Abstract

Due to the progressive use of landfills and the challenges about their effect on their surrounding environment, the
hydraulic and gas permeability of the landfill liners has always been a great concern for geotechnicians. Clay-based
materials are usually used as the main material for landfill liners. Various additives are implemented to control the
hydraulic and gas permeability of these clay liners under different climate conditions. The attempt of this research was to
investigate the effect of using four types of geo-fibers, including ordinary and web polyester, polypropylene, and
polyvinyl alcohol fibers, on reducing the hydraulic and gas permeability under wet and dry conditions. In this regard, two
sets of water and gas permeability tests were performed for clay–fiber mixtures with 0.2, 0.4, and 0.6 weight
percentages of fiber additives. The results showed an initial decrease and then a growth in the permeability coefficients
by increasing the fiber dosages, resulting in an optimum percentage for each fiber type. Among the fibers used in this
study, polyvinyl alcohol fiber with 0.2 weight per cent performed best by reducing the permeability coefficient by
approximately 65% and 75% for hydraulic and gas permeability coefficients under wet and dry conditions.