Geotechnical Materials and Compaction

Prévia do material em texto

1
• A. J. Clark School of Engineering •Department of Civil and Environmental Engineering
Sixth Edition
CHAPTER
4b
Construction Planning, Equipment, 
and Methods
GEOTECHNICAL MATERIALS, GEOTECHNICAL MATERIALS, 
COMPACTION, AND STABILIZATIONCOMPACTION, AND STABILIZATION
ByBy
Dr. Ibrahim AssakkafDr. Ibrahim Assakkaf
ENCEENCE 420 420 –– Construction Equipment and MethodsConstruction Equipment and Methods
Spring 2003 Spring 2003 
Department of Civil and Environmental EngineeringDepartment of Civil and Environmental Engineering
University of Maryland, College ParkUniversity of Maryland, College Park
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 75
Same weight but different volume. 
MATERIAL PROPERTIESMATERIAL PROPERTIES
2
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 76
Example 4Example 4
The soil borrow material to be used to The soil borrow material to be used to 
construct a highway embankment has a construct a highway embankment has a 
mass unit weight 96.0 lb per cu ft (mass unit weight 96.0 lb per cu ft (pcfpcf) ) 
and water content of 8%, and specific and water content of 8%, and specific 
gravity of soil solids is 2.66. The gravity of soil solids is 2.66. The 
specifications require that the soil be specifications require that the soil be 
compacted to dry unit weight of 112 compacted to dry unit weight of 112 pcfpcf
and that the water content be held to and that the water content be held to 
13%.13%.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Example 4 (cont’d)Example 4 (cont’d)
a)a) How many cubic yards of borrow are How many cubic yards of borrow are 
required to construct an embankment required to construct an embankment 
having a 250,000having a 250,000--cucu--yd net section yd net section 
volume?volume?
b)b) How many gallons of water must be How many gallons of water must be 
added per cubic yard of borrow material added per cubic yard of borrow material 
assuming no loss by evaporation and one assuming no loss by evaporation and one 
gallon of water equals 8.34 lb?gallon of water equals 8.34 lb?
c)c) If the compacted fill becomes saturated at If the compacted fill becomes saturated at 
a constant volume, what will be the water a constant volume, what will be the water 
content and mass unit weight of the soil?content and mass unit weight of the soil?
3
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Example 4 (cont’d)Example 4 (cont’d)
Borrow:Borrow:
Embankment:Embankment:
3
3
ft
lb89.88
08.01
96
1
66.2 8.0%, ,
ft
lb 0.96
=
+
=
+
=
===
ω
γγ
γ
d
sGω
( ) ( ) 3
3
ft
lb56.12613.011121
 13.0%, ,
ft
lb 0.112
=+=+=
==
ωγγ
γ
d
d ω
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 79
Example 4 (cont’d)Example 4 (cont’d)
(a):(a):
(b):(b):
ydcu 315,000yd)cu 001.26(250,0Required Borrow of Volume
26.1
89.88
112
eightDry Unit WBank 
eightDry Unit W CompactedFactor Shrinkage
==
===
( ) lb 000,280,98
yard
ft 27yard 000,250
ft
lb56.14 needed Water ofWeight 
ft
lb56.1411256.126
:embankmentin neededWater 
3
3
3
3
3
=










=
=−=− dγγ
4
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 80
Example 4 (cont’d)Example 4 (cont’d)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 81
Example 4 (cont’d)Example 4 (cont’d)
(b) continued:(b) continued:
( )
borrow ydcu 
gal 39.14 
lb/gal 34.8
1
ydcu 
lb120 
ydcu 
lb120
yard 315,000
lb 450,809,37 WaterdReq' of Gallons
lb 450,809,37550,470,60000,280,98Required Water Additional ofWeight 
 lb 550,470,60
yard
ft 27yard 000,315
ft
lb11.7 Borrow from Water ofWeight 
ft
lb11.789.8896
:borrow fromWater 
3
3
3
3
3
3
==
==
=−=
=










