The relative density of water is shown in the table below.Also refer to the relative density of soil for more inforamtion on civil engineering tests.

The density varies with temperature and we take the value equal to 1 at a standard temperature of 4^oC. The value of density of water changes as the temperature increases and this can be taken directly from the table in various tests like

The Specific Gravity Of Soil Test and so on.

This test is done to determine the specific gravity of fine-grained soil by density bottle method as per IS: 2720 (Part III/Sec 1) – 1980. Specific gravity is the ratio of the weight in air of a given volume
of a material at a standard temperature to the weight in air of an equal volume of distilled water at the same stated temperature.
The apparatus used:
i) Two density bottles of approximately 50ml capacity along with stoppers
ii) Constant temperature water bath (27.0 + 0.2^oC)
iii) Vacuum desiccator
iv) Oven, capable of maintaining a temperature of 105 to 110^oC
v) Weighing balance, with an accuracy of 0.001g
vi) Spatula

PREPARATION OF SAMPLE
The soil sample (50g) should if necessary be ground to pass through a 2mm IS Sieve. A 5 to 10g sub-sample should be obtained by riffling and oven-dried at a temperature of 105 to 110^oC.

Procedure to Determine the Specific Gravity of Fine-Grained Soil
i) The density bottle along with the stopper, should be dried at a temperature of 105 to 110^oC, cooled in the desiccator and weighed to the nearest 0.001g (W₁).

ii) The sub-sample, which had been oven-dried should be transferred to the density bottle directly from the desiccator in which it was cooled. The bottles and contents together with the stopper should be weighed to the nearest 0.001g (W₂).

iii) Cover the soil with air-free distilled water from the glass wash bottle and leave for a period of 2 to 3hrs. for soaking. Add water to fill the bottle to about half.

iv) Entrapped air can be removed by heating the density bottle on a water bath or a sand bath.

v) Keep the bottle without the stopper in a vacuum desiccator for about 1 to 2hrs. until there is no further loss of air.

vi) Gently stir the soil in the density bottle with a clean glass rod, carefully wash off the adhering particles from the rod with some drops of distilled water and see that no more soil particles are lost.

vii) Repeat the process till no more air bubbles are observed in the soil-water mixture.

viii) Observe the constant temperature in the bottle and record.

ix) Insert the stopper in the density bottle, wipe and weigh(W₃).

x) Now empty the bottle, clean thoroughly and fill the density bottle with distilled water at the same temperature. Insert the stopper in the bottle, wipe dry from the outside and weigh (W₄ ).

xi) Take at least two such observations for the same soil.

REPORTING OF RESULTS
The specific gravity G of the soil = (W₂ – W₁) / [(W₄-₁)-(W₃-W₂)]

The specific gravity should be calculated at a temperature of 27^oC and reported to the nearest 0.01. If the room temperature is different from 27^oC, the following correction should be done:-
G’ = kG
where,
G’ = Corrected specific gravity at 27^oC
k = [Relative density of water at room temperature]/ Relative density of water at 27^oC.

A sample proforma for the record of the test results is given below. Relative density of water at various temperatures is taken from table here. Relative Density Water

To determine the free swell index of soil as per IS: 2720 (Part XL) – 1977. Free swell or differential free swell, also termed as free swell index, is the increase in volume of soil without any external constraint when subjected to submergence in water. The apparatus used :

i) IS Sieve of size 425µm
ii) Oven
iii) Balance, with an accuracy of 0.01g
iv) Graduated glass cylinder- 2 nos., each of 100ml capacity

Procedure to determine Free Swell Index Of Soil

i) Take two specimens of 10g each of pulverised soil passing through 425µm IS Sieve and oven-dry.

ii) Pour each soil specimen into a graduated glass cylinder of 100ml capacity.

iii) Pour distilled water in one and kerosene oil in the other cylinder upto 100ml mark.

iv) Remove entrapped air by gently shaking or stirring with a glass rod.

v) Allow the suspension to attain the state of equilibrium (for not less than 24hours).

vi) Final volume of soil in each of the cylinder should be read out.

REPORTING OF RESULTS

Free swell index = [V_d - V_k] / V_k x 100%

where,

V_d = volume of soil specimen read from the graduated cylinder containing distilled water.

