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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Nanomechanical properties of C-S-H gel/cement grain interface by using nanoindentation and modulus mapping

Abstract: Investigation on the mechanical properties of cement-based materials at micron and sub-micron scales is important for understanding its overall performance. Recent progress in experimental nanomechanics opens new access to nano-engineering of cement-based composites. In this study, nanoindentation and viscoelastic modulus mapping were employed to study the interfacial properties. The interface width measured by modulus mapping was around 250 nm as compared to a rough estimation of less than 5 μm by nanoindentation, due to the fact that 2 orders of magnitude increase in spatial resolution could be achieved by modulus mapping. Both the nanoindetation and modulus mapping results indicated that the modulus of the interface falls between 60–70 GPa. The packing density in the interface was non-uniform as two peaks of value were observed for the storage modulus distribution. This interface could be regarded as a dense hydration coating around cement grains, which was less permeable and hindered the further hydration of cement.

Key words: Cement-based materials, Nanomechanical properties, Interface, Modulus mapping

Chinese Summary  <56> 纳米压痕及动态模量图研究C-S-H凝胶/水泥颗粒界面的纳米力学性能

目的:揭示水泥基材料中C-S-H凝胶/水泥颗粒界面的尺寸及微观力学特性,为从纳米尺度理解水泥基材料的性能提供依据。
创新点:采用动态模量图技术对C-S-H凝胶/水泥颗粒界面微区的尺度及力学行为进行研究,借助动态模量图的高分辨性,可获得该微区精确且有效的信息。
方法:对比利用纳米压痕及动态模量图对C-S-H凝胶/水泥颗粒界面进行研究。
结论:纳米压痕仅能粗略估计界面微区的尺寸及力学参量,相比之下,动态模量图的分辨率要高出2个数量级(表2),因此可获得更精确的测量值。C-S-H凝胶/水泥颗粒界面的尺寸在250 nm左右,模量值介于60 GPa和70 GPa之间。此界面区可认为是包覆水泥颗粒周围的一层紧密的水化层结构,其致密性将阻止内部水泥的进一步水化。

关键词组:泥基材料;界面;纳米力学特性;动态模量图


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DOI:

10.1631/jzus.A1400166

CLC number:

TU502

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On-line Access:

2015-01-04

Received:

2014-06-05

Revision Accepted:

2014-10-14

Crosschecked:

2014-12-18

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