GTE Lab Manual

Department of Civil Engineering, ANITS, Visakhapatnam

Pag

e1

Laboratory Manual

CE318 GEOTECHNICAL ENGINEERING LABORATORY I

III BE I Semester

Dr. B.N.D.Narasinga Rao

Professor & Head

Department of Civil Engineering Anil Neerukonda Institute of Technology & Sciences

(Affiliated to Andhra University) Sangivalasa-531162, Bheemunipatnam Mandal, Visakhapatnam Dt.


Pag

e2

Manual for

Geotechnical Engineering Laboratory I

Contents

S.

No.

Experiment Page

No.

Cycle-I

1 Specific gravity by Pycnometer method 2

2 Specific gravity by Density bottle method 4

3 Sieve Analysis 6

4 Liquid Limit by Casagrandes Liquid limit apparatus 10

5 Liquid Limit by Uppals Cone Penetrometer method 13

6 a) Plastic Limit 16

b) Shrinkage Limit 18

Cycle-II

7 Grain size (Sedimentation) Analysis by Hydrometer 27

8 In-situ density by Core Cutter method 33

9 In-situ density by Sand replacement method 35

10 Permeability by Constant Head test 39

11 Permeability by Variable head test 42

12 OMC and MDD by IS light compaction 46


Pag

e3

Expt.1

Determination of specific gravity by Pyknometer method

Aim

To determine the Specific gravity of coarse grained soil by using Pycnometer

Apparatus

1. Pyknometer of 900 ml capacity

2. Balance of sensitivity 0.1 g

3. 40 mm IS Sieve

4. Oven

Soil

The soil sample used is about 200 g in case of fine grained soil and 400g in case of

medium and coarse grained soils and should be oven-dried. If >10 percent of soil is retained

on 40 mm IS Sieve, such stones should be broken down to less than this size.

Principle

The steps involved in the determination of specific gravity in this method are schematically

shown in Fig.1

(a) Pycnometer (empty) (b) Pyc.+dry soil (c) Pyc.+dry soil+water (d) Pyc.+water

Fig.1 Principle of water content determination by pycnometer method (Schematic)

Procedure

1. The weight of the clean and dry Pyknometer is taken to the nearest 0.2g (W1).

2. The soil sample is placed in the Pyknometer. The Pyknometer with cover with the

contents are weighed (W2) to the nearest 0.2g.

3. About 500ml of water is added to the soil in the Pyknometer. The rubber stopper is

inserted on to the Pyknometer. For medium and coarse grained soils, the Pyknometer

and the contents are set aside for at least 4 hours. At the end of this period or

immediately after the addition of water in case of fine grained soils, the Pyknometer is

shaken by hand until the soil particles are in suspension and then placed in the

shaking apparatus and shaken for a period of 20 to 30 minutes.

4. The stopper is then removed and any soil adhering to the stopper is washed carefully

into the jar. Water is then added to the Pyknometer to within 2 mm of the top. The soil

is allowed to settle for few minutes and the Pyknometer is then filled with water to the

brim. The cover is then placed on the top of the jar taking care not to trap any air

under the cover.


Pag

e4

5. The Pyknometer and the cover are wiped with a cloth and the whole assembly is

weighed (W3) to the nearest 0.2g.

6. The Pyknometer is emptied, washed thoroughly and filled completely with water. The

glass plate is placed in position taking care not to trap any air under the plate. The

Pyknometer and the plate are then wiped outside with a cloth and the whole assembly

is then weighed (W4).

Observations

S.

No.

Observation Trial-1 Trial-2 Trial-3

1 Weight of the clean and dry

Pyknometer, W1 (g)

2 Weight of Pyknometer with cover

with the dry soil, W2 (g)


with the soil and water, W3 (g)


with water, W4 (g)

6 Specific Gravity of Soil Solids, G

)()(

)(

2314

12

WWWW

WWG

7 Average Specific Gravity, G

8 % Variation in G from the Average

Value

Room Temperature= OC

Result

Specific Gravity of the given soil sample=

Specific Gravity of different types of soil

S.No. Type of soil Specific Gravity

1 Gravel 2.63-2.67

2 Sand 2.63-2.67

3 Silt 2.65-2.7

4 Clay 2.6-2.9

Comments on the Result

% Variation in the determination of Specific gravity (Range):

What is your comment on the result obtained with respect to type of soil?

Ans.:

Reference

IS 2720 : Part III : Sec 2 : 1980 Test for Soils - Part III : Determination of Specific Gravity -

Section 2 : Fine, Medium and Coarse Grained Soils


Pag

e5

Expt.2

Specific Gravity by Density Bottle method

Aim

To determine the Specific gravity of coarse grained soil by using Density bottle

Principle

The steps involved in the determination of specific gravity in this method are schematically

shown in Fig.1

(a) density bottle (b) density bottle (c) density bottle (d) density bottle

(empty) +dry soil +soil+water +water

Fig.1 Principle of water content determination by Density bottle method (Schematic)

Procedure

1. The weight of the clean and dry density bottle with stopper is taken to the nearest

0.01g (W1).

2. About 5 to 10 g of soil sample passing through 2mm IS Sieve is dried at 105 to

1100C. Where soils are suspected to contain gypsum or organic matter, the oven

drying of the soil shall be restricted to a maximum of 60 to 800C but for longer

periods. The soil sample is placed into the density bottle. The bottle with soil and

stopper is weighed to the nearest 0.01g(W2)

3. Sufficient kerosene is added to the density bottle such that the soil in the bottle is just

covered. The entrapped air may be removed by shaking the density bottle

accompanied by occasional stirring.

4. Kerosene is added to the bottle in increments, accompanied by occasional stirring

until the bottle is full. The stopper is placed and the outside surface is wiped with a

cloth. The density bottle with stopper is weighed to the nearest 0.01g(W3)

5. The density bottle is emptied, washed with water thoroughly and rinsed with kerosene

and then filled with kerosene completely. The stopper is placed and the outside

surface is wiped dry with a cloth. The bottle with stopper is then weighed to the

nearest 0.001g (W4)


Pag

e6

Observations

S.

No.

Observation Trial-1 Trial-2 Trial-3

1 Weight of the clean and dry Density bottle, W1 (g)

2 Weight of Density bottle with cover with the dry

soil, W2 (g)

3 Weight of Density bottle with cover with the soil

and kerosene, W3 (g)

4 Weight of Density bottle with cover with

kerosene, W4 (g)

5 Specific gravity of Kerosene, GkT

6 Specific Gravity of Soil Solids, G

)()(

)(

2314

12

WWWW

GWWG kT

7 Average Specific Gravity, G

8 % Variation in G from the Average Value

Result

Specific Gravity of the given soil sample=

Room Temperature=

Specific Gravity of different types of soil

S.No. Type of soil Specific Gravity

1 Gravel

2 Sand

3 Silt

4 Clay

Comments on the Result

% Variation in the determination of Specific gravity (Range):

What is your comment on the result obtained with respect to type of soil?

Reference

IS 2720 : Part 3 : Sec 1 : 1980 Methods of test for soils: Part 3 Determination of specific

gravity Section 1 fine grained soils


Pag

e7

Expt.3

Sieve Analysis

Aim

To determine the grain size distribution of the given soil sample and classify the soil as per IS

1498 - 1970

Apparatus

1) IS Sieves: 80mm, 40 mm, 20mm, 10mm, 4.75 mm, 2.36mm. 1.18 mm, 0.6 mm

(600), 0.425 mm (425 ), 0.3 mm (300 ), 0.15 mm (150 ), 0.075 mm (75 )

Procedure

1. Air dried soil sample of quantity as given in Table 1 is taken for the test

Table 1 quantity of soil required for grain size analysis

Max. particle size present

in substantial quantities

(mm)

Quantity of soil to be taken

for the test (kg)

4.75

6.7

9.5

13.2

19

37.5

75

0.4

0.75

1.5

3.5

6.5

25

60

2. The weight of soil taken for the test is determined W1

3. The soil is sieved through 4.75mm Sieve and divided into two portions, one coarser

(gravel) another finer (sand & fines) than 4.75mm (sand & Fines)

Sieve analysis of Gravel

1. The portion of soil sample retained on 4.75mm IS Sieve is taken and its weight is

determined W2

2. The IS Sieves of sizes 40 mm, 20mm, 10mm and a pan are taken

3. The portion of soil retained on 4.75mm IS Seive is sieved through each sieve keeping

the pan at bottom.

4. Sieving shall be done with sieve of largest opening size i.e., 80 mm first and the

portion of soil passing through the sieve is then sieved through the sieve of next lower

opening size.

