Lab Manual for Soil Testing

JSPM-NTC, DEPARTMENT OF CIVIL ENGINEERING Laboratory Manual for Geotechnical Engineering (201003) SE Civil-2012 Course

Table of Content Sr. No.

Title

Date

Page No.

Sign

Remark

JSPM-NTC, DEPARTMENT OF CIVIL ENGINEERING Laboratory Manual for Geotechnical Engineering (201003) (201003) SE Civil-2012 Course

Experiment No. ___

Date:

Name of Experiment: Determination of Specific Gravity of Fine Grained Soils

Aim:To determine the specific gravity of fine-grained soil by density bottle method as per IS: 2720 (Part III/Sec 1) - 1980.

Scope:This experiment lays down the methods of test for the determination of the, specific gravity of soil particle of fine grained soils. The method may also be used for medium and coarse grained soils if the coarse particles are grained to pass 4.75 mm sieve before using.

Principle:Specific gravity is the ratio of the weight in air of a given volume of a material at a standard temperature to the weight in air of an equal volume of distilled water at the same stated temperature.

Apparatus: a.

Two density bottles of approximately 50ml capacity alongwith stoppers, 0

b. Constant temperature water bath (27 +0.2 C), c.

0

Oven, capable of maintaining a temperature of 105 to 110 C,

d. Weighing balance, with an accuracy of 0.001g, e. Wash Bottle f.

Spatula

Sample Preparation: The soil sample (50g) should, if necessary, be ground to pass through a 2 mm IS Sieve. A 0

5 to 10g sub-sample should be obtained by riffling and oven-dried at a temperature of 105 to 11 0 C. Page 1 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of Specific Gravity of Fine Grained Soils

Aim:To determine the specific gravity of fine-grained soil by density bottle method as per IS: 2720 (Part III/Sec 1) - 1980.

Scope:This experiment lays down the methods of test for the determination of the, specific gravity of soil particle of fine grained soils. The method may also be used for medium and coarse grained soils if the coarse particles are grained to pass 4.75 mm sieve before using.

Principle:Specific gravity is the ratio of the weight in air of a given volume of a material at a standard temperature to the weight in air of an equal volume of distilled water at the same stated temperature.

Apparatus: a.

Two density bottles of approximately 50ml capacity alongwith stoppers, 0

b. Constant temperature water bath (27 +0.2 C), c.

0


d. Weighing balance, with an accuracy of 0.001g, e. Wash Bottle f.

Spatula

Sample Preparation: The soil sample (50g) should, if necessary, be ground to pass through a 2 mm IS Sieve. A 0

5 to 10g sub-sample should be obtained by riffling and oven-dried at a temperature of 105 to 11 0 C. Page 1 of 59


Procedure: 0

a.

The density bottle along with the stopper, should be dried at a temperature of 105 to 110 C, cooled and weighed to the nearest 0.001g (m 1).

b. The sub-sample, which had been oven-dried, should be transferred to the density bottle directly. The bottles and contents together with the stopper should be weighed to the nearest 0.001g (m 2). c.

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

d. Entrapped air can be removed by heating the density bottle on a water bath until there is no further loss of air. e. Gently stir the soil in the density bottle and see that no soil particles are lost. f.

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

g.

Observe the constant temperature in the bottle and record.

h. Insert the stopper in the density bottle, wipe and weigh (m 3). i.

Now empty the bottle, clean thoroughly and fill the density bottle with distilled water at the same temperature. Insert the stopper in the bottle, wipe dry from the outside and weigh (m 4).

j.

Take at least two such observations o bservations for the same soil sample.

Observations and Calculations:

Sr. No.

Description

1.

Weight of density bottle (m 1) (gm)

2.

Weight of bottle and dry soil (m 2) (gm)

3.

Weight of bottle, dry soil and Water (m 3) (gm)

4.

Weight of bottle and Water (m 4) (gm)

Sample – 1 Sample –

Sample – Sample – 2

Sample – Sample – 3 3

5. 6.

Average Specific Gravity

Page 2 of 59


Reporting of Result: a. The average of the values obtained shall be taken as the specific gravity of the soil particles and shall be reported to the nearest 0.01. If the two results differ by more than 0.03 the teats shall be repeated. 0

b. The specific gravity should be calculated at a temperature of 27 C. If the room temperature is different 0

from 27 C, the following correction should be done:G' = k * G Where, 0

G' = Corrected specific gravity at 27 C,

Specific gravity of the given soil sample at a temperature of 270C =

Relative density of water at various temperatures, as given below, can be used in the above calculation:

Result: Specific Gravity of given Soil sample is ……..

Page 3 of 59


Experiment No. ___

Date:

Name of Experiment:Sieve analysis, particle size determination and IS classification as per ISCodes.

Aim:To determine the quantitative determination of grain size distribution in soils by sieve analysis as per IS: 2720 (Part 4) - 1985.

Scope:Thisexperiment lays down the methods of test for the determination of thegrain size distribution in soil passing 4.75mm IS sieve and retained on 75-micron IS sieve. Two methods are given for finding the distribution of grain sizes larger than 75-micron IS Sieve; the first method, wet sieving shall be applicable to all soils and the second, dry sieving, shall be applicable only to soils which do not have an appreciable amount of clay. Current experiment details the dry sieving method.

Apparatus: a.

A set of IS Sieves of sizes - 20mm, 10mm, 4.75mm, 2mm, 600μm, 425μm, 212μm and 75μm

b. Weighing balance, with an accuracy of 0.001 gm. c.

Hot air oven

d. Mechanical sieve shaker LID

4.75 mm

2.36 mm

2.00 mm

1.70 mm

600

425

300

150

75

PAN

SIEVE SHAKER

Principle:This method covers the quantitative determination of particle size distribution in an essentially cohesionless soil, down to fine sand size. The combined silt clay can be obtained by difference. If the soil Page 4 of 59


does not contain particles retained on a 2 mm test sieve in significant quantity, thehydrometer method shall be used.

Sample Preparation: a.

Soil sample, as received from the field, should be dried in air or in the sun. In wet weather, oven may 0

be used in which case the temperature of the sample should not exceed 60 C. The clod may be broken with wooden mallet to hasten drying. Tree roots and pieces of bark should be removed from the sample. b. The big clods may be broken with the help of wooden mallet. Care should be taken not to break the individual soil particles. c.

A representative soil sample of required quantity as given below is taken and dried in the oven at 0

105 to 120 C.

Maximum size of material present in substantial quantities (mm) 75

Weight to be taken for test (kg) 60

40

25

25

13

19

6.5

12.5

3.5

10

1.5

6.5

0.75

4.75

0.4

Procedure: a.

The soil fractions retained on and passing 4.75-mm IS Sieve shall be taken separately for the analysis.

b. The portion of the soil sample retained on 4.75-mm IS Sieve shall be weighed and the mass shall be recorded. c.

The sample shall be separated into various fractions by sieving through the Indian Standard Sieves as specified in the figure.

d. While sieving through each sieve, the sieve shall be agitated so that the sample rolls in irregular motion over the sieve. Any particles may be tested to see if they will fall through but they shall not be pushed through. e. Soil retained on each sieve is weighed.

Page 5 of 59


Observations: After completing mechanical analysis, all the observations shall be recorded in the tabular as given below to calculate percentage smaller than the specified diameter.

Weight of total Soil sample taken for analysis: …………… gm Sieve Size(A)

Weight Retained(B)

Cumulative Weight(C)

(mm)

(gm)

(gm)

Sr. No.

1.

4.75

2.

2.36

3.

2.00

4.

1.70

5.

0.600

6.

0.425

7.

0.300

8.

0.150

9.

0.075

% Weight retained(D)

% Weight passing(100D)

Reporting of Result: A grain size distribution curve shall be drawn on a semi-logarithmic chart, plotting particle size (sieve diameter) on the log scale (X-axis) against percentage finer than the corresponding size (% weight passing) on the ordinary scale (Y-axis).

IS Classification of the soilsample: Based on the grain size distribution curve plotted on a semi-logarithmic chart, calculate following: D10 = 10 percent finer than size = ………… D30 = 30 percent finer than size = ………… D60 = 60 percent finer than size = …………

C u =

C c =

Page 6 of 59


As per IS 1498, following procedure shall be adopted for classification of given sample based on grain size distribution curve:

If more than 50% sample retained on 2.36mmIS sieve: If 5% and less is passing through 75µ sieve If Cu>=4 AND Cc<=3 Then soil can be classified as ‘GW’ If Cu<7 OR Cc>3 Then soil can be classified as ‘GP’ If 5% to 12%is passing through 75µ sieve Then use dual symbols If 12% and more is passing through 75µ sieve Then Conduct Limit tests and then classify

If more than 50% sample passing through 2.36mm sieve: If 5% and less is passing through 75µ sieve If Cu>=6 AND Cc<=3 Then soil can be classified as ‘SW’ If Cu<6 OR Cc>3 Then soil can be classified as ‘SP’ If 5% to 12% is passing through 75µ sieve Then use dual symbols If 12% and more is passing through 75µ sieve Then Conduct Limit tests and then classify

Result:IS Classification of given Soil sample is ……..

