Dimensional Stability of Geosynthetic Clay Liners in Landfill Applications

Olsen, Gregory R.

doi:10.15368/theses.2011.209

Cited by 2 publications

(12 citation statements)

References 32 publications

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“…Wet-dry cycles may decrease hydraulic performance of GCLs by causing excessive shrinkage or by significantly decreasing swell capacity in conjunction with cation exchange. Wet-dry cycles may be imposed on GCLs by changes in moisture content of adjacent soils, or by daily solar heating of exposed geomembranes overlying the GCL (Olsen 2011).…”

Section: Wet-dry Cyclesmentioning

confidence: 99%

“…Overlap distances of 150 mm and 600 mm typically specified for side-of-GCL roll and end-of-roll, respectively, may be insufficient to prevent panel separation of installed GCLs (Olsen 2011). Excessive shrinkage may develop with successive wet-dry cycles that eventually exceed the overlap distance of GCLs.…”

Section: Wet-dry Cyclesmentioning

confidence: 99%

“…Hydration of GCLs from adjacent soils may be excessive for dry GCLs that are placed adjacent to wet soils, especially for low confining pressure (e.g., less than 100 kPa). Olsen (2011) of GCLs when coupled with cation exchange (e.g., Bradshaw et al 2013).…”

Section: Moisture Transfer From Adjacent Soilsmentioning

confidence: 99%

“…The procedure for wet-dry cycling followed Olsen (2011) in order to compare strain behavior of this test program with that presented in Olsen (2011). GCL panels measuring 279 mm x 356 mm were cut from bulk samples of NN1 with a sharp utility knife, in the same manner as described in Section 3.3.1.…”

Section: Gcl Specimen Preparation-wet/dry Cyclesmentioning

confidence: 99%

“…Poorly graded sand (SP) was tamped into brass rings to achieve a unit weight of 16.3 kN/m 3 ± 0.3 kN/m 3 . The dry density was selected for consistency with subgrade tests from Olsen (2011). SP samples were compacted in either dry or moist conditions because molding water content was assumed to not affect water retention for cohesionless sand.…”

Section: Preparation Of Sand (Sp)mentioning

confidence: 99%

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Development and Use of Moisture-Suction Relationships for Geosynthetic Clay Liners

Risken¹

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A laboratory test program was conducted to determine the moisturesuction relationships of geosynthetic clay liners (GCLs). Moisture-suction relationships were determined by combining suction data from pressure plate tests, contact filter paper tests, and relative humidity tests, then fitting water retention curves (WRCs) to the data. WRCs were determined for wetting processes and drying processes in terms of gravimetric moisture content and volumetric moisture content. The effects of GCL type, hydration solution, wet-dry cycles, and temperature on the moisture-suction relationships were analyzed. The three GCLs of the test program consisted of configurations of woven and nonwoven geotextiles reinforced with needlepunched fibers. A geofilm was adhesively bonded to the nonwoven side of one of the GCL products. The hydration solution tests involved hydrating GCLs with deionized water, tap water, 0.1 M CaCl 2 , or soil water from a landfill cover test plot for a 30-day conditioning period prior to testing. Cyclic wet-dry tests were conducted on the GCL specimens subjected to 20 wet-dry cycles from 50% to 0% gravimetric moisture content prior to testing. Temperature tests were conducted at 2C, 20C, and 40C. GCL type affected moisture-suction relationships. The GCLs with an adhesively-bonded geofilm exhibited lower air-entry suction and higher residual v suction than GCLs without a geofilm. The degree of needlepunched fiber pullout during hydration contributed to hysteresis between wetting WRCs and drying WRCs. Hysteresis was high for suction values below air-entry suction and was low for suction values greater than air-entry suction. Cation exchange reduced the water retention capacity for all three GCL types. The saturated gravimetric moisture contents were reduced from approximately 140% to 70% for wetting WRCs and 210% to 90% for drying WRCs for GCLs hydrated in deionized water compared to CaCl 2 solution. Hysteresis of the nonwoven product decreased from 71%, to 62%, to 28% with respect to deionized water, tap water, and CaCl 2 solution. Hysteresis of the woven product exposed to soil water was 24% and 0%, in terms of saturated gravimetric moisture content and saturated volumetric moisture content, respectively. The swell index, Atterberg Limits, mole fraction of bound sodium, and scanning electron microscopy images that were determined of bentonite from the conditioned GCLs indicated that changes in water retention capacity corresponded with cation exchange. Wet-dry cycles and temperature affected the moisture-suction behavior for GCLs. Wet-dry cycles reduced hysteresis and increased the swelling capacity of GCL specimens. Microscopy images indicated that wet-dry cycles caused weak orientation of the clay particles. Increasing temperature resulted in a small decrease in water retention capacity. Results of the test program provided a means for predicting unsaturated

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Section: Wet-dry Cyclesmentioning

confidence: 99%

Section: Wet-dry Cyclesmentioning

confidence: 99%