This document discusses various materials used in highway construction. It describes aggregates, which are granular materials used in bases, subbases and backfill. Important properties of aggregates include particle size and hardness. Particle size distribution is determined through grain-size analysis and sieving. Hardness is measured using tests such as the Los Angeles abrasion test. Bituminous materials, commonly known as asphalt, are also discussed. Types of asphalt include asphalt cement and cutback asphalt. Specifications and tests for aggregates and asphalt are provided according to standards like AASHTO and ASTM.

1. HIGHWAY MATERIALS
•Soils
•Aggregates
•Bituminous materials

2. AGGREGATES
The term "aggregate" refers to granular
mineral particles that are widely used for
highway bases, subbases, and backfill.
Aggregates are also used in combination with
a cementing material to form concretes for
bases, subbases, wearing surface and drainage
structures. Sources of aggregates include
natural deposits of sand and gravel,
pulverized concrete and asphalt pavements,
crushed stone, and blastfurnace slag.

3. Properties of Aggregates
The most important properties of aggregates
used for highway construction are
•particle size and gradation.
•hardness or resistance to wear.
•durability or resistance to weathering.
•specific gravity and absorption.
•chemical stability.
•particle shape and surface texture.
•freedom from deleterious particles or
substances

4. Particle Size and Gradation of Aggregates
A key property of aggregates used for highway
bases and surfaces is the distribution of
particle sizes in the aggregate mix.
The gradation of aggregates, that is the blend
of particle sizes in the mix, affects the density,
strength, and economy of the pavement
structure. A grain-size analysis is used to
determine the relative proportions of various
particle sizes in a mineral aggregate mix.

5. The grain-size analysis data are usually
plotted on an aggregate grading chart, as
shown in Figure. With the aid of such a
chart, engineers determine a preferred
aggregate gradation and require that the
gradation of aggregates used for highway
projects conform to the limits of a
specification band.

7. Testing sieves commonly used for highway
projects are those with 2-1/2, 2, 1-1/2, 1, 3/4,
1/2, and 3/8 in. square openings for the large
fractions and those with 4, 8, 16, 30, 50, 100,
and 200 meshes per inch for the smaller
fractions. The latter sieves are designated
No.4, No. 10, and so on.

8. Resistance to Wear
Materials used in highway pavements should
be hard and resist wear due to the loading
from compaction equipment, the polishing
effects of traffic, and the internal abrasive
effects of repeated loadings. The most
commonly accepted measure of the hardness
of aggregates is the Los Angeles abrasion test.
The machine used in the Los Angeles abrasion
test consists of a hollow steel cylinder, closed
at both ends and mounted on shafts in a
horizontal position .

10. A removable steel shelf extending the length of
the cylinder is mounted on the interior surface
of the cylinder.
To perform the Los Angeles abrasion test, a
clean sample of the aggregate to be tested is
placed in the cylinder along with a standard
weight of steel spheres as an abrasive charge.
The drum is then rotated at a speed of 30 to 33
rpm for 500 revolutions, after which the
aggregate sample is removed and sieved on a
No. 12 (1.70 mm) sieve.

11. The material retained on the sieve is
washed, dried to a constant mass, and
weighed. The difference between the
original mass and the final mass of the
sample, expressed as a percentage of the
original mass, is reported as the percentage
of wear. A detailed procedure for this test is
given by AASHTO Method T96 (2).

12. Durability or Resistance to Weathering
The durability of aggregates is commonly
measured by a soundness test, as described in
AASHTO Method Tl04 (2). This test measures
the resistance of aggregates to disintegration in
a saturated solution of sodium or magnesium
sulfate. It simulates the weathering of
aggregates that occur in nature.

13. The test is made by immersing sized fractions of the
aggregate to be tested in a saturated solution of sodium or
magnesium sulfate. The aggregate is then removed and
dried in an oven to a constant mass. This process is
repeated for a specified number of cycles, typically five.
After the repeated cycle of alternate wetting and drying,
the aggregate is divided into fractions by sieving, and the
percentage weight loss is determined for each fraction.

