An integrated microstructural-nanomechanical-chemical approach to examine material-specific characteristics of cementitious interphase regions
An integrated microstructural-nanomechanical-chemical approach to examine material-specific characteristics of cementitious interphase regions
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DOI：
10.1016/j.matchar.2018.01.045
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发表时间：
2018-04-01
影响因子：
4.7
通讯作者：
Nguyen, Charles
中科院分区：
文献类型：
--
作者：
Khedmati, Mandieh;Kim, Yong-Rak;Nguyen, Charles
水泥混合物的有效性能和结构性能基本上由界面区域的质量决定，因为它充当骨料和粘结基体之间传递力的桥梁，并且通常容易受到损坏。近年来，随着碱激活前体海耶等替代粘合剂受到广泛关注，人们越来越需要基础知识来揭示界面形成机制。本文将粉煤灰基地质聚合物和普通硅酸盐水泥两种不同类型的粘结材料与石灰石骨料混合，检查和比较界面区域的微观结构和纳米力学性能。为此，综合使用扫描显微镜的微观结构特征、纳米压痕测试的纳米力学特性以及基于能量色散光谱的化学含量空间图，以识别和研究由基体材料和石灰石之间的特定情况相互作用形成的界面区域。集成的微观结构-纳米机械-化学方法可以有效地更好地理解胶结相的材料特定性能之间的联系。更具体地说，是基于飞灰的地质聚合物糊剂。通常与骨料表面粘结良好，形成丰富的 N-A-S-H 凝胶，而普通硅酸盐水泥混凝土中骨料表面与浆体之间经常观察到界面脱粘。然而，当骨料和浆料之间形成良好的结合时，与本体浆料相比，PCC 中的界面区域在纳米力学性能方面没有表现出任何显着差异。
Effective properties and structural performance of cementitious mixtures are substantially governed by the quality of the interphase region because it acts as a bridge transferring forces between aggregates and a bindilig matrix and is generally susceptible to damage. As alternative binding agents like alkali-activated precursors haye obtained substantial attention in recent years, there is a growing need for fundamental knowledge to uncover interphase formation mechanisms. In this paper, two different types of binding materials, i.e., fly ash-based geopolymer and ordinary portland cement, were mixed with limestone aggregate to examine and compare the microstructures and nanomechanical properties of interphase region. To this end, microstructural characteristics using scanning microscopies, nanomechanical properties by nanoindentation tests, and spatial mapping of chemical contents based on the energy dispersive spectroscopy were integrated to identify and investigate the interphase region formed by the case-specific interactions between the matrix materials and limestone. The integrated microstructural-nanomechanical-chemical approach was effective to better understand links between material-specific properties of cementing phases. More specifically, the fly ash-based geopolymer paste was. usually well bonded to the aggregate surface with a rich formation of N-A-S-H gel, while interfacial debonding was often observed between aggregate surface and paste in ordinary portland cement concrete. However, when a good bonding between aggregate and paste is formed, interphase region in PCC did not show any considerable difference in nanomechanical properties compared to the bulk paste.