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WHC-SD-W100-TI-003 Rev. 0
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Waste immobilization matrices fall into several general categories. Inorganic
--- binders, thermoplastics, organic polymers, ceramics, and glasses are the
matrices that have been widely used for radioactive waste immobilization.
Inora anic Binders
Inorganic binders are commonly used materials for waste stabilization and
immobilization. They are inexpensive, readily available, and well established
in the radioactive waste management field.
Portland cement
Portland cement is the most common immobilization matrix. It is the same
material used in construction of concrete structures. Portland cement
consists mostly of hydrated calcium silicates, with some aluminates and
magnesium content. The calcium hydroxide content causes portland cement to
exhibit a high pH. The three predominant types are described below.
Type I (ordinary)
Ordinary portland cement ( OPC) is widely used for construction purposes. It
requires about one month to cure to full strength.
Type II ( sulfate-resistant)
Type II cement is resistant to sulfate ions. This gives increased durability
in saline environments.
Type III ( high-early-strength)
Type III cement is ground more finely thus increasing its reactivity. High
early strength creates higher curing exotherms.
Pozzolanic cement additives
Pozzolanic additives are used to modify the reactivity, curing time, and
ultimate strength of cement grout. Two commonly used additives are ground
blast furnace slag, and pulverized coal fly ash.
Blast furnace slag
Blast furnace slag his a higher silica content that cement. This decreases
the reactivity and eliminates the high curing exotherm. It also increases the
curing time required to attain full strength.
Pulverized fly ash
G-3