Enhancing the interfacial bond strength of cement nanocomposite with carbonate nanostructure

The future development of cementitious materials with nanoparticles or nanoscale fibers requires the ability to understand and to improve the interfacial bonding in order to develop a stronger, tougher and more robust concrete nanocomposite. The purpose of this work is to study the adhesion contact as well as the interfacial strength between calcium silicates hydrates gel (C-S-H) and calcite surfaces. The application of lateral and longitudinal strain on both surfaces shows that the elastic energy of C-S-H to ensure accommodation at the interface is lower than the one obtained for calcite. Our results show that 1 Å is the ideal distance to have a good adhesion between (001) C-S-H and (104) calcite surfaces. We also demonstrate that the presence of water molecules at the interface absorb the excess energy and thus contribute to the stabilization of the interface. Besides, the results indicate that the interfacial bonding between C-S-H and calcite improves the ductility of the cement nanocomposite when the gel porosity is about 30%. Under uniaxial and shear stresses, the nanostructure shows a heterogeneous mechanical behavior. Particularly, the interfacial shear strength enhances while applying a shear stress, which is due to the structure and the dynamic differences of the layered structure since the calcium silicate layer, constructed by Ca-O and Si-O ionic-covalent bonds, has stronger cohesive force than the interlayer H-bond network.