PERMEABILITY OF MICROCRACKED FIBER-REINFORCED CONTAINMENT BARRIERS

Cement-based containment barriers for waste landfills are at risk of c racking, thereby reducing effectiveness. Improved resistance to format ion of permeable cracks will enhance the performance of cementitious h ydraulic barriers exposed to excessive drying or to wet-dry cycles. Ad dition of fibre reinforcement was investigated as a potential means of improving crack resistance, Grout and soil cements with and Without p olypropylene fibres were subjected to different curing and exposure co nditions and tested for initial and final permeability. Permeabilities under saturated flow conditions were compared to determine whether fi bres could control permeable microcracking of subsurface containment b arriers. Fibrillated polypropylene fibres reduced the relative change in permeability for grout and soil cement cured in water and subjected to wet-dry cycles, but did not show significant benefit for materials cured in soil and allowed to dry. Addition of monofilament fibres to barrier materials caused an increase in post-cracking permeability com pared with unreinforced materials, This was attributed to increased Wo w paths created at failed fibre/matrix interfaces.