Highway Engineering Common Laboratory Tests

1. Highway Engineering
Common Laboratory Tests
Materials Research and Testing Centre (MRTC)

2. Before we start
◉ All students and staff shall wear a face mask, covering
their nose and mouth at all times.
◉ All students shall sanitize/disinfect/wash their
when entering the lab.
hands
◉ All students and staff shall abide to social distancing
limit close contact
guidelines; if not possible, .
◉ All students and staff should inform the responsible
body if they have flu like symptoms.
2

3. Before we start
◉ Do not eat or drink in the laboratory.
◉ Footwear must have enclosed toes and heals
(no sandals); especially, in the Materials
laboratory.
◉ Confine long hair, loose clothing or jewelry
when in laboratory.
◉ Report any and all accidents immediately to
laboratory staff.
3

4. Before we start
◉ Make sure to obtain the appropriate training
and/or authorization before operating any
equipment or utilize any material.
◉ Use laboratory equipment only for its intended
purpose.
◉ Place tools and equipment in proper place
after use.
4

5. Before we start
◉ Keep the workbench clear of all but the
required materials.
◉ Keep pathways free of obstruction.
◉ Clean up spills immediately.
◉ If you are uncertain about anything, ASK!
5

6. Instruction
Soil related
◉ is divided in to two, and Material
related.
◉ Each Experiment will take 2- 3 hrs.
◉ Groups of 10 – 12students
◉ All data should be collected on the
provided sheets
6

7. Objectives
◉ limited review fundamental laboratory testing used
in highway construction
◉ To understand and recall Apparatus and
procedures used in testing
◉ To perform the test according to the procedures
◉ To perform computation on test data and present
results
◉ Interpret and discuss test result
7

8. Contents
◉ Experiment-1: Moisture Content – Density
Relationship (Soil Compaction)
◉ Experiment-2: In-place Density measurement
by sand cone method
◉ Experiment- 3: California Bearing Ratio (CBR)
8

9. This laboratory instruction is given by
◉ Mathewos Endeshaw
◉ Wondwessen Tassew
◉ Shewagergesh Tadesse
◉ Abiy Fanta
◉ Workineh Kenenisa
◉ Saron Getachew
◉ Omedela Tadesse
Hello!
9

10. Experiment-1
Moisture-Density
Relationship
(Soil Compaction)
1
gqNtZGzNAw2jcnBszQii
Number of slides: 26
Duration: 20 min
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11. Background
2
• Soil compaction is the process of densification of soil through the reduction of
air void by the application of mechanical energy.
• The purpose of compaction is to improve the engineering property of the soil
by increasing its strength, reducing its compressibility and reducing its
hydraulic conductivity.
• The degree of compaction is dependent on multiple factors, including
• the moisture content at which the soil is compacted
• the amount of energy applied per unit volume of soil
• the type of compaction effort: impact, static, vibratory, kneading
• The effect of moisture content on compaction for a given soil at a given energy
input and type is represented by a moisture - density relationship.

12. Background
• The water in the pore space of the soil
can be thought of as a lubricant.
• When the water content is low the soil
particles will require a higher amount of
energy to move relative to each other
during compaction.
• As the water content increase, the water,
acting as a lubricant, will aid the relative
displacement of the particles resulting in
reduction of air voids and an increase the
density of soil.
• But too much water will interfere with the
compaction
• Hence, their is an optimum moisture
content (OMC) which results in a
maximum dry density (MDD)
3

13. Background
• At a constant water content and for a
given type of compaction effort, the
more energy applied the higher the
dry density.
• For the same type compaction effort, a
higher maximum dry density can be
achieved at a lower optimum
moisture content for a higher
energy input.
4
Braja M. Das, Principles of Geotechnical
Engineering , 2010

14. Background
5
• In the 1930s, R. R. Proctor developed a laboratory test method which involves
fixing the compaction effort to a value that is practicable and relevant to
construction equipment and the effort type to impact compaction.
• The method was called standard effort compaction (or the standard Proctor
compaction) the compaction effort proposed was 600 KJ/m3
• U.S. Army Corps of Engineers during construction of air bases developed a
similar method that set the energy input at 2700 KJ/m3. This method is called
modified effort compaction (or modified proctor compaction)
• By using such forms of laboratory compaction testing the moisture-density
relationship can be plotted.

