experiment 1 sieve and hydrometer analysis (grain...

Soil Mechanics (PAT 203) Laboratory Module

1

EXPERIMENT 1

SIEVE AND HYDROMETER ANALYSIS

(GRAIN SIZE ANALYSIS)

(PREPARED BY : AHMAD FAIZAL MANSOR)

1.0 OBJECTIVE

This test is performed to determine the percentage of different grain sizes contained

within a soil.

2.0 INTRODUCTION

Grain size analysis is a process in which the proportion of material of each grain size

present in a given soil (grain size distribution) is determined. The grain size distribution

of coarse-grained soils is determined directly by sieve analysis, while that of fine-grained

soils is determined indirectly by hydrometer analysis. The grain size distribution of

mixed soils is determined by combined sieve and hydrometer analyses.

The grain size analysis is presented as a semi log plot of percent finer versus particle size,

called a grain size distribution curve. A semi log plot is used for the particle sizes to

give both small and large diameters as nearly equal weight as possible. Percent finer is

always plotted as the ordinate using an arithmetic scale.

From the grain size distribution curve, grain sizes such as D10, D30 and D60 can be

obtained. The D refers to the size, or apparent diameter, of the soil particles and the

subscript (10, 30, 60) denotes the percent that is smaller. For example, D10 = 0.16 mm

means that 10 percent of the sample grains are smaller than 0.16 mm. The D10 size is

also called the effective size of the soil.

An indication of the spread (or range) of particle sizes is given by the coefficient of

uniformity (Cu), which is defined as

D60

Cu =

D10


2

The coefficient of curvature (Cc) is a measure of the shape of the curve between the

D60 and D10 grain sizes, and is defined as

(D30)2

Cc =

D60 * D10

2.1 Sieve Analysis

A sieve analysis consists of passing a sample through a set of sieves and weighing the

amount of material retained on each sieve. Sieves are constructed of wire screens with

square openings of standard sizes. The sieve analysis is performed on material retained

on an U. S. Standard No. 200 sieve. Table A gives a list of the U. S. Standard sieve

numbers with their corresponding size of openings.

Table A: U. S. Sieve Numbers and Associated Opening Sizes

Sieve No. Opening Size (mm) Sieve No. Opening Size (mm)

4 4.75 35 0.500

5 4.00 40 0.425

6 3.35 45 0.355

7 2.80 50 0.300

8 2.36 60 0.250

10 2.00 70 0.212

12 1.70 80 0.180

14 1.40 100 0.150

16 1.18 120 0.125

18 1.00 140 0.106

20 0.85 200 0.075

25 0.71 270 0.053

30 0.60 400 0.038


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2.2 Hydrometer Analysis

A hydrometer is an instrument used to measure the specific gravity (or relative density)

of liquids; that is, the ratio of the density of the liquid to the density of water.

A hydrometer is usually made of glass and consists of a cylindrical stem and a bulb

weighted with mercury or lead shot to make it float upright. The liquid to be tested is

poured into a tall jar, and the hydrometer is gently lowered into the liquid until it floats

freely. The point at which the surface of the liquid touches the stem of the hydrometer is

noted. Hydrometers usually contain a paper scale inside the stem, so that the specific

gravity can be read directly

A hydrometer analysis is the process by which fine-grained soils, silts and clays, are

graded. Hydrometer analysis is performed if the grain sizes are too small for sieve

analysis. The basis for this test is Stoke's Law for falling spheres in a viscous fluid in

which the terminal velocity of fall depends on the grain diameter and the densities of the

grain in suspension and of the fluid. The grain diameter thus can be calculated from a

knowledge of the distance and time of fall.

Cylindrical stem

Bulb (weighted with mercury/lead shot)


4

The operation of the hydrometer is based on the Archimedes principle that a solid

suspended in a liquid will be buoyed up by a force equal to the weight of the liquid

displaced. Thus, the lower the density of the substance, the further the hydrometer will

sink.

The relative density of a liquid can be measured

using a hydrometer. This consists of a bulb

attached to a stalk of constant cross-sectional

area, as shown in the diagram to the right.

First the hydrometer is floated in the reference

liquid (lighter colored), and the displacement

(the level of the liquid on the stalk) is marked.

