An apparatus for maintaining uniform radial expansion of a cylindrical soil specimen and measuring and calculating radial expansion during triaxial compression, unconfined and uniaxial tests and three-dimensional consolidation tests, the apparatus comprising: (i) a bottom porous disc on a specimen base for receiving the specimen, a top porous disc topped by a specimen cap, at least one membrane, which is stretchable and impervious, for installing around the cylindrical specimen, said at least one membrane surrounding top and bottom porous discs and extending to the specimen cap and the specimen base and sealed to each of said specimen cap and base by one or more stretchable O-rings; (ii) wherein for determining the three-dimensional coefficient of consolidation, the apparatus further comprising filter disks above and below the cylindrical specimen and at least one filter surrounding and in contact with the cylindrical specimen, the membrane being installed around the filter, to allow flow of pore-water both in vertical and horizontal radial directions; (iii) wherein for determining the coefficient of consolidation in a horizontal direction, the apparatus further comprising at least one filter surrounding and in contact with the cylindrical specimen, the membrane being installed around the filter, and a rigid impervious disc placed below and above the cylindrical specimen to prevent flow of pore-water in vertical direction and to allow flow of pore-water in horizontal direction to the filter; (iv) a plurality of arch-shaped plates assembled vertically such that the assembled arch-shaped plates form a cylinder surrounding and in contact with the at least one membrane, wherein the arch-shaped plates are thick to resist deformation and remain vertical during the tests; (v) one or more bands or rings, which stretch to permit the radial expansion of the cylindrical specimen while applying lateral pressure on the cylindrical specimen, wherein each of the one or more bands or rings surrounds and is in contact with each of the arc-shaped plates; (vi) means for measuring the radial expansion or displacement of the cylindrical specimen, said means selected from the group of at least one LVDT and at least one strain gage; characterized in that the at least one LVDT or the at least one strain gage is removably attached to a spring-loaded U-frame, which is in contact with at least one of the one or more bands or rings, wherein the U-frame rests on ball bearings such that during the radial expansion of the cylindrical specimen, the U-frame maintains the at least one LVDT or the at least one strain gage in proper horizontal alignment and prevents the at least one LVDT or the at least one strain gage from being inclined due to the vertical settlement of the cylindrical specimen. (i) a bottom porous disc on a specimen base for receiving the specimen, a top porous disc topped by a specimen cap, at least one membrane, which is stretchable and impervious, for installing around the cylindrical specimen, said at least one membrane surrounding top and bottom porous discs and extending to the specimen cap and the specimen base and sealed to each of said specimen cap and base by one or more stretchable O-rings; (ii) wherein for determining the three-dimensional coefficient of consolidation, the apparatus further comprising filter disks above and below the cylindrical specimen and at least one filter surrounding and in contact with the cylindrical specimen, the membrane being installed around the filter, to allow flow of pore-water both in vertical and horizontal radial directions; (iii) wherein for determining the coefficient of consolidation in a horizontal direction, the apparatus further comprising at least one filter surrounding and in contact with the cylindrical specimen, the membrane being installed around the filter, and a rigid impervious disc placed below and above the cylindrical specimen to prevent flow of pore-water in vertical direction and to allow flow of pore-water in horizontal direction to the filter; (iv) a plurality of arch-shaped plates assembled vertically such that the assembled arch-shaped plates form a cylinder surrounding and in contact with the at least one membrane, wherein the arch-shaped plates are thick to resist deformation and remain vertical during the tests; (v) one or more bands or rings, which stretch to permit the radial expansion of the cylindrical specimen while applying lateral pressure on the cylindrical specimen, wherein each of the one or more bands or rings surrounds and is in contact with each of the arc-shaped plates; (vi) means for measuring the radial expansion or displacement of the cylindrical specimen, said means selected from the group of at least one LVDT and at least one strain gage;