In order the heavy metal fixation material and the cement type solidification material, for production manner of the heavy metal fixation material, production manner of the soil improvement material, and ratio of the reduction equivalent

摘要

PPROBLEM TO BE SOLVED: To provide a heavy metal fixation material excellent in immobilization of heavy metals, duration of a reducing action and in reexhibition of strengths of a solidified treated soil, and reduced in the generation of hydrogen sulfide even under high humidity, and to provide a manufacturing method therefor, a manufacturing method for a ground improving material utilizing the heavy metal fixation material and a treatment method for a subject soil. PSOLUTION: A raw material obtained by mixing gypsum with a reducing agent in a ratio of 0.3-0.9 as a ratio of a reduction equivalent of the reducing agent to an oxidation equivalent of the gypsum, is heat-treated at 600-1,100°C under a reduction atmosphere. Thereby, the heavy metal fixation material is produced which contains 4-19 mass% of calcium sulfide and 57-95 mass% of calcium sulfate. By mixing this heavy metal fixation material into cement to prepare a cement-based solidifying material and blending it in a cohesive soil of volcanic ash to conduct fixation, the ground improving material can be manufactured. By mixing the heavy metal fixation material and cement into a polluted soil and hardening the mixture, the heavy metals in the polluted soil are sufficiently fixed. PCOPYRIGHT: (C)2006,JPO&NCIPI