14. The percentage loss is expressed as a
weighted average. For a given sieve size, the
percentage weighted average loss is the
product of the percentage passing that sieve
and the percentage passing that sieve in the
original material. The total of such values is
th percent loss test value.

15. Specific Gravity and Absorption
The specific gravity and absorption of aggregates are
important properties that are required for the design of
concrete and bituminous mixes. The specific gravity of a
solid is the ratio of its mass to that of an equal volume of
distilled water at a specified temperature. Because
aggregates may contain water-permeable voids, two
measures of specific gravity of aggregates are used:
apparent specific gravity and bulk specific gravity.

16. Apparent specific gravity, GA, is computed on the
basis of the net volume of the aggregates, that is, the
volume excluding the water-permeable voids. Thus,
w
N
V
D
M
A
=

17. where
MD = dry mass of the aggregate
VN = net volume of the aggregates, excluding
the volume of absorbed water
w = density of water
w
N
V
D
M
A
=

18. The bulk specific gravity, GB, is computed on the basis of
the total volume of the aggregates including the water-
permeable voids:
w
B
V
D
M
B
=
VB = where total volume of the aggregates, including the
volume of absorbed water

19. The difference between the apparent and
bulk specific gravities accounts for the water-
permeable voids of the aggregates. One can
measure the volume of such voids by
weighing the aggregates dry and in a
saturated, surface dry conditions, that is, with
all permeable voids filled with water. The
difference between the two masses is the mass
of the absorbed water, Mw. The absorption of
water is usually expressed as a percentage of
the mass of the dry aggregate,

20. R LEM
T o l o i
T i
o i io i T ol o
i i
i i i l i i i
o io

21. S L TI
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23. i l S ili o A
i i l o
i l i o io li io
o i l o o i io o
i l
I l i i
i i i o
o i o i o il i i
l i o i i io o l o

24. A i o o i i
i o o i i i
i o i o il i i i
o
T i i o i i i o
i ll o
i o o i il o i
i l illi o i ll
illi oi
i l
H o o i H o ili A

25. T i il o i i o i l o
o o l o i
o i i o i i
i ll o i o
o io o i
o i o o i i
l o o o i i l i i o i
o i i i o i i
o loo i i o
o i o io
i il o l o i i o il
o i i l i i il
il o

26. A i i i o
i l
o ili o ili
i lo i o l
o li l o o i
o il i i ll
o o i o i

27. I i l i i o il
i i o l i
l o o o
i l i io i io i i
ASTM S i
I io T io i io
i l ASTM I
I io o io T
I io T

28. o i o A
S i i io o i
i o io o o l
i l o i l
l li o
S i i io o i
i i o i ll i
l o l i
o o o l o
lo i l ll o
o io l i l

30. GRA LAR S ASE

31. ES RI TI
T i i ll o i o i i
i i o o o l
o i l o i o
S i i io i o
i E i

32. MATERIAL RE IREME TS
G l i l ll o i o
l o o
l o o ll
l o i o i
o l io ll o
i o il
i olli o o i
l
T i l ll o l i ollo i
i li i

33. T o i i o i o i ll
o l

34. • T i l ll io
i i li i o i i
lo Ho i A llo
E i i i l i
• T M i l ll R l o
l i o i o
AASHT T T R l ll
o i i o o i o
i i o i
i i o i o AASHT T
M o

35. T o i l i
o i o ll o
Lo A l A io
AASHT T o o o i
I o o oi i io o il
l i l o i
io S
S o l l i

36. • 1
1
.
• . 7 . 2
.42 . 4 .
• .42
2 6
.

