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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的弹性模量、压痕硬度和微观徐变,用扫描电子显微镜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 N和1.5N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及力学性能;保载时间和最大荷载会影响硬化水泥净浆力学性能的测试,保载时间越长,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;当最大荷载由0.5 N增大至1.5 N,力学性能略微增大;采用1.5 N、180 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 GPa和0.43~0.59 s。
The elastic modulus, indentation hardness and microscopic creep of the hardened cement paste were tested by using the dot-in press technique at different press-in load and hold-time, and the microstructure of the area affected by the indentation was analyzed by scanning electron microscopy Effect of Microstructure Composition on Microscopic Creep and Mechanical Properties. The results show that the microstructure and microscopic creep of the mixed phase of hardened cement paste can be reflected by the indentation-affected zone containing pore phase, hydration product phase and unhydrated cement particle phase at 0.5 N and 1.5 N And mechanical properties; loading time and maximum load will affect the test of mechanical properties of hardened cement paste, the longer the loading time, the smaller the elastic modulus and indentation hardness, the reason is related to the creep properties of hardened cement paste , But the reduction is not large. When the maximum load increases from 0.5 N to 1.5 N, the mechanical properties increase slightly. The mature hardened cement paste can be obtained by the test system of 1.5 N and 180 s with 5 × 5 press- . The contact creep function has the characteristics of a logarithmic type function. The longer the hold time, the larger the contact creep function, which is related to the increase of the contact indentation radius with the increase of the hold time. However, the maximum load Almost no effect on contact creep function. For the 0.3 cement-water-cement hardened cement paste, the creep modulus and characteristic time are 158 ~ 201 GPa and 0.43 ~ 0.59 s, respectively.