Volume 31, Issue 3 (May 2008)
Modified Fluid Loss Test as an Improved Measure of Hydraulic Conductivity for Bentonite
The Modified Fluid Loss test (MFL) was developed to measure hydraulic conductivity using the filter press method. Based upon modification of conventional filtration models, the average hydraulic conductivity of a bentonite filter cake can be obtained from the filtrate-time relationship and the water content of the filter cake. At higher effective stresses (>100 kPa), the hydraulic conductivity from MFL method showed higher values than those from flexible wall permeameter (FWP) method. In comparison to the FWP method, the MFL method-based hydraulic conductivities are on the conservative side for the stress range associated with typical bottom liners in solid waste landfills. The MFL test was found to be a convenient test method to assess the hydraulic conductivity of bentonite, especially at low effective stresses. The MFL test can be used to obtain the hydraulic conductivity of bentonite within about a day instead of several days to weeks required for the FWP test.