The reference could be any liquid, but in

practice it is usually water.

The hydrometer is then floated in a liquid of

unknown density (darker colored). The change in displacement, Δx, is noted. In the

example depicted, the hydrometer has dropped slightly in the darker colored liquid; hence

its density is lower than that of the reference liquid. It is, of course, necessary that the

hydrometer floats in both liquids.

The application of simple physical principles allows the relative density of the unknown

liquid to be calculated from the change in displacement. (In practice the stalk of the

hydrometer is pre-marked with graduations to facilitate this measurement.)

By running the hydrometer analysis test in conjunction with the sieve analysis test, the

grain-size distribution curve can be plotted and the soil can be classified. After

classifying a soil according to the Unified or the AASHTO classification system, the soil

can be used for engineering purposes.


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3.0 TEST EQUIPMENTS

a) Balance

b) Set of sieves

c) Cleaning brush

d) Sieve shaker

e) Mixer (blender)

f) 152H Hydrometer

g) Sedimentation cylinder

h) Control cylinder

i) Thermometer

j) Beaker

k) Timing device


6

4.0 PROCEDURES

4.1 Sieve Analysis

1. Write down the weight of each sieve as well as the bottom pan to be used in the

analysis.

2. Record the weight of the given dry soil sample (initially oven-dry sample of soil).

3. Make sure that all the sieves are clean, and assemble them in the ascending order

of sieve numbers (#4 sieve at top and #200 sieve at bottom). Place the pan below

#200 sieve. Carefully pour the soil sample into the top sieve and place the cap

over it.

4. Place the sieve stack in the mechanical shaker and shake for 10 minutes.

5. Remove the stack from the shaker and carefully weigh and record the weight of

each sieve with its retained soil. In addition, remember to weigh and record the

weight of the bottom pan with its retained fine soil.

4.2 Hydrometer Analysis

1. Take the fine soil from the bottom pan of the sieve set, place it into a beaker, and

add 125 mL of the dispersing agent (sodium hexametaphosphate (40 g/L))

solution. Stir the mixture until the soil is thoroughly wet. Let the soil soak for at

least ten minutes.

2. While the soil is soaking, add 125mL of dispersing agent into the control cylinder

and fill it with distilled water to the mark. Take the reading at the top of the

meniscus formed by the hydrometer stem and the control solution. A reading less

than zero is recorded as a negative (-) correction and a reading between zero and

sixty is recorded as a positive (+) correction. This reading is called the zero

correction. The meniscus correction is the difference between the top of the

meniscus and the level of the solution in the control jar (Usually about +1). Shake

the control cylinder in such a way that the contents are mixed thoroughly. Insert

the hydrometer and thermometer into the control cylinder and note the zero

correction and temperature respectively.


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3. Transfer the soil slurry into a mixer by adding more distilled water, if necessary,

until mixing cup is at least half full. Then mix the solution for a period of two

minutes.

4. Immediately transfer the soil slurry into the empty sedimentation cylinder. Add

distilled water up to the mark.

5. Cover the open end of the cylinder with a stopper and secure it with the palm of

your hand. Then turn the cylinder upside down and back upright for a period of

one minute. (The cylinder should be inverted approximately 30 times during the

minute.)

6. Set the cylinder down and record the time. Remove the stopper from the cylinder.

After an elapsed time of one minute and forty seconds, very slowly and carefully

insert the hydrometer for the first reading.

(Note: It should take about ten seconds to insert or remove the hydrometer to

minimize any disturbance, and the release of the hydrometer should be made as

close to the reading depth as possible to avoid excessive bobbing).

7. The reading is taken by observing the top of the meniscus formed by the

suspension and the hydrometer stem. The hydrometer is removed slowly and

placed back into the control cylinder. Very gently spin it in control cylinder to

remove any particles that may have adhered.

8. Take hydrometer readings after elapsed time of 2 and 5, 8, 15, 30,60 minutes and

24 hours.


8

5.0 RESULTS

5.1 Sieve Analysis:

1. Obtain the mass of soil retained on each sieve by subtracting the weight of the

empty sieve from the mass of the sieve + retained soil, and record this mass as the

weight retained on the data sheet. The sum of these retained masses should be

approximately equals the initial mass of the soil sample. A loss of more than two

percent is unsatisfactory.

