Ex No: 1 GRAIN SIZE DISTRIBUTION – SIEVE ANALYSIS METHODDate:

Aim:

To determine the distribution of coarse grain size larger than 75 microns of a soil and

to classify the given coarse grained soil.

Apparatus Required:

Mechanical sieve shaker, Set of IS Sieves, Balance accurate to 0.1g, Sieve brusher,

and Soil sample.

Formula:

(i) Percentage retained on any sieve = (Weight of soil retained/Total soil weight) x 100%

(ii) Cumulative percentage retained on any sieve = Sum of percentages retained on all coarser sieves

(iii) Percentage finer than any other sieve size = (100 - cumulative percentage retained on that sieve)

Data Representation:

The grain size distribution of a soil is presented as a curve on a semi-logarithmic plot, the

ordinate being the percentage finer than any other sieve size whereas the particle size is

represented on a logarithmic scale in abscissa.

The general slope and shape of the distribution curve can be described by

means of coefficient of uniformity (Cu ) and the coefficient of curvature (Cc) defined as

follows.

Cu = D60 / D10

Cc = D30 2

D60 X D10

The particle size such that 10% of the particles are smaller than that size is denoted by D10

Size D10 is defined as the “effective size”. Other sizes such as D30 and D60 can be defined in a

similar way.

Tabulation:

1

Weight of soil sample taken for analysis =

IS Sieve designation

in mm.

Weight of soil retained

in (g).

Percentage retained in

%

Cumulative percent

retained in %

Percent finer in %.

2

Procedure:

1) Take the 200-300g of oven dry soil as a representative sample from a bag of material.

2) Place the IS Sieve in order (i.e.) starting from 4.75mm to 75 microns at the bottom.

3) The weighed oven dried sample is placed on 4.75mm sieve. Then the sieving should

continue for at least 10 minutes in a mechanical sieve shaker.

4) The sample retained in each sieve should be weighed. The percentage retained on

each sieve is computed by dividing the weight retained on each sieve by the original

sample weight.

5) Then the percent finer is computed by starting with 100 percent and subtracting the

percent retained on each sieve as cumulative procedure.

6) The coefficient of uniformity and coefficient of curvature is calculated using the

formula.

Result:

Effective size, D10 (mm) =

Uniformity coefficient Cu =

Curvature coefficient Cc =

Gravel = %

Sand = %

Coarse sand = %

Medium sand = %

Fine sand = %

Silt and clay = %

3

4

Ex No: 2 GRAIN SIZE DISTRIBUTION – HYDROMETER

Date: ANALYSIS METHOD

Aim:

To determine the grain size distribution of the given soil sample with significant

fraction passing through 75micron sieve and its classification.

Apparatus required:

1. Hydrometer2. Thermo meter 3. Glass jar

4. Dispersing agent solution 5. Weighing balance 6. Stop watch.

Formula Used:

From Stokes Law

D = √ [30µ / 980 ( Gs-Gw)] * √ (Zr/t)

N = [100 Gs/ W s(Gs-1)] * Rc

Where,

µ = Viscosity of fluid in dyne-sec/cm2

Gs = Specific gravity of soil traction

Gw = Specific gravity of water

Zr = Height of fall, in cm

t = time of fall, in minutes

D = diameter of particles, in mm

Wd =Weight of dry soil sample taken in gms.

Rc =hydrometer reading corrected for meniscus, dispersing agent and temperature.

Corrections applied to Hydrometer test

1. Meniscus correction (Cm) =

2. Dispersing agent correction (Cd) =

3. Temperature Correction (Ct)

The hydrometer is usually calibrated to measure the specific gravity of a fluid at a particular calibration temperature, normally 20▫c. For other temperatures, a correction is required and this may be computed from

Ct = (( Gwc-Gwt)] * av (Tc))103

Gwc = Specific gravity of water at calibration temperature

Gwt = Specific gravity of temperature of test

Zr = Volume coefficient of expansion of glass

5

Tabulation:

Hydrometer No =

Weight of dry soil taken for analysis, Ws =

Specific gravity of soil solids, Gs =

Dispersing agent correction, Cd =

Meniscus correction, Cm =

Elapsed time in

min

Temp in °C

Hydrometer reading R’h

Meniscus correction Rh=R’h

+ Cm

Temperature correction

Ct

Combined correction

C=Cm+Cd+Ct

Corrected hydrometer

ReadingRc= R’h +C

ZrDiameter

D N%

½

1

2

4

8

15

30

60

120

240

480

1440

Procedure:

6

Calibration of hydrometer

Volume of hydrometer

1) Immerse the hydrometer in partially filled measuring cylinder and note down the

displacement of water, which is equal to the volume of the hydrometer in milliliters

(ml).

2) Area of the cross section of the measurement cylinder measuring the distance in cm,

between two graduation on the cylinder area of cross section then equal to the volume

included between two graduation divided by the distance between them.

3) Keep the hydrometer on the white paper. Draw its boundaries and mark the major

calibration and mark it on the paper.

4) Measure the height of the bulb from the neck to the bottom of the bulb.

5) Measure the height (H) between the neck and each major calibration mark (Rh).

6) Record the values of H Vs Rh table and calculate the effective depth of the

corresponding to each of the major calibration mark Rh.

