Abstract In Portland cement-based concrete, calcium (alumino) silicate hydrate (C-(A-)S-H) is the principal binding phase that governs its physical, mechanical, and durability properties. In this study, micromechanical properties of compacts made of synthetic C-(A-)S-H powder were investigated with nanoindentation, and various influencing factors were identified. It was revealed that a normal distribution and convergence of test data could be attained with an indentation depth > 350 nm. Higher conditioning relative humidity, pressure, and holding time aided consolidation of the powder and led to an improved elastic modulus. No remarkable influence of strain rate (0.025–0.1 s−1) and vibration frequency was noted. While the Al-incorporated C-A-S-H exhibited superior mechanical properties relative to C-S-H, all the C-(A-)S-H compacts yielded lower elastic modulus values as compared to data from fully hydrated C3S paste, mainly attributable the phase bonding, packing density, chemical composition, and the presence of phases other than C-(A-)S-H in the C3S sample.

中文翻译：

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纳米压痕实验下水合硅酸钙C-(A-)SH微观力学性能的影响因素

摘要 在波特兰水泥基混凝土中，钙（铝）硅酸盐水合物 (C-(A-)SH) 是控制其物理、机械和耐久性性能的主要结合相。在这项研究中，用纳米压痕法研究了由合成 C-(A-)SH 粉末制成的压块的微观力学性能，并确定了各种影响因素。结果表明，当压痕深度 > 350 nm 时，可以获得测试数据的正态分布和收敛。较高的调节相对湿度、压力和保持时间有助于粉末的固结并导致弹性模量的提高。没有注意到应变速率（0.025-0.1 s-1）和振动频率的显着影响。虽然掺铝的 CASH 相对于 CSH 表现出优异的机械性能，