Liquid Limit Test of Soil

How to determine liquid limit of soil

Determine by manual and visual methods the ore out of 9.2 has no or little substance retained on a 425-μm (No. 40) sieve. If that is the case, prepare 150 to 200g of material by mixing thoroughly with distilled or demineralized water on the glass plate or mixing dish with the spatula. If desired, soak the material at a mixing/storage dish with a small amount of water to soften the material before the beginning of mixing (see 8.1.1). If utilizing Liquid Limit Method A (Multipoint Method), fix the water content of the substance to deliver it into a consistency that will need roughly 25 to 35 drops of this cup of the liquid limit device (commonly known as “blows”) to close the groove. For Liquid Limit Method B (One-Point Method), the amount of drops should be between approximately 20 and 30.

If it is impractical to eliminate the coarser material by hand, then remove small percentages (less than approximately 15%) of coarser material by working the substance (having the preceding consistency) through a 425-μm sieve. During this process, use a piece of plastic sheeting, rubber stopper, or other handy apparatus provided the process doesn’t distort the sieve or degrade material that would be kept if the washing system explained in 11.1.2 were utilized. If bigger percentages of coarse material are struck during blending, or it’s considered impractical to remove the coarser material from the processes just described, wash the sample as described in 11.1.2.

When the coarse particles found during mixing are concretions, shells, or other delicate particles, don’t crush these particles to make them pass a 425-μm sieve, but remove by hand or by washing. 11.1.1.3 Set the prepared material in the mixing/storage dish, check its consistency (fix if required), cover to prevent loss of moisture, and allow to stand (cure) for at least 16 h (overnight). After the standing interval and immediately before starting the test, thoroughly remix the soil.

For Specimens Consisting of Material Containing Particles Retained on a 425-μm (No. 40) Sieve:

Place the specimen (see 9.2) at a bowl or pan and add enough water to cover the material. Permit the stuff to soak until all lumps have softened and the fines no longer adhere to the surfaces of the coarse particles. (See 8.1.1.)

If the substance contains a large portion of particles allowed on the 425-μm (No. 40) sieve, perform the subsequent washing procedure in increments, washing no more than 0.5 kg (1 lb) of material at once. Put the 425-μm sieve at the base of this clean pan. Transfer, without any lack of material, the soil-water mixture on the sieve. If gravel or coarse sand particles are found, rinse as many of them as possible with little amounts of water from a wash bottle, and discard. Alternatively, transfer the soil-water mix above a 2.00-mm (No. 10) sieve nested atop the 425-μm sieve, rinse the fine material through and eliminate the 2.00-mm sieve.

After washing and removing as much of this coarser material as you can, add enough water into the pan to deliver the level to about 13 mm (1⁄2 in.) Over the surface of this 425-μm sieve. Agitate the slurry by stirring with the fingers while raising and lowering the sieve from the pan and swirling the suspension that fine material is washed in the coarser particles. Disaggregate fine soil lumps which have not slaked by gently rubbing them within the sieve with the palms. Complete the washing operation by raising the sieve above the water and draining the material retained with a small number of clean water.

Reduce the water content of the material passing the 425-μm (No. 40) sieve until it means that the liquid limit. Reduction of water material could possibly be accomplished by one or a combination of the following methods: (a) exposing to air currents in room temperature, (b) exposing to heat air pollutants from a source such as an electric hair drier, (c) decanting clean water from outside of the suspension, (d) filtering at a Büchner funnel or utilizing filter materials, or (e) draining in a colander or plaster of Paris dish lined with high retentivity,6 high wet strength filter paper.

In the event the plaster of Paris dish is used, be careful that the dish not becomes sufficiently saturated that it neglects to absorb water into its surface. Gently dry dish between uses. During evaporation and cooling, stir the material often sufficient to prevent over-drying of the fringes and soil pinnacles on the surface of the mixture. For substances containing soluble salts, utilize a method of water reduction (a or b) that will not eliminate the soluble salts from the test specimen.

When appropriate, remove the material retained on the filter paper. Thoroughly combine this substance or the above stuff on the glass plate in the mixing dish with the spatula. Fix the water content of the mix, if necessary, by adding small increments of distilled or demineralized water or simply by letting the mix to dry in room temperature when mixing onto the glass plate. If using Liquid Limit Method A (Multipoint Method), the substance should be at a water content that will require roughly 25 to 35 drops of the cup of the liquid limit device to close the groove. For Liquid Limit Procedure B (One-Point Method), the amount of drops should be between about 20 and 30. Put, if needed, the mixed material in the storage dish, pay to reduce loss of moisture, and let to stand (fix ) for at least 16 h. Following the standing interval and immediately before starting the test, thoroughly remix the specimen.

Specimen Preparation Procedure 2 (Dry Preparation Procedure):

(See Section 6, Interferences.) Disaggregation is expedited when the material is not allowed to fully dry. On the other hand, the material needs to have a dry appearance when pulverized.

Pulverize the material in a mortar with a rubber tipped pestle or in some other way that doesn’t trigger breakdown of individual contaminants. When the rough particles found during pulverization are concretions, shells, or other fragile particles, don’t crush these particles to make them pass a 425-μm (No. 40) sieve, but remove by hand or other appropriate means, like washing. If a washing process is utilized, follow

Separate the material on a 425-μm (No. 40) sieve, vibration the sieve by hand to guarantee thorough separation of the finer fraction. Return the material saved on the 425-μm sieve into the pulverizing device and repeat the pulverizing and sieving operations. Stop this process when most of the nice material was disaggregated and material preserved on the 425-μm sieve includes individual particles.

Place material retained on the 425-μm (No. 40) sieve following the final pulverizing operations in a dish and then soak in a small amount of water. Stir this mixture and then move it to a 425-μm sieve, grabbing the water and any suspended fines in the skillet. Pour this suspension into a dish comprising the dry dirt previously sieved through the 425-μm sieve. Discard material kept on the 425-μm sieve.

See other soil testing methods here