Hc = H + (L/2) x (h – (Vh/2))

7) Draw the calibration curve Hv and Rh.

Sedimentation Test:

1) Prepare 1000ml of soil suspension as explained earlier. Mix the soil with water

completely by turning the jar upside down and place it on the table. Start the

stopwatch.

2) Remove the hydrometer from the jar and rinse it with the water and then again float it

in compression jar containing water with dispersing agent to some concentration as in

soil substance.

3) Again immerse the hydrometer in the soil suspension and the readings (Rh) after 0.5,1,

2,4,8,15,30,60,1440 minutes are recorded from the beginning of sedimentation. Take

the hydrometer out after every reading.

Result:

Thus the distribution of particle size finer than 75µ sieve is found by sedimentation

analysis using hydrometer, and then the graph is plotted between the grain size and the %

finer.

% of silt =

% of clay =

7

Ex No: 3 SPECIFIC GRAVITY OF A SOILDate:

8

Aim:

To determine the specific gravity of a soil by using Pycnometer.

Apparatus required:

1. Pycnometer

2. Soil Sample

3. Weighing Balance

4. Oven

5. 4.75mm IS sieve

Formula Used:

The specific gravity of the given soil can be calculated from the formula,

(W2 – W1) Gs(at t▫c) =

(W4 -W1) – (W3 – W2)

Where,

G - Specific gravity of the soil

W1 - Weight of empty pycnometer

W2 - Weight of pycnometer + Soil

W3 - Weight of pycnometer + Soil + Water

W4 - Weight of pycnometer + Water.

Correction To temperature:

The specific gravity of given soil at standard temperature 27◦c is computed as αGs

α =

9

where α is the ratio of the unit weight of water at the temperature t◦c of the test and at

27◦c

Tabulation:

Test No. 1 2 3

Temperature ◦ C

Weight of pycnometer (kg)

Weight of pycnometer + Soil (kg)Weight of pycnometer + Soil + Water(kg)Weight of pycnometer + Water(kg)Specific gravity of soil at t0 CSpecific gravity of soil at standard temperature 270 C

10

Procedure:

1) To clean and dry the pycnometer, wash it thoroughly with distilled water and

allow it to drain.

2) Rinse the bottle with alcohol to remove water and drain the alcohol.

3) Then rinse the bottle with ether to remove alcohol and drain the ether by turning

the bottle upside down for few minutes.

4) Find the empty weight of the pycnometer (W1).

5) Take some known quantity of oven-dried sand and transfer it carefully into the

pycnometer. Now measure the weight of the empty container with the soil sample

(W2).

6) Then pour required amount of distilled water so that it fills up to the brim. Now

again it is weighed (W3).

7) Now remove all the soil particles and wash the pycnometer and rinse it with

distilled water. Then fill the pycnometer with distilled water completely and then

it is weighed (W4).

Result:

The average specific gravity of soil sample at 27° C =

11

12

Ex no: 4 RELATIVE DENSITY OF SANDDate:

Aim:

To determine the relative density of given soil

Apparatus required:

1. Relative density apparatus

2. Mould

3. Dead load

4. Sleeve

5. Dial gauge

Formula:

Relative density Rd = X 100Where,

γf - Dry unit weight of sand in the field (Kg /cm3 )

γ 2 - Dry unit weight of sand in the densest form (Kg /cm3 )

γ1 - Dry unit weight of sand in the loosest form (Kg /cm3 )

13

Observation

Diameter of the mould (d) =

Height of the mould (h) =

Unit weight of sand in looser state:

Volume of mould (Vc =πd2h/4)

Volume of sand in mould as looser state (Vl)

Dry Weight of sand in mould (Ws)

Dry Unit weight sand at looser state (γmin)

=

Unit weight of sand in denser state:

Dry Weight of sand in mould (Ws)

Volume of sand at denser state (Vd)

Vd= , h1==reduced ht .

Dry Unit weight of sand in denser state (γmax)

14

Procedure:

1. A known weight of sample is taken. The sample is then pulverized and sieved

through the required sieve.

2. The minimum dry unit weight is found by pouring the dry soil in the mould using

poring device. The spout of the pouring device is so adjusted that the height of free

fall is always 25mm. The mass and volume of the soil deposited are found. The ratio

of Mass and volume of the soil deposit yields minimum dry weight of the soil in a

loose condition.

3. The maximum dry unit weight is also determined by dry method. In the dry method,

the mould is filled with thoroughly with mixed oven-dry soil. A surcharge is placed

on the soil surface, and the mould is fixed to the vibrator deck. The specimen is

vibrated for 8 minutes. The mass and volume of the soil in the compacted sand are

found. The ratio between maximum mass of the dry soil to the volume yields

maximum dry unit weight.

4. The unit weight of in-situ deposit is found out from three laboratory procedures such

as sand replacement method, specific gravity test and oven drying method.

Result:

The relative density of given soil sample is found to be =

15

16

Ex No: 5 ATTERBERG’S LIMITDate:

Aim:

To Classify the given fine grained soil based on its plasticity characteristics.

