The expandable jacket and flexible ring comprises of the segmented circular arch shaped plates and bands or rings around the segmented plates. The test preparation consists of a membrane surrounding a specimen with or without a filter, segmented plates surrounding the membrane, and bands or rings around the segmented plates to permit uniform radial expansion of the specimen through its height when increments of vertical load are applied during the test, thereby providing accurate values of area of cross- section, deviator stress, volume change, modulus of elasticity, Poisson's ratio and shear strength. Using the flexible ring, three-dimensional consolidation tests are performed to determine three-dimensional coefficient of consolidation and coefficients of consolidation in horizontal and vertical directions. Removable attachments are used for assembling the expandable jacket and flexible ring during the test. A calibration device is used to determine the modulus of elasticity of the membrane and expandable jacket and flexible ring.