2. Calculate the percent retained on each sieve by dividing the weight retained on

each sieve by the original sample mass.

3. Calculate the percent passing (or percent finer) by starting with 100 percent and

subtracting the percent retained on each sieve as a cumulative procedure.

4. Make a semi logarithmic plot of grain size vs. percent finer.

5. Compute Cc and Cu for the soil.

5.2 Hydrometer Analysis:

1. Apply meniscus correction to the actual hydrometer reading.

2. From Table 1, obtain the effective hydrometer depth L in cm (for meniscus

corrected reading).

3. For known Gs of the soil (if not known, assume 2.65 for this lab purpose), obtain

the value of K from Table 2.

4. Calculate the equivalent particle diameter by using the following formula:

Where t is in minutes, and D is given in mm.

5. Determine the temperature correction CT from Table 3.

6. Determine correction factor “a” from Table 4 using Gs.


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7. Calculate corrected hydrometer reading as follows:

Rc = RACTUAL - zero correction + CT

8. Calculate percent finer as follows:

Where WS is the weight of the soil sample in grams.

9. Adjusted percent fines as follows:

F200 = % finer of #200 sieve as a percent

10. Plot the grain size curve D versus the adjusted percent finer on the semi

logarithmic sheet.


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Table 1. Values of Effective Depth Based on Hydrometer and Sedimentation Cylinder of

Specific Sizes


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Table 2. Values of k for Use in Equation for Computing Diameter of Particle in

Hydrometer

Analysis

Sample Results Template/Data sheet

Table 3. Temperature Correction Factors CT Table 4. Correction Factors a for Unit Weights of Solids


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Sieve Analysis

Date Tested :

Tested by :

Project Name :

Sample Number :

Visual Classification of Soil :

Weight of Container : gm

Weight container + Dry Soil : gm

Weight of Dry Sample : gm

Sieve

Number

Diameter

(mm)

Mass of

Empty

Sieve (g)

Mass of

Sieve + Soil

Retained

(g)

Soil Retained

(g)

Percent

Retained

Percent

Passing

4 4.75

10 2.00

20 0.84

40 0.425

60 0.25

140 0.106

200 0.075

Pan ---

Total Weight=

*Percent passing = 100 – cumulative percent retained

From Grain Size Distribution Curve:

% Gravel = D10 = mm

%Sand = D30 = mm

% Fines = D60 = mm

Cu = Cc =


11

Hydrometer Analysis

Test Date :

Tested By :

Hydrometer Number (if known) :

Specific Gravity of Solids :

Dispersing Agent :

Weight of Soil Sample : gm

Zero Correction :

Meniscus Correction :

Date Tim

e

Elapse

d

Time

(min)

Tem

p.

(0C)

Actual

Hydro.

Rdg.

Ra

Hydro.

Corr. For

Meniscus

L

from

Table

1

K

from

Table

2

D

mm

CT

from

Tabl

e 3

a

from

Table

4

Corr.

Hydr

o.

Rdg.

Rc

%

Fine

r P

%

Adjuste

d Finer

PA


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Semi logarithmic Sheet

Note: You can plot your data on this graph or generate similar graph using any graphics

program (e.g. Excel)

6.0 DISCUSSIONS

(Include a discussion on the result noting trends in measured data, and comparing

measurements with theoretical predictions when possible. Include the physical

interpretation of the result, the reasons on deviations of your findings from expected

results, your recommendations on further experimentation for verifying your results, and

your findings.)

7.0 CONCLUSION

(Base on data and discussion, make your overall conclusion)


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8.0 QUESTIONS

1. What were the possible sources of error in this lab experiment?

2. What could be done to reduce the error?

3. Is it possible to carry out a sieve analysis on a sample of silt? Why?

4. State the limitation(s) of Sieve Analysis.

5. What do you personally understand about the grain size analysis, and what are the

benefits/outcomes acquired by executing this test in real engineering application?

6. How grain size distribution affects permeability?


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EXPERIMENT 2

DETERMINATION OF LIQUID LIMIT AND

PLASTIC LIMIT OF SOIL

(PREPARED BY : LIYANA AHMAD SOFRI)

OBJECTIVES

To determine the liquid limit and plastic limit of soil.