Apparatus Required:

Casagrande’s Liquid limit device with grooving tool, moisture cups, oven, plastic

limit plate soil mixing equipment (Porcelain dish, spatula, plastic squeeze bottle etc.) balance

and 425 µ IS sieve.

Formula used:

Plasticity index:

Ip = WL-Wp

Flow index:

If = W1 – W2 / (log10 N2 / N1)

Consistency index:

Ic = WL - WP / IP

Toughness index:

It = IP / If

Where

WL = Liquid limit

Wp = Plastic limit

W1 = moisture content corresponds to N1 drops

W2 = moisture content corresponds to N2 drops

17

Tabulation:

Liquid limitTrial No 1 2 3 4

No of blows

Tare No

Weight of tare, g

Weight of wet sample + tare, g

Weight of dry soil + tare, g

Weight of water, g

Weight of dry soil, g

Water content, percent

Tabulation:

Plastic limitTrial No 1 2 3 4

Tare No

Weight of tare, g

Weight of wet sample + tare, g

Weight of dry soil + tare, g

Weight of water, g

Weight of dry soil, g

Water content, percent

18

Procedure:

(a) Liquid limit test:

1. Adjust the cup to fall through a height of 1cm on

the base with the help of grooving tool gauge and adjustable screws.

2. Take about 120gm of soil sample and mix it thoroughly with water to form a

uniform paste. The amount of water to be added shall be such such as to require

30 to 35 drops of the cup to cause the required closure of the groove.

3. Place a portion of this paste in a cup, and smoothen the surface with spatula to

maximum depth of 1cm. Cut a groove through the sample along

the symmetrical axis of the cup in one stroke using standard grooving tool.

4. Turn the handle of the apparatus at the rate of two revolutions per second and

count the number of revolutions until the two parts of the soil come in contact at

the bottom of the groove along the distance of about 12mm. Note the number of

blows.

5. Collect a moisture sample in the pre-weighed moisture cups, being sure to take

the water content sample from the closed part of the groove. Weigh the sample.

6. Transfer the remaining soil to the cup of the main soil sample and add a

small amount of water to the soil in the dish and carefully mix to a consistency

to yield a blow count of between 25 and 30+ blows.

7. Repeat the sequence for two additional tests for blow counts of between 20 and

25 and between 15 and 20, for a total of four test determinations.

8. After weighing the moisture containers from the test transfer to oven (105 to

110◦ c) and dry over night. Weigh all the dry moisture samples and compute

water contents.

(b) Plastic limit test :

1. Take about 30gm of air-dried sample passing through 425µ sieve and mix it

thoroughly with water to make a plastic mass.

2. Take about 10gm of plastic mass, make a ball of it and roll it on the marble plate

with fingers to form a thread of 3mm diameter. If the thread does not crack it

shows that water content is more than the plastic limit. Knead the soil mass

further and roll into thread again.

19

3. Repeat the process of rolling and see to that the thread crumbles at 3mm

diameter.

20

4. Collect the pieces of crumbled soil thread in moisture container and

determine its water content by oven drying.

5. Repeat this process twice with fresh sample of 10gm each and also

determine its natural water content.

Result:

Liquid limit =

Plastic limit =

Plasticity index =

Flow index =

Consistency index =

Toughness index =

21

22

Ex No: 6 DETERMINATION OF SHRINKAGE LIMITDate:

Aim:

To determine the moisture content below which no further volume change of soil mass occurs.

Apparatus required:

Soil sample, IS 425 micron sieve, Water, shrinkage dish, porcelain dish, mercury,

mercury weighing dish, Glass plate with prongs, flat glass plate and distilled water.

Formula Used:

Shrinkage limit Ws = w – ((Vi – Vd) γW / Wd) x 100

Shrinkage ratio (SR) = (Wd / Vd) γW

Shrinkage Index (Is) = WL-Ws

Where,

Ws = Shrinkage limit in percent

w = water content of the wet soil pat

Vi = volume of wet soil pat in cm3

Vd = volume of dry soil pat in cm3

γW = Unit weight of water in gm/cm3

Wd = weight of oven dry soil pat in gm

23

Trial No 1 2 3Tare No

Weight of tare, g

Weight of wet sample + tare, gWeight of dry soil + tare, gWeight of water, g

Weight of dry soil, g

Water content, percentVolume of

container, Vi , cm3

Volume of dry soil

pat, Vd, cm3

Shrinkage limit, ws

Shrinkage ratio(SR)

.

24

Procedure:

i) Take about 40g of soil passing through 425-micron sieve and mix it thoroughly

with distilled water to make an easily workable paste. Use water content slightly

above liquid limit so that the paste can be placed in the shrinkage dish with out air

voids..

ii) Coat the inside of the shrinkage dish with a layer of Vaseline and find its weight.

iii) Place the soil sample in the dish by giving gentle tap to its on a firm surface.

iv) Strip of the excess soil with a straight edge.

v) Take the weight of the shrinkage dish filled with wet soil.

vi) Allow the wet soil pat to slightly air-dry until the surface of the pat changes to

light colour. Ovens dry the pat at 105-110◦ c to a period (12-18 hours) and weigh

the dish with pat immediately thereafter.

vii) Place the shrinkage dish in a porcelain dish and fill it with mercury so that it

slightly overflows in the large evaporating dish. Press a flat glass plate down on

the mercury surface to remove the excess mercury and make sure that no air is

entrapped.

viii) Weigh the dish with mercury. The weight of mercury divided by its unit weight

gives the volume of shrinkage dish, which is also the initial volume of the wet soil

pat. Determine the volume of dry soil pat by the same mercury displacement

method.

