应变率对硬化水泥净浆微观力学性能及徐变行为的影响

发布时间：2018-06-09 11:50

本文选题：硬化水泥净浆 + 力学性能　；参考：《硅酸盐学报》2017年11期

【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:通过30μm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)时,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。
[Abstract]:The influence of strain rate on the micromechanical properties and creep behavior of hardened cement paste was studied by means of continuous stiffness measurement, and the influence of microstructure of cement paste on continuous stiffness test results was analyzed by means of scanning electron microscopy (SEM). The results show that the uniform mechanical properties of cement paste can be obtained by measuring the continuous stiffness of 30 渭 m indentation depth, when the indentation depth (load) is greater than the critical minimum depth (load). The elastic modulus and indentation hardness obtained from the test remain basically unchanged, reflecting the homogeneous mechanical properties of cement paste, and the effect of strain rate variation on the elastic modulus of hardened cement paste is negligible in the range of 0.01 sm (0.50 s-1). However, the indentation hardness increases with the increase of strain rate, and the relationship between them is power function, strain rate affects the contact creep function at the stage of holding load, the greater the strain rate, the greater the contact creep function at the stage of holding load. This is related to the insufficient creep development at the loading stage with the strain rate increasing. In order to accurately test the micro creep of cement paste, it is necessary to minimize the loading time.
【作者单位】：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;
【基金】：国家自然科学基金项目(51578316,51778331)
【分类号】：TQ172.1

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