15. Purpose
6
The reasons for conducting laboratory compaction include
• To provide a water content value that will achieve the maximum dry density for the
given energy input and soil type (optimum moisture content) for construction
operations.
• The maximum dry density achieved by the laboratory compaction test is used in
compaction control operations in the field.
• Most earthwork specifications will set a minimum limit on the degree of compaction,
which is the ratio of dry density achieved on site to the maximum dry density obtained
from laboratory testing.

16. Apparatus
7
1. Compaction Mold Assembly: Cylindrical molds where the compaction occurs
• There are two types of molds
• 4-in mold: having a height of about 116.4mm and an inside diameter of about 101.6mm
• 6-in mold: having the same height but an inside diameter of about 152.4 mm
• The 4−in mold has a volume of about 944cm3 while the 6−in mold has about
2124cm3
• The reason for having two types of
molds is to accommodate both fine
grained and coarse grained soils
• The assembly also consists of an
extension collar, which is used in
assisting the compaction process and a
base plate where the assembly seats.
https://civiconcepts.com/blog/standard-proctor-test

17. Apparatus
• Rammers involve a cylindrical sleeve
housing a weight that can move freely in
the sleeve.
• The weight is attached to a rod at the top
and the sleeve is open at the bottom.
• The rammer is pulled up by the rod to the
top of the sleeve and allowed to free fall
to the bottom where it will impact the soil
surface.
• There are two types of rammers:
• The first has a weight of 24.5 N and can
free fall from a height of 30.5cm
• The second has a weight of 44.5N and
can free fall from a height of 45.7cm
2. Compaction Rammers : Impact devices to exert the required amount of
energy for compaction.
sleeve
8
Weight
https://www.ele.com/product/bs-compaction-rammer-4-5kg-wt-
rod
• The reason for having two rammers is to
account for the standard effort
compaction and modified effort
compaction methods

18. Apparatus
3. Drying oven: Thermostatically controlled oven, capable of maintaining a uniform
temperature of 110±5°C throughout the drying chamber.
4. Balance
5. Straight edge: A stiff metal straight edge of any convenient length but not less than
250 mm.
6. Sieves: The following sieves are required
Sieve
opening size
9
Alternative
designation
4.75mm No. 4
9.5mm 3/8 in
19.0 mm 3/4 in
7. Moisture Specimen Containers
8. Mixing Tools: Miscellaneous tools such as mixing pan, spoon, trowel, spatula,
graduated cylinders, water bottles.

19. Procedure
• First we will discuss the standard effort compaction test.
• There are three method, associated with the standard effort compaction test
designated as A, B and C.
• The three methods defer by the type of soil gradation used in the test.
Method Usage
Method A used if 25 % or less by mass of the material is retained
on the 4.75-mm sieve
Method B used if 25 % or less by mass of the material is retained
on the 9.5-mm sieve
Method C used if 30 % or less by mass of the material is retained
on the 19.0-mm sieve
The test method discussed here are only
applicable for material with less the 30%
passing the 19mm sieve
The procedures discussed here are
based on ASTM D698 and D1557
10

20. Procedure
1. Identify which method to use based on the grain size distribution of the soil
2. Identify the apparatus to be used based on the method identified.
Method Mold
Method A 4-in
Method B 4-in
Method C 6-in
3. Sample preparation
a. Air dry the sample
b. Select at least 5 representative subsamples as the fraction of air dried sample passing the
sieve specified by the method
Generally, a sample size of
about 3000g for each
subsample is required for
Method A & B and 5000g for
Method C
Method Sample passing sieve
Method A 4.75 mm
Method B 9.5 mm
Method C 19 mm
For the standard effort
compaction the 24.5 N
rammer is used
11

