department of civil engineering university of moratuwa … mechanics/proctor compaction test...

Department of Civil Engineering University of Moratuwa

B.Sc Engineering, Semester III, CE 2042 – Soil Mechanics & Geology - 1 of 12

Assessed By:

Signature Date

Lecturers’ Remarks

Module - CE 2042 Soil Mechanics and Geology-1

Assignment Proctor Compaction Test Marks 10%

Learning

Outcome Ability to conduct proctor compaction test of soils

Ability to analyze the results of the standard Proctor compaction test

Ability to determine the maximum dry density and optimum moisture

content of soils

Ability to discuss the importance of the above test in geotechnical

applications

Programme

Outcomes

1. Application of knowledge of mathematics, science, and engineering 1

2. Effective communication 1

3. In-depth technical competence in at least one engineering discipline 2

4. Ability to undertake problem identification, formulation and solution 2 5. Ability to utilize a systems approach to design and operational

performance 2

6. Individual and team work 1 7. Understanding of the social, cultural, global and environmental

responsibilities of the professional engineer, and the need for

sustainable development 0

8. Understanding of the principles of sustainable design and development 0 9. Understanding of professional and ethical responsibilities and

commitment to them 1

10. Expectation of the need to undertake life-long learning and capacity to

do so 0

0 – not covered under this 1– covered to some extent

2–covered to a greater extent 3– one of the main themes of the subject

Lecturer Prof. S. A. S. Kulathilaka

Student Name

Registration Number:

Date of Assignment: Date Due:

Initial Submission Date: Re Submission Date:



Important

1. Please note that plagiarism is treated as a serious offence and therefore the work you

produce must be individual and original.

2. All sources of information must be referenced using “Harvard Referencing” where

a reference list/Bibliography should be included at the end of the assignment. (You

may refer the information given in

http://libweb.anglia.ac.uk/referencing/harvard.htm)

3. Please note that the submission date given for the assignment (14 days after the date of

performance for the laboratory session) is the final date that you can submit the

assignment. If the given submission date is a public holiday, redefined submission

deadline will be at 1300 hr of the immediate following working day. Late submissions

will be graded lower.

4. Assignments returned to students for corrections must be re-submitted within 10

days

5. Failure to re-submit the previously marked assignment with the re-submitted

assignment will mean that results cannot be released for the respective unit.

6.

Plagiarism

Although research and discussion form an essential part of the assignment, deliberate

copying of the work of others or unacknowledged copying from printed or electronic

sources is NOT permitted. Disciplinary actions will be taken against those who are found

guilty of plagiarism. Signing of this sheet is required to indicate your compliance with the

above regulations.

Student’s Signature: ……………………………….. Date: .…………………

Student’s Comments, (Prior to the submission) if any:

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Student’s feedback, (After the the submission) if any:

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PROCTOR COMPACTION TEST

SOIL MECHANICS

SOIL MECHANICS LABORATORY DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF MORATUWA SRI LANKA



Standard Proctor Compaction Test

General

The purpose of the standard Proctor compaction test is to determine the optimum water

content and the maximum dry density that can be achieved with a certain compaction

effort. The relationship between the moisture content and the density of the soil will be

obtained in the process. Compaction effort designed in this laboratory test is comparable

with that obtained in the field. Compaction is the process of increasing the bulk density of

the soil or aggregate by driving out the air. For a given soil, for a given amount of

compaction effort, the density obtained depends on the moisture content.

Scope

The method given in this standard is based on the standard proctor compaction test. Soil is

compacted in a mould in three layers by dropping a 2.49 kg rammer a distance of 305mm.

(Alternatively dropping a 2.5 kg ramrner 300 mm). Dry density achieved by mixing soil

with different water contents were determined to obtain the maximum dry density and the

corresponding optimum moisture content.

There are four alternative procedures as listed below;

A - With a 101.6 mm diameter mould for material passing 4.7.5 mm sieve,

B - With a 152.4 mm diameter mould for material passing 4.7.5 mm sieve,

C - With a 1-52.4 mm diameter mould for material passing 19.0 mm sieve,

D- With a 1·52.4 mm diameter mould for material passing 19.0 mm Sieve,

Corrected by replacement for material retained on a 19.0 mm sieve,

Methods A and B

With methods A and/or B no oversize correction is required unless the material retained in

4.75 mm sieve is greater than 7%. In that case material retain in 4.75 mm sieve may be

discarded. When material retained on 4.75 mm sieve is greater than 7%, method C should

be used.

