Project on Soil

DEPTT. OF  OF CIVIL CIVIL ENGG., BIT  BIT SINDRI  SINDRI 

Project Report on Soil Tests Comparison of soil specimens

[Year]

[TYPE

THE COMPANY ADDRESS

]

 ACKNOWLEDGEMENT

I take this opportunity to extend my sincere thanks to all those people who helped and guided us, to make this endeavor of our successful one.

I am extremely grateful to Prof. J.P. SINGH of Civil Engineering Department , B.I.T. Sindri and avail this opportunity to express my most sincere appreciation and deep sense of gratitude for his guidance and immense help at all stages of  work and in the presentation of the dissertation.

I also express my deep sense of gratitude to Prof. (Dr.) R.P.Sharma, Professor & Head, Civil Engineering Department for his advice and help in tacking innumerable difficulties in connection with this work.

I would also like to express express my gratitude towards the staffs & members of Civil Engineering Department.

The assistance and co-operation rendered by following students throughout  the project work is very much appreciated. NAME

ROLL NUMBER

Amit kumar Binit kumar Jayshree bharti Mritunjay kumar Prashant soren Rajesh Ranjan Saroj rajwar Sunaram Marndi Vikash kumar Dilip kumar

080509 080519 080529 080539 080549 080559 080569 080580 080590 070538

Kanhai Ram

090502D

 ACKNOWLEDGEMENT

I take this opportunity to extend my sincere thanks to all those people who helped and guided us, to make this endeavor of our successful one.

I am extremely grateful to Prof. J.P. SINGH of Civil Engineering Department , B.I.T. Sindri and avail this opportunity to express my most sincere appreciation and deep sense of gratitude for his guidance and immense help at all stages of  work and in the presentation of the dissertation.

I also express my deep sense of gratitude to Prof. (Dr.) R.P.Sharma, Professor & Head, Civil Engineering Department for his advice and help in tacking innumerable difficulties in connection with this work.

I would also like to express express my gratitude towards the staffs & members of Civil Engineering Department.

The assistance and co-operation rendered by following students throughout  the project work is very much appreciated. NAME

ROLL NUMBER

Amit kumar Binit kumar Jayshree bharti Mritunjay kumar Prashant soren Rajesh Ranjan Saroj rajwar Sunaram Marndi Vikash kumar Dilip kumar

080509 080519 080529 080539 080549 080559 080569 080580 080590 070538

Kanhai Ram

090502D

Department Of Civil Engineering B.I.T. Sindri, Dhanbad, Jharkhand

CERTIFICATE

This is to certify that the project report entitled ´TESTS ON DIFFERENT SOIL SAMPLESµ is a record of bonafide work carried out under my supervision and guidance during the academic session 2011-2012 as a partial fulfilment of the requirement for the award of  the degree of Bachelor Of Technology(Civil Engineering) of Vinoba Bhave University , Hazaribag. The project work has been successfully completed by : NAME : ROLL NUMBER :

Date :

Prof. J.P.SINGH Dept. Of Civil Engg. B.I.T. Sindri, Dhanbad

Introduction to Soil Mechanics The term "soil" can have different meanings, depending upon the field in which it is considered. To a geologist, it is the material in the relative thin zone of the Earth's surface within which roots occur, and which are formed as the products of past surface processes. The rest of the crust is grouped under the term "rock". To a pedologist, it is the substance existing on the surface, which supports plant life. To an engineer, it is a material that can be: y y y y

built on: foundations of buildings, bridges built in: basements, culverts, tunnels built with: embankments, roads, dams supported: retaining walls

Soil Mechanics is a discipline of Civil Engineering involving the study of soil, its behaviour and application as an engineering material. Soil Mechanics is the application of laws of mechanics and hydraulics to engineering problems dealing with sediments and other unconsolidated accumulations of solid particles, which are produced by the mechanical and chemical disintegration of rocks, regardless of whether or not they contain an admixture of organic constituents. Soil consists of a multiphase aggregation of solid particles, water, and air. This fundamental composition gives rise to unique engineering properties, and the description of its mechanical behavior requires some of the most classic principles of engineering mechanics. Engineers are concerned with soil's mechanical properties: permeability, stiffness, and strength. These depend primarily on the nature of the soil grains, the current stress, the water content and unit weight.

