Thermal conductivity of a partially wet granular material

We report an experimental study of the thermal conductivity of a granular material when water is added to the system. Because of the formation of liquid bridges at the contacts between grains, the thermal conductivity increases. Below a critical amount of water, the number of bridges increases. Any additional water simply flows by gravity to the bottom of the container. Simple theoretical models account for both the critical amount of water and the measured thermal conductivity.