Long-term performance of cement-bentonite containment wall

The paper presents hydraulic conductivity, unconfined compression strength (UCS) and triaxial test results of an 11 year old slag-cement-bentonite (CB) cut-off wall material and identifies factors affecting their long-term performance. The laboratory tests were performed on three types of CB samples ranging from contaminated block field samples to uncontaminated laboratory cast samples. The results showed that hydraulic conductivity reduces till 3 years and UCS increases till 90 days, but there after it remains constant till 11 years of age. The mean hydraulic conductivity and UCS values of block field samples are inferior and have large variability than laboratory cured samples. Such variations are mainly because of heterogeneity caused by aggressive environment and impurities within the specimen. Consolidated undrained triaxial test found that under an effective confining pressure of less than 200 kPa, tension failure occurred since the minor principal stress dropped to zero value at failure. The research outcome is useful for understanding future liability of CB wall and improving their design. © 2009 IOS Press.

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The Value Handbook is a practical guide, showing how public sector organisations can get the most from ther buildings and spaces in their area. It brings together essential evidence about the benefits of good design, and demonstrates how understanding the different types of value created by the built environment (exchange value, use value, image value,social value, environmental value, and cultural value)is the key to realising its full potential.