The strength properties of fibre-reinforced sand

Consolidated-drained triaxial tests were performed on samples of a commercially-available fibre-reinforced sand, (known as 'Fibresand'), and on the same sand without fibres. Testing was carried out at different moisture contents, ranging from 12 - 18%, and at consolidating stresses ranging from 25 - 400 kPa. The test results provided output data which enabled various graphs to be drawn, and interpretations to be made therefrom. Failure envelopes for the reinforced sand samples were non-linear, with a bi-linear or curvilinear fit being more appropriate. Similarities with the behaviour of over-consolidated clays were observed for both the reinforced and unreinforced sands, but the differences between them could be construed as differences in the over-consolidation ratios. An interpretation of the behaviour in terms of critical state theory is suggested, but much more extensive testing is required to validate this approach.