INTRODUCTION

The Atterberg limits are a basic measure of the nature of a fine-grained soil. Depending

on the water content of the soil, it may appear in four states:

o solid,

o semi-solid,

o plastic and liquid.

In each state the consistency and behavior of a soil is different and thus so are its

engineering properties. Thus, the boundary between each state can be defined based on a

change in the soil's behavior. The Atterberg limits can be used to distinguish between silt

and clay, and it can distinguish between different types of silts and clays.

Shrinkage limit (SL):

The shrinkage limit is the water content where further loss of moisture will not result in

any more volume reduction. The shrinkage limit is much less commonly used than the

liquid limit and the plastic limit.

Plastic limit (PL):

The plastic limit is the water content where soil starts to exhibit plastic behavior. A thread

of soil is at its plastic limit when it is rolled to a diameter of 3 mm or begins to crumble.

To improve consistency, a 3 mm diameter rod is often used to gauge the thickness of the

thread when conducting the test.

Liquid limit (LL):

The liquid limit is the water content where a soil changes from plastic to liquid behavior.

Casagrande subsequently standardized the apparatus and the procedures to make the

measurement more repeatable. Soil is placed into the metal cup portion of the device and

a groove is made down its center with a standardized tool. The cup is repeatedly dropped

10mm onto a hard rubber base during which the groove closes up gradually as a result of


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the impact. The number of blows for the groove to close for 13 mm (½ inch) is recorded.

The moisture content at which it takes 25 drops of the cup to cause the groove to close is

defined as the liquid limit.

Another method for measuring the liquid limit is the Cone Penetrometer test. It is based

on the measurement of penetration into the soil of a standardized cone of specific mass.

Despite the universal prevalence of the Casagrande method, the cone penetrometer is

often considered to be a more consistent alternative because it minimizes the possibility

of human variations when carrying out the test.

The values of these limits are used in a number of ways. There is also a close relationship

between the limits and properties of a soil such as compressibility, permeability, and

strength. This is thought to be very useful because as limit determination is relatively

simple, it is more difficult to determine these other properties. Thus the Atterberg limits

are not only used to identify the soil's classification, but it also allows for the use of

empirical correlations for some other engineering properties.

Plasticity index (PI):

The plasticity index is a measure of the plasticity of a soil. The plasticity index is the size

of the range of water contents where the soil exhibits plastic properties. The PI is the

difference between the liquid limit and the plastic limit (PI = LL-PL).

http://en.wikipedia.org/wiki/Cone_Penetrometer


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APPARATUS

a) Liquid Limit Test

Casagrande’s liquid limit device

1. Balance

2. Liquid limit device (Casagrande’s liquid limit device)

3. Grooving tool

4. Mixing dishes

5. Spatula

6. Oven

b) Plastic Limit Test

1. Aluminium moisture tin

2. Glass plate

3. Mixing porcelain dish

4. Rod caliper

5. Flexible Spatula

Handle

Brass Cup

Revolution Counter

Grooving Tools & Gauge Block


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PROCEDURES

a) Liquid Limit Test

1. Determine the mass of each of the three moisture cans (W1).

2. Make sure to calibrate the drop of the cup using the other edge of the grooving

tool so that there is a consistency in height of drop.

3. Put about 250 g of air dried soil passing # 40 into an evaporating dish and add a

little water with a plastic squeeze bottle to barely form a paste like consistency.

4. Place the soil in the Casagrande’s cup and using a spatula, smoothen the surface

so that the maximum depth is about 8mm and using the grooving tool, cut a grove

at the centre line of the soil pat.

5. Crank the device at a rate of 2 revolutions per second until there is a clear visible

closure of 1/2” or 12.7 mm in the soil pat placed in the cup. Count the number of

blows (N) that caused the closure (make the paste so that N begins with a value

higher than 35).

6. If N ~ 20 to 40, collect the sample from the closed part of the pat using a spatula

and determine the water content weighing the weight of the can + moist soil

(W2). If the soil is too dry, N will be higher and reduces as water is being added.

7. Additional soil shouldn’t be added to make the soil dry, expose the mix to a fan or

dry it by continuously mixing it with the spatula.