=
=−=− dγγ
5
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 82
Example 4 (cont’d)Example 4 (cont’d)
(c):(c): If the fill becomes saturated all voids between the solid soilIf the fill becomes saturated all voids between the solid soil
particles are filled with water. Therefore, the total weparticles are filled with water. Therefore, the total weight is ight is 
increased by the added weight of water:increased by the added weight of water:
Water
AIR
Soil
Weight 
air = 0
Weight 
water = Ww
Total 
weight W
Weight 
soil solids 
Ws
Volume 
air 
Va
Volume
soil solids
Vs
Volume
water 
Vw
Volume
voids 
Vv
Total
volume
V
Additional
Water to 
replace Air
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Example 4 (cont’d)Example 4 (cont’d)
Total volume includesTotal volume includes
AirAir
WaterWater
Solids Solids 
6
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 84
Example 4 (cont’d)Example 4 (cont’d)
(c): (c): continuedcontinued
Weight of extra waterWeight of extra water::
3
3
3
ft 092.0233.0675.0000.1
ft 233.0
4.62
56.14
ft 675.0
)4.62(66.2
112
=−−=
===
===⇒=
v
w
w
w
ws
s
s
ws
s
s
V
WV
G
WV
V
WG
γ
γγ
3ft
lb3.13211274.556.14
%1.18181.0
112
)74.556.14(
lb 74.5)4.62(092.0
=++=
==
+
==
===
γ
ω
γ
s
w
www
W
W
VW
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 85
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
7
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 86
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
The engineering properties of 
most soils can be improved 
by compaction.
Compaction is the art of 
mechanically densifying
materials.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 87
NON-COHESIVE
SMALL GRAINED 
< #200 MESH SIEVE
COHESIVE
SOIL TYPESSOIL TYPES
8
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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ORGANIC 
SOILS
Will usually 
have to remove 
before 
building.
SOIL TYPESSOIL TYPES
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 89
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
Before the specifications for a Before the specifications for a 
project are prepared project are prepared 
representative representative soil samplessoil samples are are 
usually collected and tested in usually collected and tested in 
the laboratory to determine the laboratory to determine 
material properties. material properties. 
9
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 90
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
SOIL CLASSIFICATION SOIL CLASSIFICATION 
((AtterburgAtterburg Limits)Limits)
LL - Liquid limit
PL - Plastic limit
PI - Plasticity Index
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 91
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
SOIL LIMITSSOIL LIMITS
10
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 92
LL - Liquid limit
is the water 
content of a soil 
when it passes 
from the plastic 
to liquid state.
SOIL CLASSIFICATIONSOIL CLASSIFICATION
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 93
LL - Liquid limit
Non-cohesive or sandy soils 
have low LLs -- less than 20.
Clay soils have LLs ranging 
from 20 to 100.
SOIL CLASSIFICATIONSOIL CLASSIFICATION
11
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 94
PL - Liquid limit
is the lowest 
water content at 
which a soil 
remains plastic.
1/8 inch diameter thread
SOIL CLASSIFICATIONSOIL CLASSIFICATION
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 95
PI - Plastic Index
PI = LL - PL
The higher the PI the more 
clay that is present in the soil.
SOIL CLASSIFICATIONSOILCLASSIFICATION
12
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 96
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
Normal testing would include Normal testing would include 
graingrain--size analysissize analysis because the because the 
size of the grains and the size of the grains and the 
distribution of those sizes are distribution of those sizes are 
important properties, which important properties, which 
affect a soil's suitability.affect a soil's suitability.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Soil gradation is 
the distribution, 
in percent (%) 
by weight, of 
individual 
particle sizes.
COMPACTIONCOMPACTION
13
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
Soil Gradation (ParticleSoil Gradation (Particle--size Distribution)size Distribution)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
Maximum Dry Density/Optimum Maximum Dry Density/Optimum 
MoistureMoisture
Critical test is the construction of a 
compaction curve. 
From compaction curves the 
maximum dry unit weight (density) 
and the percent water required to 
achieve maximum density can be 
determined. 
14
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 100
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 101
COMPACTION SPECIFICATION COMPACTION SPECIFICATION 
AND CONTROLAND CONTROL
Maximum Dry Density/Optimum Maximum Dry Density/Optimum 
Moisture (cont’d)Moisture (cont’d)
This percent of water, which 
corresponds to the maximum dry 
density (for a given compactive
effort), is known as the optimum 
water content.
15
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
The standard laboratory tests that are 
used for evaluation of maximum dry 
unit weights (γd’s) and optimum 
moisture contents for various soils are:
1. The Standard Proctor Test (ASTM 
D-698 and AASHTO T-99).
2. The Modified Proctor Test (ASTM, 
D-1557 and AASHTO T-180)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Standard Proctor TestStandard Proctor Test
The soil is compacted in a mold that 
has a volume of 1/30 ft3 (943.3 cm3).
The diameter of the mold is 4 in. (101.6 
mm)
During the laboratory test, the mold is 
attached to a base plate at the bottom 
and to an extension at the top (see 
Figure 1). 
16
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Standard Proctor TestStandard Proctor Test
The soil is mixed with varying 
amounts of water and then 
compacted in three equal layers by 
a hammer (Figure 2) that deliver 25 
blows to each layer.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Figure 1. Standard Proctor Test Equipment: (a) mold; (b) hammer
17
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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PROCTOR TEST
Standard Proctor
or
AASHTO T-99
Soil sample 1/30 cubic foot
3 layers
COMPACTIONCOMPACTION
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 107
COMPACTION TESTSCOMPACTION TESTS
Figure 2Figure 2. Compaction . Compaction 
of Soil using Standard of Soil using Standard 
Proctor HammerProctor Hammer
