Short Notes for Highway Materials | Short Notes for Civil Engineering - Civil Engineering (CE) PDF Download

 Page 1


IntroDuction
Highway construction is done with diff erent types of
materials like soil, stone aggregate, bitumen and cement 
concrete. The settlement of road or resistance of the
pavement depends on the quality of all the materials. 
Therefore diff erent properties of all materials are required 
to lay the pavement.
SubgraDe 
It is a natural foundation or fi ll which forms the integral part 
of road pavement and directly receive loads from it.
Functions 
 1. It should provide support to the pavement from 
beneath.
 2. It should be stable and support the pavement even 
under adverse climate and loading conditions.
Materials UseD for Pavements
 1. Soil 
 2. Stone aggregates 
 3. Bituminous binders 
 4. Bituminous mixes 
 5. Portland cement and cement concrete 
Desirable ProPerties of Soil
 1. Stability
 2. Incompressibility
 3. Permanency of strength 
 4. Minimum changes in volume and stability under 
adverse conditions of weather 
 5. Good drainage 
 6. Ease of compaction 
Evaluation of Soil Strength 
 1. Shear tests: On relatively small soil samples. 
  Example: Direct shear test, tri-axial compression 
test, unconfi ned compression test.
 2. Bearing tests: On soil subgrade or at foundation level
in-situ.
Deformation
Diameter of loaded area
(=lowvalue is preferable).
 3. Penetration tests: On small loaded area and can be 
done in fi eld or in laboratory
 ? Introduction
 ? Subgrade
 ? Materials used for pavements
 ? Desirable properties of soil
 ? Evaluation of soil strength
 ? California bearing ratio test (CBR)
 ? Plate bearing test
 ? Stone aggregate
 ? Bituminous materials
 ? Cutback bitumen
 ? Bitumen emulsion
 ? Tar
 ? Bituminous mix design by Marshall
stability test
CHAPTER HIGHLIGHTS
Chapter 2
Highway Materials
Part III_Unit 11_Chapter 02.indd   947 5/20/2017   7:08:05 PM
Page 2


IntroDuction
Highway construction is done with diff erent types of
materials like soil, stone aggregate, bitumen and cement 
concrete. The settlement of road or resistance of the
pavement depends on the quality of all the materials. 
Therefore diff erent properties of all materials are required 
to lay the pavement.
SubgraDe 
It is a natural foundation or fi ll which forms the integral part 
of road pavement and directly receive loads from it.
Functions 
 1. It should provide support to the pavement from 
beneath.
 2. It should be stable and support the pavement even 
under adverse climate and loading conditions.
Materials UseD for Pavements
 1. Soil 
 2. Stone aggregates 
 3. Bituminous binders 
 4. Bituminous mixes 
 5. Portland cement and cement concrete 
Desirable ProPerties of Soil
 1. Stability
 2. Incompressibility
 3. Permanency of strength 
 4. Minimum changes in volume and stability under 
adverse conditions of weather 
 5. Good drainage 
 6. Ease of compaction 
Evaluation of Soil Strength 
 1. Shear tests: On relatively small soil samples. 
  Example: Direct shear test, tri-axial compression 
test, unconfi ned compression test.
 2. Bearing tests: On soil subgrade or at foundation level
in-situ.
Deformation
Diameter of loaded area
(=lowvalue is preferable).
 3. Penetration tests: On small loaded area and can be 
done in fi eld or in laboratory
 ? Introduction
 ? Subgrade
 ? Materials used for pavements
 ? Desirable properties of soil
 ? Evaluation of soil strength
 ? California bearing ratio test (CBR)
 ? Plate bearing test
 ? Stone aggregate
 ? Bituminous materials
 ? Cutback bitumen
 ? Bitumen emulsion
 ? Tar
 ? Bituminous mix design by Marshall
stability test
CHAPTER HIGHLIGHTS
Chapter 2
Highway Materials
Part III_Unit 11_Chapter 02.indd   947 5/20/2017   7:08:05 PM
3.948 | Part III 
¦
 Unit 11 
¦
 Transportation Engineering
Deformation
Diameterof loadedarea
 = High
  Example: CBR test and cone penetration test.
California Bearing Ratio 
Test (CBR) 
 • To find the strength of subgrade soil and other pave-
ment materials for the design and construction of flexible 
pavements.
 • This test denotes the measure of resistance to penetra-
tion of a soil with standard plunger under controlled test 
conditions.
 • Material passing 20 mm sieve is only used in testing.
Apparatus 
Cylindrical mould (150 mm diameter), Base plate, cylindri-
cal plunger (50 mm diameter), surcharge weight and com-
pression testing machine.
Test Procedure 
 • Specimen in mould is compacted to a dry density (practi-
cally possible).
For heavy compaction—high trafficked roads 
(Expressway NH and SH); for light compaction—Low 
volume roads
 • Specimen is soaked for four days and surcharge weight 
is placed on it.
 • This setup is placed under the plunger of loading frame 
where penetration rate is 1.25 mm per minute.
 • The loads for 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 
10 and 12.5 mm penetration are recorded and curves are 
plotted.
 • If the curve is initially concave upward due to surface 
irregularities correction is applied by drawing a tangent 
to the curve at the steepest point and the point where tan-
gent meets the horizontal axis is taken as corrected origin.
 • The test load for 2.5 mm and 5.0 mm are recorded.
CBR
(2.5or 5mm)
std(2.5or 5mm)
(%)=×
P
P
100
 • Higher of the two values is recorded as CBR value.
 • Usually CBR
2.5 mm
 > CBR
5 mm
. If CBR
5 mm
 > CBR
2.5 mm
 
