1

Gs =

1. SPECIFIC GRAVITY OF SOIL PARTICLES USING

PYCNOMETER

(I.S. 2720 : Part-III : 1974)

AIM:

To determine the specific gravity of granular soil particles

passing 4.75 mm I.S. sieve using a pycnometer. APPARATUS:

Pycnometer, Drying Oven, Balance, Distilled water, Glass rod, pipette, 4.75

mm I.S. Sieve, Distilled water.

PROCEDURE:

1. Weigh a clean dry pycnometer with the cap accurate to 0.01 g (W1).

2. Place oven-dry soil passing 4.75 mm I.S. Sieve into the pycnometer and weigh

it (W2). Soil taken will fill up one-third of the bottle.

3. Fill the pycnometer to half its height with distilled water and mix it thoroughly

with glass rod. Replace the screw top after applying grease to the screw top

and fill the pycnometer, flush with hole in the conical cap. Dry the

pycnometer from out side, and weigh it (W3).

4. Remove the contents, wash the pycnometer, pour distilled water flush with the

hole of the conical cap and weigh it (W4).

5. Repeat steps 2 and 3 for two more times to arrive at an average value.

CALCULATIONS:

The specific gravity, G is calculated from

(W2W1) Gt

(W4W1) (W3W2)

Where Gt = Specific gravity of water at the temperature of the test.

I . e x e

2

DISCUSSION:

Although the procedure is very simple, reliable results can be obtained only if

great care is exercised in the removal of entrapped air. The specific gravity of an

inorganic soil normally ranges from 2.50 to 2.80.

OBSERVATIONS:

Weight of pycnometer (W1) =

Weight of pycnometer + dry soil (W2) =

Weight of pycnometer + Soil + water (W3) =

Weight of the pycnometer + water (W4) =

Temperature of water T 0C =

RESULT: Average Specific gravity of the soil particles =

COMMENT:

3

2. SPECIFIC GRAVITY OF CLAY SAMPLE AIM:

To determine the specific gravity of clay sample.

APPARATUS:

Specific gravity bottle, Vacuum pump.

MATERIAL:

Kerosene free of water or naphtha (having a specific gravity not less than

0.7313 shall be used in the determination of specific gravity.

PROCEDURE:

1. Weigh a clean dry Specific gravity bottle with the cap accurate to 0.01 g (W1). 2. Place oven-dry soil passing 4.75 mm I.S. Sieve into the Specific gravity bottle

and weigh it (W2). Soil taken will fill up one-fourth of the bottle. 3. Fill the Specific gravity bottle to half its height with kerosene and mix it

thoroughly. Remove air voids by using a vacuum pump or by any other suitable method. Fill the Specific gravity bottle with kerosene, flush with top and replace the screw top. Dry the Specific gravity bottle from out side, and weigh it (W3).

4. Remove the contents, wash the Specific gravity bottle, pour kerosene flush with the top and weigh it (W4).

5. Remove the contents, wash the Specific gravity bottle, pour distilled water flush with the top and weigh it (W5).

6. Repeat steps 1 to 5 for two more times to arrive at an average value. OBSERVATIONS:

1. Wt. of empty dry specific gravity bottle = W1 2. Wt. of bottle + clay sample (filled 1\4 to 1\3) = W2

3. Wt. of bottle + clay sample (partly filled) + kerosene = W3

4. Wt. of bottle + Kerosene (full) = W4

5. Wt. of bottle + Water (full) = W5

Specific gravity of Kerosene S k = (W4 W1) / (W5 W1)

Specific gravity of clay sample = (W2 W1) x S k / ((W4 W1) (W3 W2))

4

RESULT:

Specific gravity of Kerosene Specific gravity of clay sample

COMMENT:

5

3. MOISTURE CONTENT USING PYCNOMETER (I.S. 2720 : Part III : 1974)

AIM:

To determine the moisture content present in the given soil sample, by

pycnometer method.

APPARATUS:

Pycnometer, Balance, Glass rod, and Distilled water.