( courtesy of John ( courtesy of John 
Hester, Carterville, IL)Hester, Carterville, IL)
18
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COMPACTION TESTSCOMPACTION TESTS
Standard Proctor Test (continued)Standard Proctor Test (continued)
The hammer weighs 5.5 lb (mass = 
2.5 kg) and has a drop of 12 in. 
(304.8 mm).
For each test, the moist unit weight 
of compaction γ can be calculated as
mV
W
=γ (28)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 109
COMPACTION TESTSCOMPACTION TESTS
Standard Proctor Test (continued)Standard Proctor Test (continued)
Where
W = weight of compacted soil in mold
Vm = volume of mold (1/30 ft3)
For each test, the moisture content w of 
the compacted soil is determined in the 
laboratory.
With known moisture content, the dry unit 
weight γd can be calculated as
19
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Standard Proctor Test (continued)Standard Proctor Test (continued)
ω
γγ
+
=
1d
(29)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 111
COMPACTION TESTSCOMPACTION TESTS
Standard Proctor Test (continued)Standard Proctor Test (continued)
Where w = moisture content
The values of γd determined from the 
above equation can be plotted 
against the corresponding moisture 
contents for the soil as shown the 
following figure (Fig. 3), which is a 
compaction for silty clay.
20
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COMPACTION TESTSCOMPACTION TESTS
Figure 3. Standard Proctor Compaction Test Results for a Silty Clay
Figure 3Figure 3
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Standard Proctor Test (continued)Standard Proctor Test (continued)
For a given moisture content ω, the 
theoretical maximum dry unit weight 
is obtained when there is no air in 
the void spaces, that is, when the 
degree of saturation S equal 100%. 
Thus, the maximum dry unit weight at 
a given moisture content with zero air 
voids can computed from
21
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Standard Proctor Test (continued)Standard Proctor Test (continued)
s
ws
s
ws
G
G
Ge
e
G
ω
γγ
ω
γγ
+
=
=
+
=
1
so , ,saturation 100%For 
1
zav
zav
(30)
(31)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 115
COMPACTION TESTSCOMPACTION TESTS
Modified Proctor TestModified Proctor Test
The soil is compacted in a mold that 
has a volume of 1/30 ft3 (943.3 cm3).
The diameter of the mold is 4 in. 
(101.6 mm)
During the laboratory test, the mold is 
attached to a base plate at the 
bottom and to an extension at the top 
(see Figure 4).
22
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 116
COMPACTION TESTSCOMPACTION TESTS
Modified Proctor Test (cont’d)Modified Proctor Test (cont’d)
The soil is mixed with varying 
amounts of water and then 
compacted in five equal layers by a 
hammer (Figure 2) that deliver 25
blows to each layer.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 117
COMPACTION TESTSCOMPACTION TESTS
Figure 4. Modified Proctor Test Equipment: (a) mold; (b) hammer
23
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 118
Soil sample 1/30 cubic foot
5 layers
COMPACTIONCOMPACTION
PROCTOR TEST
Modified Proctor
or
AASHTO T-180
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 119
COMPACTION TESTSCOMPACTION TESTS
Modified Proctor Test (cont’d)Modified Proctor Test (cont’d)
The hammer weighs 10 lb (mass = 
4.54 kg) and has a drop of 18 in. 
(457.2 mm).
For each test, the moist unit weight 
of compaction g can be calculated as
mV
W
=γ (32)
24
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 120
COMPACTION TESTSCOMPACTION TESTS
Modified Proctor Test (cont’d)Modified Proctor Test (cont’d)
W = weight of compacted soil in mold
Vm = volume of mold (1/30 ft3)
For each test, the moisture content ω of 
the compacted soil is determinedin the 
laboratory.
With known moisture content, the dry 
unit weight γd can be calculated (Eq.29)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTION TESTSCOMPACTION TESTS
Modified Proctor Test (cont’d)Modified Proctor Test (cont’d)
The values of γd determined from the 
above equation can be plotted 
against the corresponding moisture 
contents for the soil as shown the 
following figure (Fig. 5).
25
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 122
COMPACTION TESTSCOMPACTION TESTS
Figure 5. Standard and Modified Compaction Curves
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 123
Comparison between Standard Comparison between Standard 
& Modified Proctor Tests& Modified Proctor Tests
Figure 5 shows compaction Figure 5 shows compaction 
curves which illustrate the effect curves which illustrate the effect 
of varying amounts of moisture of varying amounts of moisture 
on the density of a soil subjected on the density of a soil subjected 
to given to given compactivecompactive efforts.efforts.
The two energy levels depicted The two energy levels depicted 
are known as standard and are known as standard and 
modified Proctor tests. modified Proctor tests. 
26
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 124
It should be noted that the It should be noted that the 
modified Proctor, which is a modified Proctor, which is a 
higher energy level, gives a higher energy level, gives a 
higher density at a lower higher density at a lower 
moisture content than the moisture content than the 
standard Proctor, as shown standard Proctor, as shown 
in Figure 5.in Figure 5.
Comparison between Standard Comparison between Standard 
& Modified Proctor Tests& Modified Proctor Tests
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 125
In this figure, the In this figure, the 
optimum moisture for optimum moisture for 
the standard Proctor is the standard Proctor is 
16%, versus 12% for the 16%, versus 12% for the 
modified Proctor. modified Proctor. 
Comparison between Standard Comparison between Standard 
& Modified Proctor Tests& Modified Proctor Tests
27
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 126
Example 5Example 5
The laboratory test data for a The laboratory test data for a 
standard Proctor test are given standard Proctor test are given 
as shown in Table 3. Find the as shown in Table 3. Find the 
maximum dry unit weight and maximum dry unit weight and 
the optimum moisture content.the optimum moisture content.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 127
Example 5 (cont’d)Example 5 (cont’d)
Table 3. Test Data for Example 5Table 3. Test Data for Example 5
Volume of Mold (ft3) Weight of Wet Soil in the Mold (lb) Moisture Content ω (%) 
1/30 3.88 12 
1/30 4.09 14 
1/30 4.23 16 
1/30 4.28 18 
1/30 4.24 20 
1/30 4.19 22 
 