test is repeated and if it gives the same result, higher value 
is reported as CBR value.
SOLVED EXAMPLES
Example 1
In a CBR test, the load sustained by a remoulded soil speci-
men at 5 mm penetration is 120 kg. The CBR value of the 
soil will be 
(A) 9.2% (B) 7.3%
(C) 5.84% (D) 2.4%
Solution
(CBR)
5 mm
 = 
P
P
5mm
5mmstandard
()
×100
 = 
120
2055
100 ×
 = 5.84%
Hence, the correct answer is option (C).
Plate Bearing Test 
 • To evaluate strength of subgrade in-situ to resist loads 
from pavement using relatively larger diameter plates.
 • To find Modulus of subgrade reaction of soils (K).
 • To find modulus of elasticity of soils (E
s
). 
Standard Values on Crushed Stones
Penetration (mm)
Standard 
Load (kg)
Standard Stress 
(kg/cm
2
)
2.5 1370 70
5.0 2055 105
Apparatus 
 • Plates of diameter 30, 45, 60, 75 cm are used.
 • Loading device with jack and proving ring and a reaction 
frame to give thrust through jack to plates.
 • A datum frame resting far from loaded area and dial 
gauges are used to measure the settlement of the loaded 
plate.
Reaction
Datum frame
Hydraulic 
jack
Stacked 
plates
3–4 dial ganges
Test set up for plate bearing test
A seating load to cause a pressure of 0.07 kg/cm
2
 is 
applied and released. A load sufficient to cause 0.25 mm 
settlement is applied at every loading. When the rate of 
settlement is less than 0.025 mm/minute, settlement and 
loads are recorded. Graph is plotted for bearing pressure 
(kg/cm
2
) and mean settlement (cm).
Part III_Unit 11_Chapter 02.indd   948 5/20/2017   7:08:06 PM
Page 3


IntroDuction
Highway construction is done with diff erent types of
materials like soil, stone aggregate, bitumen and cement 
concrete. The settlement of road or resistance of the
pavement depends on the quality of all the materials. 
Therefore diff erent properties of all materials are required 
to lay the pavement.
SubgraDe 
It is a natural foundation or fi ll which forms the integral part 
of road pavement and directly receive loads from it.
Functions 
 1. It should provide support to the pavement from 
beneath.
 2. It should be stable and support the pavement even 
under adverse climate and loading conditions.
Materials UseD for Pavements
 1. Soil 
 2. Stone aggregates 
 3. Bituminous binders 
 4. Bituminous mixes 
 5. Portland cement and cement concrete 
Desirable ProPerties of Soil
 1. Stability
 2. Incompressibility
 3. Permanency of strength 
 4. Minimum changes in volume and stability under 
adverse conditions of weather 
 5. Good drainage 
 6. Ease of compaction 
Evaluation of Soil Strength 
 1. Shear tests: On relatively small soil samples. 
  Example: Direct shear test, tri-axial compression 
test, unconfi ned compression test.
 2. Bearing tests: On soil subgrade or at foundation level
in-situ.
Deformation
Diameter of loaded area
(=lowvalue is preferable).
 3. Penetration tests: On small loaded area and can be 
done in fi eld or in laboratory
 ? Introduction
 ? Subgrade
 ? Materials used for pavements
 ? Desirable properties of soil
 ? Evaluation of soil strength
 ? California bearing ratio test (CBR)
 ? Plate bearing test
 ? Stone aggregate
 ? Bituminous materials
 ? Cutback bitumen
 ? Bitumen emulsion
 ? Tar
 ? Bituminous mix design by Marshall
stability test
CHAPTER HIGHLIGHTS
Chapter 2
Highway Materials
Part III_Unit 11_Chapter 02.indd   947 5/20/2017   7:08:05 PM
3.948 | Part III 
¦
 Unit 11 
¦
 Transportation Engineering
Deformation
Diameterof loadedarea
 = High
  Example: CBR test and cone penetration test.
California Bearing Ratio 
Test (CBR) 
 • To find the strength of subgrade soil and other pave-
ment materials for the design and construction of flexible 
pavements.
 • This test denotes the measure of resistance to penetra-
tion of a soil with standard plunger under controlled test 
conditions.
 • Material passing 20 mm sieve is only used in testing.
Apparatus 
Cylindrical mould (150 mm diameter), Base plate, cylindri-
cal plunger (50 mm diameter), surcharge weight and com-
pression testing machine.
Test Procedure 
 • Specimen in mould is compacted to a dry density (practi-
cally possible).
For heavy compaction—high trafficked roads 
(Expressway NH and SH); for light compaction—Low 
volume roads
 • Specimen is soaked for four days and surcharge weight 
is placed on it.
 • This setup is placed under the plunger of loading frame 
where penetration rate is 1.25 mm per minute.
 • The loads for 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 
10 and 12.5 mm penetration are recorded and curves are 
plotted.
 • If the curve is initially concave upward due to surface 
irregularities correction is applied by drawing a tangent 
to the curve at the steepest point and the point where tan-
gent meets the horizontal axis is taken as corrected origin.
 • The test load for 2.5 mm and 5.0 mm are recorded.
CBR
(2.5or 5mm)
std(2.5or 5mm)
(%)=×
P
P
100
 • Higher of the two values is recorded as CBR value.
 • Usually CBR
2.5 mm
 > CBR
5 mm
. If CBR
5 mm
 > CBR
2.5 mm
 
