Molecular dynamics study of the effect of moisture and porosity on thermal conductivity of tobermorite 14 Å

Abstract

Understanding of thermal properties of building materials is of great importance in design of buildings with efficient energy saving. In this work, we have studied the effect of moisture and porosity on thermal conductivity of tobermorite 14 Å, which is the major component of cement paste, by using molecular dynamics simulations with ClayFF potential. The calculated results have shown that the thermal conductivity of tobermorite 14 Å increases monotonically with the moisture content by mass within the interior pore at particular porosity, while the slope of the linear fitting function decreases as the porosity increases. Moreover, its normalized thermal conductivity has found to increase exponentially as increasing the moisture content by volume. We have calculated the phonon density of states of porous and moist tobermorite 14 Å to provide an explanation for the contribution of individual atoms and molecules to the thermal properties. We believe that the present results can be useful to design high thermal insulating materials based on cement and concrete for energy saving buildings.