Fibrillated polypropylene fibres were added to cementitious grouts to determine whether improved mechanical properties and durability could be achieved. The grouts were studied for suitability as subsurface containment barriers around stabilized hazardous waste landfills. Strength, wet-dry and freeze-thaw durability and shrinkage crack control were investigated. Fibres added at volume fractions of 0.1 and 0.2% were found to reduce crack widths of restrained shrinkage specimens by bridging action. Compressive and flexural strengths were not consistently affected by incorporation of fibres. Fibres did not significantly change the residual compressive strength of air entrained grouts subjected to freeze-thaw cycles.