Publication

Gas injection tests on a Sand Bentonite Mixture: Investigation on the effects of pore water chemistry

Lyesse Laloui
2013
Posters

Abstract

In this study a series of swelling and breakthrough tests were performed on a target S/B mixture in proportion 80/20 in dry mass. Tests were carried out on specimen compacted to the same dry density but changing the osmotic suction of the pore water. The tests aimed at determining the relationship between the pore water composition, the swelling behaviour and the breakthrough pressure. The obtained results showed that an increase of the osmotic suction produces a reduction of the swelling capacity and of the breakthrough pressure. This behaviour is associated with the reduction, or even a total lack, of the capacity of the bentonite to fill up the voids among the sand grains.

Official source

https://infoscience.epfl.ch/entities/publication/37170def-4c07-43e2-99c8-2914329b9e4d

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Lyesse Laloui
2013
Posters

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/37170def-4c07-43e2-99c8-2914329b9e4d

About this result

Related concepts (32)

Pore water pressure

Pore water pressure (sometimes abbreviated to pwp) refers to the pressure of groundwater held within a soil or rock, in gaps between particles (pores). Pore water pressures below the phreatic level of the groundwater are measured with piezometers. The vertical pore water pressure distribution in aquifers can generally be assumed to be close to hydrostatic. In the unsaturated ("vadose") zone, the pore pressure is determined by capillarity and is also referred to as tension, suction, or matric pressure.

Bentonite

Bentonite (ˈbɛntənaɪt) is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-montmorillonite. Bentonite usually forms from the weathering of volcanic ash in seawater, or by hydrothermal circulation through the porosity of volcanic ash beds, which converts (devitrification) the volcanic glass (obsidian, rhyolite, dacite) present in the ash into clay minerals.

Water content

Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis. Volumetric water content, θ, is defined mathematically as: where is the volume of water and is equal to the total volume of the wet material, i.