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硬化水泥净浆微观结构特征对微观徐变及力学性能的影响

作者:梁思明 魏亚 
单位:清华大学土木工程系 土木工程安全与耐久教育部重点实验室 北京 100084 
关键词:硬化水泥净浆 微观徐变 微观结构 压入技术 接触徐变函数 
分类号:TB321
出版年,卷(期):页码:2016,44(2):217-224
DOI:10.14062/j.issn.0454-5648.2016.02.06
摘要:

采用点阵压入技术在不同压入荷载和保载时间下测试硬化水泥净浆弹性模量、压痕硬度和微观徐变,结合扫描电镜技术分析压痕影响区域的微观结构组成,并分析微观结构组成对微观徐变及力学性质的影响。结果表明:对于0.5 N1.5 N的压入荷载,压痕影响区域包含孔隙相、水化产物相和未水化水泥颗粒相,可反映硬化水泥净浆混合相的微观结构组成和微观徐变和力学性能;保载时间和最大荷载是影响硬化水泥净浆力学性能测试的两大因素,保载时间越长,最大荷载越小,则弹性模量和压痕硬度越小,其原因与硬化水泥净浆的徐变性质有关,但是减小幅度不大;采用1.5 N180 s包含5×5压入点阵的试验制度可得到成熟硬化水泥净浆的微观徐变性质;接触徐变函数具有对数型函数的特征,保载时间越长,接触徐变函数越大,这与接触压痕半径随保载时间增长而增大有关,但最大荷载对接触徐变函数几乎无影响,对于0.3水灰比的硬化水泥净浆,徐变模量和特征时间分别为158~201 GPa0.43~0.59 s

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 The modulus of elasticity, indentation hardness, and micro creep of hardened cement paste were measured by indentation grids technique at different indentation loads and dwell time. The microstructure of the indentation zone was determined by scanning electron microscopy. Then effect of microstructure on the micro creep and mechanical property was analysed. The results show that at the peak dwell load of 0.5 N and 1.5 N, the affected indentation zone covers voids, hydration products and clinker, which can reflect the microstructure and mixed properties of hardened cement paste. Dwell time and peak load are the two main factors affecting the mechanical properties of hardened cement paste. The modulus of elasticity and indentation hardness both decrease when the dwell time increases or the peak load decreases. The experimental configuration of 1.5 N, 180 s containing 5×5 indentation grids can obtain the micro creep property of mature hardened cement paste. The contact creep function is closely related to the logarithmic function of time, the longer the dwell time, the greater the contact creep function will be, due to the fact that the contact radius increase with time. However, peak load has little effect on the contact creep function. The contact creep modulus is 158-201 GPa and the characteristic time is 0.43-0.59 s for hardened cement paste with 0.3 water-cement ratio.

基金项目:
国家自然科学基金项目(51578316)。
作者简介:
第一作者:梁思明(1992—),男,博士研究生。 通信作者:魏 亚(1976—),女,博士,博士研究生导师,副教授。E-mail: yawei@tsinghua.edu.cn
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