test is repeated and if it gives the same result, higher value 
is reported as CBR value.
SOLVED EXAMPLES
Example 1
In a CBR test, the load sustained by a remoulded soil speci-
men at 5 mm penetration is 120 kg. The CBR value of the 
soil will be 
(A) 9.2% (B) 7.3%
(C) 5.84% (D) 2.4%
Solution
(CBR)
5 mm
 = 
P
P
5mm
5mmstandard
()
×100
 = 
120
2055
100 ×
 = 5.84%
Hence, the correct answer is option (C).
Plate Bearing Test 
 • To evaluate strength of subgrade in-situ to resist loads 
from pavement using relatively larger diameter plates.
 • To find Modulus of subgrade reaction of soils (K).
 • To find modulus of elasticity of soils (E
s
). 
Standard Values on Crushed Stones
Penetration (mm)
Standard 
Load (kg)
Standard Stress 
(kg/cm
2
)
2.5 1370 70
5.0 2055 105
Apparatus 
 • Plates of diameter 30, 45, 60, 75 cm are used.
 • Loading device with jack and proving ring and a reaction 
frame to give thrust through jack to plates.
 • A datum frame resting far from loaded area and dial 
gauges are used to measure the settlement of the loaded 
plate.
Reaction
Datum frame
Hydraulic 
jack
Stacked 
plates
3–4 dial ganges
Test set up for plate bearing test
A seating load to cause a pressure of 0.07 kg/cm
2
 is 
applied and released. A load sufficient to cause 0.25 mm 
settlement is applied at every loading. When the rate of 
settlement is less than 0.025 mm/minute, settlement and 
loads are recorded. Graph is plotted for bearing pressure 
(kg/cm
2
) and mean settlement (cm).
Part III_Unit 11_Chapter 02.indd   948 5/20/2017   7:08:06 PM
Chapter 2 
¦
 Highway Materials | 3.949
 • Standard plate used for test is 75 cm diameter. Commonly 
used plate is 30 cm diameter (on highway pavements).
Modulus of Subgrade Reaction (K)
K is defined as the pressure sustained per unit deformation 
of subgrade at specified pressure level.
Pressure (P) corresponding to settlement of 0.125 cm is 
noted.
K
p
=
0 125
3
.
kg/cm
Correction of Soaked Sample
Soaked 
specimen
Deformation of specimen (cm)
Pressure 
(kg/cm
2
)
p
s
p
Unsoaked 
specimen
Correction for soaking in plate bearing test
Modulus of subgrade reaction for the soaked condition K
s
K
Kp
p
s
s
=
Where
p
s
 = Pressure on soaked sample 
p = Pressure on unsoaked sample
 K
s
 and K = Modulus of subgrade reaction of soaked and 
unsoaked sample.
Correction for Smaller Plate Size 
 • Assuming the subgrade to be an elastic medium with 
modulus of elasticity E(kg/cm
2
) the theoretical relation-
ship of deformation, D (cm) under a rigid plate of radius, 
‘a’ cm is (as per Boussinessq)
?
?
== ==
118
1181 18
.
..
pa
E
K
ppE
pa
E
a
 If E is constant (for a soil) Ka = K
1
a
1
 
 • For flexible plate ?=
15 . pa
E
Example 2
A plate load test was conducted on a soaked subgrade dur-
ing monsoon season using a plate diameter 30 cm.
The load values corresponding to the mean settlement dial 
readings are given below. Determine the modulus of sub-
grade reaction for the standard plate. (in kg/m
3
)
Mean 
 Settlement 
Value (mm)
0.0 0.23 0.51 0.75 1.02 1.25 1.55 1.8
Load Value 
(kg)
0.0 470 910 1180 1360 1480 1590 1630
(A) 19.34 (B) 18.57
(C) 16.75 (D) 16.7
Solution
For D = 1.25 mm = 0.125 cm
Pressure p = 
1480
15
2
p×
kg/cm
2
Modulus of subgrade reaction for 30 cm diameter plate,
K
p
1
1
2
2
1480
15 0 125
16 75 ==
××
=
? p .
. kg/cm
Modulus of subgrade reaction for standard plate of diameter 
75 cm, K = 
Ka
a
11
 
=
16 75
30
2
75
2
. ×
?
?
?
?
?
?
?
?
?
?
?
?
= 6.7 kg/cm
2
Hence, the correct answer is option (D).
As the plate load test was conducted under soaked con-
dition during monsoon season, there is no need to apply 
correction for subsequent soaking.
NOTE
Stone Aggregate 
 • These form the major part of pavement surface and 
the strength of the pavement depends upon strength of 
aggregate.
 • Aggregates of pavement surface have to resist: 
(a) The wear due to abrasive action of traffic.
(b) Deterioration due to weathering.
(c) The highest magnitude of wheel load stresses.
Tests on Aggregate 
Aggregate Impact Test (Toughness)
 • Toughness is defined as resistance to impact of aggregates.
 • Cylindrical steel cup of 102 mm diameter and 50 mm 
depth is used to fill the specimen.
 • Cylindrical metal hammer of 13.5–14 kg free fall from 38 
cm (15 blows).
 • Aggregate passing 12.5 mm and retaining on 10 mm 
sieve is used.
Part III_Unit 11_Chapter 02.indd   949 5/20/2017   7:08:07 PM
Page 4