21. Procedure
12
4. Prepare each of the 5 subsamples by adding water and mixing
• The water added should be in such a way that the five preparations bracket an
estimated OMC
• One way to do this is to prepare one of the subsamples to be at OMC through trial
addition of water, The OMC may be estimated based on the following considerations
• Typically, cohesive soils at the optimum water content can be squeezed into a lump that
barely sticks together when hand pressure is released, but will break cleanly into two
sections when “bent.”
• Cohesive soils tend to crumble at molding water contents dry of optimum; they tend to
stick together in a sticky cohesive mass wet of optimum.
• For cohesive soils, the optimum water content is typically slightly less than the plastic limit.
• For cohesion less soils, the optimum water content is typically close to zero or at the point
where bleeding occurs.
• For the rest of subsample, at least two of which should be prepared on the dry of
optimum at about 2% interval, the other two wet of optimum at 2% interval.
• If the samples are cohesive let the prepared subsamples stand for at least 16hrs in
water tight containers

22. Procedure
13
5. Compaction (After standing time is over)
a. Determine and recorded mass of mold and base plate (without the extension
collar) [Mmb]
b. Assemble the mold, base plate and extension collar
c. Take one of the five subsample
d. Compaction is to be done is layers of 3; hence, take about 1/3 of the sample and
place it in the mold.
e. Compact this layer by applying impact blows using the rammer (24.5N). The
number of blows per layer depends on the method
Method Number of Blows per layer
Method A 25
Method B 25
Method C 56

23. Procedure
f. Once you have compacted the 1st layer, repeat the compaction for the next two.
• when compacting the rammer must be raised fully and allowed to free fall.
• the rammer must be held perpendicular to the soil surface.
• When compacting one may follow a circular pattern as shown below
The top surface of the third
layer after compaction must
extended in to the extension
collar above the mold
14
ASTM D698-12

24. Procedure
6. Slowly detach the extension collar and using a straight edge, trim the excess
soil above the mold, until it is flush with the mold edges.
7. Clean the exterior of mold and base plate from any excess soil
8. Determine and record the mass of mold, compacted soil and base plate, [Mmbs]
9. Disassemble the mold and base plate. Extrude the compacted soil
10.Determine the water content of the compacted soil [w], making sure to take
representative samples from each of the three layers for moisture content
determination.
11.Repeat steps 5-11 for the remaining subsample.
For the specific procedure involved in water content/moisture content
measurement refer to previous notes.
15

25. Procedure
16
• For the case of Modified effort compaction, the procedure is similar to the
standard effort
• The modified effort compaction also has three methods
• But note the following exceptions
• The 44.5 N rammer with a free fall height of 45.7 cm is used
• Compaction of each subsample is done in 5 layers instead of 3

26. Procedure
17
Summary of Standard effort compaction
Method A Method B Method C
Sample Passing 4.75mm Passing 9.5mm Passing 19.0mm
Mold 4-in 4-in 6-in
Rammer 24.5 N@30.5cm 24.5 N@30.5cm 24.5 N@30.5cm
Number of layers 3 3 3
Number of blows per
25 25 56
layer

27. Procedure
18
Summary of Modified effort compaction
Method A Method B Method C
Sample Passing 4.75mm Passing 9.5mm Passing 19.0mm
Mold 4-in 4-in 6-in
Rammer 44.5 N@45.7cm 44.5 N@45.7cm 44.5 N@45.7cm
Number of layers 5 5 5
Number of blows per
25 25 56
layer

28. Computation
• The test data set will involve at least 5 values of Mmb , Mmbs , w for each of the
subsamples
1. Determine the bulk density (𝝆)
𝑀𝑚𝑏𝑠 − 𝑀𝑚𝑏
𝜌 =
𝑉
Where V is to the volume of mold
2. Determine the dry density (𝝆𝒅)
𝜌
𝜌𝑑 =
1 + 𝑤
19

