Interfacial shear strength of silty sand–geogrid composite

This study has been carried out to investigate the interface shear strength of sand reinforced by high-density polyethylene cogged geogrid, with variation in fines content from 0 to 45%. To this end, a set of large direct shear tests (30 × 30 × 15 cm) was systematically conducted. The behaviour of sand and silty sand reinforced with a special type of cogged geogrid is studied in terms of interfacial shear strength of the soil. An analysis of test results indicates that the reinforcement improved the shearing behaviour of the sand and silty sand samples. Attaining the peak strength at greater shear strain due to reinforcement and lowering the post-peak loss of strength of specimens with higher silt content, compared to the specimens with lower silt content, are the indications implying that the reinforcement and increasing the silt content tend to transform the shearing behaviour of sand and silty sand specimens from a brittle to a ductile manner. The results also indicated that as the silt content increases up to 35%, the combined shear strength decreases. Further increase in the silt content made no significant change to the combined shear strength of the soil samples.