Abstract
This research focused on the water absorption behavior in water retentive materials and water permeable materials, by using the neutron radiography technique. The moisture characteristic curve, which is hydraulic diffusivity as a function of volumetric moisture content, was calculated with pore size distribution of the both materials, and an unsteady water diffusion analysis was conducted. The experimentally observed water behaviors by the absorption test were well captured by the diffusion analysis. And also the results showed that the gravity effect for calculation of water movement in the water retentive and permeable materials was considerable in comparably rapid water movement.