5. While sieving through each sieve, the sieve is agitated, so that the soil sample rolls in

irregular motion over the sieve.

6. While sieving, no soil shall be pushed through the opening. The material, before

sieving may be rubbed with rubber pestle in the mortar, taking care to see that

individual soil particles are not broken and re-sieved to make sure that only individual

soil particles are retained.

7. The weight of soil retained on each sieve is determined and recorded.


Pag

e8

8. If the soil sample appears to contain more than 5% water content, the water content of

the soil is determined.

9. If the water content is less than 5%, all the computations used in Sieve analysis can be

based on wet weight only.

10. If the soil contains more than 20% gravel and the fines are very cohesive adhering to

the gravel after separation, the gravel shall be washed on 4.75mm IS Sieve using

sodium hexa meta phosphate solution if necessary.

Sieve analysis of sand

1. The sieves used for this purpose are 2.36mm. 1.18 mm, 0.6 mm (600), 0.425 mm

(425 ), 0.3 mm (300 ), 0.15 mm (150 ) and 0.075 mm (75 ) IS Sieves

2. Sieve analysis of sand may be done by wet Sieving for clayey soils and dry sieving

for soils which do not contain appreciable clay

3. Care is taken to see that the sieves are not over loaded, by ensuring that the maximum

quantity of material retained on each sieve shall be as given below

IS Sieve Max.Quantity

of soil

retained (g)

2 mm

425

75

200

50

25

4. The weight of material, retained on each sieve, is determined and recorded.

Observations

S.

No.

Sieve

size, mm

Weight of soil

retained, g

% Weight

Retained

Cumulative %

weight

retained

Cumulative %

Finer

1 80

2 40

3 20

4 10

5 4.75

6 2.36

7 1.18

8 0.6

9 0.425

10 0.3

11 0.15

12 0.075

Graph

1) A graph is plotted with sieve/ grain size on X-axis on log scale and Cumulative %

Finer on Y-axis.


Pag

e9

2) The points obtained are joined by a smooth curve, which is known as Grain size

distribution curve.

3) The grain size corresponding to Cumulative % Finer of 10, 30 and 60 are noted as

D10, D30 and D60 respectively.

Calculations

% Fines=Cumulative % Finer corresponding to 0.075 mm

% Gravel= Cumulative % Retained on 4.75 mm IS Sieve

% Sand=100 (% Fines+% Gravel)

Uniformity Coefficient, Cu = 10

60

D

D

Coefficient of Curvature, Cc = 1060

2

30

DD

D

Interpretation of Results

If % Fines% Sand, the soil is classified as Gravel, else as Sand

The coarse grained soils are classified as well graded or poorly graded soils, depending on the

values of Cu and Cc

If % Fines 4 and

Cc = 1 to 3

Well graded Gravel GW

Not meeting the Cu or

Cc or both the criteria

Poorly graded Gravel GP

Sands

Cu > 6 and

Cc = 1 to 3

Well graded Sand SW

Not meeting the Cu or

Cc or both the criteria

Poorly graded Sand SP

If % Fines>12

The soil is plotted on the plasticity chart with liquid limit and plasticity index (LL, PI) as the

X and Y coordinates.

Soil Classification Criteria Type of soil IS Classification Symbol

Gravels

Soil plots above the A-

line and Ip> 7

Clayey Gravel GC

Soil plots below the A-

line and Ip


Pag

e10

line and Ip> 7

Soil plots below the A-

line and Ip4 and Cc = 1 to 3

Soil plots above the

A-line and Ip> 7

Well graded

Clayey Gravel

GW-GC

Soil plots below the

A-line and Ip 7

Poorly graded

Clayey Gravel

GP-GC


A-line and Ip6 and Cc = 1 to 3

Soil plots above the

A-line and Ip> 7

Well graded

Clayey Sand

SW-SC


A-line and Ip 7

Poorly graded

Clayey Sand

SP-SC


A-line and Ip


Pag

e11

Expt.4

Liquid limit by Casagrandes Mechanical Method

Aim

To determine the liquid limit of the given soil sample using Casagrandes liquid limit

apparatus

Definition

Liquid limit is the water content at which a soil changes from liquid state to plastic state.It is

the minimum water content at which the soil is still in liquid state but possesses small shear

strength against flow.

As per IS 2729 (Part 5)-1985, liquid limit is defined as the water content at which, the soil

placed in the brass cup of Casagrandes liquid limit apparatus and cut into a groove of

standard dimensions, will flow together for a distance of 25.4 mm at the bottom of the groove

under 25 blows.

Apparatus

(a) LL Apparatus with Casagrande grooving tool (b) ASTM grooving tool

Fig.1 Casagrandes Liquid limit apparatus (Courtesy: AIMIL)

Procedure

1. The soil sample to be used for the test is air dried, pulverized and passed through 425

I.S. Sieve.

2. About 150g of this soil sample is mixed thoroughly with distilled water in an

evaporating dish to form a thin uniform paste.

Rubber base

Brass cup

Counter

Cam

Handle

Casagrandes grooving tool


Pag

e12

3. The brass cup and the rubber base are thoroughly cleaned. The height of fall of the

brass cup is checked and adjusted to exactly 1 cm.

4. Before conducting the test, the soil paste is remixed thoroughly. A portion of the soil

paste is placed in the cup above the spot where the cup rests on the base, squeezed

down and spread in position in such a way that the surface of the soil paste is

horizontal parallel to the surface of the rubber base and that the maximum depth of

the soil paste in the cup is 1 cm.

5. A clean sharp groove of standard dimensions is made in the soil paste using a

grooving tool. This is done by keeping the grooving tool in touch with and normal to

the surface of the brass cup at the top and rotating it along the diameter of the cup

through the centre line of the cam follower.

6. Two types of grooving tools are available. The Casagrandes grooving tool (Type A

grooving tool) is commonly used which makes a groove of size 2mm wide at bottom

11mm at top and 8mm deep. In sandy soils, the Casagrandes grooving tool tends to

tear the sides of the groove and in such cases, ASTM tool (Type B or Type C

grooving tool) is used. The ASTM tool cuts a groove of size 2mm wide at bottom

13.6mm wide at top and 10mm deep.

7. The cup is then lifted and dropped by turning the crank at a rate of 2 revolutions per

second to apply blows on the soil until the two halves of soil on either side of the

groove come in contact at the bottom of the groove for a distance of 12mm. This

distance is measured with a ruler. The number of blows required to close the groove

for the length of 12mm is recorded.

8. The water content of the soil is determined by collecting a sample of soil, in a

container, from the closed portion of the groove.

9. The experiment is repeated at least 3 more times, following the above procedure at

higher water content, each time recording the number of blows to close the groove for

a distance of 12 mm and determining the corresponding water content.

10. The number of blows obtained in each of trials should be in the range of 15 to 35. If

the blows are more than 35, the trial is discarded and the procedure is repeated by

removing the soil from the cup and using more water for the next trial. If the blows

are less than 15, the trial is discarded and the procedure is repeated by adding dry soil

powder to the soil to decrease the water content.

11. For better results, it is preferable to conduct the test with increasing water content, by

adding little more water in successive trials. The brass cup, the rubber base and the

grooving tool are cleaned before each trial.

12. Some soils tend to slide on the surface of the cup instead of flowing. If this occurs, the

results should be discarded and the test is repeated until flowing does occur. If sliding

still occurs, the test is not applicable and a note shall be made that the liquid limit

could not be obtained.


Pag

e13

Observations

S.

No.

Observation Trial1 Trial2 Trial3 Trial4

1 Number of blows

2 Cup No.

3 Weight of empty cup, W1

4 Weight of cup+wet soil, W2

5 Weight of cup+dry soil, W3

6 Water content

100)(

)(

13

32

WW

WWw

7 Liquid limit

8 Flow index

1

210

21

logN

N

wwI f

Graph

1) A graph is plotted with number of blows on X-axis on log-scale and water content on

Y-axis on arithmetic scale.

2) A best fitting straight line is drawn through the experimental points, which is known

as flow curve.

3) The liquid limit is obtained from the flow curve as the water content corresponding to

25 blows.

4) The slope of the flow curve is determined, which gives the flow index. The liquid

limit is reported to the nearest whole number.

5) The Plasticity chart is constructed showing A-line and all soil zones.

Result

Liquid Limit=

Plastic limit=

Plasticity Index=

Type of soil = (based on Plasticity chart)

Comments and Interpretation

The given soil sample is classified on the Plasticity chart as_______________

Reference

IS 2720 : Part 5 : 1985 Method of Test for Soils - Part 5 : Determination of Liquid and Plastic

Limit


Pag

e14

Expt.5

Liquid Limit by Cone Penetration Method

Aim:

To determine the Liquid limit of the given soil sample using Uppals cone penetrometer and

classify the soil on the Plasticity chart

Principle

The Principle of the method is to determine the penetration of a cone of standard sliding

weight falling freely into a soil paste filled in a brass cup. The liquid limit is determined as

the water content corresponding to 20 mm penetration.