PROCEDURE:

1. Weigh a clean dry pycnometer with the cap accurate to 0.01 g. (W1)

2. Place the wet-soil sample in to the pycnometer carefully and weigh it (W2).

3. Fill the pycnometer to half its height with distilled water and mix it thoroughly

with a glass rod. Replace the screw top after applying grease to the cap and

fill the pycnometer, flush with the hole on the conical cap. Dry the

pycnometer from outside, and weigh it (W3).

4. Remove the contents, wash the pycnometer, pour distilled water flush with the

hole of the conical cap, and weigh it (W4).

CALCULATIONS: The water content (w) is calculated from,

(W2 W1 ) (Gs 1)

w = 1 100

(W3 W4) Gs

where W1 = Weight of pycnometer W2 = Weight of pycnometer + given soil sample W3 = Weight of pycnometer + given soil + Water W4 = Weight of pycnometer + Water Gs = Specific gravity of soil solids RESULT: The water content of the given soil sample =

COMMENT:

I . e x e

6

4. LIQUID LIMIT AND PLASTIC LIMIT AIM:

To determine the liquid limit and plastic limit of soil.

PART-A: LIQUID LIMIT GENERAL:

The liquid limit is the water content at which the soil has little or no shear

strength and when it just begins to flow.

APPARATUS:

Liquid limit device (Casagrande's Apparatus), standard grooving tool

(ASTM), balance, drying oven, containers for moisture determination, graduated jar,

spatula.

PROCEDURE:

1. Weigh about 150 g of soil passing through IS 425 micron sieve. 2. Mix the soil thoroughly with a known percentage of distilled water in a dish to

form a uniform paste. 3. Place a portion of the paste in the cup of the liquid limit device and smoothen

the surface to a maximum depth of about 1 cm. The paste in the cup is divided into two halves by holding the grooving tool and drawing firmly vertically. Thus a V - shaped gap, 2mm wide at the bottom and 11mm at the top and 8mm deep will be formed. Before the commencement of the test, the height of the fall of the cup should be set for 1 cm using a measuring block.

4. Rotate the handle at a uniform rate of about two revolutions per second and count the number of revolutions till the gap between the two halves of the soil close through a distance of 10mm. The groove should be closed by the flow in the soil it self but not by slippage between the soil and the cup.

5. Take approximately 10 gm of soil in a container for moisture content determination preferably from the closed portion of groove.

6. By changing the water content suitably, repeat the experiment to obtain at least five sets of values so that the number of blows lies between 10 and 60.

7

CALCULATIONS AND GRAPH:

Draw a semi-log graph between moisture content on the Y- axis and the

number of blows on the X - axis. Draw a best-fit straight line (mean) passing through

most of the points. Read the water content corresponding to 25 blows, which is the

liquid limit of the given soil sample.

OBSERVATIONS: A. LIQUID LIMIT

1 2 3 4 5 6 Water content added (%) No. of blows. Container No. Wt. of Container (g) Wt. of Container + Wet Soil (g)

Wt. of Container + Dry Soil (g)

Actual water content (%) PART-B: PLASTIC LIMIT: GENERAL:

Plastic limit denotes the boundary between plastic and semi-solid states of a

soil, at which the soil can be moulded to any shape. Specifically, it is the water

content at which the soil tends to crack when rolled into threads of about 3 mm dia.

APPARATUS:

Glass plate, drying oven and balance, containers for moisture content determination. PROCEDURE:

1. Mix thoroughly about 30 g of soil with water. 2. Make three or four convenient parts of the soil. Make an ellipsoidal lump of

the wet soil and roll it on a glass plate with hand until a thread of 3mm is obtained. If it is not possible, dry the pat by pressing between the palms and repeat rolling till a thread of about 3 mm is possible.

3. When the thread of about 3 mm shows signs of cracks, stop the test. 4. Put the pieces of soil-thread in a moisture can and obtain the water content

which represents the plastic limit of the soil sample.

