Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show. Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.

1. 1
Geotechnical Engineering–I [CE-221]
BSc Civil Engineering – 4th Semester
by
Dr. Muhammad Irfan
Assistant Professor
Civil Engg. Dept. – UET Lahore
Email: mirfan1@msn.com
Lecture Handouts: https://groups.google.com/d/forum/2016session-geotech-i
Lecture # 14
9-Mar-2018

2. 2
Ultimate goal → to obtain compaction curve of soil
Test Procedure → Standard Proctor Test
(ASTM ASTM D-698 or AASHTO T-99)
SOIL COMPACTION –
LABORATORY EVALUATION

3. 3
Ultimate goal →
STANDARD PROCTOR TEST
(ASTM D-698 or AASHTO T-99)
Moisture content, w (%)
DryDensity,γd
Drop height = 12 in
25 blows/layer
5.5 lb
w1
γb(1) = W/V
25 blows/layer
w2 (w2 > w1)
γb(2)
Repeat the test
by adding
more water
Repeat the same
procedure by
adding more and
more water every
time.
)1( w
b
d




to obtain compaction curve of soil.
→ OMC & γd(max)

4. 4
Developed by R.R. Proctor (1933)
Equipment
 Volume of mold = 1/30 ft3 (943.3 cm3)
 Diameter of mold = 4 in (101.6 mm)
 Weight of hammer = 5.5 lb (2.45 kg)
 Drop height = 12 in (305 mm)
 Soil compacted in 3 layers
 25 blows per layer
STANDARD PROCTOR TEST
33
2
10944.0
)3()/25()3048.0()/81.9(495.2
m
layerslayerblowsmsmkg
E 



Volume of mold
Number of
blows per layer
Number of
layers
Weight of
hammer
Height of
drop of
hammer
  
E =
Compaction
Energy, E
)/375,12(/7.592 33
ftlbftmkJE 

(ASTM D-698 or AASHTO T-99)

5. 5
 Developed during World War II by U.S. Army Corps of
Engineers
 to represent compaction required at airfields to support heavy
aircrafts.
Equipment
 Volume of mold = 1/30 ft3
 Diameter of mold = 4 in
 Weight of hammer = 10 lb
 Drop height = 18 in
 Soil compacted in 5 layers
 25 blows per layer
DryDensity(γd)
Water Content (w)
Modified Effort
Standard Effort
MODIFIED PROCTOR TEST
(ASTM D-1557 or AASHTO T-180)

6. 6
Standard
Proctor Test
Modified
Proctor Test
Mold size (ft3) 1/30 1/30
Height of drop (inch) 12 18
Hammer weight (lb) 5.5 10
No. of layers 3 5
No. of blows per layer 25 25
Energy (ft.lb/ft3) 12,375 56,250
STANDARD vs MODIFIED
PROCTOR TEST

7. 7
STANDARD vs MODIFIED
PROCTOR TEST
Zero Air Voids Curve
The curve represents the
fully saturated condition (S
= 100 %).
Line of Optimums
 A line drawn through
the peak points of
several compaction
curves at different
compactive efforts.
 Will be almost parallel
to ZAV Curve.

8. 8
 OMC is typically slightly less
than the plastic limit (ASTM
suggestion).
 Typical values of OMC are
between 10% and 20%, with
an outside maximum range of
about 5% to 40%.
 Typical values of γd(max) are
around 16 to 20 kN/m3 with
the maximum range from
about 13 to 24 kN/m3.
COMPACTION – Notes

9. 9
 Lab compaction not commonly
performed on soils with fines ≤
12 %.
 Clean sands are compacted most
easily at either very dry or very
wet water contents
 At intermediate water contents,
capillary stresses in voids resist
compaction
 Bulking is term for this
phenomenon
COMPACTION – Notes
Moisture content, w (%)
DryDensity,γd

10. 10
The laboratory test for a standard proctor is shown below. Determine the
optimum water content and maximum dry density. If Gs of the soil is 2.70,
draw the ZAV curve.
PRACTICE PROBLEM #1
Volume of
Proctor Mold
(ft3)
Weight of wet soil
in the mold (lb)
Water Content
(%)
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

11. 11
Volume of
Proctor
Mold
(ft3)
Weight of
wet soil in
the mold
(lb)
Wet Unit
Weight
(lb/ft3)
Water
Content
(%)
Dry Unit
Weight
(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
PRACTICE PROBLEM #1

12. 12
PRACTICE PROBLEM #1
OMC = 16.6%
γd(max) = 109.5 lb/ft3

13. 13
Practice Problem #2

14. 14
Practice Problem #2

15. 15
Practice Problem #2

16. 16
RELATIVE COMPACTION
FIELD COMPACTION
Use of compaction curve?
 Not possible to obtain
γd(max) in field.
 In the field, contractor is
usually required to compact
the soil to 90-95% γd(max).
Relative compaction, or percent compaction is defined as the ratio of the
(γd)field to (γd max)lab.
Moisture
Content
Dry Density
γd(max)
(OMC)
ZAV
95% γd(max)

17. 17
CONCLUDED
REFERENCE MATERIAL
An Introduction to Geotechnical Engineering (2nd Edition)
By R. D. Holtz, W. D. Kovacs and T. C. Sheahan
Chapter #5
Principles of Geotechnical Engineering – (7th Edition)
Braja M. Das
Chapter #6

18. 18
Relative density (Dr) is commonly used to indicate the in-situ
denseness or looseness of granular soils.
100
minmax
max









ee
ee
Dr
RELATIVE DENSITY (Dr)

19. 19
e
G ws
d


1


minmax
max
ee
ee
Dr



1
d
wsG
e

 1
(min)
max 
d
wsG
e


1
(max)
min 
d
wsG
e


Substituting e, emin, and emax into equation of Dr
(max)(min)
(min)
11
11
dd
dd
rD





RELATIVE DENSITY (Dr)

















d
d
dd
dd



 (max)
(min)(max)
(min)

20. 20
Practice Problem-1
A sand deposit was compacted to an in-situ void ratio of 0.25. Void ratios
determined for this soil in the loosest and densest states were found to be
equal to 0.7 and 0.3 respectively. Determine the relative density and the
corresponding dry density of this soil. Assume specific gravity of the soil to be
2.65.
RELATIVE DENSITY (Dr)
Practice Problem-2
A standard test performed in lab to determine the relative density of a soil
yielded the following results;
Volume of cylinder = 600 cm3
Weight of soil filling the cylinder in loose form = 1030.4 g
Weight of soil in dense form = 1030.4 g
Volume of the cylinder when soil is in dense form = 561.5 cm3
If the in-situ void ratio of the same soil is 0.487, determine the relative density
of soil.

21. 21
Relative Compaction vs Relative Density
minmax
max
ee
ee
Dr



rC DR 2.080 
Statistical result based
on 47 soil samples.