Definition

Liquid limit is the water content at which a soil changes from liquid state to plastic state.It is

the minimum water content at which the soil is still in liquid state but possesses small shear

strength against flow.

As per IS 2729 (Part 5)-1985, liquid limit is defined as the water content at which, the soil

placed in the brass cup of Uppals liquid limit apparatus will show a cone penetration of

20mm under a total sliding weight of 80g.

Apparatus

Fig.2 Uppals Cone penetrometer for Liquid limit determination

Procedure

1. The push button is pressed and the plunger rod is adjusted to ensure that the pointer

on the graduated scale shows zero penetration reading.

2. The soil sample for the test is prepared in the same way as in Casagrandes liquid

limit test. The soil sample to be used for the test is air dried, pulverized and passed

through 425 I.S. Sieve.

Cylindrical brass cup

Cone

Penetration display


Pag

e15

3. About 150g of this soil sample is mixed thoroughly with distilled water in an

evaporating dish to form a thin uniform paste.

4. In case of clayey soils, the paste is left undisturbed for about 24 hours to ensure

uniform distribution of moisture throughout the soil paste. However, light textured

soils having low clay content may be tested immediately after thorough mixing.

5. The soil paste prepared is placed in increments in the brass cup ensuring that no air is

entrapped in the cup. The cup is completely filled with the soil paste and the excess

soil above the top of the cup is removed. The surface of the soil paste in the cup is

leveled.

6. The brass cup filled with wet soil paste is cleaned outside and is placed on the base of

the cone penetration device.

7. The plunger rod and the cone along with graduated scale are moved vertically by

releasing the clamping screw and holding the entire assembly carefully to bring the

bottom of the cone in contact with the surface of the soil in the brass cup and the

clamp is then tightened.

8. The push button is released and the cone is allowed to penetrate into the soil in the

brass cup. The penetration (P1) of the cone in the soil paste is recorded 5 seconds after

releasing the push button by noting the reading against the pointer on the graduated

scale.

9. The water content of the soil in the brass cup is determined and recorded as w1. The

remaining soil in the brass cup is removed and the cup and the cone are cleaned. More

water is added to the soil and the soil paste is thoroughly mixed.

10. The procedure is repeated to have at least four trials and corresponding values of

penetration (P2,P3,P4) and the water content (w2,w3,w4) are determined.

11. The water added to the soil in each trial should be such that the penetration obtained is

in the range of 14 to 28 mm. In case the water content in any of the trials is less than

14 mm or more than 28 mm, the result shall be discarded and another trial is made

with different water content. It is desirable to make the first trial with smaller water

content and the succeeding trials are made with increasing water content.


Pag

e16

Observations and Calculations

S.

No.

Observation Trial1 Trial2 Trial3 Trial4

1 Cone Penetration

2 Cup No.




6 Water content

100)(

)(

13

32

WW

WWw

7 Liquid limit

8 Flow index

21

21

pp

wwI f

Graph

1) A graph is plotted with cone preparation on X-axis and water content on Y-axis. A

best fitting straight line is drawn through the experimental points.

2) The water content corresponding to 20 mm penetration is read from the graph and is

taken as the liquid limit. It is reported to the nearest first decimal place.

Result

Liquid Limit=

Plastic limit=

Plasticity Index=

Type of soil = (based on Plasticity chart)

Comments and Interpretation

The given soil sample is classified on the Plasticity chart as_______________

Reference


Limit


Pag

e17

Expt.6(a)

Plastic Limit

Aim

To determine the Plastic limit of the given soil sample

Definition

Plastic limit is the water content at which a soil changes from plastic state to semi-solid state.

It is the minimum water content at which soil remains in plastic state and can be moulded to

any shape without rupture.

IS:2720 (Part 5) - 1985 describes the procedure for determination of plastic limit.

Experimentally, the plastic limit is defined as the water content at which a soil begins to

crumble (forms cracks) when rolled into a thread of 3mm diameter.

Apparatus

The apparatus consists of a flat square glass plate of minimum 45cm size and 10mm thick, a

rod of 3mm diameter, oven and containers for water content determination.

Procedure

1. About 60 g of air dried soil passing through 425 IS Sieve is taken and mixed with

sufficient water such that its water content is more than the estimated plastic limit and

such that soil becomes plastic enough to be easily moulded with fingers.

2. About 20 g of the thoroughly mixed soil is taken. A ball is made with about 8g of this

soil and rolled on the glass plate with fingers with just sufficient pressure to roll the

mass into a thread of uniform diameter, throughout its length.

3. The rate of rolling with fingers shall be at rate of 80 to 90 strokes per minute,

counting a stroke as one complete forward and backward motion of the fingers.

4. When the diameter of the soil thread reaches 3mm, the soil thread is worked back to

form a ball.

5. The procedure of rolling into thread of uniform diameter of 3 mm and kneading back

into a ball is repeated until cracks appear on the surface of the soil thread, which

begins to crumble. When this condition is reached, the water content of the pieces of

soil thread is determined.

6. The test is repeated taking another portion of the soil paste and a total of 3 trials are

made and the corresponding water contents are determined. The average water

content out of three trials to the nearest whole number is reported as the plastic limit.


Pag

e18

Observations: Plastic Limit

S.No. Observation Trial1 Trial2 Trial3

1 Cup No.




5 Water content

100)(

)(

13

32

WW

WWw

6 Plastic limit

Reference


Limit


Pag

e19

Expt.6(b)

Shrinkage limit

Aim

To determine the Shrinkage limit of the given soil sample

Definition

Shrinkage limit is the water content at which the soil changes from semi-solid state to solid

state.

Fig.1 Shrinkage of soil as a function of water content

For fine grained soils, it was observed that a decrease in water content causes a corresponding

decrease in the volume of soil, when the soil is in plastic or semi-solid state. At some water

content, a further reduction of water content does not cause any decrease in volume of soil, as

shown in Fig.1. The decrease in volume of soil with decrease in water content due to

drying/evaporation is called as shrinkage.

Thus, the minimum water content above which decrease in water content causes shrinkage of

soil is known as shrinkage limit. It is also the maximum water content below which the

volume of soil remains constant irrespective of the change in water content.

Principle

Fig.2 shows the schematic diagram in which a fully saturated soil in stage(1) having volume

V1 undergoes shrinkage and on complete drying reaches stage(3), where the entire water is

evaporated. Between stage (1) and stage (3) lies stage (2), where the soil is at shrinkage limit

water content. In stage (2), the soil is fully saturated but a further decrease in water content

does not cause any decrease in volume of soil and air occupies the space of the evaporated

water.

The volume of soil at shrinkage limit is equal to the total volume of oven dried soil. It is to be

noted that the volume of soil solids is constant throughout the shrinkage process and decrease

in volume occurs only due to decrease in volume of voids.

Weight of water in stage (1) = W1-Wd

Loss of water from stage (1) to stage (2) =(V1-V2)w

Volu

me

of

Soil

S.L. P.L. L.L.

Water content

Semi-

solid state

Plastic state

Liquid state

Solid state


Pag

e20

Weight of water in stage (2)=(W1-Wd)-(V1-V2)w

Shrinkage limit = water content of soil in stage (2)

wS=d

wd

W

VVWW )()( 211

Where, V1 = initial volume of soil

V2 = Volume of soil in dry state (stage-3)

Wd = Weight of dry soil

w = density of water

Stage (1) Soil at initial Stage (2) Shrinkage limit state Stage (3) Dry state

water content (w=S.L. & S=100%) (w=0 % & S=0%)

(w>S.L. & S=100%)

Fig.2 Shrinkage of a soil during drying

Apparatus

The apparatus for determination of shrinkage limit with all component parts is shown in

Fig.3. It consists of the following

1) Cylindrical Stainless steel Shrinkage dish 45 mm internal diameter and 15 mm

internal height.

2) Cylindrical Glass cup 50 mm internal diameter and 25 mm internal height

3) Porcelain evaporating dish

4) square Glass plate of size 75 mm 75 mm with 3 metal prongs

5) square Plain glass plate of size 75 mm 75 mm

6) Thermostatically controlled oven

Test Procedure

The test consists of the following steps:

(i) Determination of volume of wet soil

(ii) Determination of Weight of wet soil

W1 V1

Vs Ws

W2

Ws Vs

V2 Wd=Ws

Ws

1

Vs

Vd Air Water

Soil solids Soil solids Soil solids

(V1-V2)w

Water


Pag

e21

(iii) Allowing wet soil to undergo gradual shrinkage

(iv) Determination of Weight of dry soil

(v) Determination of volume of dry soil

(i) Determination of volume of wet soil

1) The weight of the clean empty shrinkage dish is determined and recorded as Wsd.