Page 7 of 59


Experiment No. ___

Date:

Name of Experiment:Determination of Consistency limits and their use in soil classification as per IS Codes

Aim: To determine the Consistency limits of fine grained soils as per IS: 2720 (Part 5 ) - 1985.

Scope: Thisexperiment lays down the methods of test for the determination of Consistency limits of fine grained cohesive soil.

Theory and Principle: The consistency of a fine grained soil is the physical state in which it exists. It is used to denote the degree of firmness of a soil. Consistency of a soil is indicated by terms as soft, firm or hard. In 1911, Atterberg, a Swedish engineer, mentioned that a fine grained soil can exist in four states, viz. liquid, plastic, semi-solid or solid state. The water contents at which the soil changes from one state to the other are known as ‘Consistency limits’ or ‘Atterberg’s Limits’.

Soil consistency provides a means of describing the degree and kind of cohesion and adhesion between the soil particles as related to the resistance of the soil to deform. Variations in the moisture content in a soil may have significant effect on its shear strength, especially on fine-grained soils.

Page 8 of 59


A.

Liquid Limit:

A soil containing high water content is in a liquid state. It offers no shearing resistance and can flow like liquids. It has no resistance to shear deformation and, therefore, the shear strength is equal to zero. As the water content is reduced, the soil becomes stiffer and starts developing resistance to shear deformation. At some particular water content, the soil becomes plastic. The water content at which the soil changes from liquid state to plastic state is known as ‘Liquid Limit’. In other words, the liquid limit is the water content at which the soil ceases to be liquid.

Apparatus: a.

Casagrande’s liquid limit device

b.

Grooving tools of both standard and ASTM types

c.

Hot air Oven

d.

Spatula

e.

IS Sieve of size 425μm

f.

Weighing balance, with 0.01g accuracy

g.

Air-tight and non-corrodible container for determination of moisture content

Casagrande Grooving Tool

ASTM Grooving Tool

Page 9 of 59



Air-dry the soil sample and break the clods. Remove the organic matter like tree roots, pieces of bark, etc.

b. About 100g of the specimen passing through 425μm IS Sieve is mixed thoroughly with distilled water in the evaporating dish and left for 24hrs for soaking.

Procedure: a.

Place a portion of the paste in the cup of the liquid limit device.

b. Level the mix so as to have a maximum depth of 1cm. c.

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

d. For normal fine grained soil: The Casagrande's tool is used to cut a groove 2mm wide at the bottom, 11mm wide at the top and 8mm deep. e. For sandy soil: The ASTM tool is used to cut a groove 2mm wide at the bottom, 13.6mm wide at the top and 10mm deep. f.

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

g.

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

h. The soil of the cup is transferred to the soil paste and mixed thoroughly after adding a little more water. Repeat the test. i.

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

j.

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

k.

Water content corresponding to 25 blows, is the value of the liquid limit. Page 10 of 59


Observations: Sample No.

Sr. No.

Descriptions 1

2

3

4

5

Observations 1.

No. of Blows (N)

2.

Water Content Dish No.

3.

Mass of empty dish (m 1) (gm)

4.

Mass of empty dish + wet soil (m 2) (gm)

5.

Mass of empty dish + dry soil (m 3) (gm)

Calculations 6.

Mass of water = (m 2 – m3)

7.

Mass of dry soil = (m 3 – m1)

8.

Water Content,

Draw a flow curve on a semi-log paper between log (N) on X-axis and water content on Y-axis.

Result:Liquid Limit (for N=25) of given Soil sample is ……..%.

Page 11 of 59


B.

Plastic Limit:

The plastic limit of fine-grained soil is the water content of the soil below which it ceases to be plastic. It begins to crumble when rolled into threads of 3mm diameter.

Apparatus: a.

Spatula

b. Container to determine moisture content c.

Balance, with an accuracy of 0.01g

d. Hot air Oven e. Ground glass plate - 20cm x 15cm f.

Rod - 3mm dia. and about 10cm long

Sample preparation: Take out 30g of air-dried soil from a thoroughly mixed sample of the soil passing through 425μm IS Sieve. Mix the soil with distilled water in an evaporating dish and leave the soil mass for nurturing. This period may be up to 24hrs.

Procedure: a.

Take about 8gm of the soil and roll it with fingers on a glass plate. The rate of rolling should be between 80 to 90 strokes per minute to form a 3mm dia.

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

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

Page 12 of 59


d. Collect and keep the pieces of crumbled soil thread in the container used to determine the moisture content. e. Repeat the process at least twice more with fresh samples of plastic soil each time.


Sr. No.

Descriptions 1

2

3

4

5

Observations 1.

Water Content Dish No.

2.

Mass of empty dish (m 1) (gm)

3.

Mass of empty dish + wet soil (m 2) (gm)

4.

Mass of empty dish + dry soil (m 3) (gm)

Calculations 5.

Mass of water = (m 2 – m3)

6.

Mass of dry soil = (m 3 – m1)

7.

Water Content,

8.

Average % water content

Result: Plastic Limit of given Soil sample is ……..%.

Plasticity Index = (Liquid Limit) – (Plastic Limit)

Plasticity Index (PI) = ………. %

IS Classification: The fine-grained soils shall be further divided into three subdivisions on the basis of the following arbitrarily selected values of liquid limit:

Page 13 of 59


a.

Silts and clays of low compressibility — having a liquid limit less than 35,

b. Silts and clays of medium compressibility — having a liquid limit greater than 35 and less than 50, c.

Silts and clays of high compressibility — having a liquid limit greater than 50.

The laboratoryclassification criteria for classifying the fine-grained soils are given in the plasticity chart as given below:

Result: IS Classification of given Soil sample is ……..

Page 14 of 59


C.

Shrinkage Limit:

Shrinkage due to drying is significant in clays, but less significant in silts and sands. If the drying process is prolonged after the plastic limit has been reached, the soil will continue to decrease in volume, which is also relevant to the converse condition of expansion due to wetting. The Linear Shrinkage value is a way of quantifying the amount of shrinkage likely to be experienced by clayey material. Such a value is also relevant to the converse condition of expansion due to wetting.Linear Shrinkage method covers the determination of the total linear shrinkage from linear measurements on a soil sample passing a 425

m test sieve, originally

having the moisture content of the Liquid Limit.

Apparatus: a.

Spatula,

b. Shrinkage dish, c.

Straight edge, glass cup,

d. Prong plate, e. Plain plate, f.

Measuring cylinder,

g.

Hot air Oven

h. 425-micron IS Sieves. i.

Balances — sensitive to 0.1 g and 0.01 gm

j.

Mercury — clean, sufficient to fill the glass cup to overflowing.

Sample Preparation: This test commonly is performed as a continuance of the Liquid Limit and Plastic Limit tests, and material for the test could therefore conveniently be prepared as part of the Liquid Limit test. Page 15 of 59


Otherwise a 150 g sample should be prepared in the same way as specified for the Liquid Limit test. A sample of material passing through a 425-micron sieve shall be thoroughly mixed with distilled water until the mass becomes a smooth homogeneous paste with moisture content at about the Liquid Limit of the soil.

Procedure: a.

Take the shrinkage dish. Clean it and determine its mass.

b. Fill mercury in the shrinkage dish. Remove excess mercury by pressing the plain glass plate over the top of shrinkage dish. c.

Transfer the mercury from shrinkage dish to mercury weighing dish and determine the mass of the mercury to an accuracy of 0.01gm. The volume of shrinkage dish (V 1) is equal to the mass of mercury in grams divided by the specific gravity of mercury (i.e. 13.6).

d. Coat the inside of the shrinkage dish with wax or grease or Vaseline. e. Place the soil specimen in the center of the shrinkage dish equal to one third the volume of the shrinkage dish. Tap the shrinkage dish on a firm surface and allow the paste to flow to the edges. f.

Repeat the process till getting full level of shrinkage dish.

g.