28
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Example 5 (cont’d)Example 5 (cont’d)
Volume, V (ft3) Weight, W (lb) γ (lb/ft3) ω (%) γ d (lb/ft3) 
1/30 3.88 116.4 12 103.9 
1/30 4.09 122.7 14 107.6 
1/30 4.23 126.9 16 109.4 
1/30 4.28 128.4 18 108.8 
1/30 4.24 127.2 20 106.0 
1/30 4.19 125.7 22 103.0 
 
( ) 33 ft
lb6.107
14.01
7.122
1
 ,
ft
lb7.122
30/1
09.4
Hence 12%, 4.09, Soil Wet ofWeight 
:nCalculatio Sample
=
+
=
+
====
==
ω
γ
ω
dγV
Wγ
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 129
Example 5 (cont’d)Example 5 (cont’d)
Plot the dry unit weight gd against the 
moisture content w as shown in the 
following figure(Figure 6). From the 
figure find the maximum γd and 
optimum ω.
Maximum dry unit weight = 109.5 lb/ftMaximum dry unit weight = 109.5 lb/ft33
Optimum moisture content = 16.5%Optimum moisture content = 16.5%
29
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Example 5 (cont’d)Example 5 (cont’d)
Figure 6. Compaction Curve for the Data of Example 5Figure 6. Compaction Curve for the Data of Example 5
102
103
104
105
106
107
108
109
110
10 12 14 16 18 20 22 24
Moisture Content, ω (% )
D
ry
 U
ni
t W
ei
gh
t, 
(lb
/ft
^3
)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 131
COMPACTION COMPACTION 
SPECIFICATIONSSPECIFICATIONS
Typically 
specifications 
give an 
acceptable range 
of water content, 
OMC ± 2% for 
example. 
30
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 132
In most specifications for earth work, In most specifications for earth work, 
the contractor is required to achieve a the contractor is required to achieve a 
compacted field dry unit weight of 90% compacted field dry unit weight of 90% 
to 95% of the maximum dry unit weight.to 95% of the maximum dry unit weight.
The maximum dry unit weight is the The maximum dry unit weight is the 
maximum unit weight that is determined maximum unit weight that is determined 
by either the by either the standardstandard or or modifiedmodified
Proctor test.Proctor test.
SPECIFICATIONS FOR FIELD SPECIFICATIONS FOR FIELD 
COMPACTIONCOMPACTION
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 133
COMPACTION COMPACTION 
SPECIFICATIONSSPECIFICATIONS
The specification 
also sets a 
minimum 
density, 90% or
95% of max. dry 
density for a 
specific test. 
123.
5
31
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 134
C
O
M
P
AC
TI
O
N
 