29. Computation
OMC
• Plot the water content - dry density points, with the water content as abscissa and
dry density as ordinate and connect the points with a smooth line.
• From the plot read the OMC and MDD
MDD
OMC = 17.9%
MDD = 1.78g/cm3
20

30. Discussion
Additional Considerations
• In presenting the results, the zero air-void line (100% saturation line) is also
plotted
• The zero-air void represents the state of the compacted soil, if all the aid void was
removed (i.e. if the soil was saturated at the molding water content)
• The zero air void line may be computed using the equation
𝜌𝑑,𝑠𝑎𝑡 =
𝑆 𝐺𝑠
𝑠
𝑤 𝐺 + 𝑆
𝜌
21
𝑤
Where, S is the degree of saturation (for the Zero air-void line, S = 1.0),
Gs is the specific gravity of the soil solids and
𝜌𝑤 is the density of water. For the purpose of this experiment, it may be taken as 1.0 g/cm3

31. Discussion
• The moisture-density relationship curve is always to the left of the zero air-void
line and does not cross it.
OMC
MDD
OMC = 17.9 %
MDD = 1.78g/cm3
22

32. Discussion
Expected results for standard effort compaction
23
Classification (USCS) OMC MDD
Soil group Soil type (%) (g/cm3
)
GW Well graded clean gravel, gravel-sand mix 11 - 8 2.00 - 2.16
GP poorly graded clean gravel, gravel-sand mix 14 - 11 1.84 – 2.00
GM Silty gravel, poorly graded gravel-sand-silt mix 12 - 8 1.92 - 2.16
GC Clayey gravel, poorly graded gravel-sand-clay mix 14 - 9 1.84 - 2.08
SW Well graded clean sand, sand-gravel mix 16 - 9 1.76 - 2.08
SP poorly graded clean sand, sand-gravel mix 21 - 12 1.60 - 1.92
SM Silty sand, poorly graded sand-silt mix 16 - 11 1.76 – 2.00
SM-SC Silty sand clay mix with slightly plastic fines 15 - 11 1.76 - 2.08
SC clayey sand, poorly graded sand-clay mix 19 - 11 1.68 – 2.00
ML Inorganic silt 24 - 12 1.52 - 1.92
ML-CL Mix of inorganic silt and lean clay 22 - 12 1.60 - 1.92
CL Lean clay 24 - 12 1.52 - 1.92
OL low pastic organic fines, organic silt or silty clay 33 - 21 1.28 - 1.60
MH Inorganic plastic silt 40 - 24 1.12 - 1.52
CH Fat clay 36 - 19 1.20 - 1.68
OH high plastic organic fines, organic clays or clayey silt 45 - 21 1.04 - 1.60
Adopted from NAVFAC DM 7.02 1986

33. Discussion
Energy input (compaction effort) [E] for laboratory compaction may be calculated as
𝐸 = 𝑚 𝑔 ℎ 𝑁𝐿 𝑁𝑏
𝑉
Where: m is the mass of the rammer weight,
g is acceleration due to gravity (g = 9.81m/s2),
h is the free fall height of the rammer weight,
NL is the number of layers,
Nb is the number of blows per layer,
V is the volume of the mold
Verify that the energy input for
standard effort compaction is 600
KJ/m3 and for modified effort
compaction is 2700 KJ/m3, using the
formula above
24

34. Discussion
25
• Sources of Error:
• The sample selected should be representative of the material under
investigation. To ensure representativeness, techniques for field sampling and
laboratory sample reduction (such as quartering) are used.(not discussed
here).
• Not allowing the subsample to stand after mixing incase of cohesive soils may
result in non-uniform moisture distribution.
• The volume of the mold needs to be calibrated to determine its “true” value
and compared against standard values. Simply using a nominal volume
provided in literature may cause errors. (not discussed here)
• The test discussed here is only applicable for soils with less than 30% retained
on the 19 mm sieve. For cases where this is not met correction factor may be
used. (not discussed here)
• During compaction, one needs to lift the weight to the top of the sleeve and let
it free fall. The weight must impact the soil surface perpendicularly.
• During water content determination the water content specimen must be
representative of all layers.

