1. 2.2.3.
Modulus of Elasticity and Strength
11/20/99 Author: Tomas U. Ganiron Jr 1

2. The Modulus of the elasticity is the ratio of
stress to corresponding strain below the
proportional limit.
• For granites and limestone the modulus of
elasticity in compression is in the range
2,000,000 – 7,000,000 psi.
• Sandstone has lower value modulus, which
may range from 1,000,000 – 5,000,000 psi.
• The modulus of elasticity of concrete
increases with increase in the modulus of
aggregate used in its manufacture.
• Creep and shrinkage of concrete are also
affected by the modulus of elasticity of the
aggregate
11/20/99 Author: Tomas U. Ganiron Jr 2

3. Compressive strengths of aggregates
depend on the compressive strengths of
original rocks.
The strength of an aggregate affects the
strength of the building material made with
it when the two strength values are close
to each other.
11/20/99 Author: Tomas U. Ganiron Jr 3

4. GRADATION
The particle size or grain-size distribution, of an
aggregate is one of the most influential aggregate
characteristics in determining how it will perform as a
pavement material. Gradation helps determine almost
every important property including stiffness, stability,
durability, permeability, workability, fatigue resistance,
frictional resistance and resistance to moisture
damage . Gradation helps determine durability,
porosity, workability, cement and water requirements,
strength, and shrinkage.
11/20/99 Author: Tomas U. Ganiron Jr 4

5. The process that determine the
GRADING particle-size distribution of a
representative sample of the
aggregate.
BLENDING The process of combining
aggregates of various size to
obtain a specified gradation
11/20/99 Author: Tomas U. Ganiron Jr 5

6. Typical Gradations
Dense or well-graded. Refers to a gradation
that is near maximum density. The most common
HMA mix designs
Gap graded. Refers to a gradation that
contains only a small percentage of aggregate
particles in the mid-size range. The curve is flat
in the mid-size range. These mixes can be
prone to segregation during placement.
11/20/99 Author: Tomas U. Ganiron Jr 6

7. Open graded. Refers to a gradation that
contains only a small percentage of aggregate
particles in the small range. This results in more
air voids because there are not enough small
particles to fill in the voids between the larger
particles. The curve is flat and near-zero in the
small-size range.
Uniformly graded. Refers to a gradation
that contains most of the particles in a very
narrow size range. In essence, all the particles
are the same size. The curve is steep and only
occupies the narrow size range specified.
11/20/99 Author: Tomas U. Ganiron Jr 7

8. 11/20/99 Author: Tomas U. Ganiron Jr 8

9. Other Gradation Terms
•Fine aggregate (sometimes just referred to as
"fines"). Defined as natural or crushed sand passing the
No. 10 sieve and mineral particles passing the No. 200
sieve.
•Coarse aggregate. Hard, durable particles or fragments
of stone, gravel or slag retained on the No. 10 sieve.
•Fine gradation. A gradation that, when plotted on the
0.45 power gradation graph, falls mostly above the 0.45
power maximum density line.
•Coarse gradation. A gradation that, when plotted on the
0.45 power gradation graph, falls mostly below the 0.45
power maximum density line. The term generally applies
to dense graded aggregate.
•Mineral filler. Defined as a finely divided mineral product
at least 65 percent of which will pass through a No. 200
sieve.
11/20/99 Author: Tomas U. Ganiron Jr 9

10. Gradation is determined using sieve analysis in which a
representative sample of the aggregate is passed
through a series of sieves and the weight retained in
each sieve
SIEVES
- is an apparatus with square
openings.
- A utensil of wire mesh or
closely perforated metal, used
for straining, sifting, or
puréeing.
11/20/99 Author: Tomas U. Ganiron Jr 10

11. STANDARD COARSE AGGREGATE SIEVES are
No.4, 1/8 in., ½ in., ¾ in., 1 in., 1 ½ in., 2
in., 2 ½ in.
STANDARD FINE AGGREGATE SIEVES are
No. 100, No. 50, No. 30, No. 16, No. 8,
No. 4,
11/20/99 Author: Tomas U. Ganiron Jr 11

12. Sieve designation Normal Opening
in. mm. in. mm. Type
2 50 2 50 H
1½ 37.5 1.5 37.5 F
1 25 1 25 H
¼ 19 0.75 19 F
½ 12.5 0.5 12.5 H
⅛ 9.5 0.375 9.5 F
No. 4 4.74 0.187 4.74 F
No. 8 2.36 0.0937 2.36 F
No. 16 1.18 0.0469 1.18 F
No. 30 600 ųm 0.0234 0.6 F
No. 50 300 ųm 0.0117 0.3 F
No. 100 150 ųm 0.0059 0.15 F
No. 200
11/20/99
75 ųm 0.003
Author: Tomas U. Ganiron Jr
0.075 F 12
H = half sieve F = full sieve

13. Other Properties
Other important aggregate
physical properties are:
•Toughness and abrasion resistance. Aggregates
should be hard and tough enough to resist crushing,
degradation and disintegration from activities such
as manufacturing stockpiling, production, placing and
compaction
•Durability and soundness. Aggregates must be
resistant to breakdown and disintegration from weathering
(wetting/drying) or else they may break apart and cause
premature pavement distress.
•Particle shape and surface texture. Particle shape and
surface texture are important for proper compaction, load
resistance and workability. Generally, cubic angular-
shaped particles with a roughU.surface texture are best. 13
11/20/99 Author: Tomas Ganiron Jr

14. •Cleanliness and deleterious materials. Aggregates
must be relatively clean when used in HMA. Vegetation,
soft particles, clay lumps, excess dust and vegetable
matter may affect performance by quickly degrading,
which causes a loss of structural support and/or
prevents binder-aggregate bonding.
•Specific gravity. Aggregate specific gravity is useful
in making weight-volume conversions and in calculating
the void content in compacted HMA (Roberts et al.,
1996).
11/20/99 Author: Tomas U. Ganiron Jr 14

15. Find the volume of Voids in a 3-yd³ coarse aggregate of
bulk density equal to 102 pcf. The specific gravity of the
particle is 2.65
Solution:
SG x W – B
Void = X 100
SG x W
Specific gravity, SG = 2.65 Density of water,
Bulk density, B = 102 pcf W = 62.4 pcf
2.65(62.4) - 102
Void = X 100
2.65(62.4)
27
Volume of voids = 38.3(3) x
11/20/99 = 31 ft³ 15
100
Author: Tomas U. Ganiron Jr