F ormation

of Soils

P hysical

weathering reduces the size of the parent rock material, without any change in the original composition of the parent rock. Physical or mechanical processes taking place on the earth's surface include the actions of water, frost, temperature changes, wind and ice. They cause disintegration and the products are mainly coarse soils. The main processes involved are exfoliation, unloading, erosion, freezing, and thawing. The principal cause is climatic change. In exfoliation, the outer shell separates from the main rock. Heavy rain and wind cause erosion of the rock surface. Adverse temperature changes produce fragments due to different thermal coefficients of rock minerals. The effect is more for freezethaw cycles. Chemical weathering not only breaks up the material into smaller particles but alters the nature of the original parent rock itself. The main processes responsible are hydration, oxidation, and carbonation. New compounds are formed due to the chemical alterations. Rain water that comes in contact with the rock surface reacts to form hydrated oxides, carbonates and sulphates. If there is a volume increase, the disintegration continues. Due to leaching, water-soluble materials are washed away and rocks lose their  cementing properties. Chemical weathering occurs in wet and warm conditions and consists of degradation by decomposition and/or alteration. The results of chemical weathering are generally fine soils with altered mineral grains.

Soil f ormation

One of the most important scientific discoveries was how soil forms spontaneously from rock. Under the influence of physical factors like deformation by heat and co ld, assault  by wind, rain, hail and ice, and the enormous levering forces of water  expanding into ice, solid rock is shattered into smaller pieces (see  picture). But however small these fragments, they still have the same  properties as the parent rock. Being formed under high pressure and temperatures, the crystals of the minerals in the rock are somewhat unstable at surface pressure and temperature. Particularly when attacked by acids that etch away the soluble components in the minerals, the crystals fall apart, albeit very slowly. It is called spontaneous weather ing, but it is accelerated considerably under the influence of vegetation and its acids (chemical weathering). Factors in soil During the weathering process, four components are released: formation: y y y y

minerals in solution (cations and anions), the basis o f plant nutrition. oxides of iron and alumina (sesquioxides Al2O3, Fe2O3). various forms of silica (silicon-oxide compounds). stable wastes as very fine silt (mostly fine quartz) and co arser quartz (sand). These have no nutritious value for plants.

y

parent material

y

time

y

climate

atmospheric composition y

y

topography

y

organisms

Depending on temperature and rainfall, new minerals are formed. The oxides of iron and alumina combine with silica to form clay. In temperate regions a three-layer clay is formed, which is weak, swells under moisture, and clogs. It is able to absorb large amounts of water but is rather heavy on plant roots, blocking the oxygen the soil organisms need. Because clay has a charged surface area, it is able to bind and retain minerals and nutrients (Cation Exchange Capacity). The valuable nutrition for plants won't leach away easily in three-layer clays. Two-layer clays are formed in hot, humid tropical regions, producing arable but easily dried soils. These clays are not able to hold much water, or nutrients, but are still very much better than sand.

Soil's

productivity is mainly due to the clays in the soils. Knowing that clay particles are very small (less than 2 microns), one can imagine that this component is easily eroded out of the soil. Its small size prevents it from sedimenting out rapidly in water, resulting in rivers, lakes and ocean water staying turbid for a long time after rains have ended. The mix of sand, silt and clay is called a loam. In this diagram, the triangle represents all possible combinations of  the three. Soil specialists use names for the various loams, as indicated in the diagram. A loam can be dried and pounded in the laboratory and passed through sieves to separate the mix by particle size. From the diagram, the official composition of 'loam' can be inferred - sand:silt:clay = 40:40:20. (Draw lines parallel to each side and read the left-hand values.) Sand

is very workable but won't hold water, or nutrients well. Loam is poor in nutrients, reasonably workable, but holds water well. Clay is difficult to work, compacts easily, but holds water and nutrients well, but is reluctant to release these to  plants. As the diagram shows, the various loams derived from the three base components, have varying workability, water holding capacity and cation exchange capacity (CEC).  Not only temperature and moisture affect soil formation but also the level of the groundwater table and the steepness and elevation. As can be seen, soil formation depends on many factors, regional and local, resulting in an almost infinite number of  different soils, each having different needs. Nutrients therefore, can vary considerably from patch to patch, requiring careful application and observation.

