TAIBAH UNIVERSITY
DEPARTMENT OF CIVIL ENGINEERING
CE 331 – principles of geotechnical engineering
Semester: 1st
Experiment Number: 3
Title of Experiment: Standard & Modified proctor compaction
tests
Instructor: Dr. Sharif Gushgari
Team4 mates:
Ibrahim Mohamed-4028023……………. B
Feras al-saadi 3901984………………….. A
Ibrahiem bin Hussien 3902680………….. A
Mohammed Shindi 4002063…………….. A
Ammar Mohammed Alahmadi 3701831… A
Hatem Hamed 3703388………….……….. A
1
Table of contents
1.
2.
3.
4.
5.
6.
7.
8.
Introduction……………………………………………………………3
Test procedure………………………………………………………....3
Test results……………………………………………………………..4
Analysis………………………………………………………………..6
Discussion……………………………………………………………...7
Conclusion……………………………………………………………..9
References……………………………………………………………..9
Appendices……………………………………………………………10
8.1 Appendix I………………………………………………………...10
8.2 Appendix II………………………………………………………..11
8.3 Appendix III……………………………………………………….12
8.4 Appendix IV……………………………………………………….13
8.5 Appendix V………………………………………………………..14
8.6 Appendix VI……………………………………………………….15
8.7 Appendix VII……………………………………………………...16
2
Standard & Modified Proctor Compaction Test
1. Introduction
For the construction of highways, airports, and other structures, it is often necessary to
compact soil to improve its strength. In this part of the report will demonstrate how to
conduct a standard Proctor compaction test in accordance with ASTM specifications. This
test was developed to evaluate the level of compaction of field compacted soils. The soil is
compacted into a mold as specific energy comparable to the energy used in the field. The
laboratory practiced is performed at varying moisture contents to establish a dry density
versus moisture content plot. From this plot the maximum value 'not weight and optimum
moisture content can be determined. The practical application of this test in geotechnical
engineering is for compacted specification of soils. The maximum dry unit weight obtained
from this test can be used to determine the relative compaction of soils in the field. This test
is referred to as the standard Proctor compaction test and is based on the compaction of the
soil fraction passing U.S. No. 4 sieve. The soil samples we tested were collecting from
Madinah city in KSA. They were enough tests carried out to be representative of the soil
available at the site. Tests method A defined on Table1 see ‘‘Appendix I’’.
2. Test Procedures
Note: Table 1 & photos mentioned in the procedures will be on (Appendices I, II, & III.)
)1(
Depending on the type of mold you are using obtain a sufficient quantity of air-dried
soil in large mixing pan. For the 4-inch mold take approximately 10 lbs, and for the 6-inch
mold take roughly 15 lbs. Pulverize the soil and run it through the # 4 sieve.
)2(
Determine the weight of the soil sample as well as the weight of the compaction mold
with its base (without the collar) by using the balance and record the weights.
)3(
Compute the amount of initial water to add by the following method:
(a)
Assume water content for the first test to be 8 percent.
(b)
Compute water to add from the following equation:
water to add (in ml) = {(soil mass in grams)8}/100
Where “water to add” and the “soil mass” are in grams. Remember that a gram of water is
equal to approximately one milliliter of water.
)4(
Measure out the water, add it to the soil, and then mix it thoroughly into the soil using
the trowel until the soil gets a uniform color (See Photos B and C).
3
)5(
Assemble the compaction mold to the base, place some soil in the mold and compact
the soil in the number of equal layers specified by the type of compaction method employed
(See Photos D and E). The number of drops of the rammer per layer is also dependent upon
the type of mold used (See Table 1). The drops should be applied at a uniform rate not
exceedingly around 1.5 seconds per drop, and the rammer should provide uniform coverage
of the specimen surface. Try to avoid rebound of the rammer from the top of the guide sleeve.
Furthermore, the only different in procedure of modifying proctor, is that the moist soil has to
be poured into the mold in five equal layers. Each layer has to be compacted by the modified
proctor hammer- see “Appendix V”- with 25 blows per layer.