IntroDuction
Highway construction is done with diff erent types of
materials like soil, stone aggregate, bitumen and cement 
concrete. The settlement of road or resistance of the
pavement depends on the quality of all the materials. 
Therefore diff erent properties of all materials are required 
to lay the pavement.
SubgraDe 
It is a natural foundation or fi ll which forms the integral part 
of road pavement and directly receive loads from it.
Functions 
 1. It should provide support to the pavement from 
beneath.
 2. It should be stable and support the pavement even 
under adverse climate and loading conditions.
Materials UseD for Pavements
 1. Soil 
 2. Stone aggregates 
 3. Bituminous binders 
 4. Bituminous mixes 
 5. Portland cement and cement concrete 
Desirable ProPerties of Soil
 1. Stability
 2. Incompressibility
 3. Permanency of strength 
 4. Minimum changes in volume and stability under 
adverse conditions of weather 
 5. Good drainage 
 6. Ease of compaction 
Evaluation of Soil Strength 
 1. Shear tests: On relatively small soil samples. 
  Example: Direct shear test, tri-axial compression 
test, unconfi ned compression test.
 2. Bearing tests: On soil subgrade or at foundation level
in-situ.
Deformation
Diameter of loaded area
(=lowvalue is preferable).
 3. Penetration tests: On small loaded area and can be 
done in fi eld or in laboratory
 ? Introduction
 ? Subgrade
 ? Materials used for pavements
 ? Desirable properties of soil
 ? Evaluation of soil strength
 ? California bearing ratio test (CBR)
 ? Plate bearing test
 ? Stone aggregate
 ? Bituminous materials
 ? Cutback bitumen
 ? Bitumen emulsion
 ? Tar
 ? Bituminous mix design by Marshall
stability test
CHAPTER HIGHLIGHTS
Chapter 2
Highway Materials
Part III_Unit 11_Chapter 02.indd   947 5/20/2017   7:08:05 PM
3.948 | Part III 
¦
 Unit 11 
¦
 Transportation Engineering
Deformation
Diameterof loadedarea
 = High
  Example: CBR test and cone penetration test.
California Bearing Ratio 
Test (CBR) 
 • To find the strength of subgrade soil and other pave-
ment materials for the design and construction of flexible 
pavements.
 • This test denotes the measure of resistance to penetra-
tion of a soil with standard plunger under controlled test 
conditions.
 • Material passing 20 mm sieve is only used in testing.
Apparatus 
Cylindrical mould (150 mm diameter), Base plate, cylindri-
cal plunger (50 mm diameter), surcharge weight and com-
pression testing machine.
Test Procedure 
 • Specimen in mould is compacted to a dry density (practi-
cally possible).
For heavy compaction—high trafficked roads 
(Expressway NH and SH); for light compaction—Low 
volume roads
 • Specimen is soaked for four days and surcharge weight 
is placed on it.
 • This setup is placed under the plunger of loading frame 
where penetration rate is 1.25 mm per minute.
 • The loads for 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 
10 and 12.5 mm penetration are recorded and curves are 
plotted.
 • If the curve is initially concave upward due to surface 
irregularities correction is applied by drawing a tangent 
to the curve at the steepest point and the point where tan-
gent meets the horizontal axis is taken as corrected origin.
 • The test load for 2.5 mm and 5.0 mm are recorded.
CBR
(2.5or 5mm)
std(2.5or 5mm)
(%)=×
P
P
100
 • Higher of the two values is recorded as CBR value.
 • Usually CBR
2.5 mm
 > CBR
5 mm
. If CBR
5 mm
 > CBR
2.5 mm
 
test is repeated and if it gives the same result, higher value 
is reported as CBR value.
SOLVED EXAMPLES
Example 1
In a CBR test, the load sustained by a remoulded soil speci-
men at 5 mm penetration is 120 kg. The CBR value of the 
soil will be 
(A) 9.2% (B) 7.3%
(C) 5.84% (D) 2.4%
Solution
(CBR)
5 mm
 = 
P
P
5mm
5mmstandard
()
×100
 = 
120
2055
100 ×
 = 5.84%
Hence, the correct answer is option (C).
Plate Bearing Test 
 • To evaluate strength of subgrade in-situ to resist loads 
from pavement using relatively larger diameter plates.
 • To find Modulus of subgrade reaction of soils (K).
 • To find modulus of elasticity of soils (E
s
). 
Standard Values on Crushed Stones
Penetration (mm)
Standard 
Load (kg)
Standard Stress 
(kg/cm
2
)
2.5 1370 70
5.0 2055 105
Apparatus 
 • Plates of diameter 30, 45, 60, 75 cm are used.
 • Loading device with jack and proving ring and a reaction 
frame to give thrust through jack to plates.
 • A datum frame resting far from loaded area and dial 
gauges are used to measure the settlement of the loaded 
plate.
Reaction
Datum frame
Hydraulic 
jack
Stacked 
plates
3–4 dial ganges
Test set up for plate bearing test
A seating load to cause a pressure of 0.07 kg/cm
2
 is 
applied and released. A load sufficient to cause 0.25 mm 
settlement is applied at every loading. When the rate of 
settlement is less than 0.025 mm/minute, settlement and 
loads are recorded. Graph is plotted for bearing pressure 
(kg/cm
2
) and mean settlement (cm).
Part III_Unit 11_Chapter 02.indd   948 5/20/2017   7:08:06 PM
Chapter 2 
¦
 Highway Materials | 3.949
 • Standard plate used for test is 75 cm diameter. Commonly 
used plate is 30 cm diameter (on highway pavements).
Modulus of Subgrade Reaction (K)
K is defined as the pressure sustained per unit deformation 
of subgrade at specified pressure level.
Pressure (P) corresponding to settlement of 0.125 cm is 
noted.
K
p
=
0 125
3
.
kg/cm
Correction of Soaked Sample
Soaked 
specimen
Deformation of specimen (cm)
Pressure 
(kg/cm
2
)
p
s
p
Unsoaked 
specimen
Correction for soaking in plate bearing test
Modulus of subgrade reaction for the soaked condition K
s
K
Kp
p
s
s
=
Where
p
s
 = Pressure on soaked sample 
p = Pressure on unsoaked sample
 K
s
 and K = Modulus of subgrade reaction of soaked and 
unsoaked sample.
Correction for Smaller Plate Size 
 • Assuming the subgrade to be an elastic medium with 
modulus of elasticity E(kg/cm
2
) the theoretical relation-
ship of deformation, D (cm) under a rigid plate of radius, 
‘a’ cm is (as per Boussinessq)
?
?
== ==
118
1181 18
.
..
pa
E
K
ppE
pa
E
a
 If E is constant (for a soil) Ka = K
1
a
1
 