V_k = volume of soil specimen read from the graduated cylinder containing kerosene.

This test is done to determine the plastic limit of soil as per IS: 2720 (Part 5) – 1985.The plastic limit of fine-grained soil is the water content of the soil below which it ceases to be plastic. It begins to crumble when rolled into threads of 3mm dia. The apparatus used:

i) Porcelain evaporating dish about 120mm dia.
ii) Spatula
iii) Container to determine moisture content
iv) Balance, with an accuracy of 0.01g
v) Oven
vi) Ground glass plate – 20cm x 15cm
vii) Rod – 3mm dia. and about 10cm long

PREPARATION OF SAMPLE
Take out 30g of air-dried soil from a thoroughly mixed sample of the soil passing through 425µm IS Sieve. Mix the soil with distilled water in an evaporating dish and leave the soil mass for naturing. This period may be upto 24hrs.

Procedure to determine The Plastic Limit Of Soil
i) Take about 8g of the soil and roll it with fingers on a glass plate. The rate of rolling should be between 80 to 90 strokes per minute to form a 3mm dia.

ii) If the dia. of the threads can be reduced to less than 3mm, without any cracks appearing, it means that the water content is more than its plastic limit. Knead the soil to reduce the water content and roll it into a thread again.

iii) Repeat the process of alternate rolling and kneading until the thread crumbles.

iv) Collect and keep the pieces of crumbled soil thread in the container used to determine the moisture content.

v) Repeat the process at least twice more with fresh samples of plastic soil each time.

REPORTING OF RESULTS
The plastic limit should be determined for at least three portions of the soil passing through 425µm IS Sieve. The average water content to the nearest whole number should be reported.

This test is done to determine the liquid limit of soil as per IS: 2720 (Part 5) – 1985. The liquid limit of fine-grained soil is the water content at which soil behaves practically like a liquid, but has small shear
strength. It’s flow closes the groove in just 25 blows in Casagrande’s liquid limit device. The apparatus used :-
i) Casagrande’s liquid limit device
ii) Grooving tools of both standard and ASTM types
iii) Oven
iv) Evaporating dish
v) Spatula
vi) IS Sieve of size 425µm
vii) Weighing balance, with 0.01g accuracy
viii) Wash bottle
ix) Air-tight and non-corrodible container for determination of moisture content

PREPARATION OF SAMPLE
i) Air-dry the soil sample and break the clods. Remove the organic matter like tree roots, pieces of bark, etc.
ii) About 100g of the specimen passing through 425µm IS Sieve is mixed thoroughly with distilled water in the evaporating dish and left for 24hrs. for soaking.

Procedure to Determine The Liquid Limit Of Soil
i) Place a portion of the paste in the cup of the liquid limit device.

ii) Level the mix so as to have a maximum depth of 1cm.

iii) Draw the grooving tool through the sample along the symmetrical axis of the cup, holding the tool perpendicular to the cup.

iv) For normal fine grained soil: The Casagrande’s tool is used to cut a groove 2mm wide at the bottom, 11mm wide at the top and 8mm deep.

v) For sandy soil: The ASTM tool is used to cut a groove 2mm wide at the bottom, 13.6mm wide at the top and 10mm deep.

vi) After the soil pat has been cut by a proper grooving tool, the handle is rotated at the rate of about 2 revolutions per second and the no. of blows counted, till the two parts of the soil sample come into contact for about 10mm length.

vii) Take about 10g of soil near the closed groove and determine its water content

viii) The soil of the cup is transferred to the dish containing the soil paste and mixed thoroughly after adding a little more water. Repeat the test.

ix) By altering the water content of the soil and repeating the foregoing operations, obtain at least 5 readings in the range of 15 to 35 blows. Don’t mix dry soil to change its consistency.

x) Liquid limit is determined by plotting a ‘flow curve’ on a semi-log graph, with no. of blows as abscissa (log scale) and the water content as ordinate and drawing the best straight line through the plotted points.

REPORTING OF RESULTS
Report the water content corresponding to 25 blows, read from the ‘flow curve’ as the liquid limit.
A sample ‘flow curve’ is given as