A Comparative Study on Shear Strength and Deformation Behaviour of Clayey and Sandy Soils Reinforced with Glass Fibre

Abstract

In this investigation, the shear strength and specimen deformation behaviour of glass fibre-reinforced clayey and sandy soils have been compared based on the results of consolidated undrained and consolidated drained triaxial tests, respectively under varying moulded states. The clayey soil specimens were moulded with varying dry unit weight, whereas sandy soil specimens were moulded at relative densities ranging from 35 to 85%. For any moulded state, no peak is noted in the stress–strain curves of reinforced clayey soil up to 20% axial strain. In case of the reinforced sandy soil, clear peak is observed well before 20% axial strain with post-peak stress reduction at all relative densities. Reinforced clayey soil shows bulging at all dry unit weights. For the reinforced sandy soil, bulging failure is noted at 35% relative density, whereas shear failure occurs at relative densities of 65% and 85%. At all dry unit weights, under undrained condition, the reinforced clayey soil exhibits only positive pore water pressure indicating contractive behaviour at all axial strains. Under drained condition, the reinforced sandy soil of 35% relative density shows contractive behaviour, while the specimens of 65% and 85% relative densities indicate contractive response at smaller axial strain followed by dilative behaviour at higher strain. The increase of shear strength is up to 0.75% and 3% fibre content in the clayey and sandy soils, respectively irrespective of moulded states. At respective optimum fibre reinforcements, the benefit of glass fibre reinforcement is greater for the sandy soil. The possible environmental impact and field application of glass fibre-reinforced soil have also been discussed.