 • For flexible plate ?=
15 . pa
E
Example 2
A plate load test was conducted on a soaked subgrade dur-
ing monsoon season using a plate diameter 30 cm.
The load values corresponding to the mean settlement dial 
readings are given below. Determine the modulus of sub-
grade reaction for the standard plate. (in kg/m
3
)
Mean 
 Settlement 
Value (mm)
0.0 0.23 0.51 0.75 1.02 1.25 1.55 1.8
Load Value 
(kg)
0.0 470 910 1180 1360 1480 1590 1630
(A) 19.34 (B) 18.57
(C) 16.75 (D) 16.7
Solution
For D = 1.25 mm = 0.125 cm
Pressure p = 
1480
15
2
p×
kg/cm
2
Modulus of subgrade reaction for 30 cm diameter plate,
K
p
1
1
2
2
1480
15 0 125
16 75 ==
××
=
? p .
. kg/cm
Modulus of subgrade reaction for standard plate of diameter 
75 cm, K = 
Ka
a
11
 
=
16 75
30
2
75
2
. ×
?
?
?
?
?
?
?
?
?
?
?
?
= 6.7 kg/cm
2
Hence, the correct answer is option (D).
As the plate load test was conducted under soaked con-
dition during monsoon season, there is no need to apply 
correction for subsequent soaking.
NOTE
Stone Aggregate 
 • These form the major part of pavement surface and 
the strength of the pavement depends upon strength of 
aggregate.
 • Aggregates of pavement surface have to resist: 
(a) The wear due to abrasive action of traffic.
(b) Deterioration due to weathering.
(c) The highest magnitude of wheel load stresses.
Tests on Aggregate 
Aggregate Impact Test (Toughness)
 • Toughness is defined as resistance to impact of aggregates.
 • Cylindrical steel cup of 102 mm diameter and 50 mm 
depth is used to fill the specimen.
 • Cylindrical metal hammer of 13.5–14 kg free fall from 38 
cm (15 blows).
 • Aggregate passing 12.5 mm and retaining on 10 mm 
sieve is used.
Part III_Unit 11_Chapter 02.indd   949 5/20/2017   7:08:07 PM
3.950 | Part III 
¦
 Unit 11 
¦
 Transportation Engineering
 • It is filled in steel up in 3 layers by tamping each layer 
with tamping rod for 25 times.
Aggregate impact value (AIV) 
Weight of finespassing 2.36 mmsi
=
e eve
Totalweight of thesample
×100
Specification:
 • For wearing course AIV > / 30%
 • For bituminous macadam AIV > / 35%
 • For water bound macadam AIV > /  40%
 • If AIV > 35, the aggregate is weak for pavement surface.
Resistance to Abrasion (Hardness)
Abrasion tests are: 
 1. Los Angeles abrasion test 
 2. Deval abrasion test 
 3. Dorry abrasion test 
Los Angeles Abrasion T ests It is commonly used as the test 
values of aggregates have been correlated with pavement 
performance. 
This gives both abrasion and impact values (practical/
similar to field condition)
 • 5–10 kg aggregate specimen and abrasive charge consist-
ing of cast iron spheres of diameter 48 mm (390–445 g 
each) is placed in machine rotated at 30–33 rpm—500 to 
1000 revolutions depending on the grading of specimen.
Abrasion value
Weight of aggregate passing 1.7 mm sieve
Tot
=
a al weight of sample
100 ×
Specifications for abrasion value:
 • Bituminous concrete or high quality pavement > / 30%
 • For cement concrete and Dense Bituminous macadam 
> / 35%
 • For granular base course and bituminous bound macadam 
> /  40% 
Aggregate Crushing Value Strength
 • To find resistance to crushing of the aggregates to gradual 
load.
 • Aggregates passing 12.5 mm and retained on 10 mm 
sieve are used. Three layers with 25 blows each by tamper 
rod 1.6 cm, 45 cm–60 cm fall—40 tonnes load is applied 
at a rate of 4 tonnes/minutes. 
Aggregate crushing value
Weight of crushed material passing 
=
2 2.36 mm
Totalweight of sample
×100
Specifications:
 • Strong aggregates give low aggregate crushing value.
 • For base course > / 45%
 • For surface course and cement concretion pavement 
> / 30%
Soundness Test
 • Resistance to weathering action.
 • As per BIS, saturated solution of sodium sulphate or 
magnesium sulphate are used for testing.
 • Aggregate is immersed in solution for 16–18 hours and 
dried in oven at 105–110°C to constant weight and cycle 
is repeated as desired.
Specifications (as per IRC):
 • Average loss in weight after 10 cycles (for pavement con-
struction) 5 cycles (for bituminous binder and surface 
course)
 • When tested with sodium sulphate > / 12%
 • When tested with Magnesium sulphate > / 18%
Specific Gravity (2.6–2.9)
 • Considered as a measure of strength or quality of material.
 • The higher is the specific gravity, higher is the quality/
strength.
 • Used for making weight volume conversions and for cal-
culating the void content in compacted bitumen mixes.
 • Preferably specific gravity between 2.6–2.9 
Water Absorption Test (> / 0.6%)
 • Aggregate is immersed in water for 24 hours and weight 
is found and oven dried at 110°C for 24 hours 
 Water absorption (w) =  
WW
W
12
2
-
 × 100
 Where
  W
1
 = Weight of aggregate after immersing in water.
  W
2
 = Weight of oven dried sample. 
Shape Tests
Angular shapes of particles are desirable for granular base 
course and in bituminous mixes due to increased stability 
derived from better interlocking.
Flakiness Index (FI) Percentage by weight of aggregate 
whose least dimension or thickness is less than 
3
5
 or 0.6 
(times their mean dimension).
Specifications (for FI):
 • For bituminous concrete and surface dressing > / 25%
 • For water bound and bituminous macadam > / 15%
Elongation Index (EI) EI is the percentage by weight of 
particles whose greatest dimension/length is greater than 
1
4
5
 or 1.8 (times their mean dimension).
Specifications:
 • Generally EI or FI > 15%
 • Elongated and flaky aggregates are less workable.
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Page 5