35. THE END
Questions ?
26

36. Experiment-2
In-Place Density
Measurement by Sand-
Cone Method
Number of slides: 14
Duration: 15 min
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earthworks/? cf_chl_managed_tk =pmd_6d9fa9fe224a5381f2144462ea38d7c10e690542-1628749586-0-
gqNtZGzNAw2jcnBszQii

37. Background
• Density is the measure of degree of packing of a material.
• Mathematically, the mass density is defined as
Where: M is mass
V is Volume
V
2
=
M

38. Background
• For soil one may define different types
of density
• Depending on the phase under
consideration or the state of the soil
mass
• For the purpose of this test we will
discuss the In-place measurement of
bulk density by using the sand-
cone method and indirectly dry
density
• Dry density can be related to bulk
density by using water content (w)
Bulk Density
Dry Density
Saturated Density
Density of soil solids
M
V
 =
d
 =
Ms
sat
V

V
=
Msat
s
s
V
 =
Ms
Where: Ms is the mass of soil solids (Mass of soil in dry sate)
Msat is the mass of soil in a saturated state
Vs is the volume the soil solids

3
d =
1+ w

39. Purpose
4
• In place density measurement is primary used as for compaction control for a
construction project.
• Most construction specifications involve a statement on the relative degree of
compaction between laboratory MDD and in-place density.
• In place density measurement is also used for determination of the natural
density of soil masses in cases where it may not be possible to collect
undisturbed soil sample by traditional methods.

40. Apparatus
5
Base Plate
1. Sand-Cone Density Apparatus: consisting of sand container, sand cone
and base plate.
2. Testing Sand: A clean dry sand, having a constant bulk density
Sand Container
Sand Cone
https://www.ele.com/product/4-sand-density-cone

41. Apparatus
6
3. Chisel and hammer
4. Balance
5. Drying Oven
6. Moisture content specimen containers
7. Miscellaneous Equipment: Scoops, Brushes, Plastic bags and Nails

42. Procedure
1. Select a location that is representative of the area to be tested.
2. Inspect the cone apparatus for damage, free rotation of the valve, and properly
matched baseplate.
3. Assemble the cone and container and fill the cone container with sand
4. Determine and record mass of sand, cone and container. [M1]
5. Prepare the surface of the location to be tested, so that it is a level plane.
6. Seat the base plate on the plane surface, secure the plate against movement using
nails pushed into the soil adjacent to the edge of the plate
7. Dig the test hole through the center hole in the base plate.
• The test hole should be deep enough to represent the layer of material being tested
• Test hole volumes are to be as large as practical to minimize errors
8. Place all excavated soil, and any soil loosened during digging, in a moisture tight
container
• Take care to avoid losing any materials.
• Protect this material from moisture loss
The procedures discussed here are based
on ASTM D1556
7

43. Procedure
8
9. Clean the flange of the base plate
10.Determine and Record the mass of the excavated material. [Mt ]
11.Mix the excavated material thoroughly and obtain a representative specimen for
water content determination. [w]
12.Invert the sand-cone apparatus and seat the sand-cone funnel into the flanged
hole
13.Open the valve and allow the sand to fill the hole, cone, and base plate
• Take care to avoid jarring or vibrating the apparatus while the sand is running
14.When the sand stops flowing, close the valve
15.Determine and record mass of the remaining sand, cone and container. [M2]

44. Computation
1. Determine the amount of sand in the hole [Msh]
Msh = M1 − M2 −Mscb
Where: Mscb is the mass of sand the is above the hole and retained in the inverted cone and
base plate
This value is determined by calibration in the lab (not discussed here, one will be
provided)
Mass of sand above the
hole b/n the cone and
base plate (Mscb)
Mass of sand in hole (Msh)
9
https://mocivilengineering.com/field-density-test-sand-cone-method/

