AS 1289.6.4.2:2016 pdf free.Methods of testing soils for engineering purposes Method 6. 4.2: Soil strength and consolidation tests—Determination of compressive strength of a soil—Compressive strength of a saturated specimen tested in undrained triaxial compression with measurement of pore water pressure.
(i) Apparatus for applying back pressure to the specimen to an accuracy of ±2 kPa or ± 0.5%, whichever is the greater. The control of this pressure shall be separate from the cell pressure.
If the effective confining pressure is less than 50 kPa the difference between the cell and back pressures shall be measured to an accuracy of ±1 kPa. A differential pressure transducer is recommended for this purpose.
(j) Seamless rubber membrane in the form of a tube, open at both ends, of internal diameter equal to the specimen diameter and of length approximately 50 mm greater than the height of the specimen. The membrane thickness should be selected having regard to the size, strength and nature of the soil to be tested. A thickness of 0.25 mm to 0.4 mm is normally satisfactory.
(k) Membrane stretcher to suit the size of the specimen.
(1) Rubber rings of circular cross-section and internal diameter smaller than the diameter of the end caps.
(m) Sampling tubes with a sharp cutting edge at the inner surface or a soil lathe for preparing test specimens of the required diameter directly from a block sample in the laboratory.
(n) Sample extruder.
(o) Trimming device, e.g. split mould or mitre box and wire saw for obtaining plane ends normal to the axis of cylindrical specimens.
(p) Mould or formers and auxiliary apparatus, for preparing rem oulded specimens.
(q) Apparatus for the determination of moisture content as described in AS 1 289.2.1 .1.
(r) A balance of appropriate capacity to measure the mass of the wet specimen.
5 PREPARATION OF SPECIM ENS
Procedures for the preparation of test specimens vary considerably in detail but the aim is to produce specimens of required dimensions while minimizing the disturbance and changes to moisture content. The diameter of the specimen is to be selected having regard to the character of the soil and the maximum size of particles present in the sample. The diameter should not be less than 38 mm.AS 1289.6.4.2 pdf download.