Wipe off all soil adhering to the outside of the shrinkage dish. Determine the mass of wet soil (m 1).

h. Dry the soil in shrinkage dish in air t ill the color of the pat turns from f rom dark to light. Then dry the pat in 0

the oven at 105 – 105 – 110 110 C to constant mass. i.

After cooling the dry pat, weigh the shrinkage dish with dry pat to find the dry mass of soil (m 2).

j.

Place a glass cup in an evaporating dish and fill it with mercury. Remove excess mercury by pressing prong plate over the top of glass cup.

k.

Remove the glass cup with full of mercury and place it in another evaporating dish with spilling any mercury from the glass cup.

l.

Take out the dry pat of the soil from shrinkage dish and immerse in the glass cup full mercury. Press prong plate on the top of cup firmly allowing spilling of mercury in the evaporating dish.

m. Collect the mercury displaced by dry pat in mercury weighing dish. Determine the mass of mercury to an accuracy of 0.01gm. n. The volume of the dry pat (V2) is equal to the mass of the mercury divided by the specific gravity of the mercury. o. Repeat the above test procedure for a tleast 3 samples.

Page 16 of 59



Sr. No.

Descriptions 1

2

3

Observations 1.

Mass of empty mercury dish (gm)

2.

Mass of empty mercury dish + Mercuryequal to volume of shrinkage dish (gm)

3.

Mass of Mercury (gm) = (2-1)

4.

Volume of Shrinkage dish,

5.

Mass of Empty shrinkage dish (gm)

6.

Mass of Empty shrinkage dish + Wet soil (gm)

7.

Mass of Wet soil (M 1) = (6-5)

8.

Mass of Empty shrinkage dish + Dry soil (gm)

9.

Mass of Dry soil (M s) = (8 – (8 – 5) 5)

10.

Mass of empty mercury dish + Mercury equal to volume of Dry pat (gm)

11.

Mass of Mercury displaced by Dry pat (gm) = (10 - 1)

12.

Volume of Dry pat,

Calculations 13.

Shrinkage limit,

14.

Shrinkage Ratio,

15.

Volumetric Shrinkage,

…….. %. Result:Average Shrinkage Limit of given Soil sample is ……..%.

Page 17 of 59


Experiment No. ___

Date:

Name of Experiment:Determination of Field Density

Aim: To determine the in-situ dry density of soil by various methods (i) core cutter method and (ii) Sand replacement method as per IS: 2720 (Part XXIX - 1975 and Part XXVIII – 1974). – 1974).

Scope: Experiment viz. Field Density by core cutter method covers the method for the determination of the in-place density of fine-grained natural or compacted soils free from aggregates using a core-cutter. For the purpose of the test, a soil shall be termed as fine-grained soil if not less than 90 percent passes through 4.75mm IS Sieve.

Determination of field density of cohesionless soil is not possible by core cutter method, because it is not possible to obtain a core sample. In such situation, the sand replacement method is employed to determine the dry density. Sand Replacement method covers the determination of the dry density of natural or compacted fine- and medium-grained soils for which a small sand pouring cylinder is used. The method is applicable to layers not exceeding 150 mm in thickness. With granular material 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.

Theory:The in situ density of natural soil is needed for the determination of bearing capacity of soils, for the purpose of stability analysis of slopes, for the determination of pressures on underlying strata for the calculation of settlement and the design of underground structures. It is very quality control test, where compaction is required, in the cases like embankment and pavement construction. By conducting field density test by either method, it is possible to determine the field density of the soil. The moisture content is likely to vary from time to time and hence the field density also. So it is required to report the test result in terms of dry density. The relationship that can be established between the dry density with known moisture content is as follows:

Where, d =

Dry Density;

b

= Bulk Density;

w = Water Content

Page 18 of 59


A. Field Density by Core Cutter Method Core cutter method of determining the field density of soil is only suitable for fine grained soil (Silts and clay). This is because collection of undisturbed soil sample from a coarse grained soil is difficult and hence the field properties, including unit weights, cannot be maintained in a core sample.

Apparatus: a.

Cylindrical core cutter

b. Steel rammer c.

Steel dolley

d. Balance e. Steel rule f.

Spade or pickaxe

g.

Straight edge

h. Knife

Procedure: a.

Determine the internal diameter and height of the core cutter to the nearest 0.25mm.

b. Determine the mass (M 1) of the cutter to the nearest 0.01gm. c.

2

Expose a small area of the soil to be tested. Level the surface, about 300mm in area. Page 19 of 59


d. Place the dolley over the top of the core cutter and press the core cutter into the soil mass using the rammer. Stop the pressing when about 15mm of the dolley protrudes above the soil surface. e. Remove the soil surrounding the core cutter, and take out the core cutter. Soil would project from the lower end of the cutter. f.

Remove the dolley. Trim the tip and bottom surface of the core cutter carefully using a straight edge.

g.

Weigh the core cutter filled with the soil to the nearest gram (M 2).

h. Remove the core of the soil from the cutter. Take a representative sample for the water content determination. i.

Determine the water content.


Sr. No.

Description 1

1.

Internal Diameter of Core Cutter (d) (mm)

2.

Internal Height of Core Cutter (h) (mm)

3.

Volume of Core Cutter (mm ),

4.

Weight of Core Cutter (gm) (M 1)

5.

Weight of Core Cutter + Field Soil (gm) (M 2)

6.

Bulk Density of soil (gm/cm )

7.

Determination of Water Content:

2

3

3

3

a.

Water Content Container No.

b.

Weight of Container (gm) (W 1)

c.

Weight of Container + Wet Soil (gm) (W 2)

d.

Weight of Container + Dry Soil (gm) (W 3)

e.

Moisture Content, 3

f.

Dry Density of soil (gm/cm )

8.

Average Dry Density (gm/cm )

3

3

Result:Average Field Dry Density of Soil is ……..gm/cm .

Page 20 of 59


B. Field Density by Sand Replacement Method The basic principle of sand replacement method is to measure the in-situ volume of hole from which the material was excavated from the weight of sand with known density filling in the hole. The in-situ density of material is given by the weight of the excavated material divided by the in-situ volume.

Apparatus: a.

Sand pouring cylinder

b. Calibrating can c.

Metal tray with a central hole

d. Standard sand (passing through 600 micron sieve) e. Weighing balance, with an accuracy of 0.01gm f.

Moisture content bins

g.

Glass plate

h. Metal tray i.

Scraper tool

Procedure: a. Calibration of the Cylinder i.

Measure the internal dimensions (diameter, d and height, h) of the calibrating can and compute its 2

internal volume, V = πd h/4.

Page 21 of 59


ii.

Fill the sand pouring cylinder with sand with 10mm top clearance (to avoid any spillover during operation) and find its weight (W 1).

iii.

Place the sand pouring cylinder on a glass plate, open the slit above the cone by operating the valve and allow the sand to run down. The sand will freely run down till it fills the conical portion. When there is no further downward movement of sand in the sand pouring cylinder, close the slit.

iv.

Find the weight of the sand pouring cylinder along with the sand remaining after filling the cone (W2)

v.

Place the sand pouring cylinder concentrically on top of the calibrating can. Open the slit to allow the sand to run down until the sand flow stops by itself. This operation will fill the calibrating can and the conical portion of the sand pouring cylinder. Now close the slit and find the weight of the sand pouring cylinder with the remaining sand (W 3).

b. Measurement of Soil Density i.

Clean and level the ground surface where the field density is to be determined.

ii.

Place the tray with a central hole over the portion of the soil to be tested.

iii.

Excavate a pit into the ground, through the hole in the plate, approximately 12 cm deep (same as the height of the calibrating can). The hole in the tray will guide the diameter of the pit to be made in the ground.

iv.

If for any reason it is necessary to excavate the pit to a depth other than 12 cm, the standard calibrating can should be replaced by one with an internal height same as the depth of pit to be made in the ground.

v.

Care should be taken in excavating the pit, so that it is not enlarged by levering, as this will result in lower density being recorded.

vi.

Collect the excavated soil into the tray and weigh the soil (W). No loose material should be left in the pit.

vii.

Determine the moisture content of the excavated soil.

viii.

Place the sand pouring cylinder, with sand having the latest weight of W 3, over the pit so that the base of the cylinder covers the pit concentrically.

ix.

Open the slit of the sand pouring cylinder and allow the sand to run into the pit freely, till there is no downward movement of sand level in the sand pouring cylinder and then close the slit.

x.

It should not be forgotten to remove the tray, before placing the sand pouring cylinder over the pit.

xi.

Find the weight of the sand pouring cylinder with the remaining sand (W 4).

Page 22 of 59


Observations: Sr. No.

Trial No.

Description

1

2

Calibration of the Cylinder 1.