8

OBSERVATIONS:

Container No. Wt. Of Container (g) Wt. of Container + Wet Soil (g)

Wt. of Container + Dry Soil (g)

Water content (%) = RESULT:

i. Liquid limit of the soil (w L) = ii. Plastic limit of the soil (w P ) = iii. Plasticity index of soil I p = (w L - w P) =

COMMENT:

9

5. GRAIN SIZE DISTRIBUTION (I.S. 2720 : Part-IV : 1985)

A. SIEVE ANALYSIS AIM:

To determine the effective size and the uniformity coefficient of a given

sample of soil

APPARATUS:

One set of sieves, cleaning brush, balance and a weight box.

THEORY:

The size of the individual grain is an important factor governing soil behaviour

and therefore, the most common soil test is the grain size analysis. The results can be

represented by numerical value that indicate some characteristic grain size and the

degree of uniformity. Allen Hazen, after performing a number of tests with filter

materials concluded that in loose state the permeability of these soils depends on the

effective size and the uniformity coefficient. The effective size is defined as the size

of material corresponding to 10% on the grain size distribution curve, denoted by D10.

This means 10% of the particles are finer and 90% are coarser than the effective size.

The uniformity coefficient is the ratio of D60 to D10 and is denoted by Cu. It gives the

measure of grading of the soil. A high uniformity coefficient means a low degree of

uniformity or a well-graded material.

If Cu is less than 5, the soil is uniform or poorly graded.

Cu is between 5 and 15 the soil is medium graded.

Cu is more than 15, the soil is well graded.

PROCEDURE:

1. Arrange the sieves of size 4.75mm, 2.00mm, 1.00mm, 600 micron, 425

micron, 150 micron and 75 micron, in the order of decreasing aperture size,

after ensuring that all of them are clean. The receiver is placed at the bottom.

10

2. Take 1 kg of dry soil in the top-most sieve. The lid is kept in position.

3. Shake the sieve for about 15 minutes holding the sieves inclined at angle of 15

Degrees to the vertical. The shaking is done in a circular motion or use the

sieve shaker for the purpose.

4. Determine the weight of soil retained on each sieve and tabulate the results.

5. Draw the 'grain-size distribution curve' with the logarithm of the aperture size

on X-axis and the percentage passing through the sieve on Y-axis. Fit in a

smooth curve and determine the values of D10 and D60.

6. Calculate the value of uniformity coefficient and the coefficient of curvature

(C c).

S. No.

IS Sieve No.

Aperture Size in mm

Wt. of soils retained

% Wt. retained

Cumulative % Wt. Retained

% passing through

1 4.75 4.75 2 2.00 2.00

3 1.00 1.00

4 600 microns 0.600 5 425 microns 0.425

6 150 microns 0.150 7 75 microns 0.075

8 Pan ---

RESULT:

1. Effective size, D10 =

2. Uniformity coefficient, Cu = D60 / D10 =

3. Coefficient of curvature CC = (D30)2 / D10 x D60 =

COMMENT:

11

6. BULK DENSITY BY CORE CUTTER METHOD (I.S. 2720 : Part XXIX : 1975)

AIM:

To determine the in-situ density of soil using a core cutter.

APPARATUS:

Core cutter, Steel Rammer, Steel Dolly, Balance, Steel rule, Pick-axe, Straight

edge and Drying oven.

PROCEDURE:

1. Measure the height and internal diameter of the core cutter.

2. Weigh the clean core cutter (W1)

3. Clean and level the place where density is to be determined.

4. Press the cutter into the soil to its full depth with the help of steel rammer.

5. Remove the soil around the cutter.

6. Remove the cutter.

7. Trim the top and bottom surfaces of the sample carefully.

8. Clean the outside surface of the cutter.

9. Weigh the cutter with the sample and take representative sample in the

containers to determine the moisture content.

OBSERVATIONS AND CALCULATIONS:

Internal diameter of Cutter (cm) =

Height of cutter (cm) =

Cross-sectional area of cutter (cm2) =

Volume of cutter, V (cm3) =

12

S.