8. Determine the corresponding w% after 24 hrs and plot the N vs w%, called the

“flow curve”.

A C B


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b) Plastic Limit Test

1. Weigh the remaining empty moisture cans with their lids, and record the

respective weights and can numbers on the data sheet.

2. Take a sample about 20 g of the original soil sample and add distilled water until

the soil is at a consistency where it can be rolled without sticking to the hands.

3. Form the soil into an ellipsoidal mass (A). Roll the mass between the palm or the

fingers and the glass plate (B). Use sufficient pressure to roll the mass into a

thread of uniform diameter by using about 90 strokes per minute. The thread shall

be deformed so that its diameter reaches 3.2 mm (1/8 in.), taking no more than

two minutes.

4. When the diameter of the thread reaches the correct diameter, break the thread

into several pieces. Knead and reform the pieces into ellipsoidal masses and re-

roll them. Continue this alternate rolling, gathering together, kneading and re-

rolling until the thread crumbles under the pressure required for rolling and can no

longer be rolled into a 3.2 mm diameter thread (See Photo C).

5. Gather the portions of the crumbled thread together and place the soil into a

moisture can, then cover it. If the can does not contain at least 6 grams of soil, add

soil to the can from the next trial (See Step 6). Immediately weigh the moisture

can containing the soil, record its mass, remove the lid, and place the can into the

oven. Leave the moisture can in the oven for at least 16 hours.

6. Repeat steps three, four, and five at least two more times. Determine the water

content from each trial by using the same method used in the first laboratory.

Remember to use the same balance for all weighing.

A C B


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RESULTS

Plastic Limit Determination

Sample No. 1 2 3 4

Moisture can and lid number

MC = Mass of empty, clean can + lid (g)

MCMS = Mass of can, lid and moist soil (g)

MCDS = Mass of can, lid and dry soil (g)

MS = Mass of soil solids (g)

MW = Mass of pore water (g)

w = Water content (%)

Liquid Limit Determination

Sample No. 1 2 3 4

Moisture can and lid number

MC = Mass of empty, clean can + lid (g)

MCMS = Mass of can, lid and moist soil (g)

MCDS = Mass of can, lid and dry soil (g)

MS = Mass of soil solids (g)

MW = Mass of pore water (g)

w = Water content (%)

No. of drops (N)


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CALCULATIONS

a) Liquid Limit Analysis

1. Calculate the water content of each of the liquid limit moisture cans after they

have been in the oven for at least 16 hours.

2. Plot the water content (w) versus number of drops, N, (on the log scale). Draw the

best-fit straight line through the plotted points and determine the liquid limit (LL)

as the water content at 25 drops.

b) Plastic Limit Analysis

1. Calculate the water content of each of the plastic limit moisture after they have

been in the oven for at least 16 hours.

2. Compute the average of the water contents to determine the plastic limit (PL).

3. Calculate the plasticity index PI = LL - PL. Report the liquid limit, plastic limit

and plasticity index to the nearest whole number, omitting the percent designation

DISCUSSIONS





your findings.)

CONCLUSION

Comment on the objective and the results obtained from the experiment


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EXPERIMENT 3

CONSTANT HEAD PERMEABILITY TEST

(PREPARED BY : NURUL HUDA HASHIM)

1.0 OBJECTIVE

The constant head permeability test is used to determine the permeability of samples of

coarse-grained soils.

2.0 INTRODUCTION

The permeability of soil is a measure of its capacity to allow the flow of water through

the pore spaces between solid particles. The degree of permeability is determined by

applying a hydraulic pressure gradient in a sample of saturated soil and measuring the

consequent rate of flow. The coefficient of permeability is expressed as a velocity.

The fundamental description of permeability is based on the equation q=vA which takes

the familiar form similar to river discharge. The variable q is the discharge (Vol/Time), v

is the apparent velocity, and A is the area that is related to the geometry of the situation.

