  The thermal conductivity of porous jennite, as the major component of cement
paste, and its porosity and temperature dependences are simulated by molecular
dynamics methods using ClayFF force field. The porous jennite models with
different porosities are created by removing atoms within the sphere from bulk
jennite model. The thermal conductivity elements of bulk jennite calculated by
equilibrium Green-Kubo method are almost identical to those by non-equilibrium
M\"{u}ller-Plathe (MP) method at 300 K. The volumetric thermal conductivity of
porous jennite is found to decrease from 1.141 W/m$\cdot$K to 0.144 W/m$\cdot$K
as increasing the porosity from 0\% to 72.22\% at 300 K, following the
empirical coherent potential model when the pore is assumed to be filled with
air. As increasing temperature, the thermal conductivity is observed to
increase from 240 K to 560 K and gradually decrease until 1100 K for porous
jennites with the porosities of 0\%, 15.99\% and 32.79\%.
