Development of In-Situ Iron Powder Mixing Treatment with Air Bubbles Using Deep Mixing Method

Iron powder mixing is one of the methods of remediating soil contaminated with volatile organic compounds (VOCs). Iron powder dechlorinates VOCs by reduction. This method has been adopted widely because its can remediate with a relatively short time and can be applied to various type of soil. Iron powder is usually supplied into contaminated soil as slurry mixed iron powder with a thickener water solution,therefore there was a problem that ground foundation becomes weaker after work. In order to control ground strength after remediation,we have developed the new method which consists of highly-concentrated iron powder slurry using specific thickener and forming agent making bubbles which tend to broke after work. This new method reduces the water addition amount to 1/5 of conventional method,so make possible to restrain that the ground becomes weaker. Laboratory tests select the kind and contents of thickener and forming agent. Field experiments confirmed that the mixing and digging performance is secured and ground strength after work.