Testing and Performance Criteria for Stabilized/Solidified Waste Forms - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 290

methods for determination of hydraulic conductivity are ASTM D5084-00 39 and BS
1377: Parts 5(5) and 6(6). 40,41 A wide range of hydraulic conductivity tests is given
in Head. 42 S/S materials normally have a low hydraulic conductivity to prevent
advection of contaminants. Therefore, a falling head test method is used, in which
the volume of water passed through a saturated monolithic specimen under pressure
in a given period of time is measured. Stegemann and Coté, 3 however, demonstrated
poor reproducibility of this method on a variety of S/S materials and suggested use
of a constant head/flow pump method.
Oxygen permeability 43 is sometimes measured for S/S materials, if it is desired
to measure permeability without concurrent sample changes due to leaching. An
intrinsic permeability, which should be independent of the fluid used to conduct the
test, can be calculated from either hydraulic conductivity or oxygen permeability.

11.3.4 W EATHERING R ESISTANCE

Freeze/thaw and wet/dry durability tests are conducted to examine the capability of
a monolithic S/S material to withstand weathering due to temperature and moisture
fluctuations. 44-48 These tests monitor the weight loss of a monolithic S/S material
over a stipulated number of repeated cycles of freezing and thawing, or immersion
and drying. Mechanical or chemical changes to the matrix are not measured. The
freeze/thaw test is considered to be the more severe of the two tests 4 and also found
to be the least reproducible. 3
Sodium or magnesium sulfate soundness 49,50 can be considered an indirect mea-
sure of weathering resistance, as it measures the ability of a monolithic material to
withstand expansive crystallization within its porosity.

11.4 OTHER CHARACTERIZATION AND EVALUATION

TESTS

Many other tests are sometimes used to characterize or evaluate the materials before
and after S/S treatment. These test methods are summarized as follows:

11.4.1 I NITIAL C ONSUMPTION OF L IME (ICL)

ICL 51 is a test for cohesive untreated materials to determine the percentage of lime
required to raise the pH of the soil to 12.4. The initial improvement, termed modi-
fication, makes the material drier and friable, enabling easy compaction, and the
improvement over time, termed stabilization, results in increased strength.

11.4.2 P ULVERIZATION

Pulverization 52 is a measure of how well the binder and water have been mixed with
the untreated material. It is determined by sieving a known mass of sample first with
minimum breakage and then after existing lumps have been separated. It is a site
control test carried out on soils that have been stabilized for earthwork purposes.