Triaxial shear behaviour of sand-gravel mixtures reinforced with cement and fibre

Abstract

Results of consolidated-drained and consolidated-undrained triaxial tests conducted on fibre-reinforced cement-treated sand–gravel mixtures are described in present study. The base soils were sand–gravel mixtures containing 30 and 50% gravel content. Cement content was 3% (dry wt.) of sand–gravel mixture and polypropylene fibres 0.012 m in length and 23 μm thick were added at 0.0, 0.5 and 1% (dry wt.) of soil–cement composite. Stress–strain curves besides volume and pore pressure changes, energy absorption and deformability characteristics of the reinforced mixture were evaluated. Mechanical behaviour of the composite was compared with the results of previous studies on fibre-reinforced cement-treated sand in both drained and undrained conditions. According to the results, impact of fibre reinforcement on shear strength of cemented sand–gravel mixture decreased with the increase in gravel content in drained condition. However, for undrained state, the strength was more influenced by the fibres in higher gravel contents. Moreover, increase in gravel content increased the potential of energy absorption and brittleness of the reinforced mixture. Using a single failure envelope for both drained and undrained tests, it was concluded that cohesion intercept was more affected by inclusion of fibres in mixture with lower gravel content.