ABSTRACTAt Oak Ridge National Laboratory, we have developed cementitious grout formulations which can incorporate up to 50 wt % of a transuranic (TRU) waste generated during startup operations at the Rocky Flats Plant Building 374, Golden, Colorado. Trial grout mixes were tested in order to minimize the water content and maximize the waste loading. The effects of water reducers and set regulators on these mixes were also examined.Durability and physical property measurements were performed on formulations containing 40 wt % waste, which are compatible with standard processing equipment. The densities, porosities, and compressive strengths of these solids are reported. Compressive strengths of the samples were found to increase by as much as 69% after the sample had been exposed to leachants for 28 d at 900 C.