On the small-strain stiffness of polypropylene fibre-sand mixtures

In this study, the effect of fibre reinforcement on the small-strain shear modulus (G_max) of sandy soils is investigated. A comprehensive set of 47 specimens composed of different types of sand reinforced with variable percentages of polypropylene fibres were tested using a Hardin-type resonant column apparatus embedded with bender element inserts to study the effect of fibre inclusion and content on the G_max of sands with different particle shapes and gradations. Accordingly, an expression of G_max for sands, previously proposed by the last two authors and their colleagues, was systematically modified in this study to include the effect of fibre content to estimate the small-strain shear modulus of fibre reinforced sands. An additional set of dynamic tests was performed to verify the newly proposed expression. It was shown that the newly developed expression can predict the G_max of sand-fibre mixtures with an accuracy of around ±20%, with the error being limited to ±10% in the majority of the cases.