Now, Darcy's Law describes the factors important in determining the value of v, which is

v=ki

where k is a constant for the material and is called the coefficient of permeability, and i

is the hydraulic gradient which is related to the water pressure. The following table lists

some soil permeabilities:

Soil Permeability Coefficient,

k

(cm/sec)

Relative

Permeability

Coarse gravel >10-1

High

Sand, clean 10-1

-10-3

Medium

Sand, dirty 10-3

-10-5

Low

Silt 10-5

-10-7

Very Low

Clay <10-7

Impervious


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There are several factors that affecting permeability such as particle size distribution,

particle shape and texture, mineralogical composition, voids ratio, degree of saturation,

soil fabric, nature of fluid, type of flow and temperature. For instance, the permeability of

a granular soil is influenced by its particle size distribution, and especially by the finer

particles. The smaller the particles, the smaller the voids between them, and therefore the

resistance to flow of water increases (i.e. the permeability decreases) with decreasing

particle size. Another example is the effect of particle shape and texture. Elongated or

irregular particles create flow paths which are more tortous than those around nearly

spherical particles. Particles with a rough surface texture provide more frictional

resistance to flow than do smooth-textured particles. Both effects tend to reduce the rate

of flow of water through the soil, i.e. to reduce its permeability.

Figure 2.0 : Constant head permeability test


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Figure 2.1 : Principle of constant head permeability test – upward flow

3.0 TEST EQUIPMENT

1. A permeameter cell.

2. A vertically adjustable reservoir tanks.

3. A supply of clean de-aerated water.

4. Filter material to be placed at end of permeameter.

5. Measuring cylinders of 1000 mL or 500 mL.

6. A calibrated thermometer reading to 0.5°C.

7. A stopwatch.

B

A

C

Thermometer

Q

h1

h2

h3

Datum

Clock

F D

E

Ls


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4.0 PROCEDURE

1. Filled the water into tank using water pipe A until full.

2. Place the soil into cylinder pot and compact it. Make sure, the soil sample in wet

condition.

3. Flow the water through valve B for filling the water into cylinder pot and also into

capillary glass.

4. Wait until a reading of water level on the capillary D, E and F become a stable.

Record that reading and the temperature of water, ToC.

5. When the experiment in progress, make sure valve B is always open, so it will

allow the water to flow into the cylinder.

6. Water flows out from the top of cylinder into the beaker. When the water over

flow, collect that water using measuring cylinder. Then, every 10 second measure

it. Assume that 1mL = 1cm3

7. Water level from capillary will be changed. Measure h1, h2 and h3 from datum.


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5.0 RESULTS

Data sheets:

Diameter of sample, D = cm

Length of sample, Ls = cm

Radius, r = cm

Area of sample, A = cm2

Volume of sample, V = cm3

kT = QL

∆hAt

k20 = μT kT

μ20

k = coefficient of permeability (cm/s)

Q = volume of water discharged during test (cm3)

L = length between manometer outlets (cm)

A = cross-sectional area of specimen (cm2)

t = time required for quantity Q to discharge during test (s)

h = difference in manometer levels during test (cm)

Test 1 2 3 4 5

Time of collection, t (s)

Temperature, T (°C)

Volume of water, Q (cm3)

Initial head, h1 (cm)

Final head, h2 (cm)

Final head, h3 (cm)

Head difference, h(h1-h2) (cm)

Head difference, h(h2-h3) (cm)

Avg head difference, havg (cm)

Length of sample, Ls (cm)

Area of sample, A (cm2)

Coefficient of permeability, kT (cm/s)

Coefficient of permeability at 20°C, k20

Average, k20


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Table 1 : Variation of some properties of water with temperature

Temperature

Density,

ρ

Viscosity,

μ Kinematic Surface Vapour Bulk

(°C) (kg/m3) (m

2/m/s viscosity, ν tension, σ pressure modulus of

(m2/s) (N/m) head,

elacticity,

K

pv/pg

(m) (MN/m2)

