Imbibition test in a clay powder (MX-80 bentonite)

• Published in: Applied clay science Vol. 26; no. 1; pp. 235 - 248
• Main Authors: Lemaire, Thibault, Moyne, Christian, Stemmelen, Didier
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 01.08.2004; Amsterdam Elsevier Science; New York, NY Elsevier
• Subjects: Biomechanics; Clogging effect; Dual porosity; Earth sciences; Earth, ocean, space; Engineering Sciences; Exact sciences and technology; Expansive clay; Hydraulic diffusivity; Mechanics; Mineralogy; Moisture movement; Physics; Silicates; Swelling pressure; γ-ray attenuation measurements; γ-ray attenuation measurements; Expansive clay; Swelling pressure; Moisture movement; Dual porosity; Clogging effect; Hydraulic diffusivity; diffusion; attenuation; time variations; hydraulics; relief; energy; models; soil moisture; porosity; clogging; swelling; pressure; transport; infiltration; grains; materials; radiation; diffusivity
• ISSN: 0169-1317; 1872-9053
• DOI: 10.1016/j.clay.2003.12.009

The MX-80 bentonite is a reference material for studies in clay barriers. This paper aims to present an investigation of the behaviour of such a material during an infiltration test from the bottom in oedometric conditions. Using dual-energy γ radiation technique, time variations of moisture content are measured at various locations along the clay sample. The transport of water occurring in this experiment can be described by the classical diffusion equation in terms of the Boltzmann variable. A parameter of hydraulic diffusivity is obtained with the Matano's method. Two fluid transport mechanisms govern the phenomena: imbibition of the microporosity in the clay grains and capillary imbibition in the mesoporosity around the grains. The competition between these two mechanisms will be put into relief by modelling the distribution of the water between and inside the bentonite grains. A clogging behaviour of the mesopores during the imbibition process will allow to explain the surprising decrease in hydraulic diffusivity.