The document discusses the properties of aggregates used in road construction. It describes the types of aggregates derived from igneous, sedimentary and metamorphic rocks. Several tests are used to evaluate aggregates including crushing value, impact value, Los Angeles abrasion and shape tests. The results of these tests are used to determine whether aggregates meet requirements for sub-base, base or surfacing layers. Requirements include maximum values for impact value, flakiness index and water absorption.

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PROPERTIES OF
AGGREGATES
DR.M.Heeralal
NIT WARANGAL

2. TYPES OF AGGREGATES
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• Natural aggregates are from
– Igneous Rocks
– Sedimentary Rocks
– Metamorphic Rocks

3. Road Making Aggregates in India
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• Basalt - Good for base & Surface
• Granite – Very good for
Bituminous courses & WBM
• Lime Stone – Good for base
• Quartzite – Good for base
• Sand Stone – Good for base

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DESIRABLE PROPERTIES OF ROAD
AGGREGATES
Desirable Property Test
Resistance to crushing or strength Crushing test
Resistance to abrasion or hardness Los Angeles abrasion value
Resistance to impact or toughness Aggregate impact test
Good shape factors to avoid too flaky and
Combined flakiness and
elongated particles
elongation index
Resistance to weathering Soundness test
Good adhesion with bituminous materials Stripping test
Resistance to polishing action under traffic Polished stone value

5. Laboratory Tests
 Gradation Test
 In order to have perfect degree of interlocking
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between aggregate
 Strength
I. Aggregate Crushing Test
 Toughness
I. Aggregate impact Test
 Hardness – Los Angels’ Test
 Specific gravity and Water absorption Tests
 Shape Factors
I. Flakiness Test
II. Elongation Test

6. GRADATION OF AGGREGATES
Dry sieve analysis is generally suitable for
gradation
Maximum size of an aggregate is the mesh
size of the smallest sieve through which
100% material will pass.
There are two types of gradation of metal
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Nominal Size Metal
Graded size Metal

7. Grading requirements for Nominal size CA
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Sl. No Nominal
Size
100%
Aggregate
should pass
through
100%
aggregate
should
retain on
1 75mm 106mm 63mm
2 63mm 90mm 53mm
3 45mm 53mm 26.5mm

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Grade I
Size varying from 90mm to 45mm and to
be laid for minimum 100mm compacted
thick (for Bottom layer only)
Grade II
Size varying from 63mm to 45mm and to
be laid for both 100 and 75mm thick (For
both Bottom and Middle layer)
Grade III
Size Varying from 53mm to 22.4mm and to
be laid for 75mm thick (For Top layer)

9. GRADING REQUIREMENTS OF COARSE
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AGGREGATES
Grade Range IS sieve
Designation
(mm)
Percent by
Weight
passing
I 90mm to 45mm 125 100
90 90-100
63 25-60
45 0-15
22.4 0-5

10. GRADING REQUIREMENTS OF COARSE
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AGGREGATES
Grade Range IS sieve
Designation
(mm)
Percent by
Weight
passing
II 63mm to 45mm 90 100
63 90-100
53 25-75
45 0-15
22.4 0-5

11. GRADING REQUIREMENTS OF COARSE
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AGGREGATES
Grade Range IS sieve
Designation
(mm)
Percent by
Weight
passing
III 53mm to 22.4mm 63 100
53 95-100
45 65-90
22.4 0.10
11.2 0-5

12. AGGREGATE CRUSHING VALUE TEST
 Assess the strength of aggregate.
 Resistance to crushing under roller
during construction
 Low ACV - Stronger aggregates
 High ACV - Soft aggregates
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LOADING NATURE
Gradually applied compressive load

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APPARATUS
Steel Cylinder with open ends of 15.2
cm dia. (Internal) on square base plate
plunger with 15.0cm dia. piston.
Cylinder jar of 11.5cm dia. and height
18cm
Steel Tamping rod
Balance capacity 3 Kgs.
Compressive testing machine of
capacity 40 tones @ uniform loading of
4 tones/Minute.

