教育部重点实验室,上海201804
相关基金：国家自然科学基金（51108341,50978200）;硅酸盐建筑材料国家重点实验室（武汉理工大学）开放基金（sYsJJ2012-08）和先进土木工程材料教育部重点实验室（同济大学）开放基金（201309）.
相关项目：C-S-H凝胶纳米孔系统中水的状态演变及其原位监测的研究

关键词：低场核磁共振, 水泥浆体, 横向弛豫, 孔结构, 比表面积, low field nuclear magnetic resonance, cement paste, transverse relaxation, pore structure, specific surface area

中文摘要：

利用低场核磁共振技术在非破损和非侵入条件下研究了水泥浆体孔结构的变化,包括水化早期浆体孔结构比表面积的动态发展,以及硬化后在不同养护龄期浆体中水的横向弛豫时间T2的分布变化.结果表明：水化早期浆体比表面积的发展可以根据增长速率的变化分为3个连续的阶段.根据水泥水化理论阐述了每一阶段的机理,并结合Powers模型对结果中出现的比表面积数值到达最大值后的回落现象进行了解释.在不同养护龄期的硬化水泥浆体中,T2分布图谱表现为1个显著的主峰和1～2个次峰.主峰跨度和范围的变化间接地反映了水泥浆体内部孔隙分布随龄期和水灰比的变化特征.研究表明低场核磁共振技术可以弥补传统测试方法的不足,用于表征水泥浆体的孔结构.

英文摘要：

Low field nuclear magnetic resonance （NMR）, as a nondestructive and noninvasive method, was used to investigate the changes of pore structure in cement paste. The dynamic development of specific surface area of pores in cement paste during the early age, as well as the distribution changes of transverse relaxation time, T2, of the water contained in paste with different cured age after hardened were studied. The results demonstrated that the development process of specific surface area during early age could be divided into three continuous stages depending on the increase rate. The mechanism for each stage was discussed based on the theory of cement hydration. The drop of the value of spe- cific surface area after reaching a maximum was also explained with the Powers model. Furthermore, in the hardened cement pastes with different cured ages the T2 distributions represent a main peak and one or two minor peaks. The distribution span and range of the main peak reflected indirectly the varying features of the internal pore structure with age. The studies indicate that the low field NMR can be used as a useful supplemental way for the traditional methods to char- acterize the pore structure of cement based materials.