Influence of moisture content on reflectance of granular materials. Part II: optical measurements and modelling

In some fields, it’s important to control the moisture content of granular materials without any invasive method. Moisture content is suspected to play a role in the occurrence of some unwanted phenomena like remobilization of particles on rock walls in caves for example. The hygrothermal conditions are important as they can modify the moisture content of the granular materials on the wall leading to a humidification or at the contrary to a drying of the powder. In this study, optical measurements are used to characterize a wet powder during its drying process. Different steps of this dynamic drying process are modelled and thanks to an adaptation of the existing Melamed’s model of scattering of light by a particulate medium, simulation results are compared with instrumental measures. The modelling of such a system allows the estimation of moisture content of a granular material and brings information about the localization of water in the particulate medium.