Results:

Shrinkage limit, Ws =

Water content, w =

Shrinkage ratio (SR) =

Shrinkage Index Is =

25

26

Ex no: 7 PROCTORS COMPACTION TESTDate:

Aim: To determine the relation between moisture content and dry density of a soils by

using proctor compaction test.

Apparatus:

1. Compaction mould with base plate and collar

2. Standard rammer

3. Sample

4. Is sieve 4.75 mm

5. Large mixing pan, scales, moisture cans

6. Measuring jar

7. Balance

Formula:

Volume of mould:

V = ((∏ d2 / 4) X h) 1000 cm3

Bulk density:

γb = (W2 - W1)/ V

Dry density:

γd = γb /(1+ w)

Zero air-voids density:

γz(av) = Gs γw / (1+(Gs w / s))

Where,

W2 - weight of mould with wet soil

W1 - weight of mould without collar

V - volume of mould

w – moisture content

Gs - specific gravity of soil

27

Observation:

Weight of soil sample taken =

Diameter of mould =

Height of mould =

Volume of mould =

Tabulation:

Description

Trials

1 2 3 4 5

Weight of mould W1 (gm)

Weight of mould + wet soil W2 (gm)

Weight of wet soil (W2- W1) gm

Bulk density of soil γb = (W2 - W1)/ V (gm/cm3)

Dry density of soil γd = γb /(1+ w) (gm/cm3)

Zero air-voids density γz(av) = Gs γw / (1+(Gs w / s))

Water content , (w)%

28

Procedure:

1. Weigh the standard proctor mould with base and without collar (W1) gm.

2. Take about 3 kg of air-dried soil passing through 4.75 mm sieve.

3. Take known quantity of water (6% by the weight of dry soil) and mix well with the

soil.

4. Attach the collar with proctor mould and fill the mixed soils in the mould in three

equal layers.

5. Compact each layer by the rammer weighing 2.6 kg allowing it to drop 25 times from

the height of 310 mm.

6. The total height of the compacted soil should be slightly more than the height of the

mould.

7. Remove the collar and cut out the projected soils to have a level surface with the top

of the mould.

8. Weigh the mould with the soil (W2) gm.

9. Remove the soil from the cylinder and break up the soil by hand. Now increase the

moisture content by 2% and mix thoroughly. Repeat the experiment.

10. In the repeating process each time raise the moisture content by 2% until there is a

considerable fall in the weight of the mould with compacted soil.

11. Take samples from each operation and calculate the moisture content and

corresponding dry density.

12. Draw the graph between dry density and moisture content. Draw the zero-air-voids

curve in the same graph.

13. Find the dry density and optimum moisture content from the graph.

Results:

1. Maximum dry density of the soil γd max =

2. Optimum moisture content =

29

30

Ex no: 8 CONSTANT HEAD PERMEABILITY TESTDate:

Aim:

To find out the coefficient of permeability of the coarse grained soil using a constant

head permeameter.

Apparatus:

1. Constant head permeameter with accessories

2. Beaker (500 ml)

3. Timer, Graduated cylinder, meter scale, thermometer

Formula:

The coefficient of permeability of the soil ( KT) = QL / Ath

The coefficient of permeability of soil

at standard temperature (K27 ) = KT * μT / μ27

Where,

K = coefficient of permeability of soil cm/sec

31

Q = total discharge in time t cm3/sec

A = area of sample perpendicular to the direction of flow of water cm2

L = length of the sample in cm

h = head causing the flow in cm

μT = viscosity of water at test temperature

μ27 = viscosity of water at standard temperature(27◦ c)

Observation:

Length of sample (L)

=

Diameter of sample (D) =

Area of sample (A) =

Total head (h) =

Temperature of water =

Tabulation:

SI.NOTOTAL HEAD

(h) cm

Volume of

water (V)

cm3

Time

(t)

sec

Discharge (V/t)

cm3/sec

KT

cm /sec

K at 270c

cm/sec

32

Procedure:

1. Weigh the permeameter mould and base plate. Take mould measurements and

compute volume of the mould, the area A and the length L of the sample.

2. Place the filter paper on the bottom porous plate. Using the given sand sample,

prepare a sample by loosely pouring several layer with varying degrees of vibration.

Place a filter paper on the top of the sand.

3. Assemble the permeameter assembly and keep it in the bottom tank.

4. Allow the water to flow into the permeameter by opening tap.

5. Unscrew the air release valve on the cap of the permeameter.

6. Then close it when air ceases and only water comes out. Now saturate the soil

specimen.

7. Open the bottom outlet valve and water allows flowing through the specimen.

8. Pour the water till it overflows in the tank.

9. When a steady state of flow has been established collect a reasonable quantity of

water (500-1000 cc) coming out of the overflow tube of the bottom tank. Record the

time required to collect this flow.