2) The shrinkage dish is filled over-flowing with mercury and the excess mercury is

removed by pressing the plain glass plate flush with the top of the dish.

3) The volume of the shrinkage dish is computed by dividing the weight of mercury

in the shrinkage dish with the specific gravity of mercury (13.6). This volume of

shrinkage dish is recorded as the initial volume of wet soil V1.

Fig.3 Apparatus for Shrinkage limit determination (Courtesy: AIMIL)

(ii) Determination of Weight of wet soil

1) About 100g of air-dried soil passing 425 IS Sieve is taken and sufficient water is

added to make a uniform thin paste. The amount of water to be added is equal to or

slightly greater than the liquid limit of the soil for friable soils and it may exceed

the liquid limit by about 10% for plastic soils.

2) The shrinkage dish is emptied of mercury, cleaned and coated with a thin layer of

silicon grease or Vaseline to prevent adhesion of soil to the inside surface of the

dish.

3) The shrinkage dish is filled with the wet soil in increments, taking care to prevent

air getting entrapped in the soil. The excess soil is removed by pressing the plain

glass plate flush with the top of the shrinkage dish.

4) The shrinkage dish is cleaned on the outside to remove the adhering soil. The

weight of the shrinkage dish with wet soil is taken and recorded as W2.

5) Weight of wet soil filling the shrinkage dish, W1 = W2-Wsd

(iii) Allowing wet soil to undergo gradual shrinkage

1) The wet soil in the shrinkage dish is allowed to dry in air for sufficient time until

the colour of the soil changes from dark to light.

Measuring jar

Plain plastic plate

Glass cup

Mercury bottle Porcelain

evaporating dish

Straight edge

Shrinkage

dish

Knife

Plastic plate with

metal prongs


Pag

e22

2) Then, the shrinkage dish is placed in an oven to dry at 105 to 1100 C for 24 hours.

After completely drying, the dish with the dry soil is cooled in a desiccator.

(iv) Determination of Weight of dry soil

1) The weight of dry soil pat plus shrinkage dish is taken and reported as W3.

2) Weight of dry soil pat Wd = W3-Wsd

(v) Determination of volume of dry soil

1) The glass cup is kept in an evaporating dish and is filled with over flowing

mercury.

2) The excess mercury is removed by pressing with glass plate with metal prongs

flush with the top of the glass cup and the mercury in the evaporating dish is

removed. The glass cup with mercury is again placed in the evaporating dish.

3) The dry soil pat is placed on the surface of mercury in the glass cup and slowly and

carefully pressed down with glass plate with metal prongs.

4) When the glass plate with metal prong is pressed flush with the top of the glass

cup, the excess mercury spills into the evaporating dish.

5) The glass cup is removed from the evaporating dish and the displaced mercury in

the evaporating dish is carefully weighed. The volume of dry soil pat, V2, is

computed by dividing the weight of displaced mercury with the specific gravity of

mercury


The Observations and Calculations are shown in Table-1

Model Calculation

Shrinkage limit, d

wds

W

VVWWw

)()( 214 (1)

shrinkage factors or parameters

1) Shrinkage Index (IS)

It is defined as the numerical difference between the plastic limit and shrinkage limit

S.I.=P.L.-S.L. (2)

Or, IS=wP-wS (3)

2) Volumetric Shrinkage

Volumetric shrinkage is defined as the ratio of decrease in volume of a soil to the dry volume

expressed as a percentage when the water content is reduced from initial water content to

shrinkage limit water content.

VS= 100)( 1

d

d

V

VV

(4)

3) Shrinkage Ratio (SR)


Pag

e23

It is defined as the ratio of given volume change expressed as a percentage of dry volume to

the corresponding change in water content.

21

21 100

ww

V

VV

SR d

(5)

Thus shrinkage ratio of a soil is equal to the mass specific gravity of the soil in the dry state.

4) Linear shrinkage

Linear shrinkage is defined as the ratio of decrease in length to the original length when the

water content is reduced from initial water content to shrinkage limit. It is usually expressed

as a percentage.

1001

1

L

LLLS d (6)

Linear shrinkage is related to the volumetric shrinkage by the relation

LS=

3/1

100

1001100

VS (7)

Result

The Shrinkage limit of the soil=


Pag

e24

Table-1 Observations and Calculations

S.

No.

Observation Equation Value

1 Weight of the clean

empty shrinkage dish

W1

2 Weight of shrinkage

dish plus mercury

W2

3 Volume of the

shrinkage dish V1. mG

WWV

)( 211

4 Weight of the

shrinkage dish with

wet soil

W3

5 Weight of wet soil pat W4 = W3-W1

6 Weight of dry soil pat

plus shrinkage dish

W5

7 Weight of dry soil pat Wd = W5-W1

8 Weight of evaporating

dish

W7

9 Weight of evaporating

dish plus displaced

mercury

W8

10 Weight of displaced

mercury

W9= W8 - W7

11 Volume of dry soil pat

mG

WV 92

12 Shrinkage limit

d

wds

W

VVWWw

)()( 214

Reference

IS 2720 : Part 6 : 1972 Methods of test for soils: Part 6 Determination of shrinkage factors


Pag

e25

Expt.7

Hydrometer Analysis

Aim

To determine the grain size distribution of the fine fraction using Pipette analysis

Principle

Hydrometer is an instrument used for determining Specific gravity of liquids. In Hydrometer

analysis, the hydrometer is used to determine the density of soil suspension in the measuring

cylinder, from which the average particle size is computed at the sampling depth.

The hydrometer gives the density of soil suspension at the mid height of the bulb. As the soil

particles, in the suspension, go on settling with time, the sampling depth is not constant, but

goes on increasing with time, unlike the case of Pipette analysis.

A special type of hydrometer with long narrow stem at top and a bulb at bottom is used for

hydrometer analysis. The stem has graduations from 0.995 at top to 1.030 at bottom.

Hydrometer is calibrated using a liquid of surface tension 55 dynes/cm.

Test Procedure

Calibration of hydrometer

Calibration of hydrometer consists of preparing a calibration chart for the

hydrometer, which is a graph between the Hydrometer reading, Rh and the effective depth,

He. Once a calibration chart is prepared, it can be used for hydrometer analysis using the

same set of hydrometer and the 1000 ml measuring cylinders.

As the effective depth is a function of volume of hydrometer bulb, cross sectional area

of 1000 ml measuring cylinder and the hydrometer reading, the same are determined for

calibration of hydrometer.

1. Volume of hydrometer bulb

The volume of the hydrometer bulb is determined using one of the following methods

Method-1

1) About 800ml of water is taken in a 1000 ml graduated measuring cylinder. The

reading of the water level in the cylinder is noted.

2) The hydrometer is now inserted into the water in the measuring cylinder. The reading

of water level in the cylinder is again noted.

3) The difference in the above two water levels gives the volume of the hydrometer bulb

plus the volume of the immersed portion of the stem. As the stem is very narrow, this

volume can be taken as the volume of hydrometer bulb without serious error.

Method-2

The weight of the hydrometer is determined to the nearest 0.1 g. The weight in g gives the

volume of hydrometer in cm3, as the density of the hydrometer is 1 g/cc. This can be taken as

the volume of hydrometer bulb, without serious error, though it includes the volume of stem.

2. Cross Sectional Area of measuring Cylinder


Pag

e26

The vertical distance between any two graduations of the measuring cylinder, for example,

100 ml mark & 1000 ml mark, is measured accurately.

The cross sectional area of measuring cylinder is given by the equation

h

VA

A = Cross sectional area of 1000 ml measuring cylinder

V=Volume between graduations (say 1000-100= 900 ml = 900 cc in this example)

h = Distance between the two (say 100 ml and 1000 ml in this example) graduations

3. Effective depth

The graduations on the stem of the hydrometer indicate the Specific gravity (or

density) at the mid height of the bulb. The distance between any hydrometer Reading

graduation mark to the mid height of the bulb is known as Effective depth.

Fig shows the 1000ml measuring cylinder containing soil suspension for which the

hydrometer analysis is carried out. The hydrometer reading is taken at the surface of the soil

suspension (aa), which gives the density of soil suspension at mid height of the bulb (level

bb). However, due to insertion of hydrometer in the soil suspension, the level aa rises to a1a1,

the difference in levels being equal to volume of hydrometer divided by the area of

measuring cylinder (Vb/A). Similarly, the level bb rises to b1b1, the difference in levels being

equal to half the volume of hydrometer divided by the cross sectional area of measuring

cylinder ( Vb/2A). The point to be noted here is that the soil particles at level b1b1 after

immersion were at the same concentration as at level bb before immersion of hydrometer.