Soil

prof ile

Whereas soil is formed from the rock below, it is eroded away from the top. A cover of plant life slows down erosion, allowing the soil layer to build up, but t here is more going on. Just above the base rock, is the Chorizon, containing the recently weathered and still weathering soil. It is rich in nutrients. The Ahorizon is where most plant roots are found and all soil organisms. Its nutrients have been used by  plants or leached downward, so it is relatively poor in nutrients, but rich in life. By comparison, the Bhorizon is the zone where new material from below and nutrients from above accumulate. Sometimes an impermeable layer or pan is formed above it (podsol), denying plants to access this rejuvenating source of new nutrients. On the surface of the soil, often a thin layer is found, rich in leaf litter and other organic material. horizon description of det ailed soil horizons O

consists mainly of organic matter f rom the vegetation, which accumulates under  conditions of free aeration.

 A

eluvial (outwash) horizon consisting mainly of mineral m atter mixed with some humified (decomposed) organic matter.

E

strongly eluviated horizons having much less organic matter and/or iron and/or clay than the horizons underneath. Usually pale coloured and high in quartz.

B

illuvial (inwashed) horizon characterised by concentrations in clay, i ron or organic matter. Some lime may accumulate, but if the accumulation is excessive, the horizon is named K.

K

horizon containing appreciable carbonate, usually mainly lime or calcium carbonate.

G

gleyed horizons which form under reducing (anoxic) conditions with impeded aeration, reflected in blueish, greenish or greyish colour.

C

weathered parent material lacking the properties of the solum and resembling more the fresh parent material.

R

regolith, the unconsolidated bedrock or parent material.

Soil

and top soil are produced naturally at a rate of 1mm in 200-400 years, averaging at about 1 ton/ha/y. A full soil profile develops in 2,000 - 10,000 years, a period which is long for humans but short for the planet. World-wide, agricultural soil is lost at a rate 10-40 times faster than its natural replacement. The U SA lost 80mm since farming began, 200 years ago. This amounts to some 18 t/ha/y. China appears to lose 40 t/ha/y. World-wide loss of agricultural land is 6 million ha per year, from a worldwide total of 1200 million ha (0.5%/y). These are compelling reasons for improving the way humans manage their soils.

Soil Classification It is necessary to adopt a formal system of soil description and classification in order to describe the various materials found in ground investigation. Such a system must be meaningful and concise in an engineering context, so that engineers will be able to understand and interpret. It is important to distinguish between description and classification: Description

of soil is a statement that describes the physical nature and state of the soil. It can be a description of a sample, or a soil in situ. It is arrived at by using visual examination, simple tests, observation of site conditions, geological history, etc. Classification

of soil is the separation of soil into classes or groups each having similar characteristics and potentially similar behaviour. A classification for engineering purposes should be based mainly on mechanical properties: permeability, stiffness, strength. The class to which a soil belongs can be used in its description. The aim of a classification system is to establish a set of conditions which will allow useful comparisons to be made between different soils. The system must be simple. The relevant criteria for classifying soils are the size distribution of particles and the plasticity of the soil.

TY PE S O F  SOIL:-  Soils as they are found in different regions can be classified into two broad categories: (1) Residual soils (2) Tr ansported soils Residual Soils Residual soils are found at the same location where they have been formed. Generally, the depth of residual soils varies from 5 to 20 m. Chemical weathering rate is greater in warm, humid regions than in cold, dry regions causing a faster breakdown of rocks.  Accumulation of residual soils takes place as the rate of rock decomposition exceeds the rate of erosion or transportation of  the weathered material. In humid regions, the presence of surface vegetation reduces the possibility of soil transportation.  As leaching action due to percolating surface water decreases with depth, there is a corresponding decrease in the degree of  chemical weathering from the ground surface downwards. This results in a gradual reduction of residual soil formation with depth, until unaltered rock is found. Residual soils comprise of a wide range of particle sizes, shapes and composition. Tr ansported Soils Weathered rock materials can be moved from their original site to new locations by one or more of the transportation agencies to form transported soils. Tranported soils are classified based on the mode of transportation and the final deposition environment. (a) Soils that are carried and deposited by rivers are called alluvial deposits. (b) Soils that are deposited by flowing water or surface runoff while entering a lake are called lacustrine deposits. Atlernate

layers are formed in different seasons depending on flow rate. (c) If the deposits are made by rivers in sea water, they are called marine deposits. Marine deposits contain both particulate material brought from the shore as well as organic remnants of marine life forms. (d) Melting of a glacier causes the deposition of all the materials scoured by it leading to formation of  glacial deposits. (e) Soil particles carried by wind and subsequently deposited are known as aeolian deposits.