45. Computation
Where: ρsand is density of the sand used for testing
This value is determined by calibration in the lab (not discussed here, one will be
provided)
3. Determine the Bulk Density of the material at the test point [ρ]
h
sand

2. Determine Volume of test hole [Vh]
V =
Msh
Vh
10
=
Mt

46. Computation
4. Determine the Moisture Content [w]
Refer to previous notes
5. Determine the Dry Density of the material at the test point [ρd]
1+ w
11
d

 =

47. Discussion
• Most construction contract specify a minimum degree of compaction for earth
work as a means of performance specification.
MDD
12
• Degree of compaction is the ratio of the laboratory MDD obtained from a
specific compaction effort to the in-place dry density, expressed as a percentage.
Degree of Compaction =

d,on−site
100

48. Discussion
13
Sources of Error
• Existence of moisture and fine material in the testing sand will affect results; hence,
the sand must be placed in air tight containers
• The sand used for testing must be uniformly graded and able to flow freely
• The sand and equipment should be calibrated regularly to determine the mass of
sand b/n the cone and base plate and the density of sand
• During calibration, if there is large variation b/n successive measurements of the
density of sand, the sand may not be viable for testing purposes and may require
adjustment or replacement.
• Loss of excavated material or addition of foreign substance to the excavated material
will cause errors
• Vibration or disturbance of sand and container during the pouring of sand in to the
hole will cause errors.

49. THE END
Questions ?
14

50. Experiment-3
California Bearing Ratio
(CBR)
Number of slides: 18
Duration: 15 min
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gqNtZGzNAw2jcnBszQii

51. Background
2
• The California bearing ratio is used to evaluate the potential strength of
subgrade, subbase, and base course material.
• It is the normalized ratio of the penetration resistance of a material at a
specified penetration.
• The CBR value forms an integral part of several flexible pavement design
methods.
• The CBR value is determined on a compacted specimen
• Factors that affect CBR value for a given soil include:
• Moisture content and
• Density

52. Background
• Depending on whether or not the effects of moisture content and density on CBR
are required, three type of CBR test may exist
• One-point test
• Three-point test
• CBR at a range of water content
• In this experiment we will only be discussing about One-point CBR testing
• One-point CBR test is used to determine the CBR value at the OMC and
MDD of a soil sample
• One-point CBR can not be used to study the effects of compaction moisture
content and density on CBR value.
This two are also called
CBR at OMC
3

53. Purpose
4
• The CBR value is one of the primary parameter for flexible pavement design. It
characterizes the strength (resistance) of the pavement to traffic loads.
• Most design method make use of CBR for determining the thickness of the
various pavement layers
• Further, subgrade, subbase, and base course material are classified according to
their CBR values.

54. Apparatus
1. CBR Mold Assembly: Cylindrical molds where the compaction and then
penetration occurs
• Having a height of about 177.8mm and an inside diameter of about 152.4mm
5
• The assembly also consists of
• extension collar, which is used in
assisting the compaction process,
• spacer disk used as a place holder
during compaction; having a height
of 61.4mm and
• Perforated base plate where the
assembly seats.
http://civil-instruments-com.sell.everychina.com/p-106461489-astm-aashto-california-bearing-ratio-cbr-mold-and-
components-soil-test-equipment.html
https://myerstest.com/product/2-part-surcharge-weight-10lb/
When the spacer disk is placed inside the
mold the height is reduced to 116.4. The
remaining volume is 2124 cm3, equal to the
6-in compaction mold
Straight Edge
Tripod
Spacer Disk
swell Plate Perforated Base Plate
Displacement Gauge
Surcharge weight