Method C

With method C unless the material retained in 19.0 mm sieve is greater than 10%, no

oversize correction should be used. If the amount of material retained on 19.0 mm sieve is

greater than 10%, method D should be used.

Method D

Material retained on 19.0 mm sieve should be passed through 75 mm sieve. Material

retained on 75 mm sieve shall be discarded. Material passing the 75 mm sieve and retained



on the 19 mm sieve shall he replaced with all equal amount of material passing a 19 mm

sieve and retained 4.75 mm sieve. Material for replacement shall be taken from the unused

portion of the sample.

Apparatus

The following apparatus are required,

a) Moulds - There shall be cylindrical moulds conforming to the moulds described

above. The mould of diameter 101.6 mm shall have a height of 116.4 mm, and

therefore will be of a volume 944 cm3.

The mould of 152.4 mm shall have a height of 116.4 mm, and therefore will be of a

volume 2124 cm3.

The moulds shall be fitted with a detachable base plate and a removable extension

approximately 50 mm high.

b) A metal Rammer - There shall be a metal rammer having a 50 mm diameter circular

face, and weighing 2.49 kg. The rammer shall be equipped with a suitable

arrangement for controlling the height of drop to 305mm. ( Alternatively there can be

rammer of 2.5 kg weight with a drop 300 mm)

c) Balances - A balance readable and accurate to 1 g ( with a capacity 20 kg) and a

balance readable and accurate to 0.01 g,

d) Sieves - A 75 mm sieve, a 19 mm sieve and a 4.75 mm sieve.

e) Mixing tools - Miscellaneous tools such as mixing pan, spoon, trowel, spatula etc.

f) Metal tray - A large metal tray ( 600 mm X 500 mm and 80 mm deep),

g) Straightedge - A Steel straightedge, 300 mm long, 25 mm wide, and 3 mm thick with

one beveled edge,

h) Sample extruder - (Optional) An apparatus ( such as a jack) for extruding specimen

from the mould,

i) An oven - Thermostatically controlled oven to provide temperature 105 -110 Co,

j) Cans - Cans to take samples for moisture content determination,



Procedure

1. Obtain approximately 3 kg of air – dried soil in the mixing pan, break all the lumps

so that it passes the sieve given in method A, B, C and D

2. Add suitable amount of water (See Note 1)

3. Determine the weight of the empty mould without the base plate and the collar (M1)

to the nearest 1g

4. Fix the collar and the base plate

5. Compact the moist soil in to the mould in three layers of approximately equal mass

(Each layer shall be compacted by 25 blows in the case of 101.6 mm diameter

mould and 56 blows in the case of 152.4 mm diameter mould. Blows must be

distributed uniformly over the surface of each layer so that the rammer always falls

freely. The amount of soil must be sufficient to fill the mould, leaving not more

than 6mm to be struck off when the extension is removed. (Note 03))

6. Detach the collar carefully without disturbing the compacted soil inside the mould

and using a straight edge trim the excess soil leaving to the mould

7. Obtain the weight of mould with the moist soil (M2) after removing the base plate

8. Extrude the sample and break it to collect the sample for water content

determination preferably at least two specimens one near the top and other near the

bottom

9. Weigh an empty moisture can, M3 and weigh again with the moist soil obtained

from the extruded sample in step 8 (M4)

10. Keep this can in the oven for water content determination

11. Repeat step 4 to 10. During this process weight M2 increases for some time with the

increase in moisture and decreases thereafter. Conduct at least two trials after the

weight starts to reduce.

12. After 24 hours get the weight of oven dried sample (M5)



Computations

The bulk density, ρ in kg/m3 of each compacted specimen shall be computed from the

equation;

Moisture content can be obtained from the equation;

Where w is the moisture content of the soil as a fraction.

The dry densities ρd, obtained in a series of determinations shall be plotted against the

corresponding moisture content, w. A smooth curve shall be drawn through the resulting

points and the position of the maximum on this curve shall be determined. Thus the

maximum dry density and the corresponding water content should be obtained from the

graph.

Where;

M1 is the mass of the mould and base, in kg

M2 is the mass of mould, base and soil, in kg

V is the volume of the mould in m3

ρ = M2 – M1

V

w= M4 -M5

M4- M3

ρ d = ρ

(1 + w)



Presentation of Results

The maximum dry density shall be reported to the nearest kg /m3, and the optimum moisture

content shall be reported to the nearest 0.01 %.

