In order to improve the loose sand mechanical properties as the countermeasures against the earthquake induced liquefaction, a chemical solution, i.e. a liquid glass material solution is frequently employed and injected into the loose sand foundation in Japan. The volume change of a liquid glass material has been observed during the chemical gel reaction of the liquid glass material in the laboratory test. The volume change of liquid glass material is assumed to affect the mechanical properties of the chemically improved sand. In this study, the micro-focus X-ray CT scanning technique has been used to investigate the effect of the volume change of liquid glass material on the density variation of the chemically improved sand specimen. The specimen has been prepared by using a silica sand sample and the neutral-acid liquid glass material. In the X-ray CT scanning of the material, the output value to be measured is the value called GL (Gray Level), which is proportional to the X-ray absorption amount and the density of the tested material. By using this relationship, the density distribution within the specimen has been obtained. The effect of volume change of a liquid glass gel material on the mechanical characteristics of chemically improved sand has been investigated by using the correlation between the GL values and the material densities.