Advanced Materials Journal – Using atomistic simulations, this work indicates that cement nanotubes can exist. The chemically compatible nanotubes are constructed from the two main minerals in ordinary Portland cement pastes, namely calcium hydroxide and a calcium silicate hydrate called tobermorite. These results show that such nanotubes are stable and have outstanding mechanical properties, unique characteristics that make them ideally suitable for nanoscale reinforcements of cements.
The problem with carbon nanotubes is that they are water insoluble. In order to make them compatible with water chemistry, they must be functionalized in advance. Inorganic oxide nanotubes would be a natural means of reinforcements of cement pastes, in view of their chemically compatibility with the cement-water system. The team focused on cement-based nanotubes fabricated from calcium silicate hydrate gel and calcium hydroxide precipitates. They succeeded in demonstrating the feasibility of these cement nanotubes in view of their stability at room temperature, with strain energies in agreement with values previously obtained for other nanotubes compounds.
Portlandite nanotubes have tensile strength of 8.4 GPa, which is about 10% of the Young’s modulus. 8 GPa greatly exceed the tensile strengths of cement pastes and are at least an order of magnitude higher than those of typical reinforcing materials such as structural steels ( which is about 0.5 GPa).
They are now determining that the cement nanotubes survival in different water solutions.