Degradation of geocomposite clay liners due to geochemical reactions in sodium bentonite
- OCCU-TEC, Inc., Kansas City, MO (United States)
Geocomposite clay liners are commonly used as permeability barriers in landfills, hazardous waste facilities, overlying caps, secondary containments for tank farms, industrial and decorative lagoons and as slurry walls. Most recent geocomposite liners are manufactured using sodium bentonite sandwiched between two polypropylene geotextile. Na-bentonite is widely used because of its high swelling capacity, its low permeability when hydrated, high cation exchange capacity and low cost. Na-bentonite used in geo-composite liners showed degradation due to numerous geochemical reactions within the clays and cover materials at the site. The clays within the liner has undergone changes in pH from pH9 to pH5, dehydration and replacement of interlayer Na by Ca and Mg ions. Cation exchange capacity (CEC) reduced from 110 meq/100 gm to 72.5 meq/100 gm. The reduction in CEC maybe attributed to transformation of clay minerals. Analytical electron microscopy data show a decrease in Na and an increase in Ca and Mg. This observation is confirmed by the results obtained from cation exchange capacity measurements and XRD. These changes in Na-bentonite increased the permeability of the liner by 2 to 4 orders of magnitude and caused the liners to leak.
- OSTI ID:
- 7207221
- Report Number(s):
- CONF-9303210--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 25:3; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540250* -- Environment
Terrestrial-- Site Resource & Use Studies-- (1990-)
58 GEOSCIENCES
580000 -- Geosciences
BENTONITE
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CLAYS
DECOMPOSITION
FAILURES
INORGANIC ION EXCHANGERS
ION EXCHANGE
ION EXCHANGE MATERIALS
KINETICS
LINERS
MANAGEMENT
MATERIALS
MATERIALS TESTING
PERMEABILITY
REACTION KINETICS
SANITARY LANDFILLS
TESTING
WASTE DISPOSAL
WASTE MANAGEMENT