Hence, Effective depth

He= H+A

V

A

Vh hh 22

Or He= H+ )2

1

A

Vh h

Where, He = Effective depth (Sampling depth)

H = Distance between the level of Hydrometer Reading graduation to the top

of

the bulb

h= height of bulb

Vh= Volume of hydrometer

A = Cross sectional area of measuring cylinder

In Eq., the terms h, Vh and A are constant. The depth H can be measured from

different hydrometer reading graduations to the zero mark, and the effective depth can thus

be computed for any hydrometer reading. The values are tabulated as shown in Table-1.


Pag

e27

Table-1

Hydrometer reading H He= H+ )

2

1

A

Vh h

0.995 H1

1.000 H2

1.010 H3

1.020 H4

1.030 H5

A graph is plotted between Hydrometer Reading, Rh, on X-axis and Effective depth He on Y-

axis. This graph is known as calibration chart of Hydrometer. From the calibration chart, the

effective depth, He, corresponding to any Hydrometer Reading, Rh, can be determined.

Pretreatment of soil

1) If the soluble salts present in the soil are more than 1%, the soil is washed with

distilled water, taking care to see that the soil particles are not lost.

2) Two samples of about 50 g (for clayey soil) to 100 g (for sandy soil) of air dried soil

passing 4.75 mm IS Sieve is taken. The water content (w1) of one sample is

determined. The weight of the other sample (W1) is determined accurately to the

nearest 0.01 g. The sample is placed in the wide-mouth conical flask, fitted with a

filter paper.

3) About 150 ml of hydrogen peroxide is added to the soil in the conical flask, and the

mixture is stirred gently with a glass rod for a few minutes and then left to stand

overnight after placing a cover.

4) The mixture in the conical flask is gently heated, taking care to avoid frothing over,

stirring the contents periodically. After vigorous frothing has subsided, the contents

are heated further, to reduce its volume to about 50 ml. For organic soil, more

quantity of hydrogen peroxide will be required to completely oxidize the organic

matter. In case, the soil is inorganic, this step may be omitted.

5) In case, the soil sample contains calcium compounds, about 50 ml of hydrochloric

acid (HCl) is added to the sample after cooling. The solution is stirred with a glass

rod, for a few minutes, and allowed to stand for minimum one hour. More quantity of

HCl may be added, until the solution gives acid reaction to the Litmus test. In case,

the sample does not contain calcium compounds, this step may be omitted. The

mixture is then filtered and washed with warm water until the filtrate shows no acid

reaction to Litmus.

6) An evaporating dish is taken and its weight is determined. The soil on the filter paper

and funnel is transferred to the evaporating dish, using a small quantity of jet of

distilled water, taking care to see that soil particles are not lost. The contents are

placed in an oven and dried at 1050 to 110

0 C and then cooled in a desiccator. The

weight of dry soil and the evaporating dish is determined, to the nearest 0.01g.

7) Weight of soil remaining after pretreatment Wb= W3 W2


Pag

e28

8) Weight of soil taken for hydrometer analysis before pretreatment Wa= 1

1

100 w

W

Dispersion of soil

1) About 100 ml of dispersing agent is added to the soil in the evaporating dish, and the

mixture is warmed gently, for about 10 minutes. The contents of the evaporating dish

are transferred to the cup of mechanical mixer, using a small quantity of jet of

distilled water, taking care to avoid loss of soil particles.

2) The soil suspension is stirred well in the mechanical mixer, for about 15 minutes. The

contents are then transferred to the 75 IS Sieve, placed on a receiver. Care is taken

to transfer the entire soil from the cup of mechanical mixer on to the sieve, using a jet

of distilled water, and also avoiding loss of soil particles. The total quantity of water

to be added, during the operation, is about 500 ml, during which the soil is washed on

the sieve.

3) The soil suspension, passing through the sieve and collected in the receiver, is

transferred carefully to the 1000 ml measuring cylinder and made up to exactly 1000

ml mark, using distilled water. The soil suspension in the 1000 ml cylinder is used for

sedimentation analysis, as explained in the next section. The soil retained on 75 IS

Sieve is oven dried, and subjected to sieve analysis.

Sedimentation

Table -2 Observations

S.

No.

Time

(min)

Hydrometer

Reading

Rh

Hydrometer Reading

in Comparison

Cylinder C

Corrected

Hydrometer Reading

Rh = Rh+C

Effective

Depth

He

1 0

2

3 1

4 2

5 4

6 8

7 15

8 30

9 1 hr

10 2 hr

11 4 hr

12 8 hr

13 24 hr

1) A rubber bung is placed over the measuring cylinder, which is then shaken

vigorously. Finally the measuring cylinder is inverted end to end and then placed in

erect position and the stop watch is started immediately.

2) The hydrometer is immersed into the cylinder, to a depth slightly below its floating

position, and then allowed to float freely. Hydrometer readings are taken after , 1, 2


Pag

e29

and 4 minutes. The hydrometer is then slowly removed from the cylinder, rinsed in

distilled water and then placed in the comparison cylinder.

3) The comparison cylinder is a 1000 ml measuring cylinder, in which 100 ml of

dispersion agent is added. The cylinder is then completely filled with distilled water

up to the 1000 ml mark and the contents are mixed. The hydrometer readings are

taken in the comparison cylinder, at regular intervals, to determine the combined

correction for the hydrometer readings.

4) Hydrometer readings in the measuring cylinder containing soil suspension are then

taken at 8, 15 and 30 minutes and then at 1, 2 and 4 hours, from the time of

commencement of the test. After 4 hours, the hydrometer readings are taken once or

twice in 24 hours. The final reading is taken at 24 hours time.

5) The hydrometer readings are taken by inserting and withdrawing the hydrometer

gradually, into the soil suspension, taking 10 sec. for each operation without

disturbing the soil suspension.

6) The observations are tabulated as shown in Table-2.

Calculations

1) The combined correction to Hydrometer Reading is obtained, from the Hydrometer

Reading in the Comparison Cylinder (C). This correction is applied to the observed

Hydrometer Reading, Rh, at different time intervals, to determine the corrected

Hydrometer Reading, Rh.

2) The Effective depth, He, corresponding to each corrected Hydrometer Reading, is

taken from the Calibration chart (Fig.)

3) The particle size (Equivalent diameter), corresponding to different time intervals, is

determined from the Effective depth (He) using the Eq.

t

H

GGD e

w )(980

30

4) The cumulative % Finer, corresponding to each time interval or Particle size, is

determined from the Eq.

h

b

RGW

GN .

)1(

100

Corrections to the Hydrometer Reading

Temperature Correction (Ct)

The hydrometer is calibrated to read density of soil suspension at 270

C. If the temperature of

soil suspension is more than 270

C, the suspension will become lighter than that at 270

C.

Hence temperature correction is

i) Positive when T > 27 0C

ii) Negative when T < 27 0C


Pag

e30

Meniscus Correction (Cm)

When the hydrometer is inserted into the soil suspension, during sedimentation analysis, a

meniscus is formed at the contact surface due to surface tension. As the soil suspension is

opaque, the hydrometer reading is taken at the top of the meniscus, above the surface of soil

suspension. As the hydrometer reading increases in downward direction, Meniscus correction

is always positive.

The Meniscus correction can be found by inserting the hydrometer in measuring cylinder,

containing distilled water, and taking the hydrometer reading at the bottom and top of the

meniscus. The difference between the two hydrometer readings gives the meniscus

correction, Cm.

Dispersing agent correction Cd

The addition of dispersing agent increases the density of soil suspension. Dispersing agent

correction is always negative.

Composite correction

The corrected hydrometer reading

Rh = Rh+ Cm Cd Ct

Or Rh = Rh C

Where C = Composite correction to hydrometer reading = Cm Cd Ct

The Composite correction to hydrometer reading can be directly found by taking hydrometer

reading in a 1000 ml comparison cylinder containing distilled water. The dispersing agent is

added to the distilled water in the same quantity as in the soil suspension. The hydrometer

reading is taken in the Comparison cylinder at the top of the meniscus. The negative of this

hydrometer reading gives the composite correction (C) to the hydrometer reading. The

hydrometer reading is taken in the Comparison Cylinder along with the hydrometer reading

in soil suspension during Sedimentation analysis to determine the corresponding combined

correction to every hydrometer reading in soil suspension.