)6(
The soil should completely fill the cylinder and the last compacted layer must extend
slightly above the collar joint. If the soil is below the collar joint at the completion of the
drops, the test point must be repeated. (Note: For the last layer, watch carefully, and add more
soil after about 10 drops if it appears that the soil will be compacted below the collar joint.)
)7(
Carefully remove the collar and trim off the compacted soil so that it is completely
even with the top of the mold using the trowel. Replace small bits of soil that may fall out
during the trimming process (See Photo F).
)8(
Weigh the compacted soil while it’s in the mold and to the base, and record the mass
(See Photo G). Determine the wet mass of the soil by subtracting the weight of the mold and
base.
)9(
Remove the soil from the mold using a mechanical extruder (See Photo H) and take
soil moisture content samples from the top and bottom of the specimen (See Photo I). Fill the
moisture cans with soil and determine the water content.
)10( Place the soil specimen in the large tray and break up the soil until it appears visually
as if it will pass through the # 4 sieve, add 2 percent more water based on the original sample
mass, and re-mix as in step 4. Repeat steps 5 through 9 until, based on wet mass, a peak value
is reached followed by two slightly lesser compacted soil masses.
3. Test Results
Forward table is given to us as a data sheet on ‘Appendix IV’. Appropriately;
Volume of mold = 1/30 ft3
4
The way of calculation the moisture content and the dry unit weight will be furthermore
expanded to see in “Appendix V & Appendix VII”.
Weight of mold and base plate
(g)
Weight of mold and base plate +
moist soil
(g)
Weight of moist soil
(g)
Moist unit weight γ
(Ib/ft3)
Mass of moisture can
(g)
Mass of can + moist soil
(g)
Mass of can + dry soil
(g)
Moisture content w
(%)
Dry unit weight of compaction γd
(Ib/ft3)
1
2
Test
3
4
5
8.31
8.31
8.31
8.31
8.31
11.61
11.66
12.43
12.10
11.70
3.30
3.36
4.13
3.80
3.40
99.00
100.65
123.75
113.85
101.97
18.10
18.10
18.40
18.50
18.40
100.00
102.00
103.00
115.00
120.00
96.60
97.40
93.00
99.00
102.00
4.33
5.80
13.41
19.88
21.53
94.89
95.13
109.12
94.97
83.90
115
Dry unit weight (lb/ft^3)
110
105
100
95
90
85
80
3
5
7
9
11
13
15
17
Moisture content (%)
From graph the maximum dry unit weight of compaction = 109.12 lb/ft^3
The optimum moisture content wopt = 13.41%
5
19
21
23
4. Analysis
First, the compaction water content (w) of the soil sample is calculated using the average of
the three measurements obtained (top, middle and bottom part of the soil mass).
Subsequently, the dry unit weight (γd) is calculated as follows:
where:
W = the weight of the mold and the soil mass (kg)
Wm = the weight of the mold (kg)
w = the water content of the soil)%(
V = the volume of the mold (m3, typically 0.033m3)
This procedure should be repeated for 4 more times, given that the selected water contents
will be both lower and higher from the optimum. Ideally, the selected points should be well
distributed with 1-2 of them close to the optimum moisture content.
The derived dry unit weights along with the corresponding water contents are plotted in a
diagram along with the zero-voids curve, a line showing the dry unit weight correlation with
the water content assuming that the soil is 100% saturated. No matter how much energy is
provided to the sample, it is impossible to compact it beyond this curve. The zero-voids curve
is calculated as follows:
where:
GS = the specific gravity of soil particles (typically, GS~2.70)
γ
W
= the saturated unit weight of the soil (kN/m3)
Typical curves derived from the Standard and Modified Proctor tests, as well as the zero air
voids curve are presented in Figure3. Although, see “Appendix VI”.
Figure 3 Typical curves derived by the Standard and Modified Proctor tests. The zero air voids curve is also shown
6
5. Discussion
The degree of the compaction depends on the soil properties, the type and amount of energy
provided by the compaction process and the soil’s water content. For every soil, there is an
optimum amount of moisture for which it can experience its maximum compression. In other
words, for a given compactive effort, a soil is reaching its maximum dry unit weight
(γd,max), at an optimum water content level (wopt).
