A composite calcium silicate hydrate model of molecular dynamics simulations for mechanical properties

•A new multiple C-S-Hs model at atomic scale including C-S-H layers and water.•The strength of multiple C-S-Hs model are closer to that of cement paste at macroscale.•Low interlayer spacing greatly affects the mechanical properties of the system.•High strain rate enhances the mechanical properties of the model.•The structure of C-S-H stay intact in the composite model during tension process.