Soil compaction means increasing soil density that makes working with soil easy, helps in erecting stable structures, and reduces maintenance costs. Read to learn about the desirable, and undesirable, effects of  mechanical soil compaction on construction and agricultural works.

Soil Compaction Compaction of soil brings stability and strength with it. Foundations fail most commonly because of improper  compaction methods or poorly compacted soil that allows water to seep through the foundation and cause structural damage. Implementing mechanical methods to compact soil means densifying the soil, filling the pore spaces, improving the shear resistance of soil, and providing better water movement through the soil particles. The compaction process largely depends upon the type of soil you are dealing with because different soils have different physical properties and accordingly different compaction methods should be adopted. Compaction also prevents frost damage of soil and increases its durability. Factors

Affecting the Compaction Process

Compaction of soil depends upon various factors. Among them, grain size distribution of soil, optimum

moisture content, maximum

dry density, layer thickness, and environmental

factors are some of the important things to consider. Optimum moist ure content(OMC) is the percentage of  water present in soil mass at which a specific compaction force can dry the soil mass to its maximum dry weight. The adjacent graph (please click to enlarge) shows that the void ratio at and soil is densely compacted. For different types of soils,

OMC

OMC

is approximately zero

and maximum dry density curves are

different. In the figure, W stands for water content and (d) stands for Dry Density of soil mass.

Standard P roctor and Modified P roctor tests are conducted to determine OMC and the dry density of soil masses. The basic difference between these two tests is the size and weight of hammer used to compact the soil mass. The number of blows remains the same, but the falling height is changed from 12 inches to 18 inches in the Modified Proctor test.

Other

popular methods of determining

OMC

and maximum

dry density are mentioned below. Sand Cone Test - Suitable for a large sample, delivers accurate results but requires huge area and more time to perform. Shelby Tube Test - Suitable for deep and under pipe haunches, not suitable for gravels and only works for  a small sample. Nuclear

Gauge Test - Statistically reliable, easy to redo and fast method.

Different

Compaction Methods

Compaction of soil, in simple words, means applying external pressure to the soil mass so that its characteristic properties improve with regard to construction purposes. Technically speaking, static and vibr ator y for ces bring soil particles together by exerting pressure on them. Static forces apply load on the surface of soil particles, exerting dead weight of the machine in a downward direction. These forces do not go skin deep and work only for the upper surface of the soil mass. Vibratory forces, on the other hand, work for the whole soil mass and are not limited to the upper surface only. Along with the dead-weight of machine, compactors and vibrators are connected that not only exert pressure on the soil mass, but also shuffle the entire soil mass so that the overall soil mass is compacted uniformly. Both the top and deeper layers get blows from the vibrator and compactor resulting in denser and tightly packed soil. For mechanical soil compaction, four main compaction techniques are mentioned here. Kneading

Compaction

Pressure Compaction Vibr ation Compaction Impact

Compaction

Compaction equipment is selected based on the type of soil. For clayey soils, kneading techniques and equipment have to be used because clay soils exist in the form of clods and kneading is the best way to

break the clods and densify clay soils.

On

the other hand, for granular soils, a vibratory or shaking motion of 

the compacting device is required so that uniform compaction is achieved. Popular compaction equipment types are mentioned below. Smooth Wheel Rollers - Single axle, equipped with a steel cylinder, sand or water are used to increase its self-weight. Pushes the soil in the direction of movement and results in soil compaction. Sheep Foot Roller - Different style of sheep rollers, can be used for different types of soil, best suited for  cohesive soils. Covers less surface area but pressure per unit area is very high resulting in healthy compaction. Vibr ator y Dr um Roller - Suitable for compaction of sand, gravel, asphalt, and other heavy aggregates.Very powerful compaction devices, provide uniformly dense soil because of vibrator attached to them. Vibr ator y Padfoot

Compactors

- Compactors work mainly in landfill regions and padfoot compactors have

pads attached to their drums making them work fast and deliver efficient results in confined and tight areas. Tamping Foot Rollers - Basically, these devices are compac t or s but are popularly known as tamping foot roller s. Kneading, impact compaction and pressure compaction happen simultaneously with these devices. Different classification systems divide soils according to their characteristic properties and accordingly compaction method is selected.

