Capillary barriers incorporating non-woven geotextiles

Abstract

Capillary barriers can be an effective solution to minimise or delay infiltration of liquids in soils. These alternative barriers may be particularly appropriate and cost-effective in cover systems of waste disposal systems in arid and semi-arid regions. The mechanism of flow control in a capillary barrier involves the impedance of flow moving from a porous medium of small voids to another porous medium of larger voids, due to differences in the water storage between the two materials for the same suction at their interface. Granular soils have been used to induce a capillary barrier. However, the use of geotextiles as barriers can offer not only the relevant difference in water storage but also the repeatability and consistency of properties offered by manufactured materials, besides other advantages. The objective of this paper is to investigate the behaviour of capillary barriers using non-woven geotextiles under controlled laboratory conditions. Accordingly, fine-grained soil and geotextiles with different properties were used in the testing programme. Granular materials (sand and gravel) were also utilised to form granular capillary barriers for comparison purposes. Overall, the experimental results show that geotextiles can develop capillary barriers with similar storage capability as those provided by natural granular materials.