C
O
M
P
AC
TI
O
N
 
SP
EC
IF
IC
AT
IO
N
S
SP
EC
IF
IC
AT
IO
N
S 123.5
Must 
work in 
the box.
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 135
COMPACTION COMPACTION 
SPECIFICATIONSSPECIFICATIONS
Lift.Lift. A layer of soil placed 
on top of soil previously 
placed in an embankment. 
The term can be used in 
reference to material as 
spread or as compacted.
32
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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COMPACTIONCOMPACTION
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
The specification for field The specification for field 
compaction can be based compaction can be based 
either oneither on
(1) relative compaction RC or
(2) relative density Dr
33
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
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Slide No. 138
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
The relative compaction (RC), is therefore, 
defined as the ratio of the dry unit weight 
of the soil in the field to the maximum dry 
unit weight of the same soil determined in 
the laboratory
100(%) 
lab) (max,
(field) ×=
d
dRC
γ
γ
(33)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 139
The relative density Dr is given by
(34)
( ) 


 −
−
=
RC
R
R
Dr 0
0
1
1
1
(max)
(min)
0
d
dR
γ
γ
=
where
γd(min) = dry unit weight in the loosest condition
(at a void ratio of emax)
γd(max) = dry unit weight in the densest condition
(at a void ratio of emin) 
SPECIFICATIONS FOR FIELD SPECIFICATIONS FOR FIELD 
COMPACTIONCOMPACTION
34
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 140
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
ASTM Test Designation DASTM Test Designation D--2049 2049 
provides a procedure for the provides a procedure for the 
determination of the minimum and determination of the minimum and 
maximum dry unit weights of maximum dry unit weights of 
granular soils.granular soils.
For sands, this done by using a For sands, this done by using a 
mold with a volume of 0.1 ftmold with a volume of 0.1 ft33 (2830 (2830 
cmcm33).).
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No.141
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
For determination of the minimum For determination of the minimum 
dry unit weight, sand is loosely dry unit weight, sand is loosely 
poured into the mold from a funnel poured into the mold from a funnel 
with a 1/2with a 1/2--in (12.7in (12.7--mm) diameter mm) diameter 
spout.spout.
The average height of the fall of The average height of the fall of 
sand into the mold is kept at about sand into the mold is kept at about 
1 in (25.4 mm)1 in (25.4 mm)
35
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 142
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
The value of The value of γγdd(min(min)) can then be can then be 
determined asdetermined as
m
s
d V
W
=(min)γ
where
Ws = weight of sand required to fill the mold
Vm = volume of the mold (0.1 ft3)
(35)
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 143
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
The maximum dry unit weight is 
determined by vibrating sand in the 
mold for 8 min.
A surcharge of 2 lb/in2 (13.8 kN/m2) is 
added to the top of the sand in the 
mold.
The mold is placed on a table that 
vibrates at a frequency of 3600 
cycles/min and that has an amplitude 
of vibration of 0.025 in (0.635 mm).
36
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 144
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
The value of The value of γγdd(max(max)) can then be can then be 
determined at the end of the determined at the end of the 
vibrating period with the knowledge vibrating period with the knowledge 
of the weight and volume of sand.of the weight and volume of sand.
An empirical formula has been An empirical formula has been 
developed by Lee and Singh (1971) developed by Lee and Singh (1971) 
to give a relationship between to give a relationship between RCRC
and and DDrr..
CHAPTER 4b. GEOTECHNICAL MATERIALS & COMPACTION
ENCE 420 ©Assakkaf
Slide No. 145
SPECIFICATIONS FOR SPECIFICATIONS FOR 
FIELD COMPACTIONFIELD COMPACTION
For granular soils, the relationship For granular soils, the relationship 
is given asis given as
RC (%) = 80 +0.2 Dr
According to Lee and Singh (1971), the correlation 
between RC and Dr was based on the observation 
of 47 soil samples.
(36)