The compressibility of a relatively dry soil increases as water is added to it. That is, for water
content levels dry of optimum (wopt), the water acts as a lubricant, enabling soil particles to
slide relative to each other, thus leading to a denser configuration. Beyond a certain water
content level (wet of optimum, w>wopt), excess water within the soil results in pore water
pressure increase that pushes the soil particles apart. A typical correlation between the dry
unit weight and the water content is presented in Figure 1. Also, it is worthwhile to note that,
as it can be seen in Figure 2, for a given soil, the highest strength is achieved just dry of
optimum (Figure 2a), while the lowest hydraulic conductivity is achieved just wet of
optimum (Figure 2b). The effect of the compactive effort on the maximum dry unit weight
(γd,max), and the optimum water content level (wopt) can be observed in Figure 3. With
increased in compactive effort, γd,max increases, while wopt decreases. That is, a smaller
water content level is sufficient to saturate a denser sample.
Figure 1 Effect of water content on the dry unit weight during compaction of a soil
7
Figure 2 Effect of water content on soil a) strength, and b) hydraulic conductivity
The standard Proctor test includes a 0.95-liter volume cylindrical mold in which the soil mass
is placed and compacted in 3 layers. Each layer is compressed by dropping 25 times a 2,5 kg
weight falling from an elevation of 30 centimeters.
A modified version of the test was introduced after World War II, in the 1950’s, when heavy
machinery could result in higher compaction. In the new approach, the cylindrical mold
remains the same, however, the drop weight is increased to 4,5kg and the dropping height to
45 centimeters. In addition, the soil is compacted in 5 layers with 25 blows per layer.
The test is conducted for 5 moisture contents to obtain the optimum water content (wopt), for
which the value of the dry unit weight is maximum (γd,max).
8
6. Conclusion
Compaction of soil is an important process which helps in achieving various physical
properties required for proper soil behaviour under loading. For example, proper compaction
of highway embarkment or earthen dam decreases the probabilities of its settlement by
increasing the shear strength of the soil, reduces soil permeability and increases soil density.
Standard proctor compact test was carried out successfully and all the objectives were
satisfied. The curves that relate moisture content with dry unit weight and zero-air unit
weight of the soil was also obtained.
7. References
Ronaluna. “Proctor Compaction Test.” Online video clip. YouYube. YouTube, 6 Jun. 2012.
Web. 20 Oct. 2021.
Principles of foundation engineering, ninth edition. Braja M. Das. Nagaratnam Sivakugan.
GlobalGilson.com. Available from: https://www.globalgilson.com/. [ 20 Oct. 21 ].
ContentFence. Available from: https://contentfence.com/ . [ 20 Oct. 21 ].
Engineering Properties of Soils Based on Laboratory Testing Prof. Krishna Reddy, UIC.
CEEN 341 - Lecture 6 - Soil Compaction, 2 Feb 2017. (video file). Available from:
< https://youtu.be/Q69a_LiqC3s>. [ 20 Oct. 21 ].
9
8. Appendices
Appendix I
Table 1 Alternative Proctor Test Methods
Standard Proctor
ASTM 698
Material
For test
sample, use
soil passing
Mold
No. of
Layers
No. of
blows/layer
Modified Proctor
ASTM 1557
Method A
Method B
Method C
Method A
Method B
Method C
 20%
Retained on
No.4 Sieve
>20%
Retained on
No.4
 20%
Retained on
3/8” Sieve
>20%
Retained on
No.3/8”
<30%
Retained on
3/4” Sieve
 20%
Retained on
No.4 Sieve
>20%
Retained on
No.4
 20%
Retained on
3/8” Sieve
>20%
Retained on
No.3/8”
<30%
Retained on
3/4” Sieve
Sieve No.4
3/8” Sieve
¾” Sieve
Sieve No.4
3/8” Sieve
¾” Sieve
4” DIA
4” DIA
6” DIA
4” DIA
4” DIA
6” DIA
3
3
3
5
5
5
25
25
56
25
25
56
Note: Volume of 4” diameter mold = 944 cm3 , Volume of 6” diameter mold = 2123
cm3 (verify these values prior to testing).