55. Apparatus
2. Tripod, Swell plate and Displacement gauge:
for measurement of swelling
3. Surcharge weights: to simulate over burden
pressure. Each surcharge has mass of 2.27 Kg
4. Compaction Rammers: identical to the ones
used for compaction
5. CBR loading Machine: used for applying
penetration load
• Consists of a loading mechanism, a frame, load
measuring device, displacement gauge and
penetration piston
• The penetration piston has an penetration area
of 1935cm2
6
https://www.ele.com/product/cbr-test-50-machine

56. Apparatus
6. Drying oven: Thermostatically controlled oven, capable of maintaining a uniform temperature of
110±5°C throughout the drying chamber.
7. Balance
8. Straight edge: A stiff metal straightedge of any convenient length but not less than 250 mm.
9. Sieves: The following sieves are required
Sieve
opening size
7
Alternative
designation
4.75mm No. 4
9.5mm 3/8 in
19.0 mm 3/4 in
7. Moisture Specimen Containers
8. Soaking tank
9. Miscellaneous tools such as mixing pan, spoon, trowel, spatula, graduated cylinders, water
bottles, filter paper

57. Procedure
1. Sample Preparation:
a. Air dry the sample
b. Select one representative subsample (about 6000 g)
• If all of the subsample pass 19mm sieve use the subsample as is
• Otherwise remove the fraction retained the 19mm sieve and replace by by an equal
amount of material passing the 19.0mm sieve and retained on the 4.75mm.
c. Take a small fraction (about 1000g) of the prepared subsample and determine its
moisture content
2. Prepare the subsample by adding water to bring it’s moisture content to OMC.
To bring the water content, w, of a subsample of mass M, to OMC, the amount of water that
needs to be added can be found as
𝑂𝑀𝐶 − 𝑤 𝑀
1 + 𝑤
Before one-point CBR test is conducted, the OMC and MDD of the soil sample
must be known.
The procedures discussed here are
based on AASHTO T193
Similar to compaction, it is necessary to
let the soil-water mix stand for at least 16
hrs. in the case of plastic soils
8

58. Procedure
9
3. Compaction
a. Determine and recorded mass of mold and base plate (without the extension collar
and spacer disk) [Mmb]
b. Assemble the mold, base plate and extension collar
c. Place the spacer disk in to the mold and place a filter paper on top of the disk
d. Compact the sample according to the selected compaction method (Expriment-1)
4. Remove the extension collar, and using a straightedge, trim the compacted soil
even with the top of the mold
5. Remove the base plate and spacer disk
6. Place a filter paper on the perforated base plate
7. Invert the mold and compacted soil and place on the filter paper, so the
compacted soil is in contact with the filter paper
8. Reassemble the plate and mold.

59. Procedure
10
9. Clean the exterior of mold and base plate from any excess soil
10. Determine and record the mass of mold, compacted soil and base plate, [Mmbs]
11. Collect the trimming and determine the water content [w]
12. Soaking
a. Place the swell plate in the mold
b. Apply sufficient weights to produce an intensity of loading equal to the mass of the subbase
and base courses and surfacing above the material. A minimum of 4.45 Kg (2 weights) is
required.
c. Place the tripod with dial indicator on top of the mold and make an initial dial reading [H0].
d. Immerse the mold in water, make sure to allow free access of water at top and bottom of the
specimen.
e. Soak the specimen for 96 hours (4 days)
f. At the end of 96 hrs, make a final dial reading on the soaked specimens, [Hf].
g. Remove the specimens from the soaking tank, pour the water off the top and allow to drain
h. downward for 15 min

60. Procedure
11
13.Penetration
a. Place one annular weight on the specimen. Seat the penetration piston with a load
of no more than 44 N
b. After seating the penetration piston, place the remainder of the surcharge weights
around the piston.
c. Set the penetration dial indicator and the load indicator to zero.
d. Apply the loads to the penetration piston so the rate of penetration is uniform at
1.3mm/min
e. Record the load when the penetration is 0.64, 1.27, 1.91, 2.54, 3.81, 5.08, and
7.62, 10.16 and 12.70mm. The last two are optional.