15. CRUSHING TEST
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Metal Measures and Tamping
Rods

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PROCEDURE
Aggregate passing 12.5 sieve and retained
on 10mm sieve
Heated up to a temp.100o C to 110o C for a
period of 4 Hours and cooled to a room temp.
Cylindrical jar to be filled by aggregate in 3
layers each layer should be tamped level of
the jar by tamping rod.
Weigh the sample nearly equal to 6.5 Kgs.
Pour the aggregate in cylinder test apparatus
placed in position on the base plate in three
layers.

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Place the cylinder along with plunger
under compressive testing machine
Load is applied up to 40 tonnes at
the rate of 4 tonnes per minute.
Aggregate including the crushed
portion should be sieved on 2.36mm
sieve
Weigh the material which passes the
sieve.

30. 09/13/14
CALCULATION
Total weight of dry sample = W1 Grams
Weight of the crushed material passing
2.36mm = W2
Aggregate crushing value = 100 x W2/W1

31. Aggregate Impact Test
 APPARATUS
1. Impact Testing Machine
2. Measure : Metal Cylinder internal dia
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7.5cm and depth 5cm
3. Tamping Road
4. Sieves : IS sieves 12.5mm,
10mm and 2.36mm
5. Balance : Capacity >500gms, up to
0.1gm accuracy
6. Oven

32. IMPACT TEST
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43. PROCEDURE
Test sample aggregates passing through
12.5mm sieve and retained on 10mm
Sample over dried at 100 C for 4 hours
Fill the aggregates in three layers in the
cylinder and tamped for 25 times with
tamping rod. Repeat it 3 times
Surplus aggregates trimmed off with
tamping rod
Weigh the sample say W1 gms
Transfer the test sample to the cup and
compact it with 25 strokes.
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44. Allow free fall of hammer from 38cm
above the aggregates to a total of 15
blows at an interval of 1 second between
each blow.
Sieve it through 2.36mm sieve, and
weigh the fraction passing 2.36m sieve
(W2 gms)
Weight the fraction retained on 2.36m
sieve (say W3 gms)
AIV = 100W2 %
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W1

45. CHECK
Weight of metal retained on 2.36mm sieve
(W3)+Weight of metal passing through
2.36mm W2=W1(up to 1gms accuracy)
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46. 09/13/14
RESULT
AIV < 10% Exceptionally strong
AIV 10% to 20% Strong
AIV 20% to 30% Satisfactory

47. WATER ABSORPTION TEST AND SPECIFIC
GRAVITY
Concept:
 In order to know the porosity of the
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metal.
 If the metal is porous the water
absorption will be more, less
strength of the metal.

48. APPARATUS
Balance of Capacity : 3 Kgs (Accuracy up
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to 0.5gms)
1.Oven : 110c
2.Wire Basket : 6.3mm mesh
3.Container :”Capacity”- C
4.Air tight container of “capacity” - C
5.Shallow Tray, Clothes.

49. SPECIFIC GRAVITY TEST
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Buoyancy
Balance
With Accessory

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PROCEDURE
2 Kg of washed aggregate free from dust is
weighed In water with basket (say W1 gms)
Measure weight of basket suspended in
water (Say W2 gms)
Wt of aggregate in Water=W in water=(W1-
W2) gms.
Weight of Dry aggregates after removing its
wetness by cloth (Say W with Water, gms)

51. Place the aggregate in an oven at 110C for
24 hours cool it (Dry Weight W gms)
Weight of water equal to the volume of
aggregates= (W with water-W in Water in
gms)
Specific Gravity=Dry weight of
aggregate/Weight of equal volume of water
Water Absorption =
W With water-Dry Wt.of Aggregate x 100
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Dry Weight

52. 09/13/14
RESULT
Sp Gravity of Aggregates Ranges from 2.5
to 3.0
High Sp. Gravity aggregate means High
Strength. Average Value – 2.68
Water absorption is measure of its porosity
of aggregates
Water absorption Ranges from 0.1% to 2%
More absorption of water of aggregate,
more porous material – less strength

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54. 09/13/14
SHAPE TEST
1. Flakiness Index
2. Elongation Index
3. Angularity Number
FLAKINESS INDEX
 APPARATUS
1. Standard Thickness guage
2. I.S.Sieves 63,50,40,31.5,25,20,16,12,5, 10 &
6.3mm
3. Weighing balance, to an accuracy of 1 gms

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PROCEDURE
Particles whose least dimension (thickness
is less than three fights (0.6) of their mean
dimension.
Not applicable for sizes of metal smaller
than 6.3mm
A minimum of 200 pieces of each fraction
to be tested are to be taken

59. FI = (w1+w2+w3+…….) x 100
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( W1+W2+W3)
Where w1, w2, w3 are weights of the
materials passing each of the specified
gauge
Where W1, W2, W3 weight of the materials
passing & retained on the specified sieves.

60. 09/13/14
ELONGATION INDEX
 APPRATUS
1. Length guage
2. Set of sieves as stated above
3. Weighing balance 0.1 gms accuracy
 PROCEDURE
 A minimum of 200 pieces of each fraction
is taken and Weighed
 Particles whose greatest dimension
(length) is greater than one and four fifth
times (1.8 times) their mean dimensions
 Not applicable to size smaller than 6.3mm.

61. Elongation Index=(X1+X2+X3+….) x100 =100X %
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(W1+W2+W3+…) W
Where X1+X2+X3 are weight of materials from
each fraction retained on the specified length
W1, W2, W3……… Total weights of each
fraction

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66. Angularity Number
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• The amount by which the % voids
exceeds 33 after being compacted
in a prescribed manner.
• Angularity Number
= 67 – 100W/CG
• AN = 0 Highly rounded gravel
• AN = 11 Freshly Crushed Angular
Aggregate

67. SHAPE TEST
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Type of pavement Maximum combined
flakiness and
elongation index
MoRTH specifications
Bituminous layers 30%
WBM / WMM / CRM 30%
Rural Roads Manual
Sub-base course (Flakiness index) 40%
Base course (Flakiness index) 30%
Bituminous layers (Combined index) 35%

68. Stripping Value of Road Aggregates
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• IRC has specified the max.
stripping value as 25% for
aggregates to be used in
bituminous constructions like
surface dressing, PM, BM and
carpet

69. Los Angels Abrasion Test
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• Abrasion – rubbing action
between different particles
• Attrition – rubbing action between
similar particles

70. LOS ANGELES ABRASION TEST
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Los Angeles
Abrasion
Machine

71. Los Angels Abrasion Test
Grading Sieve Range Sample Wt. Wt. Of Charge Revolutions
A 40mm-10mm 5 kg 12 spears 500
B 20mm–10mm 5 kg 11 500
C 10mm-4.75mm 5 kg 8 500
D 4.75mm-
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2.36mm
5kg 6 500
E 80mm-40mm 10kg 12 1000
F 50mm-25mm 10kg 12 1000
G 40mm-20mm 10kg 12 1000

72. PHYSICAL REQUIREMENTS OF AGGREGATES FOR SUB-BASE,
BASE COURSE AND BITUMINOUS SURFACING LAYERS (As per
Rural Roads Manual)
Layer Test Test Method Requirement
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(Percent.
Max.)
Sub-base
course
Aggregate Impact value IS: 2386 (Part 4)
-1963
50
Flakiness Index IS: 2386 (Part 1)
-1963
40
Moisture or water
absorption
IS: 2386 (Part 3)
-1963
06
Base
course
Aggregate Impact value IS: 2386 (Part 4)
-1963
40
Flakiness Index IS: 2386 (Part 1)
-1963
30
Moisture or water
absorption
IS: 2386 (Part 3)
-1963
03

73. PHYSICAL REQUIREMENTS OF AGGREGATES FOR SUB-BASE,
BASE COURSE AND BITUMINOUS SURFACING LAYERS (As per
Rural Roads Manual)
Bituminou
s
Surfacing
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Los Angeles abrasion
value
IS: 2386 (Part 4)
-1963
40
Aggregate Impact value IS: 2386 (Part 4)
-1963
30
Combined Flakiness and
Elongation Index
IS: 2386 (Part 1)
-1963
35
Stripping value IS: 6241- 1971 15
Soundness Loss with
Sodium Sulphate (5 cycles)
Loss with Magnesium
Sulphate (5 cycles)
IS: 2386 (Part 5) –
1963
12
18
Water absorption IS:2386 (Part 3) –
1963
02

74. Thank You!
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