Slag-Based Saltstone Formulations

1987 ◽  
Vol 112 ◽  
Author(s):  
C. A. Langton
Keyword(s):  
Fly Ash ◽  
Heat Of Hydration ◽  
Waste Form ◽  
Savannah River ◽  
Ion Release ◽  
Alkaline Salt ◽  
Savannah River Plant ◽  
Physical Entrapment ◽  
Class F Fly Ash ◽  
Class F

AbstractApproximately 400 × 106 liters of low-level alkaline salt solution will be treated at the Savannah River Plant (SRP) Defense Waste Processing Facility (DWPF) prior to disposal in concrete vaults at SRP. Treatment involves removal of Ca+and Sr+2 followed by solidification and stabilization of potential contaminants in saltstone, a hydrated ceramic waste form.Chromium, technetium, and nitrate releases from saltstone can be significantly reduced by substituting hydraulic blast furnace slag for portland cement in the formulation designs. Slag-based mixes are also compatible with Class F fly ash used in saltstone as a functional extender to control heat of hydration and reduce permeability. (Class F fly ash is locally available at SRP.)A monolithic waste form is produced by the hydration of the slag and fly ash. Soluble ion release (NO3−) is controlled by the saltstone microstructure (bulk porosity and pore size and connectivity). Chromium and technetium are 103−104 times less leachable from slag mixes than from cement-based waste forms. Results suggest that chemical stabilization rather than physical entrapment, as in the case of nitrate is responsible for this improved leaching. Reduction of Cr+6 and Tc+7 to Cr+3 and Tc+4 by ferrous iron or Mn+2 in the slag and subsequent precipitation of the relatively insoluble phses Cr(OH)3 and TcO2 are proposed as the stabilizing reactions.

Thermal Properties of Fly Ash-Slag Cement Waste forms for Disposal of Savannah River Plant Salt Waste

1985 ◽  
Vol 65 ◽  
Author(s):  
S. Kaushal ◽  
D. M. Roy ◽  
P. H. Licastro ◽  
C. A. Langton
Keyword(s):  
Thermal Properties ◽  
Fly Ash ◽  
Thermal Stresses ◽  
Waste Form ◽  
Savannah River ◽  
Granulated Blast Furnace Slag ◽  
Savannah River Plant ◽  
High Calcium ◽  
Mechanical Durability ◽  
Concentrated Solution

ABSTRACTWaste processing at the Savannah River Plant will involve reconstitution of the salts (NaNO3, NaNO2, Na2 SO4 and NaOH) into a concentrated solution followed by solidification in a cement-based waste form. Phase stability and mechanical durability of this material will depend to a considerable extent on the thermal properties of the waste form. Fly ash has been used to moderate the hydration and setting processes so as to avoid high temperatures which could cause thermal stresses. Both high-calcium (Class C) and low-calcium (Class F) fly ashes were studied. Other constituents of the mixes include granulated blast furnace slag and finely crushed lime-stone. The adiabatic temperature increases and thermal conductivities were measured and related to matrix mineralogy and microstructure as determined by x-ray diffraction and scanning electron microscopy, respectively.

scholarly journals Mix proportions and mechanical properties of concrete containing very high-volume of Class F fly ash

2013 ◽  
Vol 46 ◽  
pp. 71-78 ◽  
Author(s):  
Chung-Ho Huang ◽  
Shu-Ken Lin ◽  
Chao-Shun Chang ◽  
How-Ji Chen
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
High Volume ◽  
Class F Fly Ash ◽  
Very High ◽  
Class F

Physical Properties of Saltstone: Physical Properties of Saltstone: A Savannah River Plant Waste Form

1984 ◽  
Vol 44 ◽  
Author(s):  
Christine A. Langton
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Field Tests ◽  
Waste Form ◽  
Savannah River ◽  
X Ray Diffraction ◽  
Near Surface ◽  
Leach Rate ◽  
Savannah River Plant ◽  
Water To Cement Ratio

AbstractA cement-based waste form, “saltstone,” has been designed for disposal of Savannah River Plant low-level radioactive salt waste. Laboratory and field tests indicate that this stabilization process greatly reduces the mobility of all of the waste constituents in the surface and near-surface environment. Bulk properties of this material have been tailored with respect to salt leach rate, permeability, and compressive strength. Microstructure and mineralogy were characterized by SEM and x-ray diffraction analyses.Compressive strength was found to increase as the water to cement ratio decreased. Porosity and mean pore size increased with increasing water to cement ratios. Bulk diffusivities of the various ions dissolved in the pore solutions were also found to increase as water to cement ratios increased.

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