Internal Diameter of calibrating container (d) (cm)

2.

Internal Height of calibrating container (h) (cm)

3.

Volume of calibrating container (cm ),

4.

Weight of sand pouring cylinder + sand, W 1 (gm)

5. 6.

3

Weight of sand pouring cylinder + sand, W 2 (gm) (After filling conical portion on a flat surface). Weight of sand pouring cylinder + sand, W 3 (gm) (After filling calibrating can).

7.

Weight of sand required to fill cone, Wc = W1-W2 (gm)

8.

Weight of sand required to fill cone & can Wcc=W2-W3 (gm)

9.

Weight of sand in calibrating can = Wcc-Wc (gm)

10.

Unit weight of sand, γsand = (Wcc-Wc)/V (gm/cm )

3

Determination of Field Density of Soil 11.

Weight of sand pouring cylinder, W4 (gm) (After filling the hole & conical portion)

12.

Weight of sand in the hole and cone (W3-W4) (gm)

13.

Weight of sand in the pit Wp = (W3-W4)-Wc (gm)

14.

Volume of sand required to fill the pit Vp=Wp/γsand (cm )

15.

Weight of the excavated soil from the pit ( W) (gm)

16.

Wet unit weight of the soil γwet=W/Vp (gm/cm )

3

3

Determination of Water Content 17.


18.

Weight of Container (gm) (M 1)

19.

Weight of Container + Wet Soil (gm) (M 2)

20.

Weight of Container + Dry Soil (gm) (M 3)

21.

Moisture Content,

22.

Dry unit weight of the soil γdry=γwet/(1+w) (gm/cm )

3

3

Result: Average Field Dry Density of Soil is ……..gm/cm .

Page 23 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of coefficient of permeability.

Aim: To determine the coefficient of permeability of a soil using constant head method and variable head method.

Scope: The knowledge of coefficient of permeability is much useful in solving problems involving yield of water bearing strata, seepage through earthen dams, stability of earthen dams, and embankments of canal bank affected by seepage, settlement etc. This experiment covers the methods for laboratory determination of coefficient of permeability of soils using falling head and the constant head methods as per the procedure mentioned in IS 2720-Part XVII.

Theory:The rate of flow under laminar flow conditions through a unit cross sectional area of soil medium under unit hydraulic gradient is defined as coefficient of permeability. The permeability is the ease with which water can easily flow through soil medium. A soil is highly pervious when water can flow through it easily. In an impervious soil, the permeability is very low and water cannot easily flow through it. A completely impervious soil does not permit the water to flow through it. However, such completely impervious soils do not exist in nature, as all the soils are pervious to some degree. A soil is termed impervious when the permeability is extremely low.

The coefficient of permeability is equal to the rate of flow of water through a unit cross-sectional area under a unit hydraulic gradient. In the constant head permeameter, the head causing flow through the specimen remains constant throughout the test. The coefficient of permeability (k) is obtained from the relation:

Where, q = Discharge; Q = Total volume of water; t = Time period, h = Head causing flow; L = Length of specimen; A = Cross sectional area Page 24 of 59


A.

Coefficient of permeability by Constant Head Method

The coefficient of permeability of a relatively more permeable soil can be determined in a laboratory by the constant head permeability test.

Apparatus: a.

The permeability mould assembly (including drainage base and drainage cap),

b. Compaction Rammer, c.

Constant Head Tank

d. mixing pan, e. Graduated cylinder, f.

Measuring scale,

g.

Stop watch etc.

Constant Head Test set-up

Variable Head Test set-up

Preparation of Sample: a.

A 2.5 kg sample shall be taken from a thoroughly mixed oven dried material.

b. Add water to bring the test specimen, to slightly below the apparent optimum moisture content or sufficient water to assure good compaction. c.

Mix the soil thoroughly. Page 25 of 59


d. Weigh the empty permeameter mould. e. After greasing the inside slightly, clamp it between the compaction base plate and extension collar. f.

Place the assembly on a solid base and fill it with sample in three layers and compact each layer thoroughly.

g.

After completion of a compaction the collar and excess soil are removed.

h. Find the weight of mould with sample. i.

Place the mould with sample in the permeameter, with drainage base and cap having saturated porous stones. Now the specimen is ready for the test.

Procedure: a.

For the constant head arrangement, the specimen shall be connected through the top inlet to the constant head reservoir.

b. Open the bottom outlet. c.

Establish steady flow of water.

d. The quantity of flow for a convenient time interval may be collected. e. Repeat three times for the same interval.

Observations and Calculations: Head of Water (H)

= ………… cm;

Height of Specimen (L)

= ………… cm

Hydraulic Gradient, (i) = (K/L)

= ………….

0

Water temperature = ……… C

Cross Section area of the specimen/mould (A) = …………… cm

Sr. No.

Description

2

Trial-1

1.

Time Elapsed (t) (Seconds)

2.

Discharge collected (Q) (cm )

Trial-2

Trial-3

Trial-4

Trial-5

3

Permeability (cm/sec), 3.

4.

Average Permeability (cm/sec)

Page 26 of 59


Result: The viscosity of the water changes with temperature. As temperature increases viscosity decreases and the 0

permeability increases. The coefficient of permeability is standardized at 27 C, and the permeability at any temperature ‘T’ is related to K 27 by the following ratio:

Where, 0

k27 = Permeability at 27 C T and

27 =

0

Coefficient of water viscosities at the temperature 'T' and at 27 C respectively.

From the following table obtain the viscosities and compute K 27.

Temperature 0 ( C) 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Viscosity (Poise) 0.01005 0.00981 0.00958 0.00936 0.00914 0.00894 0.00874 0.00855 0.00836 0.00818 0.00801 0.007768 0.007568 0.007368 0.007169 0.006969 0.006769 0.006569 0.006369 0.006169 0.00597

Average Coefficient of Permeability of Soil is …….. cm/sec =

……..m/sec

Page 27 of 59


B.

Coefficient of permeability by Variable Head Method

The falling head permeability test is a common laboratory testing method used to determine the permeability of fine grained soils with intermediate and low permeability such as silts and clays. This testing method can be applied to an undisturbed sample.

Apparatus: a.

The permeability mould assembly (including drainage base and drainage cap),

b. Compaction Rammer, c.

Constant Head Tank

d. mixing pan, e. Graduated cylinder, f.

Measuring scale,

g.

Stop watch etc.


Take 800 to 1000 gm of representative soil and mix it with water to get optimum moisture content (OMC).

b. Assemble the permeameter for compaction. Grease the inside of the mould and place it upside down on the firm base. Weigh the assembly correct to a 0.01gm (W1 ). Put the 3 cm collar to the other end. c.

Now, compact the wet soil in 2 layers with 15 blows to each layer with a 2.5 kg tool. Remove the collar and then trim off the excess. Weigh the mould assembly with the soil (W2).

d. Place the filter paper or fine wire mesh on the top of the soil specimen and fix the perforated base plate on it. e. Turn the assembly upside down and remove the compaction plate. Insert the sealing gasket and place the top perforated plate on the top of soil specimen. And fix the top cap. Now, the specimen is ready for test.

Procedure: a.

Before starting the flow measurements, the soil sample is saturated and the standpipes are filled with de-aired water to a given level.

b. The test then starts by allowing water to flow through the sample until the water in the standpipe reaches a given lower limit.

Page 28 of 59


c.

The time required for the water in the standpipe to drop from the upper to the lower level is recorded.

d. Often, the standpipe is refilled and the test is repeated for couple of times. e. The recorded time should be the same for each test within an allowable variation of about 10% otherwise the test is failed.

Observations and Calculations: Diameter of specimen (D)

= …………… cm

Length of specimen (L)

= …………… cm

Area of specimen (A= /4*D )

2

= …………… cm

2

Volume of specimen (V=A*L)

= …………… cm

3

Area of stand-pipe (a)

= …………… cm

2

Temperature of water

= …………… C

Sr. No.

0

Description

1.

Initial Time (Ti) (seconds)

2.

Initial Head (h1) (cm)

3.

Final Time (Tf ) (seconds)

4.

Final Head (h2) (cm)

Trial – 1

Trial – 2

Trial – 3

(cm/sec)

5.

6. 7.

0

Permeability at 27 C,

(cm/sec)

Average Coefficient of Permeability of Soil is …….. cm/sec =

……..m/sec

Page 29 of 59


Experiment No. ___

Date:

Name of Experiment:Determination of Shear Strength of soil by Direct Shear Test

Aim: To determine the shear strength of soil by direct shear test as per IS: 2720 (Part X III) - 1986.