33

10. Repeat the test for two or three additional readings until two readings agrees

reasonably well. Record the temperature of the test and ensure that the discharge is

atleast 15 to 20 cm3 /minute during these tests.

RESULTS:

Coefficient of permeability of the given soil at 27oC (K27o ) =

34

Ex no: 9 VARIABLE HEAD PERMEABILITY TEST

Aim:

To find out the coefficient of permeability of the given fine grained soil using a

variable head permeameter.

Apparatus:

1. Variable head permeameter with accessories

2. Beaker (500 ml)

3. Timer, Graduated cylinder, meter scale, thermometer

Formula:

The coefficient of permeability of the soil ( KT) = 2.303 X a L / At log 10 (h1 / h2)

The coefficient of permeability of soil

at standard temperature (K27 ) = KT * μT / μ27

Where,

K= coefficient of permeability of soil cm/sec

35

A = cross sectional area of the specimen (cm2)

L = length of the specimen in cm

T1 = time in sec for the head to fall from h1 to h2

A = area of standpipe (cm2)

h1 = initial head

h2 = final head

μT = viscosity of water at test temperature

μ27 = viscosity of water at standard temperature(27◦ c)

Observation:

Length of sample (L) =

Area of sample (A) =

Area of the stand pipe (a) =

Height of stand pipe (h) =

Temperature of water =

Tabulation:

SI.

NO

INITIAL HEAD

(h1) cm

FINAL HEAD

(h2) cm

Time (t)

secLog10 (h1 / h2 )

KT

cm/sec

K at

270c

cm/sec

36

Procedure:

1. Fill the permeameter mould with either an undisturbed sample or a sample of

cohesive material disturbed and compacted to some desired density.

2. Water is filled in the standpipe up to a particular level.

3. Connect the outlet of the standpipe to the inlet of permeameter.

4. Allow the water to flow through the soil specimen for some time to make the flow

constant.

5. Now initial head level of water in the standpipe is noted and the time interval

required for the water level to fall from a known initial head to known final head as

measured above the centre of the outlet.

6. Similarly the time taken for a fall of water in between selected initial and final heads

h1 and h2. is noted and by substituting in the formula, K value at test temperature is

determined. Apply the temperature correction and report the value of K at 27◦ C.

Results:

Coefficient of permeability of the given soil at 27oC (K27 ) =

37

38

Ex No: 10 DIRECT SHEAR TESTDate:

Aim:

To determine the shear strength of soils with a maximum particle size of 4.75mm, by

direct shear test.

Apparatus required:

1. Shear box assembly

2. Balance

3. Proving ring

4. Dial guage

5. Weights

Formula:

Normal stress:

σ = Pv/A

Shear stress:

τ = Ph/A

Angle of internal friction:

39

Φ = tan-1 (τ / σ)

Where

Pv = Normal load

Ph = Shear load

A= Initial area of the sample

Observation:

Calibration factor for proving ring, 1 div =

Area of sample =

Volume of sample =

Weight of sample =

Tabulation:

Sl. No. Proving ringreading Shear

force, Ph kgApplied load kg

Normal force(Pv)

Normal stress(Kg/cm2)

Shear stress (Kg/cm2)

Initial Final

40

Procedure:

1. Put the shear box assembly using the pin.

2. Place the bottom grid plate in position so that, the groove in the grid plate

should be perpendicular to the direction of shear.

3. For the given density calculate the weight of soil sample required.

4. Place the calculated weight of soil sample in layers; damp each layer to the

required density.

5. Place the top grid plate and loading pad on top of the soil sample.

6. Place the normal load frame on the loading pan.

7. Set the proving ring to read zero.

8. Apply the required normal load.

9. Remove the pins from shear box assembly.

10. Turn the separating screw to have a gap of 1mm between the two halves.

11. Rotate the hand wheel to apply the shear load.

12. Record the maximum deflection in the proving ring, which gives the maximum

shear stress.

13. Release the shear load, the normal load and then shear box is removed.

41

14. Repeat the test with a fresh sample of soil for other normal load. A minimum of

three(preferably four) tests should be conducted on separate samples placed at

the same density.

15. Draw graph between the normal stress (x-axis) and the corresponding shear

stress at failure (y-axis).

16. Find the shear parameter φ from the graph.

Result:

The ultimate friction angle from graph (Φ) =

Cohesion (C) =

42

Ex no: 11 DETERMINATION OF UNCONFINED COMPRESSIVE STRENGTHDate:

Aim:

To determine an approximate and quick procedure for evaluating the shear strength of

cohesive soil .

Apparatus:

1. Unconfined compression testing machine

2. Specimen trimmer

3. Oven

4. Balance

5. Dial gauge

6. Sampling tube

7. Sample ejector

8. Vernier Caliper

Formula:

Unconfined compression strength:

qu = P/Ae

Ae = (Ao/1-£)

43

£ = ∆L/Lo

c = qu/2

Where,

P = Axial load at failure

Ae = corrected area,

Ao = initial area of the specimen

Lo = initial area of the specimen

∆L = change in length of the specimen

Observation and Tabulation:

Rate of strain =

Initial diameter of sample, do, cm =

Initial length of sample, Lo, cm =

Initial area of cross section, Ao , cm2 =

Least count of strain dial, 1 div =

Calibration factor for proving ring, =

1 div =

Initial weight of the sample =

Oven dry weight of the sample =

Water content of the sample =

Tabulation:

Sl.

