Effects of the difference of the fraction of air foam in a light weight soil to the permeability and absorption characteristics are discussed in this paper. Permeability tests using triaxial apparatus and absorption tests of light weight soil specimens with different fraction of air foam were conducted.During these tests, pervious state and absorbed state during these tests are investigated using X-ray CT scanner. Estimating the density distribution change and water absorbed zones of the specimens by analyzing CT images. Relationship between permeability and absorption characteristics are discussed.
　Followings are the main conclusions in this study;
1) Effect of the fraction of air foam to the characteristics of permeability and absorption of light weight soil is prominent.
2) Pervious phenomena of the light weight soil are divided into two categories; one is that air foam works as impermeable media, the other is that air foam works as the zone easy to permeate the water by making a string of hole. Latter mechanism is getting prominent when the fraction of air foam is larger than 30%.
3) Absorption velocity of light weight soil is affected by the amount of the isolated volume of air, permeability, and suction of the specimen.