0 999.9

1.792

(x103) 1.792 (x10

-6) 7.62 (x10

-2) 0.06 2040

5 1000 1.519 1.519 7.54 0.09 2060

10 999.7 1.308 7.480 7.48 0.12 2110

15 999.1 1.14 1.141 7.41 0.17 2140

20 998.2 1.005 1.007 7.36 0.25 2200

25 997.1 0.894 0.897 7.26 0.33 2220

30 995.7 0.801 0.804 7.18 0.44 2230

35 994.1 0.723 0.727 7.10 0.58 2240

40 992.2 0.656 0.661 7.01 0.76 2270

45 990.2 0.599 0.605 6.92 0.98 2290

50 988.1 0.549 0.556 6.82 1.26 2300

55 985.7 0.506 0.513 6.74 1.61 2310

60 983.2 0.469 0.477 6.68 2.03 2280

65 980.6 0.436 0.444 6.58 2.56 2260

70 977.8 0.406 0.415 6.50 3.2 2250

75 974.9 0.38 0.390 6.40 3.96 2230

80 971.8 0.357 0.367 6.30 4.86 2210

85 968.6 0.336 0.347 6.20 5.93 2170

90 965.3 0.317 0.328 6.12 7.18 2160

95 961.9 0.299 0.311 6.02 8.62 2110

100 958.4 0.284 0.296 5.94 10.33 2070


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6.0 QUESTIONS

1. Plot graph coefficient of permeability (k) versus hydraulic gradient (i) in the

specimen.

2. Calculate the coefficient of permeability, k for each specimen.

3. Correct the coefficient of permeability measured to that for 20°C. This is done

by means of a chart that is in the laboratory.

4. Explain what you understand with the coefficient of permeability obtained

from the experiment.

5. How can you relate the coefficient of permeability with the soil classification?

7.0 DISCUSSIONS





your findings.)

8.0 CONCLUSION

(Base on data and discussion, make your overall conclusion)


28

EXPERIMENT 4

STANDARD PROCTOR COMPACTION TEST

(PREPARED BY : MUHAMMAD MUNSIF AHMAD)

1.0 OBJECTIVE

To obtain the maximum dry density and the optimum moisture content.

2.0 INTRODUCTION

Compaction of soil is the process by which the solid soil particles are packed more

closely together by mechanical means, thus increasing the dry density, (Markwick, 1994).

It is achieved through the reduction of air voids in the soil. At low moisture content, the

soil grain is surrounded by a thin film of water, which tends to keep the grains apart even

when compacted. In addition of more water, up to certain point, more air to be expelled

during compaction. At that point, soil grains become as closely packed together as they

can, that is at the dry density is at its maximum. When the amount of water exceeds that

required to achieve this condition, the excess water begin to push particles apart, so the

dry density reduced.

The optimum water content is the water content that results in the greatest density for a

specified compactive effort. Compacting at water contents higher than (wet of ) the

optimum water content results in a relatively dispersed soil structure (parallel particle

orientations) that is weaker, more ductile, less pervious, softer, more susceptible to

shrinking, and less susceptible to swelling than soil compacted dry of optimum to the

same density. The soil compacted lower than (dry of) the optimum water content

typically results in a flocculated soil structure (random particle orientations) that has the

opposite characteristics of the soil compacted wet of the optimum water content to the

same density.


29

3.0 TEST EQUIPMENT

3.1 Clylindercal metal mould

3.2 Metal rammer with 50mm diameter face weighing 2.5 kg

3.3 20 mm BS sieve and receiver

3.4 Measuring cylinder

3.5 Moisture cans

3.6 mixing pan

3.7 Electronic balance

3.8 Jacking apparatus

3.9 Drying oven

3.10 Straight edge

3.11 Trowel

4.0 PROCEDURES

4.1 Determine the weight of the mould body (not the extension) by using the

balance and record the weights, m1 (g). Measure its internal diameter (D)

mm and length (L) mm in several places and calculate the mean

dimensions.

4.2 Apply with an oily cloth on the internal surface of mould to ease the

removal of soil later on.

4.3 Measure the empty pan mixing and ±5 kg of dried soil sample that has

passing through sieve (20 mm).

4.4 Place the mould assembly on a solid base, such as concrete floor.

4.5 Pour the moist soil into the mold in three equal layers. Each layer should

be compacted uniformly by the standard Proctor hammer 25 times before

the next layer of loose soil is poured into the mold.

Note: do not attempt to grab the lifting knob before the rammer has come

to rest. The sequence as shown in Figure 4.0 has to be followed. Repeat

for the second and third layer that the final layer shall not more than 6 mm

above the mould body.

