Abstract The compressive strength and failure of concrete and cement exhibit strong size effect over various length scales. To investigate possible size effect on compressive strength and failure mechanism of Calcium-Silicate-Hydrates (C-S-H) in cement paste, micropillar compression experiments were performed on micropillar geometries fabricated by focused ion beam milling on potential C-S-H locations identified through coupled backscatter electron imaging (BSE) and energy dispersive spectroscopy (EDS) analysis. The compressive strength of C-S-H (181–1145 MPa) measured from C-S-H micropillars of varying diameters indicated presence of a size effect with strong increase in strength with decreasing diameter. The deformation mode at failure also exhibited size effect: the dominant failure mode changed from axial splitting to plastic crushing as the pillar diameter was decreased. The observed relationship between strength and pillar diameter can be modeled by an inverse square root dependency which closely corresponds to Bazant's scaling law of quasi-brittle failure.

中文翻译：

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微柱压缩尺寸对水泥浆中硅酸钙 (CSH) 微尺度强度和破坏机制的影响研究

摘要 混凝土和水泥的抗压强度和破坏在不同长度尺度上表现出强烈的尺寸效应。为了研究对水泥浆中硅酸钙 (CSH) 的抗压强度和破坏机制可能产生的尺寸影响，在通过耦合背散射电子成像 (BSE) 识别的潜在 CSH 位置上通过聚焦离子束铣削制造的微柱几何形状上进行了微柱压缩实验) 和能量色散光谱 (EDS) 分析。从不同直径的 CSH 微柱测量的 CSH 的抗压强度 (181–1145 MPa) 表明存在尺寸效应，强度随着直径的减小而显着增加。破坏时的变形模式也表现出尺寸效应：随着支柱直径的减小，主要的破坏模式从轴向分裂变为塑性破坏。观察到的强度和支柱直径之间的关系可以通过平方根反比关系建模，这与 Bazant 准脆性破坏的标度定律密切对应。