No

Observations and Calculations 1 2

1 Wt. Of Core cutter, W1 (g)

2 Wt. Of cutter +Wet soil, W2 (g)

3 Wt. Of Wet Soil, (W2-W1) (g)

4 Bulk density, t =(W2-W1)/V g/cc

MOISTURE CONTENT

5 Container No.

6 Wt. of Container (g)

7 Wt. of Container + wet Soil (g)

8 Wt. of Container + dry Soil (g)

9 Wt. of Water = (7) (8) (g)

10 Wt. of dry Soil = (8) (6) (g)

11 Moisture Content, w (%)

12 Dry density, dry (g/cc)

RESULT:

1. In situ density of soil (bulk) t = g/cc

2. Dry density of soil, d = t / (1+w) = g/cc

COMMENT:

13

7. DRY AND BULK DENSITY BY SAND REPLACEMENT

METHOD (I.S. 2720 : part XXVII : 1974)

AIM:

To determine the bulk density of soil using sand replacement method.

APPARATUS:

Sand pouring cylinder with calibrating can, A square tray, with a circular hole

equal to the diameter, Balance, Drying oven, Sand passing through 600 - micron IS-

sieve and retained on the 300 - micron IS- sieve.

GENERAL:

The bulk density is the total weight of soil, including weight of solids and

weight of water in the voids, divided by the total volume of the soil mass. Dry

density is the weight of soil solids alone divided by the total volume of the soil.

PROCEDURE:

1. Close the sliding valve and fill up the sand pouring cylinder with dry sand of uniform grain size and find the weight (W1).

2. Keep it over a flat surface and open the valve. When the sand has ceased running down, close the valve and find the weight of sand pouring cylinder again (W2).

3. Keep the cylinder over the calibrating can and open the valve. As before when the sand has ceased to run down close the valve and find the weight of sand pouring cylinder (W3).

4. Determine the volume of the calibrating can either by measuring the dimensions or by measuring the weight of water required to fill the can (V).

5. Select a place about 30 cm square in the locality where the density of soil is to be determined. Clean the site and level the area.

6. Placing the square tray over the site, excavate the hole of 10cm diameter and 15 cm deep taking care that all excavated soil is collected on the tray.

7. Fill the sand pouring cylinder, with dry sand of uniform grain size to about 3/4th full and determine the weight (W4).

14

8. Place the sand pouring cylinder over the excavated the hole and let the sand run down. When the flow has ceased, close valve and find the weight of the sand pouring cylinder (W5).

9. Find the weight of the excavated earth collected in the tray (W6). 10. Take a small representative sample of the soil in a container for determination

of moisture content. CALCULATIONS:

I. BULK DENSITY OF SAND USED

1. Weight of sand filling the conical spreader (g) = (W1 W2) =

2. Weight of sand filling the spreader and the calibrating can.(g) = (W2 W3) =

3. Weight of sand filling the calibrating can alone (g) = (W2 W3) (W1 W2) =

4. Volume of the calibrating can (cc) = V =

Bulk density of sand used = t (g/cc) = (W2 W3) (W1 W2)

V

II. FIELD DENSITY OF THE SOIL (t)

1. Weight of sand filling the conical spreader and the excavated pit in the site (g) =

(W4 W5) =

2. Weight of sand filling the pit only (g) = (W4 W5) (W1 W2) =

3. Volume of the pit (cm3) = (W4 W5) (W1 W2) / bulk density of sand =

4. Hence bulk density of soil, = W6 / Volume of the pit =

III. WATER CONTENT OF THE SOIL Weight of empty container (W1)

Wt. of container + Wet soil (W2)

Wt. of container + Dry soil (W3)

Wt. of water present in the soil (W2 W3)

Water content of the soil (W) = (( W2 W3) / (W3 W1)) x

100

15

IV. DRY DENSITY (d)

Dry density d = t / (1+w)

RESULT:

1. Bulk density of sand = g / cm 3

2. Bulk density of soil = g / cm 3

3. Dry density of the soil, d = g / cm 3

COMMENT:

16

8. COEFFICIENT OF PERMEABILITY BY FALLING HEAD

METHOD (I.S. 2720 : Part XVII : 1966)

AIM:

To determine the coefficient of permeability of a given remoulded soil

sample Using falling head method.

