Critical state interpretation of effects of fines in silty sands

The effect of the fines content in silty sands on the location of the critical state line (CSL) has been investigated by performing standard drained and undrained triaxial tests on reconstituted samples containing Sydney sand, feldspar fines and mixtures of the two at 20, 40 and 60% fines content. In the e-log p′ plane, CSLs of silt–sand mixtures shifted parallel to one another. The transitional fines content of silt–sand mixtures was 40%. Transitional soil behaviour was also observed in silt–sand samples that contained 40 and 60% fines as densely and loosely prepared samples with these fines contents failed on two different and parallel CSLs