Membrane efficiency and diffusive tortuosity of a dense prehydrated geosynthetic clay liner

Limiting membrane and diffusion behavior of a geosynthetic clay liner

“…Shackelford et al / Geotextiles and Geomembranes xxx (2016) 1e12 As indicated in Table 3, the values of u o and u ave decrease with increasing values of C ot , which is consistent with the results of previous studies (e.g., Malusis and Shackelford, 2002b;Shackelford, 2009, 2011;Malusis and Daniyarov, 2016). This behavior has been explained in terms of classical DDL theory, whereby an increase in C ot results in an increase in the salt concentration in the pore water of the bentonite which, in turn, results in compression of the DDLs surrounding the individual clay particles, an increase in the sizes of the pores, and a decrease in solute restriction (Fritz, 1986).…”

“…However, unlike Meier et al (2014), two different values of u are distinguished in Table 3, i.e., values of u designated as u o that were calculated using the source concentrations (i.e., C ot and C ob ), and values of u designated as u ave that were calculated using the averages of the top and bottom boundary concentrations defined as follows (Malusis et al, 2001;Malusis and Shackelford, 2002b;Shackelford, 2013a, b;Malusis and Daniyarov, 2016):…”

“…In addition to economy of use and the potential for low k, GCLs have been shown to exhibit semipermeable membrane behavior, which refers to the ability of clays to restrict the migration of dissolved chemical species or solutes (e.g., Malusis and Shackelford, 2002b;Kang and Shackelford, 2011;Malusis et al, 2015;Malusis and Daniyarov, 2016). Solute restriction is a function of the sizes of the clay pores, with smaller pore sizes resulting in greater solute restriction.…”

“…However, the mass flux resulting from solute migration through clay membranes is reduced relative to that in the absence of solute restriction. As a result, the chemical containment function of a GCL can be enhanced by the existence of membrane behavior Shackelford, 2013a, b;Malusis and Daniyarov, 2016).…”

“…The ability of GCLs to restrict solute migration also is known to decrease as the salt concentration within the pore water of the bentonite contained within the GCL increases (Malusis and Shackelford, 2002b;Shackelford, 2011, Shackelford, 2013aMalusis and Daniyarov, 2016). This trend of decreasing solute restriction with increasing solute concentration occurs because, as the concentration of the solutes in the pore water increases, the thicknesses of the DDLs and associated electric fields controlling solute restriction decrease, resulting in progressively larger pores and correspondingly lesser solute restriction (Fritz, 1986).…”