Influence of Fibers on Hydro-Mechanical Properties of Bentonitic Mixtures

This paper reports the influence of fibre inclusion on the hydro-mechanical properties of bentonitic mixtures at varying compaction states. Pond ash–bentonite and sand–bentonite mixtures are synthesized by adding 20% commercial bentonite to pond ash and sand respectively. Discrete polypropylene fibres ranging from 0 to 1% are added to the mixtures. The hydro-mechanical properties of specimens; compacted to either standard or modified Proctor density; are investigated for a wide range of molding water content varying from dry to wet side of optimum. Though the inclusion of fibre has insignificant effect on optimum moisture content and maximum dry density of mixtures, the compressive strength, failure strain, unit cohesion and frictional angle of the compacted specimens are found to increase whereas the volumetric shrinkage strains are found to decrease irrespective of the molding water content. Both unreinforced and reinforced specimens exhibited the maximum unconfined compressive strength at relative water contents of 90% and 80% when compacted to standard and modified Proctor density respectively. With an addition of 1% fibre, these values are found to increase by 2 to 3 times. The specimens compacted at dry of optimum did not show any significant variation in hydraulic conductivity whereas specimens compacted at wet of optimum exhibited an increased hydraulic conductivity with fibre content. However, specimens compacted at optimum moisture content showed an insignificant change in hydraulic conductivity with increase in fibre content. Furthermore, the increase in volumetric shrinkage strain with relative water content is reduced as the fibre content increases.