Result

% Clay=

% Silt=

Reference

IS 2720 : Part 4 : 1985 Methods of Test for Soils - Part 4 : Grain Size Analysis


Pag

e31

Expt.8

Determination of In-situ Density by Core Cutter method

Aim

To determine the in-situ density of fine-grained natural or compacted soils free from

aggregates using a core-cutter.

Principle

A Core cutter is driven into the undisturbed soil in the site and the in-situ density is

determined by taking the weight and volume of soil along with the core cutter. The method is

suitable only for fine-grained natural or compacted soils free from aggregates

Apparatus

1) Cylindrical Core-Cutter - of seamless steel tube, 130 mm long and 10 cm internal

diameter, with a wall thickness of 3 mm, bevelled at one end. The cutter shall be kept

properly greased or oiled.

2) Steel Dolley - 2.5 cm high and 10 cm internal diameter with a wall thickness of 75

mm with a lip to enable it to be fitted on top of the core-cutter

3) Steel Rammer -With solid mild steel foot 140 mm diameter and 75 mm height with a

concentrically screwed 25 mm diameter solid mild steel staff. The overall length of

the rammer including the foot as well as the staff should be approximately 900 mm.

The rammer (foot and staff together ) should weigh approximately 9 kg.

4) Balance - Accurate to 1 g.

5) Palette Knife -A convenient size is one having a blade approximately 20 cm long and

3 cm wide.

6) Steel Rule

7) Grafting Tool or Spade or Pick Axe

8) Straight Edge - A steel strip about 30 cm long, 2.5 cm wide and 3 to 5 mm thick, with

one bevelled edge will be suitable.

9) Apparatus for Determination of Water Content

Procedure

1) The internal volume, (VC) of the core-cutter in cubic centimetres shall be calculated

from its dimensions which shall be measured to the nearest 0.25 mm.

2) The cutter shall be weighed to the nearest gram (WC ).

3) A small area, approximately 30 cm square of the soil layer to be tested shall be exposed

and levelled.

4) The steel dolly shall be placed on top of the cutter and the cutter shall be rammed down

vertically into the soil layer until only about 15 mm of the dolly protrudes above the

surface, care being taken not to rock the cutter.

5) The cutter shall then be dug out of the surrounding soil, care being taken to allow some

soil to project from the lower end of the cutter. The ends of the soil core shall then be

trimmed flat to the ends of the cutter by means of the straight edge.

6) The cutter containing the soil core shall be weighed to the nearest gram ( WS ).

7) The soil core shall be removed from the cutter and a representative sample shall be

placed in an air-tight container and its water content ( w ) determined.


Pag

e32

8) It is necessary to make a number of repeat determinations (at least three) and to average

results, since the dry density of the soil varies appreciably from point to point. The

number of determinations should be such that an additional one would not alter the

average significantly.

Remarks

1) Length of Cutter - If the average density over a smaller depth is required then the

appropriate length of cutter should be used.

2) The cutting edge should be kept sharp. The cutter should not be used in stony soils.


Natural Moisture content

S.

No.

Observation Equation Trial1 Trial2 Trial3

1 Cup No.

2 Weight of empty cup W1

3 Weight of cup+Wet soil W2

4 Weight of cup+dry soil W3

5 Water content

100

)(

)(

13

32

WW

WWw

6 Average Moisture

content 3

)( 321 wwww

In-situ density

S.

No.

Observation Equation Trial-1 Trial-2 Trial-3

1 Inside diameter of core

cutter

d

2 Inside height of core cutter

without dolly

h

3 Volume of Core cutter

4

2hdV

4 Weight of empty core cutter WC

5 Weight of core cutter plus

wet soil

WS

6 In-situ Bulk density of Soil ( )s c

c

W W

V

7 Natural moisture content of

soil

w

8 In-situ dry density of soil

)1( wd


Pag

e33

Result

In-situ Bulk density of Soil=

Natural moisture content of soil=

In-situ dry density of soil=

Reference

IS 2720- Part XXIX -1975 (Reaffirmed 1995): Methods of Test For Soils PART XXIX

determination of dry density of Soils in-place by the core-cutter method


Pag

e34

Expt.9

Determination of In-situ Density by Sand Replacement method

Aim

To determine, in-place dry density of natural or compacted fine-and medium-grained soils

Sand replacement method. The method is applicable to layers not exceeding 150 mm in

thickness

NoteWith granular materials having little or no cohesion, particularly when they are wet,

there is a danger of errors in the measurement of dry density by this method. These errors are

caused by the slumping of the sides of the excavated density hole-and always result in an

over estimation of the density.

Apparatus

1) Sand-Pouring Cylinder

2) Tools for Excavating Holes-a scraper tool to make a level surface: bent spoon, dibber.

3) Cylindrical Calibrating Container - with an internal diameter of 100 mm and an

internal depth of 150 mm fitted with a flange approximately 50 mm wide and about 5

mm thick surrounding the open end. The volume of the container should be given to

an accuracy of 0.25 percent.

4) Balance - accurate to 1 g.

5) Plane Surface : Glass or Perspex Plate or Other Plane Surface - about 450 mm square

and 9 mm thick or larger.

6) Metal Containers - to collect excavated soil. A convenient size is one about 150 mm

diameter and 200 mm deep with a removable cover.

7) Cylindrical Steel Core-Cutter - of steel, 127.4 + 0.1 mm long and 100 mm + 0.1 mm

internal diameter with a wall thickness of 3 mm bevelled at one end. The cutter shall

be kept adequately greased.

8) Metal Tray with Hole - 300 mm square and 40 mm deep with a 100 mm hole in the

centre.

Material (Sand)

Clean, uniformly graded natural sand passing the 1.0 mm IS Sieve and retained on 600-

micron IS Sieves hall be used. It shall be free from organic matter, and shall have been oven

dried and stored for a suitable period to allow its water content to reach equilibrium with

atmospheric humidity

Procedure

Calibration of Apparatus

Calibration of the Apparatus consists of determination of the Bulk density of sand.

1) The pouring cylinder shall be filled so that the level of the sand in the cylinder is

within about 10 mm of the top. Its total initial weight (W1) shall be found and shall be

maintained constant throughout the tests for which the calibration is used.

2) A volume of sand equivalent to that of the excavated hole in the soil (or equal to that

of the calibrating container) shall be allowed to run out of the cylinder under gravity.

The shutter on the pouring cylinder shall then be closed and the cylinder placed on a

plane surface, such as a glass plate.


Pag

e35

3) The shutter on the pouring cylinder shall be opened and sand allowed to run out.

When no further movement of sand takes place in the cylinder, the shutter shall be

closed and the cylinder removed carefully.

4) The sand that has filled the cone of the pouring cylinder (that is, the sand that is left

on the plane surface) shall be collected and weighed to the nearest gram.

5) These measurements shall be repeated at least three times and the mean weight taken.

6) The internal volume (V) in ml of the calibrating container shall be determined from

the weight of water contained in the container when filled to the brim. The volume

may also be calculated from the measured internal dimensions of the container.

7) The pouring cylinder shall be placed concentrically on the top of the calibrating

container after being filled to the constant weight (W1) as in step 1. The shutter on the

pouring cylinder shall be closed during this operation. The shutter shall be opened and

sand allowed to run out. When no further movement of sand takes place in the

cylinder, the shutter shall be closed. The pouring cylinder shall be removed and

weighed to the nearest gram. These measurements shall be repeated at least three

times and the mean weight taken.

Measurement of Soil Density

The following method shall be followed for the measurement of soil density.

1) A flat area, approximately 450 mm square, of the soil to be tested shall be exposed

and trimmed down to a level surface preferably with the aid of the scraper tool.

2) The metal tray with a central hole shall be laid on the prepared surface of the soil with

the hole over the portion of the soil to be tested. The hole in the soil shall then be

excavated using the hole in the tray as a pattern, to the depth of the layer to be tested

up to a maximum of 150 mm.

3) The excavated soil shall be carefully collected, leaving no loose material in the hole

and weighed to the nearest gram (Wm). The metal tray shall be removed before the

pouring cylinder is placed in position over the excavated hole.

4) The water content (w) of the excavated soil shall be determined by the method

specified in IS 2720 (Part 2) : 1973.

5) The pouring cylinder filled to the constant weight (W1) as in step 3 shall be so placed

that the base of the cylinder covers the hole concentrically. The shutter on the pouring

cylinder shall be closed during this operation. The shutter shall then be opened and

sand allowed to run out into the hole.

6) When no further movement of sand takes place the shutter shall be closed. The

cylinder shall be removed and weighed to the nearest gram (W,) (see Note).

