AS 1289.3.9.1:2015 pdf download.Methods of testing soils for engineering purposes Method 3.9.1: Soil classification tests-Determination of the cone liquid limit of a soil.
4 PROCEDURE
The procedure shall be as follows:
(a) Obtain a test portion, prepared in accordance with AS 1289.1.1, and pass enough material through the 425 urn sieve to produce 250 g of soil. Alternatively, all soil that passes a 425 pm sieve may be used in the natural state with minimal further preparation.
NOTES:
I When a soil is tested in the natural condition the results may differ from those obtained if the soil has been air-dried or oven-dried at low temperature (50°C).
2 If the plasticity index is to be calculated using the results from this test then use the same method of preparation for both the liquid limit and the plastic limit tests.
(b) Mix the sample thoroughly in the container, or on the flat plate, using the palette knife while incrementally adding water from the wash bottle until the soil becomes a homogenous paste.
NOTES:
I Inadequate mixing may result in an erroneous value being obtained for the liquid limit (usually below the true value). This is due to the time necessary for water to penetrate into absorptive particles and into the internal structure of some clays, and for mechanical disturbance to break up aggregations of finer particles, particularly clays. The sample should be mixed to a paste by using firm pressure with the palette knives against the surface of the container or the flat plate. For highly plastic clays other techniques may be needed, in the initial stages of water addition, to bring the material to a suitable consistency.
2 Soils of medium to high plasticity will require mixing times of more than 3 mm. Mixing times of over 5 mm may be required for high plasticity clays to obtain uniform distribution of moisture.
3 The consistency of the soil mixture should be such that, when tested according to Steps (e) to (k), the cone penetration is about 15 mm.
(c) Cover the soil in a container and allow it to cure for at least 1 2 h at room temperature.
NOTE: After final mixing and before testing the sample should stand at least 12 h in a container with a close fitting lid to minimize moisture loss and to allow the water to permeate throughout the soil. Certain soils, particularly clayey soils, may need to stand for at least 24 h to allow thorough permeation of the water through the soil. If tested with inadequate curing of the sample unreliable and/or non-repeatable results will be obtained.
(d) After completion of the curing thoroughly remix the cured soil for more than I mm.
(e) Carefully fill the clean cup with the soil paste using a palette knife to place the soil in the bottom of the cup and exert sufficient pressure on the knife to exude the paste outwards to ensure removal of any air from the mixture. Continue adding the soil to the cup in this manner until the soil is above the level of the cup rim.
NOTES:
I The presence of air hubbies within the soil sample in the cup can affect the penetration of the cone, leading to unreliable results. This aspect is critical and care is essential in the filling of the cup to avoid entrapping air.
2 When not otherwise required for mixing or filling the cup, the soil sample in the container should be covered with either a close fitting lid or a damp cloth to prevent the sample from drying out.
(f) Holding the straight edge or palette knife at low angle to the cup surface and using less than three strokes remove excess material to leave a smooth surface that is level with the rim of the cup.
(g) Carefully place the cup plus levelled soil centrally under the cone making sure that both the cup and the penetrometer stand are squarely seated on firm clean and horizontal base.
(h) Lower the cone carefully so that its tip just contacts the surface of the soil then clamp it in that position. Carefully lower the dial gauge plunger to contact the top of the sliding shaft and record the dial gauge reading, (R1), to the nearest 0.1 mm. Alternatively, where the cone and dial gauge are mounted on the same arm, the initial reading (R1) may be taken before the cone is lowered to the surface of the soil.
(i) Release the cone and allow to freely penetrate into the soil for a period of 5 ±1 s. Then reclamp it taking care not to jerk the apparatus.
(j) Lower the dial gauge plunger carefully to contact the top of the sliding shaft and record the dial gauge reading, (R2), to the nearest 0. 1 mm.AS 1289.3.9.1 pdf download.