IntroDuction
Highway construction is done with diff erent types of
materials like soil, stone aggregate, bitumen and cement 
concrete. The settlement of road or resistance of the
pavement depends on the quality of all the materials. 
Therefore diff erent properties of all materials are required 
to lay the pavement.
SubgraDe 
It is a natural foundation or fi ll which forms the integral part 
of road pavement and directly receive loads from it.
Functions 
 1. It should provide support to the pavement from 
beneath.
 2. It should be stable and support the pavement even 
under adverse climate and loading conditions.
Materials UseD for Pavements
 1. Soil 
 2. Stone aggregates 
 3. Bituminous binders 
 4. Bituminous mixes 
 5. Portland cement and cement concrete 
Desirable ProPerties of Soil
 1. Stability
 2. Incompressibility
 3. Permanency of strength 
 4. Minimum changes in volume and stability under 
adverse conditions of weather 
 5. Good drainage 
 6. Ease of compaction 
Evaluation of Soil Strength 
 1. Shear tests: On relatively small soil samples. 
  Example: Direct shear test, tri-axial compression 
test, unconfi ned compression test.
 2. Bearing tests: On soil subgrade or at foundation level
in-situ.
Deformation
Diameter of loaded area
(=lowvalue is preferable).
 3. Penetration tests: On small loaded area and can be 
done in fi eld or in laboratory
 ? Introduction
 ? Subgrade
 ? Materials used for pavements
 ? Desirable properties of soil
 ? Evaluation of soil strength
 ? California bearing ratio test (CBR)
 ? Plate bearing test
 ? Stone aggregate
 ? Bituminous materials
 ? Cutback bitumen
 ? Bitumen emulsion
 ? Tar
 ? Bituminous mix design by Marshall
stability test
CHAPTER HIGHLIGHTS
Chapter 2
Highway Materials
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Deformation
Diameterof loadedarea
 = High
  Example: CBR test and cone penetration test.
California Bearing Ratio 
Test (CBR) 
 • To find the strength of subgrade soil and other pave-
ment materials for the design and construction of flexible 
pavements.
 • This test denotes the measure of resistance to penetra-
tion of a soil with standard plunger under controlled test 
conditions.
 • Material passing 20 mm sieve is only used in testing.
Apparatus 
Cylindrical mould (150 mm diameter), Base plate, cylindri-
cal plunger (50 mm diameter), surcharge weight and com-
pression testing machine.
Test Procedure 
 • Specimen in mould is compacted to a dry density (practi-
cally possible).
For heavy compaction—high trafficked roads 
(Expressway NH and SH); for light compaction—Low 
volume roads
 • Specimen is soaked for four days and surcharge weight 
is placed on it.
 • This setup is placed under the plunger of loading frame 
where penetration rate is 1.25 mm per minute.
 • The loads for 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 
10 and 12.5 mm penetration are recorded and curves are 
plotted.
 • If the curve is initially concave upward due to surface 
irregularities correction is applied by drawing a tangent 
to the curve at the steepest point and the point where tan-
gent meets the horizontal axis is taken as corrected origin.
 • The test load for 2.5 mm and 5.0 mm are recorded.
CBR
(2.5or 5mm)
std(2.5or 5mm)
(%)=×
P
P
100
 • Higher of the two values is recorded as CBR value.
 • Usually CBR
2.5 mm
 > CBR
5 mm
. If CBR
5 mm
 > CBR
2.5 mm
 
