GROUT-TREATED SOIL FOR LOW-PERMEABILITY BARRIERS AROUND WASTE LANDFILLS

The objective of this work was to produce grout-treated soils with per meability coefficients less than 10(-7) cm/sec that would be suitable as containment barriers around hazardous waste landfills. The role of such admixtures as superplasticizers and silica fume in grouts for mix ing with soil was investigated. Grouts were designed to be used with s oil-mixing or jet-grouting techniques for in situ installation of barr iers. Materials with a range of soil-cement ratios were tested for per meability and strength under wet and simulated subsurface curing condi tions. Permeability coefficients of the order of 10(-10) cm/sec were m easured for soil cements with soil-cement ratios by mass up to 5, depe nding on how the materials were cured. The use of superplasticizers in parent grouts to reduce water-cement ratio decreases permeability up to four orders of magnitude compared to soil cements produced from con ventional high water-cement ratio grouts. The significant improvement in performance results in reduced thickness of barriers for hydraulic and physical isolation of contaminants, and hence greater cost effecti veness.