61. Computation
1. Determine the actual moisture content and dry density of the compacted
sample (in the CBR mold) using data from steps 3a, 8 and 9 (refer to
Experiment-1 on the computation)
• This intended to check that the CBR value obtained is actually at OMC and MDD
2. Determine the Percent swell as
𝐿𝑓 − 𝐿0
𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑠𝑤𝑒𝑙𝑙 =
3. Compute penetration resistance
116.4 𝑚𝑚
a. For each of the readings load value:
𝑙𝑜𝑎𝑑 = 𝑙𝑜𝑎𝑑 𝑟𝑒𝑎𝑑𝑖𝑛𝑔 × 𝑝𝑟𝑜𝑣𝑖𝑛𝑔 𝑟𝑖𝑛𝑔 𝑓𝑎𝑐𝑡𝑜𝑟
Where the proving ring factor (N/div) is determined by calibration (one will be provided during the testing)
b. For each load computed, determine the resistance
𝑙𝑜𝑎𝑑 𝑙𝑜𝑎𝑑
𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 = = × 10 (𝐾𝑃𝑎)
𝑝𝑖𝑠𝑡𝑜𝑛 𝑝𝑒𝑛𝑒𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑎𝑟𝑒𝑎 1935 𝑐𝑚2
12

62. Computation
13
4. Plot the penetration vs. resistance curve. Penetration as the abscissa and
resistance as the ordinate.
5. Load correction: in some cases the initial penetration takes place without a
proportional increase in the resistance to penetration and the curve may be
concave upward.
If this happens, the location of the origin must be adjusted as follows
• Extend the straight line portion of the pen. Vs res. curve downward until it intersects
the abscissa
• Use this intersection point as the new origin

63. Computation
14
AASHTO T193-13
Curve 1 does not require correction
but curve 2 and 3 do due to the
concave upward shape of the curve
near the origin.
Consider Curve 3:
Before this adjustment the resistance
at 2.5mm was 689KPa
The correction shift the origin by
1.25mm.
Now to find the corrected resistance
at 2.5mm read from the original curve
the resistance at 3.75mm (2.5mm +
1.25mm) which is about 1300KPa.
1
2
3
1.25

64. Computation
6. Determine CBR value:
• First read the correct resistance value at penetrations of 2.54mm and 5.08mm (after
correction, if necessary)
• Then CBR is
𝐶𝐵𝑅 =
𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑 𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒
× 100
15
Where: corrected resistance are the loads at 2.54mm and 5.08 mm read from the plot by considering the
adjusted origin and
standard loads are 6900KPa and 10300KPa for the 2.54mm penetration and 5.08mm penetration,
respectively.
Note that you have 2 values (lets call me them CBR2.54 and CBR5.08).
The CBR is then selected as
• If CBR2.54 > CBR5.08, CBR = CBR2.54
• If CBR5.08 > CBR2.54, rerun the test, if the condition repeats, CBR = CBR5.08

65. Discussion
16
• Soaking of the specimen may not be conducted for cases where the proposed
project is in an arid environment.
• The one-point method has limited practical application since it dose not account
for the effect of variation of compacting moisture content and dry density.
• The three-point CBR method takes in to consideration the effect of density, this is
done by determining CBR values for 3 different subsamples compacted at different
energy but at the same OMC
• The CBR at a range of water content method takes in to consideration both
compaction water content and density; hence, this method is the most general.
• The compaction mold for the CBR is equivalent to the 6-in mold (after
consideration for the spacer disk is made)
• For soils where the OMC and MDD was determined using the 4-in mold, the
density obtained by compacting in the CBR mold (computation step 1) may be
slightly smaller than the MDD.

66. Discussion
17
• Sources of Error
• Errors in compaction (refer to Experiment 1)
• One needs to check if the actual density and water content are equivalent to the
OMC and MDD
• One needs to make sure that there is free access for water to enter the compacted
specimen during soaking
• The CBE loading machine and measurement instruments must be regularly checked
• The penetration piston must be properly placed on the specimen

67. THE END
Questions ?
18