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# Gas flow in compacted clays

 dc.contributor.author Halayko, Krista Sophia Gelmich en_US dc.date.accessioned 2007-05-15T19:08:45Z dc.date.available 2007-05-15T19:08:45Z dc.date.issued 1998-09-01T00:00:00Z en_US dc.identifier.uri http://hdl.handle.net/1993/1306 dc.description.abstract Compacted clays and clay-sand mixtures are being used increasingly to isolate wastes from the biosphere. Clay buffers are commonly used in landfills and are proposed for use in the Canadian nuclear fuel waste disposal concept. This study will investigate the effect of high gas pressures on gas migration through compacted clay materials. Illite, illite/sand and bentonite specimens, 50mm in diameter and 24mm thick, were tested in a gas breakthrough apparatus with a capacity of 10 MPa. The inlet pressure was either increased in steps or was held constant. Gas breakthrough was said to occur when a response was noted at the outlet side of the specimen. In the forty-two illite/sand specimens tested with effective clay dry densities, $\rho\sb{\rm c}$, ranging from 1.30-2.10 Mg/m$\sp3$, gas breakthrough was found to be between 0.2 and 6.4 MPa. For most of the fifty-six increasing pressure tests on bentonite ($\rho\sb{\rm c}$ = 0.6-1.2 Mg/m$\sp3$) however, the upper capacity of the test equipment was reached before gas breakthrough was observed. The increased resistance to gas breakthrough is because of an increased proportion of bound water in bentonite which blocks all but the largest continuous pores. Below a certain degree of saturation, no resistance to gas flow was observed in either clay due to the fact that continuous gas pathways existed. This threshold was $\approx$85% for illite and $\approx$93% for bentonite. Capillary and advection theories were compared with the test data. The advection theories were found to provide a more realistic representation of the real system and an estimate of gas breakthrough pressure within an order of magnitude for increasing pressure tests. en_US dc.format.extent 9853085 bytes dc.format.extent 184 bytes dc.format.mimetype application/pdf dc.format.mimetype text/plain dc.language en en_US dc.language.iso en_US dc.title Gas flow in compacted clays en_US dc.degree.discipline Civil Engineering en_US dc.degree.level Master of Science (M.Sc.) en_US
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