Molecular dynamics study of interfacial stress transfer in graphene-oxide cementitious composites

Graphene oxide has been recently used to create cementitious nanocomposites with enhanced mechanical properties and durability. To examine the improvement on the mechanical properties of cement by adding graphene oxide, the understanding of the interfacial stress transfer is a key. In this work, pull-out tests were carried out using molecular dynamics simulations, incorporating cement and graphene oxide, to determine the shearing mechanism at the interface. For the first time, the shear stress-displacement curve, which represents the bond-slip relation has been calculated for a graphene oxide/cement nanocomposite at the molecular scale. This relation is significant and essential in multi-scale numerical modeling as it defines the mechanical properties for the interface elements. A yielding-like phase is found prior to the shear strength and a roughly bilinear softening phase (i.e. fracture/damage). Furthermore, the shear strength has been found in the range of 647.58 ± 91.18 MPa, based on different repeated simulations, which indicates strong interfacial bonding strength in graphene oxide cement.