Note 1 -

The amount of water to be added with air dried soil at the commencement of the test will

vary with the type of soil under test. In general, with sandy and gravely soil a moisture

content of 4% to 6% would be suitable, while with cohesive soils a moisture content of

about 8% to 10% below the plastic limit of the soil, would be usually be suitable.

Note 2 -

It is important that the water is mixed thoroughly and adequately with the soil, since

inadequate mixing gives rise to variable test results. This is particularly important with

cohesive soil when adding a substantial quantity of water to the air dried soil.

With clays of high plasticity, or where hand mixing is employed, it may be difficult to

distribute the water uniformly through the air dried soil by mixing alone, and it may be

necessary to store the mixed sample in a sealed container for a minimum period of about 16

hours before continuing with the test.

Note 3 -

It is necessary to control the total volume of the soil compacted; since it has been found

that if the amount of soil struck off after removing the extension is too great, the test results

will be inaccurate.

Note 4 -

The water added for each stage of the test should be such that a range of moisture contents

is obtained which includes the optimum moisture content. In general, increments of 1 % to

2% are suitable for sandy and gravely soils and of 2% to 4% for cohesive soils. To increase

the accuracy of the test it is often advisable to reduce the increments of water in the region

of the optimum moisture content.



Proctor Compaction Test – Specimen work sheet

University Of Moratuwa

Soil Mechanics Laboratory

Proctor Compaction Test Results

Moisture Content Sample 1 Moisture Content sample 2 Average m. c. and Dry

Density

Trial Mass of Mass of

Mould + Soil

(kg)

Moisture

can No

Mass of

wet soil+can

(g)

Mass of

dry soil+can

(g)

Mass of

can (g)

m. c 1

Moisture

can No

Mass of

wet

soil+can(g)

Mass of

dry

soil+can(g

)

Mass

of

can (g)

m. c 2

Ave. mc

%

Bulk

Density

Kg/m3

Dry

Density

Kg/m3 No. Mould kg

1 1.954 3.752 9 129.840 124.93 9.83 0.0427 k5 151.41 145.47 9.17 0.0436 4.31 1904.66 1825.93

2 1.954 3.813 12 145.830 138.26 10.26 0.0591 er 164.72 156.46 27.42 0.0640 6.16 1969.28 1855.05

4 1.954 3.915 f 134.170 124.88 10.13 0.0810 f56 188.62 175.41 28.78 0.0901 8.55 2077.33 1913.66

5 1.954 4.018 g1 123.590 112.93 10.60 0.1042 h7 120.59 109.69 8.79 0.1080 10.61 2186.44 1976.71

6 1.954 4.036 g6 134.500 120.76 10.13 0.1242 h89 126.35 112.96 10.26 0.1304 12.73 2205.51 1956.47

7 1.954 4.033 78 123.590 110.38 8.21 0.1293 ki 125.15 111.22 9.55 0.1370 13.32 2202.33 1943.54

8 1.954 3.976 k 139.200 121.32 8.74 0.1588 kp 112.97 97.56 8.45 0.1729 16.59 2141.95 1837.20



Specimen Calculation

Consider set 2 (Trial number 2)

Mass of compacted soil inside the mould = 3.813 - 1.954 = 1.859 kg

Volume of the mould = 944 cm 3

Bulk density of the soil = 1.859/( 944 x 10-6

)

= 1969.28 kg/m3

Moisture content Sample 1

Moisture content = Mass of water/mass of dry soil

= (145.83-138.26)/(138.26-10.26)

= 0.0591

Moisture con lent Sample 2

Moisture content = Mass of water/ mass of dry soil

= (164.72-156.46)/(156.46 - 27.42)

=0.0640

Average moisture content = (0.0591+0.0640)/2.0

= 0.0616 = 6.16 %

Dry Density = 1969.28/(1 +0.0616)

= 1855.05 kg / m3

Plot dry density against the moisture content

The peak will give the maximum dry density achieved

The corresponding moisture content is the optimum moisture content (omc)



Maximum Dry Density = 1978 kg/m3

Optimum moisture content = 11.0%



Marking Scheme:

Measurements 35%: Precision, Reliability

Calculations & Results 25%: Accuracy, Methodology, Presentation

Discussion 25%: Content, Arrangement, Presentation

Coursework Presentation 15%: Neatness, Clarity, Accordance to the format

department of civil engineering university of moratuwa … mechanics/proctor compaction test...

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