APPARATUS:

The permeameter mould is a cylinder 100mm dia X 127.3mm height of

internal volume 1000 cc. It is provided with flanges near the top and bottom

ends which aid in assembling the mould, the top cap and the perforated base plate. A

rubber gasket provided under the top cap ensures water tightness. The top perforated

plate is used to check swelling tendency of the specimen which occurs with certain

soils.

The top cap has an inner seating to suit the 0.2 litre cuter which is to be used

for testing undisturbed specimens. The vertical stem fitted to the top cap is meant for

fixing a stand pipe or a constant level overhead tank depending upon the test

conditions.

The whole assembly is placed in the bottom tank having a water outlet for

permitting accurate control of the water level for falling head tests. The bolts of the

perforated base plate keep the permeameter mould assembly slightly raised in the

bottom tank allowing free flow of water through the base perforating. For soils with

low permeability the falling head test is most applicable.

PROCEDURE:

Take a known quantity of dry soil and mix up thoroughly with the required

percentage of water. Alternately determine the moisture content of an already given

moist-soil. Calculate the weight of the wet soil to give the intended dry density when

occupying the permeameter mould.

The weight of wet soils required = W = 300 (1+w)

17

Where is the weight dry density (g/cc) at which permeability is to be determined

(1.65g/cc)

w is the optimum moisture content (ratio) of the soils.

This amount (W) of the soil is compacted into the mould by static or dynamic

methods.

Apply thinly a little grease or Vaseline to the inside surface of the mould.

Attach the two compaction collars to the mould and support the assembly vertically

(upside down) over the split collar kept around the one of the end plugs. Put the

correct weight of the soil into the mould. Tamp the soil by hand during the process of

pouring. Insert the plug. Keep the entire assembly in a press. Remove the split collar

gently and compact the specimen by pressing both the end plugs until the flanges of

the plugs touch the collars. Give a rest period of about 1/2 minute before releasing

the pressure. Remove the plug and collar above the mould. Put the fine mesh gauge

or filter paper and fix up the perforated base plate. Turn the mould upside down.

Remove the plug and the collar and placed the fine mesh gauge over the specimen.

Place the top perforated plate. Fix up the top cap after putting the washer, connect the

permeameter to the falling head stand pipe. Saturate the specimen. When a steady

state of flow is established, measure the head above the tail water level in the bottom

tank at a particular instant. After a known interval of time, measure the dropped head.

THE COEFFICIENT OF PERMEABILITY:

K = 2.303 (aL / At) * log 10 (h1 / h2)

Where K = Coefficient of permeability (cm / sec.)

a = Area of internal cross-section of stand pipe = sq. cm

A = Area of cross-section or sample = sq. cm

L = Length of the sample = cm

h1 = Head at start of observation = cm

h2 = Head at the end of time interval = cm

t = Time in seconds = cm

18

OBSERVATIONS:

S. No.

Time t (sec) Initial Head

h1 (cm) Final Head

h2 (cm) log 10 (h1 /

h2) K (cm/sec)

1

2

3

4

RESULT: Coefficient of permeability of the given soil sample =

COMMENT:

19

9. COEFFICIENT OF PERMEABILITY BY CONSTANT

HEAD METHOD

AIM: To determine the coefficient of permeability of a given soil sample using

constant head method.

APPARATUS:

A permeameter mould is of 100mm dia x 127.3mm height and internal volume

1000 cc, constant head set-up stop-watch, graduated jar.

PROCEDURE:

1. Apply a thin layer of grease to the inside surface of mould. 2. Fit the mould with collars, up side down, fill it with wet soil. Tamp the soil

during pouring. Remove the collar and check the density of the mould. 3. Place the permeameter assembly in the bottom tank. Connect the water inlet

nozzle to the constant level head tank. Open the air valve at the top cap and allow the water to flow without bubbles. When all the air has been expelled out, close the air valve.

4. Take a number of readings of discharge. 5. Calculate the coefficient of permeability using the formula: k = (Q / t) * (L /

h) * (1 / A) where k = Coefficient of permeability (cm / sec.) =

Q = Total quantity of flow (c.c.) in a given time t = L = Length of sample (cm) = A = Area of the sample (sq.cm) = h = Head causing flow (cm) =

OBSERVATIONS:

S. No

Time (t) (Sec)

Head (h) (cm)

Quantity (cc)

Permeability K (cm / sec.)

