Hydraulic Cement Systems for Stabilization/Solidification - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 70

TABLE 4.4
Specification on CKD for S/S Purposes 1

Catalog Property Criteria

Visual Observation Free-flowing powder

No lumps larger than 3/8 in.
No impurities (rocks, plant fragments, etc.)

Chemical Property pH of 10% slurry > 10

Alkalinity as CaO > 15%

Moisture Content at 105°C < 1%

Loss of ignition at 1100°C < 30%

Temperature rise 20°C

Physical Property Apparent bulk density (loose) 35-60 lb/ft 3

Apparent bulk density (packed) 35-60 lb/ft 3

Fineness (+8 mesh) < 1

Fineness (-325 mesh) < 90

and Recovery Act. Although the proposed rule does not limit the beneficial use of
CKD in a commercial landfill, the handling and transportation regulations could
potentially pose difficulties for customers and haulers.

4.7 FLY ASHES

As discussed above, since Class C fly ash has a high content of lime and exhibits
some cementitious properties, it can be used alone for S/S purposes. Redd et al. 113
conducted a series of experiments to stabilize the phenolics in foundry sands from
Kansas using four different types of binders: portland cement, Class C fly ash,
kaolinite, and bentonite. Strength and leachability of stabilized mixes of foundry
sand were analyzed to assess their feasibility in construction and geotechnical appli-
cations. The results suggest that compressive strength was acquired relatively faster
in Class C fly ash than in cement and, in general, varied inversely with the proportion
of foundry sand in the stabilized mix. Lesser amounts of phenolic compounds
leached from Class C fly ash-stabilized mixes than from cement-stabilized mixes.
The leachate analyses for both total phenolics and 2,4,6-trichlorophenol indicate that
increasing percentage replacement of foundry sands enhances stabilization. SEM
observations confirmed that the cement-stabilized wastes were more porous than the
Class C fly ash-stabilized wastes. 113

REFERENCES

1. Conner, J. R., Chemical Fixation and Solidification of Hazardous Wastes , Van Nos-

trand Reinhold, New York, 1990.

2. IAEA, Improved Cement Solidification of Low and Intermediate Level Radioactive

Wastes , Technical Report Series No. 350, International Atomic Energy Agency,
Vienna, 1993.