Mechanical properties of calcium silicate hydrate (C-S-H) at nano-scale: A molecular dynamics study

Calcium silicate hydrate (C-S-H) is the most important binding phase of cement paste and can determine the mechanical properties of cementitious material. The multi-scale nature of C-S-H gel brings about challenges in interpreting the mechanical properties of C-S-H. C-S-H models at the nano scales are commonly formulated by the aggregation of colloids that consist of layered molecular structures. In this study, the mechanical properties of C-S-H were investigated at the molecular level (∼5 nm). Uniaxial tension testing in the x, y, z directions was applied to the layered structure of C-S-H. The structural difference in the layer leads to heterogeneous mechanical properties in three directions. Particularly in the z direction, the C-S-H layer connected by H-bonds and Ca2+, has the weakest tensile strength. Resulting from the investigation, it can be concluded that the simulation can provide molecular insights into the linkage between molecular and larger scale structures.