1 2 3 4 5 6

Average permeability, k = RESULT: Coefficient of permeability of the given soil sample = COMMENT:

20

10. STANDARD PROCTOR COMPACTION TEST AIM:

To find the optimum moisture content and maximum dry density for a

soil sample compacted as per Standard Proctor or AASHTO method.

APPARATUS

Standard Proctor mould with collar and base, standard rammer of 2.59 kg

weight, I.S. Sieve No. 4.75, balance, oven, measuring cylinder.

PROCEDURE:

1. Determine the weight of the empty mould (W1) Assemble the base and collar

and apply a thin coat of oil inside.

2. Weight about 2.5 kg of soil passing through sieve I.S. 4.75 mm into a tray and

spread it.

3. Add a known quantity of water and mix the soil thoroughly.

4. Place the moist soil in the mould in three layers. Compact each layer with 25

blows of the rammer falling through 30 cm. The blows should be uniformly

spread over the entire surface of the soil. Each layer is scarified before the

next one is spread for proper bond. The final compacted soil should extend

slightly beyond the top of the mould into the collar.

5. Rotate the collar slightly and remove it by pulling it upwards slowly.

6. Trim the soil with a straight edge and level the top of the mould. Remove the

soil cake from the base and weigh it (W2).

7. Take a representative sample of soil from the cake for water content

determination after it is taken out using an extractor.

8. Increase the water content in increments depending upon the rate of increase

in the weight of the soil and its decrease later.

9. Repeat the observations as at 6 and 7 above with each water content.

CALCULATIONS:

Weight of empty mould = W1 g

Weight of mould + compacted soil = W2 g

21

Water content (%) added = w

Weight of soil = (W2 - W1) g

Volume of soil = volume of mould = 1000 cc

Bulk density of soil = (W2-W1)/1000 = g/cc

OBSERVATIONS:

S. No.

Container No.

Wt. of empty container (g)

Wt. of container with wet soil (g)

Wt. of container with

dry soil (g)

Moisture content %

1

2

3

4

5

S. No.

Wt. of empty

mould (g)

Wt. of compacted soil

(g)

Bulk density of soil (g/cc)

Moisture content %

Dry density (g/cc)

1

2

3 4

5

RESULT:

1. Optimum moisture content =

2. Dry density of the soil =

COMMENT:

22

11. UNCONFINED COMPRESSION TEST

AIM:

To determine the undrained shear strength of a remoulded soil sample.

APPARATUS:

Proctor mould with its accessories, Proving ring, loading frame.

PROCEDURE:

1. Apply thin layer of oil to the mould, collar and base plate.

2. Take 2.5 kg of the given soil sample and mix thoroughly with a known

quantity of water.

3. Compact the sample in the mould in three layers with 25 blows on each layer.

Take care to scarify the layer before the next layer is spread.

4. Remove the collar, trim the sample to the top of the mould with a spatula.

5. Extract the sample from the mould and place it in the loading unit.

6. Apply the load at the rate of 1.25 mm/min.

7. Measure the load at regular intervals of strain in the specimen. Note down the

calibration of the Proving ring.

8. Tabulate the readings and draw a graph - load vs. deformation and read the

ultimate load.

9. Calculate average area of cross section using:

A = Ao/(1-) where Ao = Initial area of cross - section.

A = Corrected area of cross - section.

= h / ho

ho = Initial height of the specimen.

h = change in length

23

Diameter of Specimen = d = cm

Initial Height of the Specimen = ho = cm

Least count of strain dial gauge =

Calibration of proving ring dial gauge =

OBSERVATIONS:

Proving ring dial gauge reading S.

