Lightweight materials using in-situ clay soil contain large amounts of fine grain andcement for increasing the strength, lighter weight to increase liquidity for the foam and the bulkof the material is conducted by the water.Domestic cases, Light weight soil to improve cementation and lightness using demountablemixing device is defined Smartsoil. Typical features are their self-leveling, self-compaction, folwability. By adjusting the amount of cement, the strength can be controlled artificially. And re-excavation is easy.In this paper, pre-loading method using the road due to the displacement of adjacent structures under construction as an alternative SmartSoil introduces the design and construction practices Is to discuss and improve.