(57) An environmentally friendly cement comprises (1) an active filler comprising waste materials composed of a thermal insulation wool and a waste thereof; (2) an inert filler comprising metakaolin and an aggregate optionally selected from cement, fine sand, gravel, waste to be solidified, and organic resin; and (3) an aqueous solution of sodium metasilicate as an alkaline compound. A method for producing the environmentally friendly cement comprises mixing ingredients (1) and (3) and ingredients (2) and (3) respectively to obtain a slurry A and a slurry B respectively; mixing the slurry A and B; and hardening the final slurry, whereby elements silicon and aluminum in the ingredient (1) are dissolved out in the basic solution of the ingredient (3), and a closed framework structure is formed by bonding silica and alumina as tetrahedrons. The environmentally friendly cement has excellent fire tolerance, heat insulation, acid and alkaline resistance, and mechanical properties.
(71) Institute of Nuclear Energy Research, Atomic Energy Council, Executive Yuan, R.O.C. (TW)