Scope: This experiment covers the methods for determination of shear strength of soil with a maximum particle size of 4.75 mm in undrained, consolidated undrained and consolidated drained conditions. The undrained test can be performed only for highlyimpermeable clays. When silty clays and silts are involved, partial drainage is inevitable.

Principle:In the direct shear test a square prism of soil is laterally restrained and sheared along a mechanically induced horizontal plane while subjected to a pressure applied normal to that plane. The shearing resistance offered by the soil as one portion is made to slide on the other is measured at regular intervals of displacement. Failure occurs when the shearing resistance reaches the maximum value which the soil can sustain. By carrying out tests on a set of specimens of the same soil under different normal pressures, the relationship between measured shear stress at failure and normal applied stress is obtained.

The shear box apparatus can be used only for carrying out drained tests for the determination of effective shear strength parameters. There is no control of drainage, and the procedure cannot be used for undrained tests. The test specimen is consolidated under a vertical normal load until the primary consolidation is completed. It is then sheared at a rate of displacement that is slow enough to prevent development of excess pore pressures.

Apparatus: a.

The shear box including grid plates, porous stones, base plates, and loading pad and water jacket etc,

b. Weights - for providing the required normal loads, c.

Proving-Ring of suitable capacity,

d. Sample Trimmer, e. Stop Clock, f.

Balance,

g.

Spatula,

h. Straight edge etc. Page 30 of 59



Cohesive soils may be compacted to the required density and moisture content. The sample extracted and then trimmed to the required size. Alternatively, the soil may be compacted to the required density and moisture content directly into the shear box after fixing the two-halves of the shear box together by means of the fixing screws.

b. Cohesionless soils may be tamped in the shear box itself with the base plate and grid plate or porous stone as required in place at the bottom of the box. c.

The cut specimen shall be weighed and trimmings obtained during cutting shall be used to obtain the moisture content. Using this information, the bulk dry density of the specimen in the shear box shall be determined.

For Undrained Test: The shear box with the specimen, plain grid plate over the base plate at the bottom of the specimen, and plain grid plate at the top of the specimen should be fitted into position in the load frame. The orientations of the grid plates should be at right angles to the direction of shear.As porous stones are not used for the undrained tests, plain plates of equal thickness should be substituted in their place so as to maintain the shear plane in the sample in the middle of its thickness.

For Consolidated Undrained and ConsolidatedDrained Test: The apparatus should be assembled in a way similar to that for 'Undrained test' except that instead of the plain grid plates, perforated grid plates and saturated porous stones should be used at the top and bottom of the specimen.

Page 31 of 59


Procedure: I.

Initial Adjustment:

a.

Position the box on its bearings on the machine bed, and adjust the drive unit to the correct starting point of the shear test. Secure the horizontal displacement gauge in position.

b. Assemble the loading system so that the loading yoke is supported by the ball seating on top of the load cap. c.

Secure the vertical deformation gauge in position so that it can measure the vertical movement of the center of the loading cap, ensuring that it allows enough movement in either direction.

d. Record the initial zero reading.

II.

Consolidation:

e. Apply a normal force to the specimen, to give the desired vertical stress, smoothly and as rapidly as possible without jolting. Start the clock at the same instant if consolidation readings are significant. f.

Except when testing dry soils, as soon as possible after applying the normal force fill the box with water to a level just above the top of the specimen, and maintain it at that level throughout the test.

g.

Record readings of the vertical deformation gauge and elapsed time at suitable intervals. Continue until the vertical deformation readings shows saturation (which indicates that primary consolidation is complete).

III.

Shearing:

h. Remove the clamping screws which lock the two halves of the shearbox together. i.

Record the initial readings of the horizontal displacement gauge, the vertical deformation gauge and the force measuring device.

j.

Start the test and at the same instant start the timer. Record readings of the force measuring device, the horizontal displacement gauge, the vertical deformation gauge and elapsed time, at regular intervals of horizontal.

k.

Continue shearing and taking readings beyond the maximum force, or until the full travel of the apparatus has been reached if there is no defined peak, then stop the test.

l.

Reverse the direction of travel of the carriage and return the two halves of the shear box to their original alignment.

m. If the specimen was sheared under water, siphon off the water from around the specimen and allow to stand for about 10 min to enable free water to drain from the porous plates. Page 32 of 59


n. Remove the vertical force and loading yoke from the specimen. o. Transfer the specimen from the shear box to a small tray, taking care not to lose any soil. Remove any free water with a tissue. p. Weigh the specimen on the tray to 0.01 gm. 0

0

q. Dry the soil in an oven at 105 C to 110 C and determine its dry mass (m d) to 0.01 gm, and its final moisture content.

Observations and Calculations: Soil Specimen Measurements: Dimensions of the Specimen

: …… (cm) x …… (cm)

2

Area of specimen (As) (cm )

:

Thickness of specimen (cm)

:

3

Volume of specimen (cm )

:

Before Starting Test

Description

After Completing Test

Wet weight of Specimen (gm) Water Content Container No. Weight of Container (gm) (M 1) Weight of Container + Wet Soil (gm) (M 2) Weight of Container + Dry Soil (gm) (M 3) Moisture Content, Bulk density of specimen( Dry density of specimen(

b) d)

3

(gm/cm ) 3

(gm/cm )

Void ratio, Degree of Saturation (%), For sandy soils, a rate of strain of 0.2 mm/min may be suitable. For clayey soils, a rate of strain of 0.01 mm/min or slower may be used.

Rate of displacement (mm/min)

:

Proving ring constant (PRConst)

:

Least Count of dial gauge

: Page 33 of 59


) A ( g n i d a e R ) l m a i m D ( l a t n o z i r o H

t l n a t e n m o e c z i a r l o p H s i D f e o g C u L a g * l ) a i A d (

Normal Stress = 2 ………..kg/cm (B) g n i g R n i g d n i a v e R o r P

Hor. Shear (C) t s n o C

R P * ) B (

Normal Stress = 2 ………..kg/cm

Shear Stress 2 kg/cm s

A * ) C (

(D) g n i g R n i g d n i a v e R o r P

Hor. Shear (E) t s n o C

R P * ) D (

Normal Stress = 2 ………..kg/cm


A * ) E (

(F) g n i g R n i g d n i a v e R o r P

Hor. Shear (B) t s n o C

R P * ) F (


A * ) F (

Page 34 of 59


Sr. No.

Normal Stress 2 (kg/cm )

Max. Shear Stress 2 (kg/cm )

1. 2. 3.

Plot a graph between Normal stress (on X-axis) and Shear stress (on Y-axis) and find: i.

Cohesion intercept (C), and

ii.

Angle of Internal friction ( ) or shearing resistance.

Result: a. CohesionIntercept of given Soil sample is

: …….. kg/cm

b. Angle of Internal friction ( )of given Soil sampleis

: ……..

2

0

Page 35 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of Unconfined Compressive Strength

Aim: To determine the Unconfined Compressive Strength(UCS) of soil as per IS: 2720 (Part X) - 1991.

Scope: This experiment describes the method for determining the unconfined compressive strength of c layey soil, undisturbed, remolded or compacted, using controlled rate of strain.

Principle:The unconfined compression test is used to measure the shearing resistance of cohesive soils which may be undisturbed or remolded specimens. An axial load is applied using either strain-control or stresscontrol condition. The unconfined compressive strength is defined as the maximum unit stress obtained within the first 20% strain. The unconfined compressive strength (q u) is the load per unit area at which the cylindrical specimen of a cohesive soil falls in compression.

Where, P = Axial load at failure A = Corrected area of the specimen = A0 = Initial area of the specimen = axial strain = The undrained shear strength (S) of the soil is equal to the half of the unconfined compressive strength.

Apparatus: a.

Compression device

b. Load and deformation dial gauge c.

Sample trimming equipment

d. Balance, accurate up to 0.01gm e. Moisture can

Page 36 of 59


Preparation of Sample: The type of soil specimen to be used for test shall depend on the purpose for which it is tested and may be compacted, remolded or undisturbed.There will be a significant variation in strength of undisturbed and remolded samples.

The specimen for the test shall have a minimum diameter of 38 mm. The height to diameter ratio shall be within 2 to 2.5. Measurements of height and diameter shall be made with suitable measuring device to the nearest 0.1 mm.

Undisturbed sample: a. Specimen of required size may be carved from large undisturbed specimens. b. When the sample is ejected horizontally, a curved plate may be provided to butt against the sampling tube such that the ejected specimen slips over it freely. This will avoid bending of the specimen and facilitate bringing specimen to vertical position.

Page 37 of 59


c.

