The strength origin of C-S-H matrix is a key question in cement and concrete research, which remains largely unclear despite a century of study. Here we present a novel approach to endow strength integrity to C-S-H powders via mechanical compaction at room temperature. The unprecedented 2000 MPa compaction load results in a bulk C-S-H with tensile strength (~24 MPa) one order of magnitude higher than C-S-H matrix from hydration. This practice enables observations on how Ca/Si ratio (C/S) and initial moisture conditions affect their overall mechanical properties (hardness and strength), which are correlated with the micro-structures studied by ¹H NMR and electronic microscope. We conclude that the bond between closely-contacted C-S-H particle, rather than the total porosity, is key to the bulk strength. The bond is clearly weakened when excessive water exists between C-S-H particles. This work provides novel insight to the strength origin of C-S-H.

CSH 基体的强度起源是水泥和混凝土研究中的一个关键问题，尽管经过了一个世纪的研究，但在很大程度上仍不清楚。在这里，我们提出了一种在室温下通过机械压实赋予 CSH 粉末强度完整性的新方法。史无前例的 2000 MPa 压实载荷导致块状 CSH 的抗拉强度 (~24 MPa) 比水合 CSH 基质高一个数量级。这种做法可以观察到 Ca/Si 比 (C/S) 和初始水分条件如何影响它们的整体机械性能（硬度和强度），这与^{1研究的微观结构相关}H NMR和电子显微镜。我们得出结论，紧密接触的 CSH 颗粒之间的键，而不是总孔隙率，是体积强度的关键。当 CSH 颗粒之间存在过多的水时，这种结合明显减弱。这项工作为 CSH 的强度起源提供了新的见解。