 Standard Compaction Test   Equipment 

1. Proctor mould with a detachable collar assembly and base plate. 2. Manual rammer weighing 2.5 kg and equipped to provide a height of drop to a free fall of 30 cm. 3. Sample Extruder. 4. A sensitive balance. 5. Straight edge. 6. Squeeze bottle 7. Mixing tools such as mixing pan, spoon, trowel, spatula etc. 8. Moisture cans. 9. Drying Oven

Test procedure 1. Obtain approximately 10 lb (4.5 kg) of air-dried soil in the mixing pan, break all the lumps so that it  passes No. 4 sieve. 2. Add approximate amount of water to increase the moisture content by about

5%.

3. Determine the weight of empty proctor mould without the base plate and the collar. W 1 4. Fix the collar and base plate 5. Place the first portion of the soil in the Proctor mould as explained in the class and compact the layer  applying 25 blows. 6. Scratch the layer with a spatula forming a grid to ensure uniformity in distribution of compaction energy to the subsequent layer. Place the second layer, apply 25 blows, place the last portion and apply 25 blows.

. 7. The final layer should ensure that the compacted soil is just above the rim of the compaction mould when the collar is still attached. 8. Detach the collar carefully without disturbing the compacted soil inside the mould and using a straight edge trim the excess soil leveling to the mould 9. Determine the weight of the mould with the moist soil W 2, (lb). Extrude the sample and break it to collect the sample for water content determination preferably from the middle of the specimen. 10. Weigh an empty moisture can, W3, (g) and weigh again with the moist soil obtained from the extruded sample in step9, W4, (g). Keep this can in the oven for water content determination 11. Break the rest of the compacted soil with hand (visually ensure that it passes US Sieve No.4). Add more water to increase the moisture content b y 2%.

. 12. Repeat steps 4 to 11. During this process the weight W 2 increases for some time with the increase in moisture and drops suddenly. Take two moisture increments after the weights starts reducing. Obtain at least 4 points to plot the dry uni t weight, moisture content variation. 13. After 24 hrs recover the sample in the oven and determine the weight W 5, (g).

Standard proctor test  soil sample I: Diameter of mould, d (cm) = 10cm Height of mould, h (cm) = 12.73cm Volume of mould, V (cm 3) = 944 cm3 Mass of mould, W (g) = 1933g

soil sample II: Wt. of rammer (kg) =2.6kg No. of layers =3 No.of blows/layer =25 Ht. of fall=30.48 cm

Density determination:Test

No.

1

2

3

4

Mass of mould + compacted soil (g)

3457.2

3721.2

3909.0

3782.5

Wt. Mass of compacted soil,

1524.2

1788.2

2176

2149

1.615

1.894

2.093

1.959

10

12

14

16

1.50

1.71

1.86

1.69

W t 

(g)

Bulk density,  Average water content,

Dry density,

w  (%)

(g/cc )

Moisture c ontent  d etermination:Object Determination of moisture content (water content) of soil. Appar atus Drying oven, Non-corrodible metal cans with lids, Balance (0.001 g accuracy for fine-grained soils), Spatula, Gloves, Tongs. Procedure 1. Record the number of can and lid. Clean, dry, and record their weight. 2. Using a spatula, place about 15-30 g of moist soil in the can. Secure the lid, weigh and record. 3. Maintain the temperature of the oven at 110 ± 5°C.

Open

the lid, and place the can in the oven. Leave it overnight.

4. After drying, remove the can carefully from the oven using gloves or tongs. Allow it to cool to room temperature. 5. Weigh the dry soil in the can along with lid. 6. For each soil, perform at least 3 sets of the test.

Can No.

A

B

C

D

1

2

3

4

Mass of can with lid,

7.78

7.83

7.71

7.9

Mass of can with lid + wet soil,

11.78

11.05

10.71

11.1

Mass of can with lid + dry soil,

11.48

10.81

10.41

10.75

Mass of water,

0.29

0.24

0.30

0.35

Mass of dry soil,

3.70

2.98

2.7

2.85

7.9

8.1

11.1

10.9

Test

No.

Moisture content,

Optimum Moisture Content = 13.1

%

Maximum Dry Density = 1.87 g/cm3

DEN SITY DE T ER MI NATIO N  O F  S   AM PL   E  2:-  Test

No.