The specimen shall be of uniform circular cross-section with ends perpendicular to the axis of the specimen.

d. Three specimens obtained by trimming and carving from undisturbed soil samples shall be tested.

Remolded Specimen: The specimen may be prepared either from a failed undisturbed specimen or from a disturbed soil sample. In the case of failed undisturbed specimen, the material shall be wrapped in a thin rubber membrane and thoroughly worked with the fingers to assure complete remolding. Care shall be taken to avoid entrapped air, to obtain a uniform density, to remold to the same void ratio as that of the undisturbed specimen, and to preserve the natural water content of the soil.

Compacted Specimen: a. Compactionof disturbed material shall be done using a mould of circular cross-section with dimensions as given. Compacted specimen may be prepared at any predetermined water content and density. b. After the specimen is formed, the ends shall be trimmed perpendicular to the long axis and removed from the mould. Representative sample cuttings shall be obtained or the entire specimen and shall be used for the determination of water content after the test.

Procedure:

a.

The initial length, diameter and weight of the specimen shall be measured and the specimen shall be placed on the bottom plate of the loading device. The upper plate shall be adjusted to make contact with the specimen.

b. The deformation dial gauge shall be adjusted to a suitable reading, preferably in multiples of 100. Force shall be applied so as to produce axial strain at a rate of 0.5 to 2% per minute. The force reading shall be taken at suitable intervals of the deformation dial reading. Up to 6% axial strain force, readings may be taken at an interval of 0.5 mm of the deformation dial reading. After 6% axial strain, the interval may be increased to 1.0 mm and, beyond 12% axial strain it may be increased even further. c.

The specimen shall be compressed until failure surfaces have definitely developed, or the stressstrain curve is well past its peak, or until an axial strain of 20% is reached.

d. The angle between the failure surface and the horizontal may be measured, if possible, and reported. Page 38 of 59


e. The water content of the specimen shall be determined.

Observations and Calculations: Diameter of the Specimen

: …..…… cm

Area of specimen (A0)

: …..…… cm

Proving ring Constant (PRConst)

:

Sr. No.

Height of specimen (L0) : …..…… cm 2

Description

1.

Proving Ring reading at Failure (A)

2.

Load at Failure (P) = (PRConst) * A

3.

Dial gauge reading at Failure (B)

4.

Deformation at Failure ( L) = LC * B

5.

Axial Strain,

6.

Corrected Area,

7.

Specimen Stress,

8.


9.

Weight of Container (gm) (M 1)

S

Least Count of the dial gauge (LC):

Sample – 1

Sample – 2

Sample – 3

= P/A’

10. Weight of Container + Wet Soil (gm) (M 2) 11. Weight of Container + Dry Soil (gm) (M 3) 12. Moisture Content,

a.

Values of stress

S,

and strain obtained shall be plotted on a graph.

b. The maximum stress from this plot gives the value of the UCS, q u. c.

In case no maximum stress occurs within 20% axial strain, the UCS shall be taken as the stress at 20% axial strain.

d. In the case of soils which behave as if the angle of shearing resistance

0

= 0 , the undrained shear

strength or cohesion of the soil may be taken to be equal to half the UCS.

Result: a. Unconfined Compressive Strength of given Soil sample is

: …….. kg/cm

b. Undrained Shear Strength orCohesion (C)of given Soil sample is

:…….. kg/cm

2

2

Page 39 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of Undrained Shear Strength by laboratory Vane Shear test

Aim: To determine the Undrained Shear Strengthof soil as per IS: 2720 (Part XXX) - 1980.

Scope: This experiment covers the procedure of conducting laboratory vane shear test on cohesive soils of low shear strength for determining their undrained shear strength.

Need of Test:The vane shear test is an in-situ geotechnical testing methods used to estimate the undrained 2

shear strength of fully saturated clays of low shear strength (less than 0.3 kg/cm )without disturbance. The test is relatively simple, quick, and provides a cost-effective way of estimating the soil shear strength; therefore, it is widely used in geo technical investigations. Under special condition, the vane shear test can be also carried out in the laboratory on undisturbed soil specimens; however, the use of the vane shear test in in-situ testing is much more common.

Apparatus: a.

Vane shear apparatus: The vane shear test apparatus consists of four stainless steel blades fixed at right angle to each other and firmly attached to a high tensile steel rod. The length of the vane is usually kept equal to twice its overall width. The diameters and length of the stainless steel rod were limited to 2.5mm and 60mm respectively.

b. Specimen, c.

Specimen container,

d. Calipers

Sample Preparation: Prepare two or three specimens of the soil sample of dimensions of at least 37.5 mm diameter and 75 mm length in specimen. (L/D ratio 2 or 3).

Page 40 of 59


Procedure: a.

Measure the height and overall diameter of vane.

b. Mount the specimen container with the specimen on the base of the vane shear apparatus and fix it securely to the base. c.

Gently lower the shear vanes into the specimen to their full length without disturbing the soil specimen so that the top of the vane is at least 10 mm below the top of the specimen.

d. Note the readings of the torque indicator/angle of twist. 0

e. Rotate the vane at a uniform rate approximately 0.1 /second by suitable operating the torque application handle until the specimen fails. f.

Note the final reading of the torque indicator/angle of twist.

g.

Torque readings and the corresponding strain readings may also be noted at desired intervals of time as the test proceeds.

For vane testing instruments that do not read tile torque directly, a calibration curve to convert the readings to cm.kgf of torque shall be used.

This test is being performed based o n the following assumptions: a.

Shearing strengths in the horizontal and vertical directions are the same;

b. At the peak value, shear strength is equally mobilized at the end surfaces as well as at the centre; Page 41 of 59


c.

The shear surface is cylindrical and has a diameter equal to the diameter of the vane.

Observations: Height of vane (H) (cm)

:

Diameter of vane (D) (cm)

:

Spring Constant

:

Sr. No.

Initial Reading

Final Reading

Difference

Torque (T)

G

Shear Strength of Soil = T * G

Average Shear Strength

(Degrees)

(Degrees)

(Degrees)

(kg-cm)

(1/cm3)

(kg/cm2)

(kg/cm2)

1. 2. 3.

Result: Undrained Shear Strength of given Soil sample is: ……..kg/cm

2

Page 42 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of Water Content-Dry Density relation using Light and Heavy Compaction

Aim: The objective of this test is to obtain relationships between compacted dry density and soil moisture content, using two magnitudes of manual compaction effort as per IS: 2720 (Part VII-1980 and VIII-1983). The first is a light compaction test using a 2.5 kg rammer (Standard Proctor). The second is a heavy compaction test using a 4.5 kg rammer with a greater drop on thinner layers of soil (Modified Proctor). The test is used to provide a guide for specifications on field compaction.

Scope: The purpose of a laboratory compaction test is to determine the proper amount of mixing water to be used, when the soil in the field is being compactedand the resulting degree of denseness which can be expected from compaction at optimum moisture content. To accomplish this, a laboratory test which will give a degree of compaction comparable to that obtained by the field method used is necessary. This procedure is satisfactory for cohesive soil, but does not lend itself well to the study of the compaction characteristics of clean sand or gravels which displace easily when struck with the rammer.

Principle:The dry density which can be achieved for a soil depends on the degree of compaction applied and the moisture content. The moisture content which gives the highest dry density is called the optimum moisture content for that type of compaction. In general the optimum moisture content is less than the Plastic Limit.

Apparatus: a.

Cylindrical Metal mould (with internal diameter of 105 mm, internal height of 115 mm and volume of 3

1000cm ) b. Balance of sensitivity to 0.01gm, c.

Hot Air Oven

d. Containers for measuring Water content, e. Steel straightedge f.

Sieves of sizes 20mm and 4.75mm

g.

Mixing tools

h. Metal rammer Page 43 of 59


Sample Preparation (For Standard as well as Modified Proctor Test): a.

A representative portion of air dried soil material and large enough to provide about 6 kg of material passing 20-mm IS sieve (for soils not susceptible to crushing during compaction), or about 15 kg of material passing a 20-mm IS sieve (for soil susceptible to crushing during compaction), shall be taken. This portion shall be sieved on a 20-mm IS sieve and the coarse fraction rejected after its proportion of the total sample shall be recorded.

b. Aggregations of particles shall be broken down so that if the sample was sieved on a 4.75mm IS sieve, only separated individual particles would be retained.

Procedure (For Standard Proctor Test): a.

Obtain about 6kg of sample as prepared.

b. Add water to the materials and mix thoroughly to bring the moisture content to about 5%. c.

Determine the empty weight of the Proctor Mold + base plate (not extension).

d. Attach the extension to the top of the mold.

