Mechanical properties of crystalline calcium-silicate-hydrates: Comparison with cementitious C-S-H gels

This work explores from a theoretical viewpoint the mechanical properties of the most important hydration product present in cementitious environments, the so called C-S-H (calcium-silicate-hydrate) gel. The dependence of the bulk (K), shear (G) and Young's (E) modulus for the C-S-H crystals respect to its composition and the length of its silicate chains is analysed by lattice dynamic simulations with parameterised two-body and three-body potentials. Our simulations reveal that the mechanical properties of C-S-H crystals show a strong dependence on their composition. Nevertheless our calculated numbers systematically overestimate the experimental values for C-S-H gels. Only when the finite length of the silicate chains is taken into account this discrepancy disappears.