1

2

3

4

Mass of mould + compacted soil (g)

5520

5625

5682

5765

Wt. Mass of compacted soil,

1630

1735

1792

1875

1.729

1.840

1.901

1.989

0.1062

0.1372

0.1518

0.1744

1.623

1.625

1.650

1.694

W t 

(g)

Bulk density,  Average water content,

Dry density,

w  (%)

(g/cc )

MOISTU RE  CO N TE   N T DE TE   R MI NATIO N  O F  S  AM PL   E  2:-  Can No.

A

B

C

D

1

2

3

4

Mass of can with lid,

15.6

13.82

13.77

14.40

Mass of can with lid + wet soil,

45.28

42.4

54.42

57.8

Mass of can with lid + dry soil,

42.4

39.05

49.15

51.8

Mass of water,

2.88

3.35

5.27

6.0

Mass of dry soil,

26.8

25.23

35.38

37.4

10.74

13.27

14.89

16.04

Test

No.

Moisture content,

S PE CI F IC G RAV ITY DE TE   R MI NATIO N  Pur pose: This lab is performed to determine the specific gravity of soil by using a pycnometer. Specific gravity is the ratio of the mass of unit volume of soil at a stated temperature to the mass of the same volume of gas-free distilled water at a stated temperature. Significance: The specific gravity of a soil is used in the phase relationship of air,

water, and solids in a given volume of the soil. Equipment: Pycnometer, Balance, Vacuum pump, Funnel, Spoon. Test Procedure: (1) Determine and record the weight of the empty clean and dry

pycnometer, W P. (2) Place 10g of a dry soil sample (passed through the sieve No.10) in the pycnometer. Determine and record the weight of the pycnometer containing the dry soil, W PS. (3) Add distilled water to fill about half to three-fourth of the pycnometer. Soak the sample for 10 minutes. (4) Apply a partial vacuum to the contents for 10 minutes, to remove the entrapped air. (5) Stop the vacuum and carefully remove the vacuum line from pycnometer. (6) Fill the pycnometer with distilled (water to the mark), clean the exterior surface of the pycnometer with a cl ean, dry cloth. Determine the weight of the pycnometer and contents, W B. (7) Empty the pycnometer and clean it. Then fill it with distilled water  only (to the mark). Clean the exterior surface of the pycnometer  with a clean, dry cloth. Determine the weight of the pycnometer  and distilled water, W A.

(8) Empty the pycnometer and clean it.

OBS ERVATIO N  AN D C  ALCUL ATIO N  Wt. of soil (gm.) = 200 gm. Test No. Pycnometer / Density bottle No. Mass of pycnometer, W 1 (g) Mass of pycnometer + dry soil, W 2 (g) Mass of pycnometer + soil + water, W 3 (g) Mass of pycnometer + water, W 4 (g)

Sample 1

Sample 2

1

2

687 gm.

687 gm.

887 gm.

887 gm.

1684 gm.

1683 gm.

1564 gm.

1564 gm.

2.5

2.4691

Specific gravity of  soil, GS= (W2-W1)/{(W2-W1)-(W3-W4)}

R esult:- 

Specific gravity of soil sample 1 = 2.5 Specific gravity of soil sample 2 = 2.4691

 ATT ER BER G

LIMITS :- 

Object Determination of the liquid and plastic limits of a soil. Appar atus Liquid limit device and grooving tools, Metal rod of 3 mm diameter, Apparatus for moisture content determination, Porcelain evaporating dish, Spatula, Wash bottle filled with distilled water, Measuring cylinder, Glass plate. Procedure for Liquid Limit 1. Take about 150 gm of dry soil passing 425 micron sieve, and mix it with distilled water in a porcelain dish to form a uniform paste. 2. Place a portion of the paste in the cup of liquid limit device with a spatula, press the soil down to remove air  pockets, spread it to a maximum depth of 10 mm, and form an approximately horizontal surface. 3. By holding a grooving tool perpendicular to the cup, carefully cut through the sample from back to front, and form a clean straight groove in the centre by dividing into two halves. 4. Turn the crank handle of the device at a steady rate of two revolutions per second. Continue turning until the two halves of the groove is closed along a distance of 13 mm. Record the number of blows to reach this condition. 5. Take about 15 gm of the soil from the joined portion of the groove to a moisture can for determining water  content. 6. Transfer the remaining soil from the cup into the porcelain dish. Clean and dry the cup and the grooving tool. 7. Repeat steps 2 to 6, and obtain at least four sets of readings evenly spaced out in the range of 10 to 40 blows. P rocedure

for P lastic Limit  1. Use the remaining soil from the porcelain dish.