Page 44 of 59


e. Pour the moist soil in three equal layers. Compact each layer 25 times uniformly with the light hammer (2.5kg) (dropping from a height of 310mm) before each additional layer of loose soil is poured. f.

At the end of the three-layer compaction, the soil should extend slightly above the top of the rim of the compaction mold.

g.

Remove the extension carefully.

h. Trim excess soil with a straight edge. i.

Determine the weight of the Proctor Mold + base plate + compacted moist soil.

j.

Remove the base plate from the mold. Extrude the compacted moist soil cylinder using a jack.

k.

From the moist soil extruded, collect sample for determining moisture content.

l.

Break the rest of the soil cylinder by hand and mix with leftover moist soil. Add more water and mix to raise moisture content by 2%.

m. Repeat steps from ‘d’ to ‘k’. In this process, the weight of the mold + base plate + moist soil will first increase with the increase in moisture content and then decrease. n. Continue the test until at least two successive decreased readings are obtained.

Observation (For Standard Proctor Test):

Sr. No.

Description

1.

Weight of Mold + base plate (W 1) (gm)

2.

Weight of Mold + base plate + moist soil (W 2) (gm)

3.

Weight of compacted Moist Soil (W 2 – W1) (gm)

4.

Bulk Density (gm/cm ),

5.


6.

Weight of Container (gm) (M1)

7.


8.


9.

Moisture Content,

10.

Dry Density (gm/cm ),

Trial1

Trial2

Trial3

Trial4

Trial5

3

3

Page 45 of 59


Plot a graph showing γ d (On X-axis) and % Water content (On Y-axis).Determine the maximum dry unit weight of compaction, γd(max) and corresponding optimum moisture content. Also plot zero air void line.

Procedure (For Modified Proctor Test): a.

Follow the same procedure as mentioned for the ‘Standard Proctor Test’ by considering the only variations as mentioned below: i.

Use of Heavy rammer (of 4.5kg) instead of light rammer (of 2.5kg) dropping from a height of 450mm.

ii.

Pouring the moist soil in five equal layers instead of three layers.

Observation (For Modified Proctor Test): Sr. No.

Description

1.

Weight of Mold + base plate (W 1) (gm)

2.

Weight of Mold + base plate + moist soil (W 2) (gm)

3.

Weight of compacted Moist Soil (W 2 – W1) (gm)

4.

Bulk Density (gm/cm ),

5.


6.

Weight of Container (gm) (M1)

7.


8.


9.

Moisture Content,

10.

Dry Density (gm/cm ),

Trial1

Trial2

Trial3

Trial4

Trial5

3

3

Plot a graph showing γ d (On X-axis) and % Water content (On Y-axis).Determine the maximum dry unit weight of compaction, γd(max) and corresponding optimum moisture content. Also plot zero air void line.

Page 46 of 59


Result: Sr. No.

Standard Proctor Test

Description

Modified Proctor Test

3

a.

Maximum Dry Density of given Soil sample (gm/cm )

b.

Optimum Moisture Content of given Soil sample (%)

Page 47 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of Free Swell Index (Differential Free Swell) of Soils.

Aim: To determine the free swell index of soil as per IS: 2720 (Part XL) – 1977.

Scope: The purpose of determination of free swell index is to understand the increase in volume of soil without any external constraint when subjected to submergence in water.

Theory:The expansive clays have a tendency to swell in small or more proportion when comes in contact with water. The possibility of damage to structures due to swelling of expansive clays need be identified, by an investigation of those soils likely to possess expansion characteristics. Inferential testing is resorted to reflect the potential of the system to swell under different simulated conditions. Actual magnitude of swelling pressures developed depends upon the dry density, initial water content, surcharge loading and several other environmental factors.

Apparatus: a.

0

0

Oven (105 C to 110 C),

b. Balance (0.01g accuracy), c.

Sieve (425 micron),

d. Graduated glass cylinder (100ml capacity),

Soil Sample

Soil Sample in Kerosene

Soil Sample in distilled water Page 48 of 59


Procedure: a.

Take two representative oven dried soil samples each of 10gm passing through 425 micron sieve.

b. Pour each soil sample in to each of the two glass graduated cylinders of 100ml capacity. c.

Fill one cylinder with kerosene and the other with the distilled water up to the 100ml mark.

d. Remove the entrapped air in the cylinder by gentle shaking and stirring. e. Allow the samples to settle in both the cylinders. f.

Sufficient time, not less than 24 hours shall be allowed for soil sample to attain equilibrium state of volume without any further change in the volume of the soils.

g.

Record the final volume of the soils in each of the cylinders.

Observations and Calculations: The level of the soil in the kerosene graduated cylinder shall be read as the original volume of the soil samples, kerosene being a non-polar liquid does not cause swelling of the soil. The level of the soil in the distilled water cylinder shall be read as the free swell level.

Volume of soil in cylinder containing Kerosene

Volume of soil in cylinder containing distilled water

Free Swell Index

Sample No. 3

(Vk) cm

3

(Vd) cm

1 2 3

Average Free Swell Index (%)

Result: Free Swell Index (Differential Free Swell) of given Soil sample is: …….. %

Page 49 of 59


Experiment No. ___

Date:

Name of Experiment:Determination of Shear Strength of soil by Triaxial Shear Test

Aim: To determine the shear strength of unconsolidated undrained soil specimen without measurement of pore water pressure by triaxial shear test as per IS: 2720 (Part XI) - 1993.

Scope: The Triaxial test is primarily designed to determine the shear strength parameters of a soil sample either in terms of total stresses, i.e. the angle of shear resistance ( ), the cohesion (C) and the undrained shear strength (Cu),or in terms of effective stresses, i.e. the angle of shear resistance ( ') and the cohesion (C). These values may be used to calculate the bearing capacity of a soil and the stability of slopes.This experiment covers the methods for determination of the shear strength of unconsolidated undrained specimen of saturated cohesive soil in the triaxial compression apparatus under conditions in which the cell pressure is maintained constant and there is no change in the total water content of the specimen.

Principle:Triaxial test is more reliable because we can measure both drained and untrained shear strength. Generally specimen shall be used: in case of undisturbed sample; nominal diameter 38, 50, 70 and 100 mm and of height approximately equal to twice the nominal diameter and in case of remolded samples; ratio of diameter of specimen to maximum size of particle in the soil should not be less than 5. Specimen is encased by a thin rubber membrane and set into a plastic cylindrical chamber. Cell pressure is applied in the chamber (which represents σ3’) by pressurizing the cell fluid (generally water).Vertical stress is increased b y loading the specimen until shear failure occurs. Total vertical stress, which is σ 1 is equal to the sum of σ 3 and deviator stress (σd). Measurement of σ d, axial deformation, pore pressure, and sample volume change are recorded. Depending on the nature of loading and drainage condition, triaxial tests are conducted in three different ways. a.

Unconsolidated Undrained (UU) Triaxial test

b. Consolidated Undrained (CU) Triaxial test c.

Consolidated Drained (CD) Triaxial test

Test Conditions: The following test conditions shall be specified before starting a series of tests: a.

Size of test specimen,

b. Number of specimens to be tested (minimum 2 - 3),

Page 50 of 59


c.

Cell confining pressures,

d. Whether undisturbed or remolded specimens are to be tested, e. For remolded specimens the moisture content, and either the dry density to be achieved or the compactive effort to be applied.

Apparatus: a.

Triaxial test cell with all necessary accessories,

b. Split Mould, c.

Trimming knife,

d. Measuring Scale, e. Seamless rubber membrane, f.

Rubber rings,

g.

Balance, accurate up to 0.01gm,

h. Apparatus for moisture content determination


The largest particle contained within the test specimen must be smaller than one sixth of the specimen diameter.

b. Specimens should have a minimum diameter of 7 0 mm. Page 51 of 59


c.

The height to diameter ratio should be between two and three, measured to the nearest 0. 3 mm.

d. Prepare undisturbed specimens from samples obtained from thin walled sampling tubes or other acceptable undisturbed tube sampling procedures. e. Handle specimens carefully to minimize disturbance, changes in cross section, or loss of moisture content. f.

Specimens should be of uniform circular cross section, with ends perpendicular to the axis.

g.

Remolded samples prepared at the desired moisture and density by static and dynamic methods of compaction or by any other suitable method, where necessary.

h. Determine weight and dimensions of specimen, enclose in the rubber membrane, and immediately seal it to the specimen base and cap.

Test Procedure: a.

Position the specimen in the chamber and assemble the triaxial chamber.

b. Bring the axial load piston into contact with the specimen cap several times to permit proper seating and alignment of the piston with the cap. c.