Standard Proctor compaction test
(a) Mold & (b) Hammer
10
Appendix II
Equipment:
Molds, Manual rammer, Extruder, Balance, Drying oven, Mixing pan, Trowel,
#4 sieve, Moisture cans, Graduated cylinder, Straight Edge.
11
Appendix III
12
Appendix IV
Lab data sheet signed by all members in team4,
Units
test1
test2
test3
test4
test5
weight(g)
proctor mold + base 3775.0g 3775.0g 3775.0g 3775.0g 3775.0g
(W1)
weight(g)
proctor mold + base 5275.0g 5300.0g 5650.0g 5500.0g 5320.0g
+soil (W2)
No.
weight(g)
Moisture can 1
number
can (W4) 18.1g
2
3
4
5
18.1g
18.4g
18.5g
18.4g
weight(g)
moist soil + can (W5) 100.0g
102.0g
103.0g
115.0g
120.0g
weight(g)
dry soil + can (W6) 96.6g
97.4g
93.0g
99.0g
102.0g
Ibrahim Mohamed.... ……………………signed………………….………
Mohammed Shindi… ……………………… signed …………..….………
Ibrahiem bin Hussien ………………………… signed ………….………...
Ammar Mohammed Alahmadi ………………… signed ……….………...
Hatem Hamed……… ………………………… signed ……..…….……..
Feras al-saadi ………………………………… signed ……………..……
13
lab
measurement
(W1)
lab
measurement
(W2)
lab
measurement
(W4)
lab
measurement
(W5)
lab
measurement
(W6)
Appendix V
Volume of mold = 1/30 ft3 = 943 m3
test1
test2
test3
test4
test5
3775.0
3775.0
3775.0
3775.0
3775.0
lab measurment
(W1)
5275.0
5300.0
5650.0
5500.0
5320.0
lab measurment
(W2)
1500
1525
1875
1725
1545
W2-W1=(W3)
moist unit
weight
(g/mm3)
moisture can
number
can (W4)
1.591
1.617
1.988
1.829
1.638
W3/943=γ
1
2
3
4
5
18.1g
18.1g
18.4g
18.5g
18.4g
moist soil +
can (W5)
dry soil +
can (W6)
moist soil
(w7)
dry soil
(W8)
moisture
percentage
(ω%)
dry unit of
weight of
compaction
(𝛾𝑑)
(g/m3)
100.0g
102.0g
103.0g
115.0g
120.0g
96.6g
97.4g
93.0g
99.0g
102.0g
81.9g
83.9g
84.6g
96.5g
101.6g
lab measurment
(W4)
lab measurment
(W5)
lab measurment
(W6)
W5-W4=W7
78.5g
79.3g
74.6g
80.5g
83.6g
W6-W4=W8
4.33
5.80
13.40
19.88
21.53
proctor
mold + base
(W1)
(g)
proctor
mold + base
+soil (W2)
(g)
moist soil
calculation
(g)
1.525
1.529
1.753
14
1.526
ω% =
{(𝑊7−𝑊8)/(𝑑𝑟𝑦
𝑠𝑜𝑖𝑙)}*100
1.348 𝛾𝑑=𝛾/(1+((𝜔%)⁄100))
Appendix VI
Standard Proctor Vs Modified Proctor
15
Appendix VII
Specific Gravity of Soil
Solids Gs
Assumed Moisture
Content w (%)
Unit Weight of Water
γw (Ib/ft3)
γzav (Ib/ft3)
2.68
5
62.4
147.5
2.68
10
62.4
131.9
2.68
15
62.4
119.3
2.68
20
62.4
108.9
2.68
25
62.4
100.1
DRY UNIT WEIGHT OF COMPACTION ΓD (IB/FT3)
Plots of γd vs w (%) and γzav vs w (%)
130
125
120
115
γzav (Gs=2.68)
γd(max) = 109.8 Ib/ft3
110
105
100
Optimum
moisture
content = 14%
95
90
85
80
0
5
10
15
(%) MOISTURE CONTENT W
16
20
25
30