Volume 33, N. 2

May-August 2010

Hydraulic Conductivity and Shear Strength Behavior of Compacted Lateritic Soil-Bentonite Mixtures Used for Sanitary Landfill Liners

Article

Volume 33, N. 2, May-August 2010 | DOWNLOAD PDF (13 downloads)

Abstract

The use of soil-bentonite mixtures for sanitary landfill liners with the purpose of retaining pollutants is becoming very common. This work shows the results of hydraulic conductivity and shear strength tests performed with soil-bentonite mixtures with bentonite contents of 3%, 5% and 7%. Additionally, shear strength test results carried out with a mixture with bentonite content of 9%, are shown. The selected natural soil for this research is a lateritic residual clayey sand originated from Adamantina Formation sandstones of the Bauru Group. Samples of this soil were collected in the Pindorama County, which is located in the northeast of the State of Sao Paulo, Brazil. The hydraulic conductivity tests were performed with rigid and flexible wall permeameters. Test results show that mixtures with bentonite content higher than 6% are suitable, in terms of hydraulic conductivity, for the construction of sanitary landfill liners. The shear strength parameters of natural soil and mixtures were assessed by performing undrained triaxial compression tests and unconfined compression tests. It was found that there is a tendency showing that the cohesion increases when the bentonite content is increased. The addition of bentonite to natural soil causes the friction angle to decrease. However, it cannot be concluded from test results, that the higher the bentonite content, the lower the friction angle. In terms of shear strength, the unconfined compression test results have shown that mixtures with bentonite content of 5% are suitable for the construction of sanitary landfill liners when relative compaction is equal or higher than 95%.

Keywords: Sanitary landfill, Liners, Bentonite, Hydraulic conductivity, Shear strength,


Submitted on December 16, 2008.
Final Acceptance on June 22, 2009.
Discussion open until December 31, 2010.
DOI: 10.28927/SR.332069