Other Binders - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 121

16. Wagh, A.S., M. D. Maloney, G. H. Thomson, and A. Antink, Investigations in Ceram-

icrete Stabilization of Hanford Tank Wastes, Proc. Waste Management '03 , Tucson,
AZ (2003).

17. Dole, L. R., G. Rogers, M. Morgan, D. Stinton, J. Kessler, S. Robinson, and J. Moore,

Cement-Based Radioactive Waste Hosts Formed Under Elevated Temperatures and
Pressures (FUETAP Concrete) for Savannah River Plant High-Level Waste, Report
No. ORNL/TM-8579, Oak Ridge National Laboratory (1983).

18. Dole, L. R. and H. A. Friedman, Radiolytic Gas Generation from Cement-Based

Waste Hosts for DOE Low-Level Radioactive Wastes, Report No. CONF-860605-
14, Oak Ridge National Laboratory (1986).

19. Siskind, B., Gas Generation from Low-Level Waste: Concerns for Disposal, Report

No. BNL-NUREG-47144, Brookhaven National Laboratory (1992).

20. Bates, D. J., R. W. Goles, L. R. Greenwood, R. C. Lettau, G. F. Piepel, M. J.

Schweiger, H. D. Smith, M. W. Urie, J. J. Wagner, and G. L. Smith, Vitrification and
Product Testing of C-104 and AZ-102 Pretreated Sludge Mixed with Flowsheet
Quantities of Secondary Wastes, PNNL-13452, Pacific Northwest National Labora-
tory, Richland, WA (2001). Note that currently there is no accepted WAC for Yucca,
but this report suggests a possible WAC for the disposal facility.

6.3 SULFUR POLYMER CEMENT (SPC)

Paul D. Kalb

Elemental sulfur is a thermoplastic material that can be melted at around 119°C,
mixed with aggregates, and cooled to form a concrete. While its potential use as an
alternative to conventional hydraulic cement probably dates back to ancient times,
evidence of its use in Latin America as early as the 1600s to join metal and stone
can still be seen today. 1-3 However, as the molten sulfur cools to a solid and then
further cools to ambient temperature, it undergoes an allotropic solid phase trans-
formation from the more loosely packed monoclinic crystalline form (S) above 96°C
to the more densely packed orthorhombic crystal lattice form (S α ) below 96°C. Since
the orthorhombic form has a slightly higher density, the solid undergoes a volume
reduction of 6% following the phase transition, creating stress within the solid. This
phenomenon leads to poor durability or mechanical failure as the stresses are
relieved, especially under freeze/thaw cycling or if the solid is shocked. 4 These
limitations hindered the more widespread use of sulfur until the relatively recent
introduction of modified sulfur compounds, e.g., sulfur polymer.
Surpluses of elemental sulfur following World War I led researchers to begin to
look for ways to modify the sulfur matrix and make it more durable and thus suitable
for construction applications in place of conventional cement. 5 Although unsuccess-
ful, this work paved the way for further development of modified sulfur binders.
The advent of sulfur removal from petroleum and flue-gas desulfurization from coal-
burning power plants that resulted from new environmental regulations in the early
1970s created even larger surpluses of by-product sulfur and encouraged new efforts
to develop techniques for using sulfur for construction applications.
Work conducted at the U.S. Bureau of Mines (USBM) 2,6,7 and in Canada 8-10 and
elsewhere 11 explored the use of organic modifiers to form polysulfides that plasticize