Mechanical Properties of an Artificially Cemented Clayey Material

As part of an ongoing investigation on the behavior of the brittle cemented sensitive clays of eastern Canada, static penetrometer and vane shear tests had to be performed in the laboratory. Because it was impossible to sample undisturbed blocks of clay of the necessary size, an artificial model material was developed to simulate the response of sensitive clays, namely, brittle response at low stresses and loss of strength upon remolding. The model material consists of a mixture of kaolinite, bentonite, portland cement, and water. Two mixes were produced: a softer 6.25 % cement content and a stiffer 14 % cement content. It is shown that the materials are characterized by stress-strain behaviors similar to those of soft to medium sensitive clays. It is also shown that the artificially bonded materials simulate quite well other mechanical properties of sensitive clays of eastern Canada, such as high water contents and void ratios; brittle failure at low confining pressures; high G _u/S_u ratios, where G_u=shear modulus and S_u=undrained shear strength; and severe collapse of the structure for vertical effective stresses in excess of the materials’ preconsolidation pressures. Specimens cured 21 days were used successfully for laboratory indentation, vane shear, and unconfined and triaxial compression tests, as well as oedometer tests. In addition, the variation of the undrained shear strength of the 14 % cement content specimens was followed for a maximum curing period of one year, by means of vane shear tests and unconfined compression tests.