No.

Strain

dial

reading

Axial

deformation

∆l, mm

Axial

strain

£

Corrected

area of cs, a

cm2

Proving ring

dial reading

Axial

load

p, kg

Axial

stress

σ1 = p/a

kg/cm2

44

Procedure:

1. Prepare undisturbed cylindrical specimens (38mm diameter, 76mm length) from

large undisturbed field samples by using a trimmer, or directly obtain field samples

in thin sampling tubes of the same diameters as that of specimen.

2. Measure the dimensions of the specimen. Weigh the specimen and keep

epresentative samples for water content determination.

3. Place the specimen on the bottom plate of the loading device and adjust the upper

plate to make contact with the specimen.

4. Adjust the deformation and proving ring dial to zero and apply the axial load with a

strain rate of .5 to 2% per minute.

5. Record force and deformation readings at suitable intervals, with closer spacing

during initial stages of the test.

6. Apply the load till the failure surfaces have definitely developed or until an axial

strain of 15-20% is reached.

7. Carefully sketch the failure pattern and if the specimen has failed with a

pronounced failure plane, measure the angle of the failure surface with the

horizontal.

45

8. Weigh the sample after oven drying to constant weight at 110◦ c and find its

moisture content.

Result:

Unconfined compression strength for the soil sample qu =

Cohesion c =

Angle of friction φ =

46

Ex no: 12 TRIAXIAL COMPRESSION TESTDate :

Aim:

To determine the shear strength of the given soil sample by triaxial compression test.

Apparatus:

1. Triaxial compression testing

machine

2. Triaxial cell

3. Rubber membrane

4. Membrane stretcher

5. Specimen trimmer

6. Pore pressure apparatus

7. Volume measuring device

8. Dial gauge

9. Spilt mould

10. Knife

Formula:

Axial strain:

£ = ∆L/Lo

corrected area:

47

Ae = here (Ao/1-£)

Deviator load:

P = Proving ring reading X calibration factor

Deviator Stress:

σd = P/A kg/cm2

Where

P = Axial load at failure

Ao = initial area of the specimen

Obtain a plot of deviator stress σd versus axial strain £ and scale off the peak, value of

the σd or σd corresponding to 20% axial strain £ if it occurs earlier. With this deviator stress

obtain the value of major principle stress

σ1 = σ3 + σd

Plot, Mohr’s circle for three or more number of tests and fit a tangent to these circles

passing through the origin and obtain the slope of the tangent as the angle of internal friction

of the sand sample tested.

Compute the tangent modulus and the secant modulus using the slope of the stress

strain curve and report the observed values.

Observation and Tabulation:

Rate of strain =

Initial diameter of sample, do, cm =

Initial length of sample, Lo, cm =

Initial area of cross section, Ao , cm2 =

Least count of strain dial, 1 div =

Calibration factor for proving ring, =

1 div =

Cell pressure σd , kg/cm2 =

Tabulation:

Sl.

No.

Deformation

dial

reading

Axial

deformation

∆l, mm

Axial

strain,

£ = ∆l/lo

Corrected

area of cs, A =

(Ao/1-£) cm2

Proving

ring dial

reading

Deviator

load P, kg

Deviator

stress

σd = P/A

kg/cm2

48

Procedure:

1. Prepare undisturbed cylindrical specimens (38mm diameter, 76mm length) from large

undisturbed field samples by using a trimmer, or directly obtain field samples in thin

sampling tubes of the same diameters as that of the specimen.

2. Measure the dimensions of the specimen. Weigh the specimen and keep

representative samples for water content determination.

3. Place a solid Perspex platen over the specimen, which in turn is placed over another

Perspex platen. Place the loading cap on the top platen.

4. Insert a rubber membrane by using a membrane stretcher and fix two ‘o’ rings one at

the bottom and the other on the top of the platen or loading cap.

5. Close the drainage valve, fill the cell with water, and apply the pre-determined

chamber pressure.

6. Place the specimen on the bottom plate of the loading device and adjust the upper

plate to make contact with the specimen.

7. Adjust the deformation and proving ring dial to zero and apply the axial load with a

strain rate of 0.05 to 1cm per minute.

49

8. Record force and deformation readings at suitable intervals, with closer spacing

during initial stages of the test.

9. Apply the load till the failure surfaces have definitely developed or until an axial

strain of 20% is reached.

10. Unload the specimen and drain off the cell fluid. Dismantle the cell and carefully

remove the membrane and note down the mode of failure.

11. Weigh the specimen and take water content representative samples from the failure

zone of the specimen.

12. Repeat the test on three or more identical specimens under increased cell pressures.

Result:

Angle of internal friction φ =

Initial tangent modulus =

Secant tangent modulus =

50

Ex no: 13 ONE DIMENSIONAL CONSOLIDATION TEST Date:

Aim:

To obtain the time compression relationship of given saturated fine grained soil and the

coefficient of consolidation for one load increment.

