Polypropylene fiber reinforced bentonite for waste containment barriers

The present study examines the relevance of placement conditions on the behaviour of polypropylene fiber reinforced bentonite. The laboratory testing program includes conducting standard and modified Proctor compaction tests, tracing shrinkage behaviour, performing hydraulic conductivity and unconfined compression strength tests on both unreinforced and fiber reinforced bentonite. An overall acceptable zone in terms of water content and dry unit weight is established by considering the hydraulic conductivity, strength and volumetric shrinkage criteria. The experimental results showed that the volumetric shrinkage criterion controlled the overall acceptable zone for unreinforced and fiber reinforced bentonite specimens in compacted state. However, the hydraulic conductivity values of fiber reinforced bentonite specimens subjected to wet-dry cycles show that the shrinkage criteria may not be appropriate for materials such as bentonite and bentonite-enhanced clays which possess good self sealing properties; and for such materials the hydraulic conductivity needs to be evaluated after wet-dry cycles. As the basic ingredient of geosynthetic clay liners (GCLs) is bentonite clay, the relevance of the placement conditions is discussed for the GCLs.