During this procedure, take care not to apply a deviator stress to the specimen exceeding 0.5% of the estimated compressive strength.

d. Place the chamber in position in the axial loading device. e. Carefully align the axial loading device, the axial load-measuring device, and the triaxial chamber to prevent the application of a lateral force to the piston during testing. f.

Attach the pressure-maintaining and measurement device.

g.

Fill the chamber with the confining fluid to a predetermined level.

h. Adjust the pressure-maintaining and measurement device to the desired chamber pressure and apply pressure to the chamber fluid. i.

The chamber will produce an upward force on the piston that will react against the axial loading device. Start the test with piston slightly above the specimen cap, and before the piston comes in contact with the specimen cap, measure and record the initial piston friction and upward thrust of the piston produced by the chamber pressure.

j.

Record the initial reading on the deformation indicator when the piston contacts the specimen cap.

k.

A rate of axial compression shall be selected such that failure is produced within a period of approximately 5 to 15 minutes.

l.

The test shall be commenced, a sufficient number of simultaneous readings of the load and compression measuring gauges being taken to define the stress strain curve. Page 52 of 59


m. The test shall be continued until the maximum value of the stress has been passed or until an axial strain of 20 percent has been reached. The specimen shall then be unloaded and the final reading cf the load measuring gauge shall be recorded as a check on the initial reading. n. The cell shall be drained of fluid and dismantled, and the specimen taken out. The specimen shall be weighed and samples for the determination of the moisture content of the specimen shall be taken. o. Prior to placing the specimen (or portion thereof) in the oven to dry, sketch a picture or take a photograph of the specimen showing the mode of failure (shear plane, bulging, etc.).

Observations and Calculations: Rate of strain OR displacement (mm/min)

:

Proving ring constant (PRConst)

:

Least Count of dial gauge (mm)

:

Cell Pressure = Description

2

………..kg/cm

Cell Pressure = 2

………..kg/cm

Cell Pressure = 2

………..kg/cm

Diameter of the Specimen (D S) (mm) Length of specimen (LS) (mm) 2

Area of specimen (A s) (cm ) 3

Volume of specimen (V s) (cm ) Wet weight of Specimen (gm) Water Content Container No. Weight of Container (gm) (M 1) Weight of Container + Wet Soil (gm) (M 2) Weight of Container + Dry Soil (gm) (M 3) Moisture Content, 3

Bulk density of specimen( b) (gm/cm ) Dry density of specimen(

d)

3

(gm/cm )

Page 53 of 59


Cell Pressure(

Strain Gauge Reading (mm)

Change in length of specimen ( H) Strain Gauge * LC of dial gauge

Axial Strain (%)

Proving Ring Reading

3)

= ………..kg/cm2

Deviatric Force (kg)

Proving Ring * PRConst

Corrected 2 area(cm )

Deviatric Stress ( 1) 2 (kg/cm )

Effective Normal Stress

Deviatric Force / AC

(

1+

3)

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 525 550 575 600

Page 54 of 59


Sr. No.

Cell Pressure (

3)

Max. Deviatric Stress ( 1)

(kg/cm2)

(kg/cm2)

Radius of Mohr Circle

Center of Mohr Circle

(

(

1-

3)

/2

1+

3)

/2

1. 2. 3.

Result Presentation: a.

Record the observations atleast for three samples minimum with various cell pressure.

b. With radius of ( (

1-

3)

/ 2) and center point at ( (

1 +

3)

/ 2)plot Mohr’s circle for each cell pressure

having Normal stress (on X-axis) and Shear stress (on Y-axis). c.

Draw a smooth common tangent to the circlesfind: i.

Cohesion intercept (C), and

ii.

Angle of Internal friction ( ) or shearing resistance.

d. Slope of the tangent designates Angle of internal friction ( ) and Y-intercept designates Cohesion.

Result: a. Cohesion Intercept of given Soil sample is

: …….. kg/cm

b. Angle of Internal friction ( )of given Soil sample is

: ……..

2

0

Page 55 of 59


Experiment No. ___

Date:

Name of Experiment: Determination of SwellingPressure of Expansive Soils.

Aim: To determine the swellingpressure of expansive soil as per IS: 2720 (Part XLI) – 1977.

Scope: This experiment covers the laboratory method of conducting one dimensional swelling pressure test using floating rings on remolded soils in the partially saturated condition to determine the swelling pressure of the soil. Method, viz. consolidometer method, in which the volume change of the soil is permitted and the measurement of corresponding pressure required to bring back the soil to its original volume is explained.

Theory:Swelling Pressure is the pressure which the expansive soil exerts, if the soil is not allowed to swell or the volume change of the soil is arrested. The main purpose of swelling pressure test is to determine the intrinsic swelling pressure of the expansive soil tested. The expansive clays increase in their volume when they come in contact with water owing to surface properties of these clay types. Light structures founded on such type of clays-popularly known in India as black cotton soil, experience severe structural damage due to the swelling of the subsoil. Since the intrinsic swelling pressure is to be associated with the design of structures against such damages, measurement of swelling pressure assumes importance. The swelling pressure is dependent upon several factors namely: a.

The type and amount of clay in the soil and the nature of the c lay mineral,

b. The initial water content and dry density, c.

The nature of pore fluid,

d. The stress history of the soil including the confining pressure and e. Drying and wetting cycles to which the soils have been subjected to. Besides the dependence of swelling pressure on volume change makes a precise measurement of swelling pressure difficult.

Apparatus: a.

Consolidometer which provides means for submerging the sample and also enable dial gauge to fix

b. Porous stones, c.

Dial gauge accurate upto 0.002mm

d. Proving ring of 200kg capacity, e. Water reservoir, Page 56 of 59


f.

Soil trimming tool,

g.


0

0

h. Weighing balance, with an accuracy of 0.01gm, i.

Containers for water content determination

Sample Preparation from disturbed soil specimen: a.

In case where it is necessary to use disturbed soil samples the soil sample shall be compacted to the desired field density and water content in a standard compaction proctor mould. Samples of 60mm diameter and 20mm thick are cut from it. The diameter to thickness ratio shall be a minimum of 3.

b. The initial water content shall be at the shrinkage limit or field water content, so that the maximumswelling pressure shall berecorded.

Procedure: a.

The porous stones shall be saturated. Theporous stones shall be saturated by boiling in distilled water for at least 15minutes.

b. All surfaces of the consolidometer which are to be enclosed shall be moistened. The consolidometer shall be assembled with the soil specimen (in the ring) and porous stones at top and bottom of the specimen, providing a filter paper rendered wet between the soil specimen and the porous stone. The loading block shall then be positioned centrally on the top porous stone.

Page 57 of 59


c.

This assembly shall then be mounted on the loading frame such that, the load when applied is transmittedtothesoilspecimen through the loading cap. The assembly shall be so centered that the load applied is axial.

d. The holder withthedialgauge to recordtheprogressive vertical heaveof the specimen under no load,shallthenbe screwedin placeand adjustedinsuch awaythatthedial gaugeisnear the end ofits release run, allowing smallmargin forthe compression of the soil, if any. 2

e. An initial setting loadof 0.05 kgf/cm shallbeplacedontheloading hanger andtheinitial reading of thedialgauge shallbe noted. f.

The

systemshallbeconnectedtoawaterreservoir

beingataboutthesamelevelasthesoil

with

specimen

the

levelof

andwater

water

allowed

inthereservoir to

flow

inthesample.Thesoilshallthen be allowed to swell. g.

2

2

Thefreeswellreadingsshownby thedial gaugeunderthe seating loadof5kN/m (0.05 kgf/cm )shall berecorded atdifferent timeintervals.

h. The dialgauge readings shall be taken till equilibriumis reached. The equilibrium swellingis normally reached over a periodof 6 to 7daysin generalfor all expansivesoils.

Observations and Calculations: Sr. No.

Description

1.

Weight of container ring (gm) (W 1)

2.

Weight of container ring + Wet Soil specimen (gm) (W 2)

3.

Diameter of soil specimen (d) (cm)

4.

Thickness of specimen (h) (cm)

5.

Volume of soil sample (cm ),

6.

Wet Density of soil (gm/cm )

7.

Determination of Water Content:

8.

Before Test

After Test

3

3

a.


b.

Weight of Container (gm) (W 1)

c.

Weight of Container + Wet Soil (gm) (W 2)

d.

Weight of Container + Dry Soil (gm) (W 3)

e.

Moisture Content, 3

Dry Density of soil (gm/cm )

Page 58 of 59

Lab Manual for Soil Testing

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