test is repeated and if it gives the same result, higher value 
is reported as CBR value.
SOLVED EXAMPLES
Example 1
In a CBR test, the load sustained by a remoulded soil speci-
men at 5 mm penetration is 120 kg. The CBR value of the 
soil will be 
(A) 9.2% (B) 7.3%
(C) 5.84% (D) 2.4%
Solution
(CBR)
5 mm
 = 
P
P
5mm
5mmstandard
()
×100
 = 
120
2055
100 ×
 = 5.84%
Hence, the correct answer is option (C).
Plate Bearing Test 
 • To evaluate strength of subgrade in-situ to resist loads 
from pavement using relatively larger diameter plates.
 • To find Modulus of subgrade reaction of soils (K).
 • To find modulus of elasticity of soils (E
s
). 
Standard Values on Crushed Stones
Penetration (mm)
Standard 
Load (kg)
Standard Stress 
(kg/cm
2
)
2.5 1370 70
5.0 2055 105
Apparatus 
 • Plates of diameter 30, 45, 60, 75 cm are used.
 • Loading device with jack and proving ring and a reaction 
frame to give thrust through jack to plates.
 • A datum frame resting far from loaded area and dial 
gauges are used to measure the settlement of the loaded 
plate.
Reaction
Datum frame
Hydraulic 
jack
Stacked 
plates
3–4 dial ganges
Test set up for plate bearing test
A seating load to cause a pressure of 0.07 kg/cm
2
 is 
applied and released. A load sufficient to cause 0.25 mm 
settlement is applied at every loading. When the rate of 
settlement is less than 0.025 mm/minute, settlement and 
loads are recorded. Graph is plotted for bearing pressure 
(kg/cm
2
) and mean settlement (cm).
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Chapter 2 
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 • Standard plate used for test is 75 cm diameter. Commonly 
used plate is 30 cm diameter (on highway pavements).
Modulus of Subgrade Reaction (K)
K is defined as the pressure sustained per unit deformation 
of subgrade at specified pressure level.
Pressure (P) corresponding to settlement of 0.125 cm is 
noted.
K
p
=
0 125
3
.
kg/cm
Correction of Soaked Sample
Soaked 
specimen
Deformation of specimen (cm)
Pressure 
(kg/cm
2
)
p
s
p
Unsoaked 
specimen
Correction for soaking in plate bearing test
Modulus of subgrade reaction for the soaked condition K
s
K
Kp
p
s
s
=
Where
p
s
 = Pressure on soaked sample 
p = Pressure on unsoaked sample
 K
s
 and K = Modulus of subgrade reaction of soaked and 
unsoaked sample.
Correction for Smaller Plate Size 
 • Assuming the subgrade to be an elastic medium with 
modulus of elasticity E(kg/cm
2
) the theoretical relation-
ship of deformation, D (cm) under a rigid plate of radius, 
‘a’ cm is (as per Boussinessq)
?
?
== ==
118
1181 18
.
..
pa
E
K
ppE
pa
E
a
 If E is constant (for a soil) Ka = K
1
a
1
 
 • For flexible plate ?=
15 . pa
E
Example 2
A plate load test was conducted on a soaked subgrade dur-
ing monsoon season using a plate diameter 30 cm.
The load values corresponding to the mean settlement dial 
readings are given below. Determine the modulus of sub-
grade reaction for the standard plate. (in kg/m
3
)
Mean 
 Settlement 
Value (mm)
0.0 0.23 0.51 0.75 1.02 1.25 1.55 1.8
Load Value 
(kg)
0.0 470 910 1180 1360 1480 1590 1630
(A) 19.34 (B) 18.57
(C) 16.75 (D) 16.7
Solution
For D = 1.25 mm = 0.125 cm
Pressure p = 
1480
15
2
p×
kg/cm
2
Modulus of subgrade reaction for 30 cm diameter plate,
K
p
1
1
2
2
1480
15 0 125
16 75 ==
××
=
? p .
. kg/cm
Modulus of subgrade reaction for standard plate of diameter 
75 cm, K = 
Ka
a
11
 