No Time %

Strain Sp1 Sp2 Sp3 Load

Average area of cross

section

Stress kN/m2

1

2 3

4

5 6

7 8

Graphs:

1. Draw the stress-strain curve

2. Draw the Mohrs circle and determine Cu.

RESULT:

Unconfined compressive strength of the soil sample =

Undrained Cohesion of the soil sample =

COMMENT:

24

12. DIRECT SHEAR TEST ON SAND (I.S. 720 : Part XIII : 1965)

AIM:

To determine the angle of shearing resistance of the given sample of sand. APPARATUS:

Shear box assembly and loading unit. PROCEDURE:

1. Place the lower half on the shear box on a level base. 2. Place proper gripper plate with its grooves facing up and perpendicular to

direction of motion. 3. Place the top half of the shear box over the bottom half. 4. Connect the top half to the lower half by means of two locking pins, which are

removable. 5. Pour sand inside the box over the bottom gripper plate and level to about 1.5

to 2.0 cm depth. 6. Place the top gripper plate with grooves facing the sample. 7. Place the loading cap, steel ball etc. and seat the set-up on the loading unit.

OBSERVATIONS: Calibration of the proving ring dial gauge: 1 div = kN

S. No

Normal stress (Kg / Cm2)

Max. reading on proving ring dial

gauge

Max. Shear force (T)

Shear stress (Kg / Cm2)

1

2

3

4

GRAPH: Soil parameters are obtained from the graph.

RESULT: C =

= COMMENT:

25

13. DETERMINATION OF RELATIVE DENSITY OF

COHESIONLESS SOILS

AIM:

To determine the relative density of cohesionless soil .

APPARATUS:

Vibrating table (75 cm x 75 cm), Cylindrical moulds of 3000 cm3 and 15000

cm3 capacity, surcharge weights with lifting handle and spanners. PROCEDURE:

1. Compute the volume of the cylindrical mould (V1) 2. Take oven dried free-draining soil without lumps. 3. Pour the soil using a funnel / scoop into the mould (W1) in a spiral motion.

Level it at the top with one continuous pass of a straight edge. Note its weight (W2).

4. Pour the soil in layers with scoop held very close to the surface so as to allow soil particles to slide sown rather than fall in layers. Level the top with one continuous pass of a straight edge. Note its weight (W3).

5. The entire mould assembly (W3) is fixed on the vibrating deck and is vibrated after placing the surcharge weight for 8 minutes.

6. Measure the volume of soil in the mould (V2) OBSERVATIONS:

1. Wt. of empty mould =W1

2. Volume of empty mould =V1

3. Wt. of mould + soil sample(filled in spiral motion) = W2 (in the loosest state) 4. Wt. of mould + soil sample (filled in layers) =W3 (in the natural state) 5. Volume of soil sample (after vibrating) =V2 (in the densest state)

26

CALCULATIONS: Relative Density = emax. e / emax. emin.

Where emax. = Void ratio in the loosest state

emin. = Void ratio in the densest state e = Void ratio in the natural state

{ e = ( Gw / d ) 1 } RESULT:

Relative density of the soil sample =

COMMENT:

27

14. DETERMINATION OF SHRINKAGE LIMIT OF SOIL

(I.S. 2720 : Part VI : 1972) AIM:

To determine shrinkage limit, shrinkage ratio and volumetric shrinkage.

MATERIAL AND EQUIPMENT:

Evaporating dishes, shrinkage dish, glass cup, glass plates one plane and

another having three metal prongs, spatula, straight edge, 425 microns IS sieve,

balance, mercury and wash bottle containing distilled water.

PROCEDURE:

1. Preparation of soil paste: Take about 100g of soil passing 425 micron IS sieve.

2. Place about 30 g of the above sample in a dish and mix it thoroughly with

distilled water. Water added should be about 2 to 3 times the liquid limit to

make a thin slurry.

3. Clean the shrinkage dish and determine its weight accurately. Place the dish in

an evaporating dish and fill the shrinkage dish with mercury till it overflows.

Then remove the dish and press a flat plate on top to remove excess mercury.

Wipe off any mercury adhering to the out side of the shrinkage dish. Weigh

the mercury to find volume of the dish.

4. Coat the inner side of the shrinkage dish with a thin layer of vaseline/grease.

Pour the soil slurry into the dish with help of a spatula. Tap the dish gently on

a rubber sheet and allow the paste to flow towards the edges. Repeat the

process till the dish is completely filled and the excess soil overflows. Strike

off the excess soil paste with a straight edge. Wipe off the soil adhering to the

out side of the dish.