Precautions

1) Since variations in atmospheric humidity affect the water content of the sand, and

hence its bulk density, the calibration should be made (or at least checked) during

each days work. To overcome the effects of slight variations in grading and particle

shape between batches of sand, each batch should be sampled and calibrated.

2) If for any reason it is necessary to excavate the holes to depths other than 150 mm, the

calibrating container should be replaced by one, the depth of which is the same as the

hole excavated or its effective depth should be reduced to that of the hole excavated.


Pag

e36

3) Care shall be taken in excavating the hole to see that the hole is not enlarged by

levering the dibber against the side of the hole, as this will result in lower densities

being recorded.

4) It is necessary to make a number of repeated determinations (at least three) and to

average the results, hence the dry density of the soil varies appreciably from point to

point. The number of determinations should be such that an additional one would

make no significant difference to the average.

5) Generally a storage period, after oven drying, of about 7 days is sufficient for the

water content of the sand to reach equilibrium with the atmospheric humidity. The

sand should not be stored in air-tight containers and should be thoroughly mixed

before use. If sand is salvaged from holes in compacted soils after carrying out the

test, it is advisable to sieve, dry and store this and again before it is used in further

sand replacement tests.


a) Bulk density of Sand

S.

No.


1 Inside diameter of Calibrating container d

2 Inside height of Calibrating container h

3 Volume of Calibrating container

4

2

1

hdV

4 Weight of Sand pouring cylinder plus Sand W1

5 Weight of Sand pouring cylinder plus Sand

after filling the Calibrating container

W2

6 Mean weight of sand in cone (of pouring

cylinder)

W3

8 Weight of sand in the Calibrating container Ws=W1- W2- W3

9 Bulk density of Sand

1

ssand

W

V

b) Volume of Site hole

S.

No.


1 Weight of Sand pouring cylinder plus Sand

after filling the Site hole

W6

2 Weight of Sand filling the Site hole W7 =W1 W3 W6

3 Volume of excavated soil

sand

WV

7

c) Natural Moisture content


Pag

e37

S.

No.

Observation Equation Trial1 Trial2 Trial3

1 Cup No.

2 Weight of empty cup W9

3 Weight of cup+Wet soil W10

4 Weight of cup+dry soil W11

5 Water content

10 11

11 9

( )100

( )

W Ww

W W

6 Average Moisture

content 3

)( 321 wwww

d) In-situ density

S.

No.


1 Weight of excavated soil W8

2 In-situ Bulk density of Soil

V

W8

3 Natural moisture content of soil w

4 In-situ dry density of soil

)1( wd

Result

Bulk density of Sand=

In-situ Bulk density of Soil=

Natural moisture content of soil=

In-situ dry density of soil=

Reference

IS 2720 : Part 28 : 1974 Methods of test for soils: Part 28 Determination of dry density of

soils in-place, by the sand replacement method


Pag

e38

Expt.10

Constant head permeability test

Aim

To determine the permeability of given sample of coarse grained soil by Constant head

method

Definition

The property of the soil, which permits flow of water through its voids with ease, is known as

permeability. Quantitatively, permeability is defined as the velocity of flowing water under

unit hydraulic gradient. In other words, permeability indicates the ease with which water

flows through the soil. The units of permeability are the same as that of velocity i.e., cm/s or

m/day.

Principle

Permeability of coarse grained soils having high permeability is determined in the

laboratory by constant head test. The principle of the test is to measure the volume of water

flowing through a soil specimen in a given time and determine the permeability from the

discharge using Darcys law. The constant head permeability test is suitable only for coarse

grained soils, for which significant volume of water can be collected in a reasonable time

interval.

Apparatus

Fig.1 Schematic diagram for constant head permeability test set up

Fig.1 shows the schematic diagram for constant head permeability test. The

equipment for the test, known as Permeameter, consists of a cylindrical mould, a drainage

cap with an inlet valve and an air release valve and a drainage base plate with an outlet pipe.

The mould is of 10 cm diameter and 12.73 cm internal height. The base plate has a recess at

the centre in which the bottom porous disc is placed. A filter paper is placed over the bottom

porous disc.

Test Procedure


Pag

e39

1. The soil is compacted into the Permeameter mould at the required density and water

content. Alternately, undisturbed soil sample from the soil sampler is cut into the

Permeameter mould, taking care to avoid leakage through the side walls. A filter

paper is placed over the top surface of the soil specimen and the top porous disc is

placed on the filter paper.

2. Before commencement of the test, the soil specimen should be completely saturated,

so that Darcys law is valid. To ensure complete saturation of the soil specimen, the

air in the soil specimen is removed by i) Allowing water to flow upward by attaching

the constant head reservoir to the drainage base for sufficient time and opening the air

release valve and ii) by Applying a vacuum pressure of about 70 cm of mercury

through the drainage cap for about 15 minutes after closing the drainage valve.

3. After the soil sample has been completely saturated, the constant head reservoir is

connected to the drainage cap of the Permeameter mould. Water is allowed to flow

through the soil sample for sufficient time till a steady state is established.

4. When the steady state is established, water is collected from the bottom tank in a

graduated measuring jar for a convenient time period, which is measured using a stop

watch.

5. The test is repeated several times and average of the several permeability

determinations is taken as the permeability of the soil.

Observations

S.

No.

Item Trial-1 Trial-2 Trial-3

1 Diameter of the soil sample

2 Length of the soil sample

3 Head of water causing flow

4 Volume of water collected

5 Time

6 Permeability

7 Average Permeability

8 % Error

Model Calculation

(9.7)

Where

k = coefficient of permeability of soil sample

i = hydraulic gradient h

l

h = head causing flow = difference in water levels between the constant head reservoir and in

bottom tank

l = length of flow = length of soil sample

A = Total as area of soil


Pag

e40

Result

Permeability of the given soil sample=

Type of soil sample=

Comment on the Result

Classification of soils based on permeability

Table 1 Classification of soils based on permeability*

S.

No.

Permeability

cm/s

Soil Classification

1 < 10-6

impervious

2 10-6

to 10-4

semi-pervious

3 > 10-4

pervious

*As per USBR Earth Manual

Typical range of Permeability of soils

Table 2 Typical range of Permeability of soils

S.

No.

Type of soil Permeability

cm/s

1 Clean gravels 1.0 to 10

2 Coarse and medium sand 10-3

to 1.0

3 Fine sand and loose silt 10-5

to10-3

4 Dense silt and clayey silt 10-6

to10-5

5 Silty clay and clay 10-9

to10-6

What is your comment on the result with respect to the permeability and type of soil?

How do you classify the soil based on permeability?

Reference

IS 2720 : Part 36 : 1987 Methods of test for soils: Part 36 Laboratory determination of

permeability of granular soils (constant head)


Pag

e41

Expt.11

Falling Head Permeability Test

Aim

To determine the permeability of given sample of coarse grained soil by Variable head

method

Definition

The property of the soil, which permits flow of water through its voids with ease, is known as

permeability. Quantitatively, permeability is defined as the velocity of flowing water under

unit hydraulic gradient. In other words, permeability indicates the ease with which water

flows through the soil. The units of permeability are the same as that of velocity i.e., cm/s or

m/day.

Principle

For soils of low permeability, the quantity of water collected in the graduated jar of

the constant head permeability test is very small and cannot be measured accurately. For such

soils, the variable head permeability test is used. As per Lambe (1969), the variable head

permeability test is also more convenient for cohesionless soils than the constant head test

because of simpler instrumentation.

Apparatus

The permeameter in the falling head test is the same as that used for constant head test

having 10 cm diameter, 12.73 cm height and 1000 cc capacity. A vertical graduated stand

pipe of known cross sectional area, a, is fitted to the top of the permeameter. The

permeameter mould has a drainage base with a recess for porous disc and a drainage cap with

inlet valve and air release valve, as shown in fig.1.

Fig.1 Schematic diagram for Falling head permeability test

Procedure

1. The soil sample is compacted into the permameter mould and the top porous disc is

placed on the compacted soil after placing the bottom porous disc. The porous disc

and water tubes should be deaired before placing the sample.


Pag

e42

2. Before conducting the test, removal of entrapped air and full saturation of soil sample

must be done. This is achieved by applying vacuum through the drainage cap, after

closing the drainage valve in the drainage base and air release valve in the drainage

cap. The vacuum pressure is slowly increased to 70 cm of mercury and maintained for

about 15 minutes. The soil sample is saturated by allowing de-aired water to flow

upward from the drainage base under vacuum. When the soil sample is saturated, both

the top and bottom outlets are closed.

3. The stand pipe is filled with water to the required height. After the steady state of

flow has been established, the time required for the water level in the stand pipe to fall

from a height h1 to a height h2 is noted. The head is measured with reference to water

level in the bottom tank.