=
16 75
30
2
75
2
. ×
?
?
?
?
?
?
?
?
?
?
?
?
= 6.7 kg/cm
2
Hence, the correct answer is option (D).
As the plate load test was conducted under soaked con-
dition during monsoon season, there is no need to apply 
correction for subsequent soaking.
NOTE
Stone Aggregate 
 • These form the major part of pavement surface and 
the strength of the pavement depends upon strength of 
aggregate.
 • Aggregates of pavement surface have to resist: 
(a) The wear due to abrasive action of traffic.
(b) Deterioration due to weathering.
(c) The highest magnitude of wheel load stresses.
Tests on Aggregate 
Aggregate Impact Test (Toughness)
 • Toughness is defined as resistance to impact of aggregates.
 • Cylindrical steel cup of 102 mm diameter and 50 mm 
depth is used to fill the specimen.
 • Cylindrical metal hammer of 13.5–14 kg free fall from 38 
cm (15 blows).
 • Aggregate passing 12.5 mm and retaining on 10 mm 
sieve is used.
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 • It is filled in steel up in 3 layers by tamping each layer 
with tamping rod for 25 times.
Aggregate impact value (AIV) 
Weight of finespassing 2.36 mmsi
=
e eve
Totalweight of thesample
×100
Specification:
 • For wearing course AIV > / 30%
 • For bituminous macadam AIV > / 35%
 • For water bound macadam AIV > /  40%
 • If AIV > 35, the aggregate is weak for pavement surface.
Resistance to Abrasion (Hardness)
Abrasion tests are: 
 1. Los Angeles abrasion test 
 2. Deval abrasion test 
 3. Dorry abrasion test 
Los Angeles Abrasion T ests It is commonly used as the test 
values of aggregates have been correlated with pavement 
performance. 
This gives both abrasion and impact values (practical/
similar to field condition)
 • 5–10 kg aggregate specimen and abrasive charge consist-
ing of cast iron spheres of diameter 48 mm (390–445 g 
each) is placed in machine rotated at 30–33 rpm—500 to 
1000 revolutions depending on the grading of specimen.
Abrasion value
Weight of aggregate passing 1.7 mm sieve
Tot
=
a al weight of sample
100 ×
Specifications for abrasion value:
 • Bituminous concrete or high quality pavement > / 30%
 • For cement concrete and Dense Bituminous macadam 
> / 35%
 • For granular base course and bituminous bound macadam 
> /  40% 
Aggregate Crushing Value Strength
 • To find resistance to crushing of the aggregates to gradual 
load.
 • Aggregates passing 12.5 mm and retained on 10 mm 
sieve are used. Three layers with 25 blows each by tamper 
rod 1.6 cm, 45 cm–60 cm fall—40 tonnes load is applied 
at a rate of 4 tonnes/minutes. 
Aggregate crushing value
Weight of crushed material passing 
=
2 2.36 mm
Totalweight of sample
×100
Specifications:
 • Strong aggregates give low aggregate crushing value.
 • For base course > / 45%
 • For surface course and cement concretion pavement 
> / 30%
Soundness Test
 • Resistance to weathering action.
 • As per BIS, saturated solution of sodium sulphate or 
magnesium sulphate are used for testing.
 • Aggregate is immersed in solution for 16–18 hours and 
dried in oven at 105–110°C to constant weight and cycle 
is repeated as desired.
Specifications (as per IRC):
 • Average loss in weight after 10 cycles (for pavement con-
struction) 5 cycles (for bituminous binder and surface 
course)
 • When tested with sodium sulphate > / 12%
 • When tested with Magnesium sulphate > / 18%
Specific Gravity (2.6–2.9)
 • Considered as a measure of strength or quality of material.
 • The higher is the specific gravity, higher is the quality/
strength.
 • Used for making weight volume conversions and for cal-
culating the void content in compacted bitumen mixes.
 • Preferably specific gravity between 2.6–2.9 
Water Absorption Test (> / 0.6%)
 • Aggregate is immersed in water for 24 hours and weight 
is found and oven dried at 110°C for 24 hours 
 Water absorption (w) =  
WW
W
12
2
-
 × 100
 Where
  W
1
 = Weight of aggregate after immersing in water.
  W
2
 = Weight of oven dried sample. 
Shape Tests
Angular shapes of particles are desirable for granular base 
course and in bituminous mixes due to increased stability 
derived from better interlocking.
Flakiness Index (FI) Percentage by weight of aggregate 
whose least dimension or thickness is less than 
3
5
 or 0.6 
(times their mean dimension).
Specifications (for FI):
 • For bituminous concrete and surface dressing > / 25%
 • For water bound and bituminous macadam > / 15%
Elongation Index (EI) EI is the percentage by weight of 
particles whose greatest dimension/length is greater than 
1
4
5
 or 1.8 (times their mean dimension).
Specifications:
 • Generally EI or FI > 15%
 • Elongated and flaky aggregates are less workable.
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 • The above tests (EI and FI) are applicable for sizes larger 
than 6.3 mm.
Combined Index (CI)
 • This is combined flaky and elongation index.
 • First FI test is conducted on the selected sample and on 
non-flaky aggregate elongation index test is conducted.
CI = FI + EI
Specification: 
CI > /  30%
Angularity Number (AN)
 • In case of gravel, shape may be expressed in terms of 
angularity number.
 • The degree of packing of single sized aggregates depends 
on shape and angularity of the aggregate.
 • Round well compacted, single sized aggregate would 
have solid volume = 67% (V oid volume = 33%)
 • Angularity number is defined as the voids in excess of 
33%.
 
 • Angularity Number (AN) = 67 – (% solid volume of 
aggregate) 
AN =- 67
100W
CG
a
Where
W = Weight of aggregate in cylinder 
C = Weight of water in cylinder 
G
a
 = Specific gravity of aggregate 
 • AN is expressed as the neared whole number.
 • AN of aggregates used in construction ranges from 0 to 
11.
 • AN does not apply to any aggregate which breaks down 
during test (weaker aggregate).
Example 3
An aggregate sample of 250 gm passing through 12.5 mm 
and retaining on 10 mm sieve. When filled into a cylinder 
the void percentage = 40%, find the angularity number.
(A) 3 (B) 5
(C) 7 (D) 11
Solution
Angularity number = V oids in excess of 33% = 40 – 33
AN = 7
Hence, the correct answer is option (C).
Bitumen Adhesion Test
 • Static immersion test is commonly used to find adhering 
capacity of bitumen with aggregate as it is quite easy and 
simple.
 • The aggregate and binder mixer taken into a beaker (500 
ml) and cooled for 2 hours, distilled water added to the 
aggregate binder and kept in water both at 40°C for 24 
hours.
 • Stripping value 
=
Average uncoveredarea
Totalareaofaggregate
Specifications:
Stripping value > / 25% [or surface dressing/bituminous 
macadam] 
> / 10% [For open graded premix carpet] 
Bituminous Materials 
 1. Bitumen: It is hydrocarbon/complex organic material 
of either natural or artificially obtained during 
fractional distillation of petroleum.
 2. Tar: Viscous liquid obtained when natural organic 
materials (wood/coal) are destructively distilled in 
the absence of air.
 3. Asphalt: It is bitumen with inert materials of 
minerals.
 4. Cutback: If viscosity of bitumen is reduced by 
volatile diluents like kerosene or oil it is called 
cutback.
 5. Emulsion: It is the bitumen which is suspended in a 
finely divided condition in water and stabilized with 
an emulsifier.
Tests on Bitumen 
Penetration Test
 • To determine hardness or softness of bitumen. It is indi-
rect measurement of consistency. Grading of bitumen is 
also done.
 • Basic principle of the test is the measurement of penetra-
tion (in 
1
10
mm) of a standard needle in bitumen sample 
at standard temperature of 25°C in 5 seconds, where the 
total weight of needle assembly is 100 gm.
 • Penetration grades are represented as 
80
100
, 
60
70
, 
30
40
. 
 •
80
100
 means the penetration value ranges between 80 and 
100.
 • As road tars are soft, penetration tests cannot be carried 
out on these.
 • In hot climate 30/40, grade is used due to its low penetra-
tion value.
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