5. Weigh the shrinkage dish and keep it in the oven at 1050 for 24 hours.

Remove and place the dish in a desiccator and weigh it immediately.

6. Keep the glass cup in a china dish. Fill the cup with mercury and remove the

excess mercury by pressing the glass plate with the three prongs firmly over

the top of the cup. Transfer the cup into another china dish and place the oven

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dried soil pat on the surface of mercury. Press carefully the pat into the

mercury by pressing it by the glass plate having three metal prongs. Collect

the displaced mercury and weigh. The volume of the dry soil pat is then

determined by dividing this weight by the unit weight of mercury.

OBSERVATIONS:

Description 1 2 3

a) Water content of wet soil: 1. Shrinkage dish No. 2. Wt. of shrinkage dish (g) 3. Wt. of shrinkage dish +Wt. Soil pat (g) 4. Wt. of shrinkage dish + dry soil pat (g) 5. Wt. of dry soil pat (Wd) (g) 6. Wt of water evaporated (g) 7. Water content of soil (w) %

b) Volume of wet soil sample: 8. Dish No 9. Wt. of dish 10. Wt. of mercury + shrinkage dish (g) 11. Wt. of mercury filling shrinkage dish 12. Volume of wet soil sample V = (11)/13.6

cc

c) Volume of dry soil pat: 13. Evaporating dish No. 14. Wt. of evaporating dish (g) 15. Wt. of mercury displaced by dry soil pat + wt. of

dish (g)

16. Wt. of mercury displaced by dry soil pat (g) 17. Vol. of dry soil pat Vd = (16) / 13.6 cc

d) Calculations: 18. Shrinkage limit: Ws = ( W (VVd) / Wd) 100 19. Shrinkage ratio: SR = Wd/( Vdw) 20. Volumetric shrinkage Vs = (W- W s)/ SR RESULT: 1. Shrinkage Limit :

2. Shrinkage ratio :

3. Volumetric shrinkage :

COMMENT:

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15. LABORATORY VANE SHEAR TEST

AIM:

Determination of undrained shear strength of a purely cohesive soil

specimen in the laboratory.

APPARATUS:

Laboratory vane shear apparatus, container for soft clay sample, helical spring

of known spring constant to give torque, shear vane of length 24mm and diameter

12mm.

DESCRIPTION:

A shear vane consists of four blades welded together at right angles to each

other and attached to a central shaft. The apparatus is either hand operated or motor

operated. The vanes are lowered or raised by an operating wheel along a shaft fixed at

the base of the apparatus. The soil specimen of soft consistency is placed in the

container and it is clamped to the base. The vane is rotated at a uniform rotation of 60

per minute manually or electrically after lowering the vane into the soil specimen.

Four torque springs are provided with spring constants of 2,4,6and 8 cm-kg to be used

in accordance with the consistency of the soil. By rotating the vane, the twist of the

rod is measured on a graduated disc through having a pointer.

PROCEDURE:

The soil specimen is mixed with a moisture content corresponding to the

consistency of plastic limit. The soil paste is kneaded into the container and placed at

the base of the apparatus and clamped. The vane is lowered into the specimen slowly

so that the top of the vane is at least 10mm below the top of the specimen. The initial

reading on the graduated disc is noted. The vane is rotated at a uniform rate of 60 per

minute by operating the torque handle until the specimen fails. Note the final reading

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of the torque indicator. From the difference in the initial and the final reading, torque

is calculated. Perform the experiment with different moisture contents.

OBSERVATIONS AND CALCULATIONS:

= T / [ D2 H / 2 + D3 / 6 ]

Where = Shear Strength in kg/cm2 T = Torque in kgcm = (spring constant x twist angle in radians) D = Overall dia. of the vane in cm H = Height of vane in cm

Torque

indicator Reading

S. No

Spring constant Kg-cm Initial Final

Twist angle

in degrees

Twist angle

in radians

Torque (T)

Kg-cm

Shear stress

() kg/cm2

Water content

w%

RESULT: COMMENT: