Laboratory and In Situ Tests for Long-Term Hydraulic Conductivity of a Cement-Bentonite Cutoff Wall
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 136, Issue 4
Abstract
Slurry trench cutoff walls, constructed using self-hardening slag-cement-bentonite (Slag-CB), are the most common form of in-ground vertical contaminant barrier in the U.K., Europe, and Japan, and are increasingly being used in the United States. This paper presents a case study of the hydraulic conductivity evaluation of an 11-year-old Slag-CB wall material at a sulfate-contaminated site, using different in situ techniques and laboratory tests. The laboratory results suggest that the hydraulic conductivity of the samples, which vary in age from 4 weeks to 11 years, decreases with time for the first 3 years but then remains constant. The results indicate that the long-term performance of these containment walls is influenced by various parameters such as aging, the type/duration of contaminant exposure, mixing of surrounding soil during construction, and wall depth. Piezocone tests, packer tests, and self-boring permeameter tests were carried out in the field to determine the suitability of different in situ techniques and compare with the laboratory results. The hydraulic conductivity is affected by the type of in situ technique used and the geometric scale of the test section.
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Acknowledgments
The authors would like to thank the EPSRC-GB for funding of the research project (Grant No. EPSRC-GBGR/R98150/01), as well as the Cambridge Commonwealth Trust. Also, gratitude must be paid to the assistance provided by Ken Watts of BRE in conducting the Piezocone work, as well as in the project management of the site. Steve Chandler and Chris Knight of Cambridge University Engineering Department are to be acknowledged for general assistance in the laboratory and field studies.
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Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 136 • Issue 4 • April 2010
Pages: 562 - 572
Copyright
© 2010 ASCE.
History
Received: Oct 17, 2008
Accepted: Sep 5, 2009
Published online: Sep 11, 2009
Published in print: Apr 2010
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