Mechanical Behaviour of a Weakly Structured Soil at Low Confining Stress

Artificially cemented soft soil samples were produced by mixing kaolin, beta hemihydrate and water. Oedometer and triaxial tests were performed on this material, which was shown to demonstrate many of the characteristics of natural soft clays. Tests were performed on the material at a range of consolidation pressures and at different strain rates. It was shown that the shear strength behaviour of the material exhibits complex characteristics that require explicit consideration of soil structure at the loading stage. Similarly to other natural clays, the critical state could not be achieved in the triaxial apparatus; rather, it was shown that a post-rupture state was achieved which appears remote from the intrinsic critical state. Different normalisation techniques were compared. It is recommended that normalisation of behaviour should be based on the virgin consolidation line as it defines a space in which the soil can only exist due to structure.