The Effect of Air Foam Inclusion on the Permeability and Absorption Properties of Light Weight Soil

Cement-treated clay with air foam, which is called Super Geo-Material (SGM), was developed to utilize dredged clay in an effective way. As SGM is mainly used at levels below the ground water table, water permeability and absorption properties of SGM will affect the durability of the material. In this research, the changes in SGM permeability and absorption as functions of the air foam fraction were investigated. First, permeability tests with triaxial apparatus and constant rate of consolidation tests were conducted on samples containing less than 10% of air foam by volume. From the results, air foam was found to be an impermeable medium in SGM. Secondly, a series of permeability tests and absorption tests were conducted for the SGM with different fractions of air foam while observing the specimen with a micro focus X-ray Computed Tomography (CT) scanner. The results showed that the permeability of SGM increased dramatically due to the appearance of interior water channels when the air foam fraction exceeded 30% by volume. The density distribution change and water absorbed zones of the specimens during absorption tests were estimated using the X-ray CT data. From these results, the air in the SGM was found to be progressively substituted with water from the surface to the inside of the specimen and the substituted zone expanded as it made its way to the specimen interior. The expansion velocity of the substituted zone was not affected by the coefficient of permeability but by the fraction of the air in the specimen.