4. The procedure is repeated by taking head of water in the stand pipe at different time

intervals

5. The elapsed times required for the fall of head from h1 to and from to

h2 must be compared, which should be same. If these times do not agree within 2% to

3%, the stand pipe shall be refilled with water and the test is conducted again.

Observations

1. Diameter of the soil sample (cm)=

2. Cross sectional area of the Soil specimen (cm2)=

3. Length of the soil sample (cm)=

4. Height from the outlet level of the permeameter to the zero reading of the graduation

scale of the stand pipe (cm)=

S.

No.

Elapsed

time

(s)

Height of Water

level in stand

pipe

(cm)

Head of

water

(cm)

11 iii hhh % Error in

observations

Permeability

(cm/s)

Average Permeability


Pag

e43

Model Calculations

(1)

Where

k = coefficient of permeability of soil sample

i = hydraulic gradient h

l

h1 = head corresponding to time t1

h2 = head corresponding to time t2

l = length of flow = length of soil sample

A = Total as area of soil

The coefficient of permeability is reported at .

(2)

Result

Permeability of the given soil sample=

Type of soil sample=

Maximum % error=

Minimum % error in observations=

Average % Error in observations=

Comment on the Result

Classification of soils based on permeability

Table 1 Classification of soils based on permeability*

S.

No.

Permeability

cm/s

Soil Classification

1 < 10-6

impervious

2 10-6

to 10-4

semi-pervious

3 > 10-4

pervious

*As per USBR Earth Manual

Typical range of Permeability of soils

Table 2 Typical range of Permeability of soils

S.

No.

Type of soil Permeability

cm/s

1 Clean gravels 1.0 to 10

2 Coarse and medium sand 10-3

to 1.0

3 Fine sand and loose silt 10-5

to10-3


Pag

e44

4 Dense silt and clayey silt 10-6

to10-5

5 Silty clay and clay 10-9

to10-6

What is your comment on the result with respect to the permeability and type of soil?

How do you classify the soil based on permeability?

Reference

IS 2720 : Part 17 : 1986 Methods of Test for Soils - Part 17 : Laboratory Determination of

Permeability


Pag

e45

Expt.11

I.S. Light Compaction Test

Aim

The object of the IS light compaction test is to determine the relation between water

content and dry density of compacted soil and determine the maximum dry density and

optimum moisture content from this test. The compaction energy used to compact the soil

corresponds to that of standard Proctor test

Principle

The soil is compacted using standard compaction specifications at different moisture contents

and the corresponding dry density of compacted soil is determined. The water content

corresponding to maximum dry density, known as Optimum Moisture Content (OMC) is

obtained by plotting a graph with water content on X-axis and Dry density on Y-Axis.

Equipment

The equipment for the test consists of

Compaction mould

It is a cylindrical mould of 10 cm internal diameter and 12.73 cm internal height with

a total volume of 1000.cm3. It is made of copper alloy or brass and attached to a mild steed

base plate

Rammer

The rammer consists of a 2.6 kgf weight, falling through a height of 31cm to apply

blows on the soil for compaction. It is made of mild steel or brass and the base has a diameter

of 5 cm

The compaction parameters in IS light compaction test are

W = weight of Hammer blow = 2.6 kgf

h = Height of fall = 31 cm

n = number of blows per layer = 25

l = number of layers = 3

Vm = 1000 cubic centimetre (cc)

The total compaction energy imparted on the soil per unit volume in this test is

6045325316.2 WhnlE kgf cm

The total compaction energy imparted on the soil per unit volume in this test is

045.61000

6045E kgf cm/cm

3

Soil


Pag

e46

About 6 kgf of soil passing 20 mm IS sieve is taken for the test. When sieved through

20mm IS sieve, the percent soil retained on IS sieve should not be more than 5 percent, for

accurate results. If more than 5 percent of soil is retained on 20mm IS sieve, it will lead to

errors in the result. In such cases, the soil passing 40 mm IS sieve should be used for the test.

In this case, a bigger compaction mould of 15 cm internal diameter and 12.73 cm internal

height with a total volume of 2250 cm3 is used

(a) Compaction mould with collar and base plate

(b) Compaction Rammer


Pag

e47

Fig.1 Laboratory Compaction Test Equipment

Procedure

1) Aggregations of soil particles shall be broken and the soil is mixed with a suitable

amount of water. The amount of water to be added initially for the first trial is 4 to 6

percent for sandy or gravelly soil and 8 to 10 percent below plastic limit (PL-8 or PL-

10) of the soil for cohesive soils.

2) The soil and water should be mixed thoroughly and it is required to store mixed sample

in a sealed container for about 16 hours in case of high plastic clays for uniform

distribution of moisture throughout the volume of the soil

3) The compaction mould with the base plate attached is weighed to the nearest 1 g using

a balance of capacity 10 kgf (W1)

4) The mould with base plate is placed on a solid base, such as concrete floor. About 2.5

kgf of the wet soil is taken and divided approximately in to 3 parts. One part of the wet

soil is placed in the mould and compacted by applying 25 blows with the 2.6 kgf

rammer, falling through exactly 31cm on the soil for each blow. The blows should be

uniformly distributed over the entire area of the mould

5) The second and third parts of the soil are also placed in the compaction mould

successively, each time compacting this soil with 25 blows. Before placing the third

part of soil in to the mould, the collar is attached to the top of the mould to

accommodate the entire loos soil and for applying the blows effectively.

6) The collar is now removed from the top of the mould and excess soil above top of the

mould should be trimmed off and the surface is levelled with a straight edge. The

amount of soil placed in the mould should be just sufficient so that the compacted soil

does not project more than 5 mm above top of the mould

7) The mould with base plate along with compacted soil is then weighed to the nearest

1.g (W2)

8) The compacted soil is now removed from the mould and placed in the tray. A

representative sample of soil is taken for water content determination (w1)

9) The reminder of the compacted soil specimen is broken up to individual particle level

by hand knife and by rubbing through the 20 mm IS sieve, and then mixed with the

remainder of the original sample

10) The inside surface of compaction mould collar and rammer are cleaned of soil

11) Suitable amount of water is now added to the wet soil, 1 to 2 percent for sandy or

gravelly soils and 2 to 4 percent for cohesive soil

12) The procedure in steps 2 to 11 is repeated to get at least 5 trials, so that the weights W1,

W2, W3, W4 and W5 as well as the water contents w1, w2, w3, w4 and w5 are obtained.

The range of water content covered with the trails should be such that the OMC lies

between w2 and w4

Calculations & graph

1) The bulk density and dry density is computed for each trial from the

2 1W W

V

(1)


Pag

e48

Where

= Bulk density in the first trial

W2= Weight of mould + base plate+ compacted soil

W1= Weight of empty mould + base plate

V= volume of mould

1d

w

(2)

Where

d= dry density in first trial

w= water content in the first trial

2) The values of d are computed similarly using Eq.(1) & (2) in other trials

3) A graph is plotted with water content on x-axis and dry density on y-axis. The

experimental points are joined by a smooth curve, which is known as compaction

curve.

4) The maximum dry density is read from the compaction curve and the water content

corresponding to maximum dry density is taken as optimum moisture content (OMC)

Observations

S.

No.

Description Trial-1 Trial-2 Trial-3 Trial-4 Trial-5

Determination of Bulk density

1 Diameter of the mould, d

2 Internal Height of the mould, h

3 Volume of the mould,

2

4

dV h

4 Weight of compaction mould with the

base plate (W1)

5 Weight of compaction mould and wet

soil with the base plate (W2)

6 Bulk density of the soil, 2 1

W W

V

Determination of Water Content

7 Cup No.




11 Water content, 4 5

5 3

( )100

( )

W Ww

W W

Determination of Dry density

12 Dry density of compacted soil,

1d

w


Pag

e49

Precautions

1) In case more than 5 percent of soil is retained on 20 mm IS sieve, the soil passing 40

mm IS sieve should be used. In this case, the bigger mould of 15 cm diameter, 12.73

cm height with 2250 cm3 volume is used. The soil is compacted in 3 layers using 55

blows of the 2.6 kgf rammer for each layer.

2) For soils which are susceptible to crushing, each trial of determining W and w should

be done using a fresh soil sample instead of using the compacted soil. In this case,

water added for each trial should be the sum of water added in the preceding trial and

the increment of water.

The soil is considered susceptible to crushing, if the sample contains granular material of

a soft nature such as soft lime stone, sand stone etc., which is reduced in size by the

action of the 2.6 kgf rammer.

3) The inside

GTE Lab Manual

Documents

Transcript of GTE Lab Manual