| 摘要 |
PROBLEM TO BE SOLVED: To greatly reduce the amount of eluted heavy metals and the like to fall below the environmental standard level without detriment to manifesta tion of the strength by adding an amorphous silica to a cement solidifying material in solidifying contaminated soil which contains various heavy metals in such an amount that ordinary cement solidifying materials cannot decrease the amount of eluted heavy metals and the like to fall below the environmental standard level. SOLUTION: To 90-99.9 wt.% of a cement solidifying material is added 0.1-10 wt.% of an amorphous silica. Preferably, the compounded amount of the amorphous silica is 0.1-5 wt.%. As the amorphous silica is preferable one having a BET specific surface area of 100-450 m2/g, 200-400 m2/g in particular. As the amorphous silica can be exemplified one obtained by hydrolyzing silicon tetrachloride gas in flames of hydrogen and oxygen, collecting and recovering. The kinds of cement solidifying materials are not particularly limited and those on the market as ordinary solidifying materials for soil conditioning can be used. There can be exemplified those obtained by adding plaster to an ordinary Portland cement or a blast furnace cement. |
