Cementitious grouts and soil cements were evaluated for use as subsurface barriers to contain buried stabilized hazardous wastes. The environmnent of focus was arid, although the results may also be relevant to other environments. Optimization of the physical and mechanical properties of grouts and soil cements such as permeability, leach resistance, strength and shrinkage cracking was studied through variation of mix proportions. Material costs were compared with permeabilities to evaluate the relative cost effectiveness of the different barriers. Field scale demonstration is required to confirm that acceptable performance can be achieved in practice.