Small amplitude oscillatory sweep (SAOS) techniques have been identified as valuable non-destructive methods to investigate the microstructure of cement pastes, but relatively few studies exist in the literature. Moreover, these studies focused primarily on the evolution of storage modulus over time, while change in the critical strain parameter has remained unexplored. In this investigation, an ordinary Portland cement (OPC), and a Portland limestone cement (PLC), mixed at different w/c ratios were subjected to amplitude sweeps to observe time-evolution of critical strain during the induction period. As hydration progressed, critical strains were found to increase and had an inverse correlation with the w/c ratio. The increase was quantified by an equation with a good fit using w/c ratio and time as the dependent variables. The results and hypotheses presented here can serve as foundations for improving measurement protocols, and for further explorations of microstructure evolution during the induction period of cement pastes.

中文翻译：

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水合波特兰水泥浆体的临界应变测量：对微观结构发展的新认识

小振幅振荡扫描（SAOS）技术已被认为是研究水泥浆体微观结构的有价值的非破坏性方法，但文献中的研究相对较少。此外，这些研究主要集中在储能模量随时间的演变，而临界应变参数的变化仍未得到探索。在这项研究中，对以不同水灰比混合的普通波特兰水泥（OPC）和波特兰石灰石水泥（PLC）进行振幅扫描，以观察诱导期间临界应变的时间演变。随着水合作用的进行，发现临界应变增加，并且与水灰比呈负相关。使用 w/c 比率和时间作为因变量，通过拟合良好的方程对增加进行量化。这里提出的结果和假设可以作为改进测量方案和进一步探索水泥浆体诱导期微观结构演变的基础。