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应变率对硬化水泥净浆微观力学性能及徐变行为的影响
作者:魏亚 梁思明 高翔 
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 力学性能 微观徐变 连续刚度测试 应变率 
分类号:TB321
出版年,卷(期):页码:2017,45(11):0-0
DOI:
摘要:

 采用连续刚度测试研究应变率对硬化水泥净浆微观力学性能及徐变行为的影响,结合扫描电镜技术分析水泥净浆的微观结构对连续刚度测试结果的影响。结果表明:采用30 μm 压入深度的连续刚度测试可以得到水泥净浆均匀的力学性能,当压入深度(荷载)大于临界最小深度(荷载),测试得到的弹性模量和压痕硬度基本保持不变,反映了水泥净浆均匀的力学性质;在0.01 s–1~0.50 s–1 应变率范围内,应变率变化对硬化水泥净浆弹性模量的影响可忽略不计,但压痕硬度随着应变率的增大而增大,且二者具有幂型函数关系;应变率影响持载阶段的接触徐变函数,应变率越大,持载阶段的接触徐变函数越大,这与应变率越大时加载阶段的徐变发展越不充分有关。为了准确测试水泥净浆的微观徐变,需尽可能减小加载阶段的用时。

 The strain rate effect on the elastic modulus, indentation hardness, and micro creep of hardened cement paste was investigated via continuous stiffness measurement. The microstructure of the indentation zone was determined by scanning electron microscopy. The effect of microstructure on the mechanical and creep property was analyzed. The results show that the homogeneous mechanical properties of cement pastes can be measured via continuous stiffness measurement with a maximum depth of 30 μm. When the indentation depth (force) is greater than the critical minimum depth (force), the measured elastic modulus and indentation hardness will remain nearly a constant, reflecting the homogeneous mechanical properties of cement pastes. Within the strain rates ranging from 0.01 s–1 to 0.50 s–1, the strain rate has a negligible effect on the elastic modulus. However, the indentation hardness increases with increasing the strain rate, and their relationship can be well expressed by an empirical power law equation. Strain rate also affects the contact creep function during the holding stage. The greater the strain rate, the greater the contact creep function is, which is due to the fact that the creep will develop less during the loading stage at a greater strain rate. It is thus necessary to minimize the loading time to ensure correct measurement of the creep property. The findings can provide a reference to evaluate the strain rate effect on the mechanical and creep properties of cement pastes.

基金项目:
国家自然科学基金项目(51578316,51778331)。
作者简介:
魏亚(1976—),女,博士,博士研究生导师,副教授。
参考文献:
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