Figure 4.0: sequence of blows using hand rammer


30

4.6 Remove the top attachment from the mold. Be careful not to break off any

of the compacted soil inside the mold while removing the top attachment.

4.7 Using a straight edge, trim the excess soil above the mold (Fig. 4.1). Now

the top of the compacted soil will be even with the top of the mold.

Figure 4.1: Excess soil being trimmed

4.8 Determine the weight of the mould + base plate + compacted moist soil in

the mould, m2 (g).

4.9 Remove the base plate from the mould. Using a jack, extrude the

compacted soil cylinder from the mould.

4.10 Take a moisture container and determine its mass, w0 (g).

4.11 From the moist soil extruded in (Step 4.9), collect a moisture sample in the

moisture can (Step 4.10) (preferable one each layer). This must do

immediately before the soil dry out and determine the mass of the

container + moist soil, w1 (g).

4.12 Place the moisture container with the moist soil in the oven to dry to a

constant weight.

4.13 Break the rest of the compacted soil by hand and mix it with the left- over

moist soil in the pan. Repeat Steps 4.5 through 4.11. Add more water and

mix it to raise the moisture content, approximately as follows :

Sandy and gravelly soils: 1-2% (50-100 ml of water to 5 kg of soil)

Cohesive soils: 2-4% (100-200 ml of water to 5 kg of soil)

4.14 After 24 hrs recover the sample in the oven and determine the weight w2

(g).


31

5.0 SAMPLE CALCULATION

5.1 Calculate the bulk density, ρ of each compacted specimen from the

equation

32 1 /

1000

m mMg m

if volume = 1000 cm

3

Where: m1 – mass of mould; m2- mass of soil and mould

32 1 /

m mMg m

V

if volume = V cm3

2

4

D LV

(check all conversion of unit)

5.2 Calculate moisture content, w n% for each compacted specimen.

2 1

1 0

100n

w ww

w w

Where: w0 – weight of empty container, w1 – weight of dry soil +

container, w2 – weight of moist soil + container

5.3 Calculate the average value of moisture content, w% for each compacted

specimen.

1 2 3

3

w w ww

5.4 Calculate corresponding dry density, ρd

100

100d

w

Mg/m

3


32

5.5 Plot of graph dry density, ρd against moisture content, w. draw a smooth

curve through the points.

5.6 Plotting Of Air Voids Line, Va

Va = 0%, 5% and 10% (use Gs = ρs = 2.65)

wa – assumed water contain.

Use the equation below using ρw = 1Mg/m3

3

1100 /

1

100

a

da

s

V

Mg mw


33

6.0 RESULTS

6.1 Test Criteria

Test Method: _____________________________________________________

Date Tested: _____________________________________________________

Tested By: _______________________________________________________

Project Name: ____________________________________________________

Sample Number: __________________________________________________

Visual Classification of Soil: __________________________________________

6.2 Density Calculation Volume Of Cylinder Mould =

Measurement No. 1 2 3 4 5

Mould + soil (g)

Mould (g)

Soil mass (g)

Wet density, ρ

6.3 Moisture Content


Assumed water contain wa(%)

Wet soil + container (g)

Dry soil + container (g)

Empty container (g)

Moisture content, wn (%)

Average Moisture, w%


34

6.4 Dry Density Calculation (Use Actual Volume Of Cylinder)


Actual Avg Moisture, w%

Dry Density, ρd

7.0 DISCUSSION/ EVALUATION/ EXERCISES

a) Calculate the wet density in gram per cm3 of the compacted soil sample by

dividing the wet mass by the volume of the mold used.

b) Calculate the moisture content of each compacted soil specimen by using

the average of three water contents.

c) Compute the dry density using the wet density and water content

determined in step 7.2.

d) Using the tabulated data table, plot the graph of Dry Density against

Moisture content. Attach the graph to your answer sheet.

e) On the same graph, plot the Air Voids Line, Va = 0%, 5% and 10%. Show

the calculation.

f) Identify and report the optimum moisture content of compaction used on

data sheet.

g) Define and explain what is meant by optimum moisture content?

h) State the problem factors that affect the accuracy of experiment?

8.0 CONCLUSION

Comment on the objective and the results obtained from the experiment

experiment 1 sieve and hydrometer analysis (grain...

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