Apparatus:

1) One dimensional consolidation unit with fixed ring container and deflection dial

2) Stop clock

3) Oven

4) Balance

5) Evaporating dishes

6) Scale

7) Loading weights

8) Knife for trimming/wire saw

Formula:

51

The results of time compression relationship can be presented either in a square root of time

or log plot and coefficient of consolidation can be evaluated for the given load increment

through appropriate fitting methods.

Square root time fitting method (D.W. Taylor):

Cv = 0.848 H2 / t90 cm2 /s

Log fitting method (Casagrande):

Cv = 0.197 H2 / t50 cm2 /s

Where,

H = one half of the average thickness during the load increment in cm

t90 , t50 = corresponding time t obtained from √t or log t plots in s.

Observation and calculation:

Diameter of sample, D (cm) =

Height of sample, 2H (cm) =

Least count of compression dial 1 div =

Temperature =

Pressure increment, from kg/cm2 = to kg/cm2

Weight of the fixed ring sample container, W1 = g

Weight of sample + fixed ring sample container, W2 = g

Tabulation:

Elapsed time t

minutes

√t log t Compression dial reading Compression in

mm

0

0.25

1.00

2.5

52

4.00

6.25

9.00

12.25

16

20.25

25

49.00

64.00

81.00

144.00

480.00

900.00

Procedure:

1) Measure the inside diameter D (cm) and height 2H (cm) of the fixed ring sample

container and lubricate the inside surface with thin film of soil and find the weight W1

(g).

2) Carefully feed the soil sample into the fixed ring sample container with the help of

sample ejector. Trim the ends of the sample with least disturbance to soil structure.

3) From the left over of the trimmed soil sample obtain two-sample specimen and after

weighing put them in the oven for water content determination.

4) Find the weight of soil sample and the fixed ring container, W2 (g).

5) Place the bottom porous stone after soaking in water on the base of the odometer unit

and give connection to water level and gradually raise the water level above the

porous stone.

6) Place the sample container on the porous stone. Put the second porous stone, which

has been well soaked in water and a loading block on the soil sample.

7) Feed the rubber washer and place the outside ring and tighten the whole system with a

given set of screws.

53

8) Mount the odometer assembly in the consolidation load frame immerse the sample

completely in water.

9) Adjust the loading platform till the loading yoke touches the loading block, apply a

seating load of 0.05 kg/cm2 and allow the sample to reach equilibrium condition note

the initial dial reading.

10) After a lapse of 24 hours note the dial reading d2, and apply the first load increment,

usually o.5 kg/cm2 and simultaneously take deformation readings at elapsed times of

0, 0.25, 1, 2.25, 4, 6.25, 9, 12.25, 15, 20.25, 25, 36, 49 minutes etc., until about 90 to

95¼ , consolidation is reached.

11) At the end of 24 hrs take the final reading and increase the load intensity with the next

desired load increment.

12) The test will be continued under load intensities of 1,2,4,8 and 16 Kg/cm2 to get a

complete picture of load intensity versus compression and compression versus time

relationship at different load intensities. At the end of the test the sample container

will be dismantled and final weight of container and the sample will be noted. Then

the sample will be oven dried for final water content determination.

Moisture content determination

Tare No

Weight of tare, g

Weight of wet sample + tare, g

Weight of dry soil + tare, g

Weight of water, g

Weight of dry soil, g

Water content, percent

54

Results:

The Coefficient of consolidation of the given soil sample for the specified pressure

increment

By square root time fitting method =

By Logarithmic fitting method =

55

56

Ex no: 14 FIELD DENSITY TEST – CORE CUTTER METHODDate:

Aim:

To determine the dry density of natural or compacted fine grained soils by core cutter

method.

Apparatus:

1. Cylindrical core cutter, 100mm internal diameter and 130mm long;

2. Steel dolly,25 mm high and 100mm internal diameter

3. Oven

4. Weighing Balance accuracy 1g;

5. Evaporating dishes

6. Straight edge and steel rule

7. Steel rammer , mass 9 Kg, overall length, with the foot and staff about 900mm

57

Observation and calculation:

Diameter of core cutter =

Height of core cutter =

Tabulation:

Sl.

No.Description

1 Weight of core cutter (Wc) in g

2 Volume of core cutter (Vc) in cm3

3 Weight of core cutter and wet soil (Ws) in g

4 Weight of wet soil (Ws -Wc) in g

5 Bulk density γb = (Ws -Wc) / Vc g / cm3

58

6 Weight of container (W1) in g

7 Weight of container & wet soil (W2) in g

8 Weight of container & dry soil (W3) in g

9Water content (w) in %

W = ((W2 - W3 )/ (W3 – W1 )) x 100

10 Dry density of insitu soil γd = γb / (1+w) g/cc

11 Void ratio [(G γw ) / γd ] - 1

12 Degree of saturation WG / e

Procedure:

1. Measure the dimension of the core cutter. Note down its internal diameter and height.

2. Weigh (Wc) the empty cutter. Apply grease from inside of the cutter.

3. Clear a small area (about 300mm x 300mm) at ground where field density is to be

determined and level it.

4. Place the cutter with beveled edge on the ground. Place the dolly on it.

5. Apply pressure manually so that the cutter gets embedded in soil.

6. Further push the cutter vertically by rammer until only about 15mm of the dolly

protrudes above the surface.