2. Take about 10 gm of the soil mass in the hand, form a ball, and roll it between the palm or the fingers and the glass plate using complete motion of the hand forward and reverse. 3. Apply only sufficient pressure to make a soil thread, and continue rolling until a thread of 3 mm diameter is formed. Comparison can be made with the metal rod. 4. If the diameter becomes less than 3 mm without cracking, turn the soil into a ball again, and re-roll. Repeat this remoulding and rolling process until the thread starts just crumbling at a diameter of 3 mm. 5. Gather the pieces of crumbled thread and place them in a moisture can for determining water content. 6. Repeat steps 2 to 5 at least two more times with fresh samples of 10 gm each.

Determin ation

of Liquid Limit

Test No. No. of blows Can No. Mass of can (g) Mass of can + wet.soil, (g) Mass of can + dry soil, (g) Mass of water (g) Mass of dry soil (g) Water content (%)

1 31 11 22.23 28.56 27.40 1.16 5.03 23.06

2 29 1 23.31 29.27 28.10 1.17 4.79 24.43

3 20 5 21.87 25.73 24.90 0.83 3.03 27.39

4 14 4 22.58 25.22 24.60 0.62 2.02 30.69

Liquid Limit = Water content corresponding to 25 blows=26% Determin ation

of Plastic Limit

Test No. Can No. Mass of can (g) Mass of can + wet soil, (g) Mass of can + dry soil, (g) Mass of water (g) Mass of dry soil (g) Water content (%)

1 7 7.78 16.39 15.28 1.11 7.5 14.8

2 14 7.83 13.43 12.69 0.74 4.86 15.2

3 13 15.16 21.23 20.43 0.8 5.27 15.1

Plastic Limit = Average of the computed water contents =15,

Plasticity Index = LL-PL= 11

PAR TICLE  SIZ E  DIST R IBUTIO N  Object Determination of quantitative size distribution of particles of soil down to fine-grained fraction. Appar atus Set of sieves (4.75 mm, 2.8 mm, 2 mm, 1 mm, 600 micron, 425 micron, 300 micron, 150 micron, 75 micron), Balance (0.1 g accuracy), Drying oven, Rubber pestle, Cleaning brush, Mechanical shaker. Procedure 1. Take a suitable quantity of oven-dried soil. The mass of soil sample required for each test depends on the maximum size of material. 2. Clean the sieves to be used, and record the weight of each sieve and the bottom pan. 3. Arrange the sieves to have the largest mesh size at the top of the stack. Pour carefully the soil sample into the top sieve and place the lid over it. 4. Place the sieve stack on the mechanical shaker, screw down the lid, and vibrate the soil sample for 10 minutes. 5. Remove the stack and re-weigh each sieve and the bottom pan with the soil sample fraction retained on it

OBS ERVATIO N  T  ABLE  Initial mass of soil sample taken for analysis (kg) =1 kg Sieve size

(mm) 4.75 mm 2 mm 1 mm 600 micron 425 micron 212 micron 150 micron 75 micron Pan

Particle size Soil retained Cumulative (mm)

(g)

soil retained (g)

Per cent retained (%)

4.75 2 1 0.6 0.425 0.212 0.15 0.075 0

47.5 98.5 167 115 122 216.5 92.5 108 31

47.5 146 313 428 550 766.5 859 967 998

4.75 14.6 31.3 42.8 55 76.65 85.9 96.7 99.8

Per cent finer 

95.25 85.4 68.7 57.2 45 23.35 14.1 3.3 0.2

(%)

1. Obtain the mass of soil retained on each sieve. The sum of the retained masses should be approximately equal to the initial mass of the soil sample. 2. Calculate the percent retained on each sieve by dividing the mass retained on the sieve with the total initial mass of the soil. 3. Calculate the cumulative percent retained by adding percent retained on each sieve as a cumulative procedure.

4. Calculate the percent finer by subtracting the cumulative percent retained from 100 percent. 5. Make a grain size distribution curve by plotting sieve size on log scale and percent finer on ordinary scale. 6. Read off the sizes corresponding to 60%, 30% and 10% finer. Calculate the uniformity coefficient (C u) and the curvature coefficient (Cc) for the soil.