American Society of Civil Engineers


Durability Study of Eleven Years Old Cement-Bentonite Cut-Off Wall Material


by Kaushal Joshi, Ph.D., (Student, University of Cambridge, UK, CB2 1PZ E-mail: kdj22@cam.ac.uk), Kenichi Soga, (Professor, University of Cambridge, UK, CB2 1PZ E-mail: ks207@cam.ac.uk), Man Yin Albert Ng, (Ph.D student, University of Cambridge, UK, CB2 1PZ E-mail: myan2@cam.ac.uk), and Cedric Kechavarzi, (Lecturer, Cranfield University, UK, MK43 0AL E-mail: c.kechavarzi@Cranfield.ac.uk)
Section: Reactive and Hydraulic Vertical Barriers, pp. 620-627, (doi:  http://dx.doi.org/10.1061/40970(309)78)

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Document type: Conference Proceeding Paper
Part of: GeoCongress 2008: Geotechnics of Waste Management and Remediation
Abstract: Comprehensive understanding of the long-term performance of cement-bentonite slurry trench cut-off walls is essential as these mixes may degrade when exposed to aggressive environments or when subjected to prolonged drying. A series of wetting-drying and immersion experiments was carried out to evaluate the durability characteristics of laboratory mixed samples and block field samples from 40 days to 11 years of age. For the wetting-drying tests, the samples buried in medium graded sand were subjected to periodical flooding and drying cycles. They were then used for permeability testing and unconfined compressive strength (UCS) testing. For the immersion tests, the samples confined in perforated molds were submerged in magnesium sulfate solution for 16 weeks and their microstructures were then analyzed using X-ray diffraction (XRD) technique. This paper identifies the effects of contaminant exposure on durability of cement-bentonite and the effects of aging by comparing 11 years old samples to younger samples. Test results showed that young or previously contaminated cement-bentonite mixes are more susceptible to sulfate attack than old or less contaminated mixes.


ASCE Subject Headings:
Walls
X rays
Slurries
Dewatering