7. Remove the soil surrounding the cutter with a knife and take out the core cutter.

8. Remove the dolly. Trim the top and bottom surfaces of the core cutter carefully using

a straight edge.

9. Weigh the cutter with the soil (Ws)

59

10. Extract the soil from the cutter. Take a representative sample and determine its water

content.

Result:

i. Field Density of Soil, g/cc =

ii. Water Content % =

iii. Dry Density of soil, g/cc =

iv. Void ratio =

v. Degree of saturation =

60

Ex no: 15 FIELD DENSITY TEST – SAND REPLACEMENT METHOD Date:

Aim:

To determine the field density of natural or compacted fine and medium grained soils by sand

replacement method.

Apparatus:

1. Sand pouring cylinder

2. Calibrating container

3. Metal tray with hole

4. Balance

5. Evaporating dishes

6. Tools of excavating hole

7. Scale

Formula:

Weight of the sand required to fill the calibrating container:

Wa = (W1 –W3) – (W1 – W2)

The Calibrated bulk density of sand:

61

γs = Wa / V

The Weight of the sand required to fill the excavated hole:

Wh = (W1 – W4)-(W1 – W2)

The Bulk density of the wet soil:

γb= (Ws/ Vs) γs

The dry density of the soil:

γd = γb / (1+w) Where

W1 =Weight of sand pouring cylinder with sand, g

W2 =Weight of sand pouring cylinder with sand after pouring into calibrating cylinder, g

W3 = Weight of sand pouring cylinder with sand with remaining sand after filling the

cone and calibrating container, g

Wa =Weight of sand in the calibrating cylinder

Ws =Weight of excavated soil, g

W4 =Weight of sand pouring cylinder with sand after filling the hole, g

Vs =Volume of hole

Observation and calculation:

Height of calibrating cylinder, cm =

Internal diameter of calibrating cylinder, cm =

Tabulation:

1 A.CALIBRATION OF APPARATUS

Weight of sand pouring cylinder with sand W1, g

2 Weight of sand pouring cylinder with sand after pouring into calibrating cylinder

W2, g

3 Weight of sand pouring cylinder with sand with remaining sand after filling the

cone and calibrating container, W3, g

62

5 Weight of sand in the calibrating cylinder Wa = (W1 –W3) – (W1 – W2)

6 Volume of calibrating container, V cm3

7 Calibrated bulk density of sand γb = Wa / V, g/cm3

B.Measurement of in-situ soil density

Weight of excavated soil, Ws g

9 Weight of sand pouring cylinder with sand after filling the hole, W4 g

10 Weight of sand in the hole

Wh = (W1 – W4)-(W1 – W2), g

11 Volume of hole Vs = Wh / γb cm3

12 Bulk density of in-situ soil γb= Ws/ Vs g/cc

Determination of water content

13 Weight of container (w1) =

14 Weight of container + wet soil (w2) =

15 Weight of container + dry soil (w3) =

16 Water content of insitu soil w% = w2 – w3 / w3 – w1

17 Dry density of insitu soil γd = γb / (1+w) g/cc18 Void ratio [(G γw ) / γd ] - 1

19 Degree of saturation = wG / e

Procedure:

a) Calibration of apparatus

1. Determine the internal volume (V) of calibrating container by filling it with water up

to the brim or by measurement.

2. Take about 5kg of standard sand if available or use clean sand passing 600 microns

sieve and retained in 300-micron sieve.

3. The sand-pouring cylinder shall be filled so that the level of the sand in the cylinder is

with in about 10mm of the top and weight in W1 (g).

4. Place the sand-pouring cylinder on a plane surface such as glass plate. Open the

shutter and allow the sand to run out and fill bottom lying cone.

63

5. When no further movement of sand takes place in the cylinder carefully and notes the

weight of sand pouring cylinder with remaining sand. Repeat these measurements at

least three times and record the mean weight W2 (g).

6. Place the sand pouring cylinder filled with sand to weight W1, concentrically on the

top of the calibrating container, open the shutter and allow the sand the run out.

7. When no further movement of sand takes place, close the shutter. The pouring

cylinder is removed and weighs it. Repeat these measurement atleast three times and

record the mean weight W3 (g).

b) Measurement of field density

1. A flat area, approximately 45 cm square of the soil to be tested shall be exposed and

trimmed to a level surface with a scraper.

2. The metal tray with a central hole shall be laid on the prepared surface with the hole

in the soil shall then be excavated using the hole in the tray as a pattern upto 15cm

deep. No loose material shall left in the hole.

3. The excavated soil shall be carefully collected and weigh it Ws (g).

4. A representative sample of the excavated soil shall be weighed and oven-dried to find

the percentage of moisture content, W of the in-site soil.

5. The sand-pouring cylinder filled with sand to constant weight W1, is placed

concentrically over the hole.

6. The shutter is opened and sand allowed to run out. When no further movement of

sand takes place, close the shutter, remove the cylinder and weigh it W4 (g).

64

Result:

i. Field Density of Soil, γb = g/cm3

ii. Water Content of insitu soil = %

iii. Dry Density of soil, γd = g/cm3

iv. Void ratio =

v. Degree of saturation =

65

66