37. • I o i i o i o
i l o ll i i l o
o i i ll llo o
i i llo
E i i o i i i l
i o o l
• S i l o ll l ll
i i i

38. R SHE AGGREGATE ASE
RSE

39. ES RI TI
T i i ll o i o i i
i o i o o
o l o A
o o
o i i o i o
i S i i io i
o i E i

40. MATERIAL RE IREME TS
M i l o o
ll o i o l l
o o o I ll l
o o i l o l
o l io T i l ll
o i o
il i olli o o
i l o o l i l i i
T o
ll o l i ollo i i
li i

42. • T io o i l ll
oo i i lo li i
o G i A o i lo
• A i l i o
i o ll o i o i l o
i l i i
ll i l i
i i o o
• T o ll
o Lo A l
A io AASHT T o o
o o

43. • T i l ll lo o l
l o i l
o So i S l So
o i o AASHT T
• T i l i o i
o AASHT T ll o l
o i o io o ill
i l i l i l i
o i ll li i li i
o o l i i i o
o i o
i AASHT T T

44. • T i l i i
ll R l o i i
i o i o
AASHT T T R l ll
o i i
i i o i o
AASHT T M o
• L i i l ll o
i o o l ol o
o

45. ill o l i
I ill i i io o ll
i o i l
i o i i
i o o i o o i o
i l i ll i o l l i
o i l i l
o i ill l o i o

46. T i l o o ll
o i o o o
E i T i l ll
o o i i l l
l l o o l io
ll o o o ollo i
i

47. Ho o i
i i o i l ill ll i
i io o

48. IT MI S MATERIALS
i i o i l i l o
o o io i il o
i ll i i o i o
i oo i o i ll
i l i l lo o i i o
i l o i i il o i
i o i o ASTM i l o
l o d d oli o i o
i io o o i l o
i ol l i o o
i i io i i ol l i o i l i

49. i i o i l i i i o o
o o i
as a s
a s

50. •A l i o ol
oil A o i o l
o i o i
o oil l o l
o i ll i l
•T i o i
i ill io o o i o l
oo o ol T o i o
i i ill io i
o i o o
o

51. A l o o o o i o
i l i l o
i o o li
o o o i
A l ill i ol i ol oil
ill o T o
o l o
o l o i o oil i o l
A l l i olo
ll o l i olo
To o i l i
o i

52. So o o i i A l
ol A l o io
i i
i o i i i ll o
ol ll d
l i o
i i

53. l l I i l ollo i
•L A l
•Ro A l

54. L A l
T l l o i o a as a
o o I l o T i i o o
o o So A i T i l o
l o o o l
o o i i o
o i o illio o o i l
ollo i io l i o
o i o oi
o i o o l
i o i o i o oo l
o o T i i E o
R i T i i L A l

55. T i l l o i ll
o i o i
i l
o i
ollo i i o i l i o
E l i i i l i
o o io il i o io o
i i i i l o
i i
o l i i i il li i

56. i i l l

57. T i i L A l

58. a a as a s
a a as a s i l li o
o i i
i ll o l i
Hi o i ll l o l i
i o o l T
io i S i l o G
io i
W il i i o i i
S l o l l
lo i o o io i
o

60. R TI AS HALT
A io li l i
o o i o ol oil A
i i o i o
i i ill io o ol
l i o ol io
o o o l o
i o i o i l
o i i o o
i i o oil o
o i o l i o o
o i o lo

61. A l
A l o o
i ill io i se s
oo ll o
o ili i i
l o o o
o o li i I o
o l o o i o ili
oo
li i oo

62. T o o li l
i o o i o
• i ol l i ol
• E l i i i

63. W ol il ol i i
l o li i o
i i ll l
A l i o o i
ol il ol o l
i i i i o i i l
i i i o
ol ili o ol o
i o l o
i o l ollo i
o l
ol

64. R i i R oli o
M i i M o
Slo i S o oil
l i o i ll il l i
i o i T l T
i o l M
i i i i i o i i i o
o i l
e s o R M S i
i ASTM
i l l i i i l
i l l i i l i
o i l

65. E l i i A l
E l i i l i i o l
l i i
T o i
i l o l i o olloi ill o o
l ll lo l o l
i i
T l i i i l i
io i o io i o o
l i l i o
l o o l i l
o o o l

66. T l i i l o i i
l o l l li o l
o
W l i i l i o o
i lo o i i i
o l lo l
i i o i
o l i o

67. T o io o i i
i i ll io i
l i i l o
El o i l o i
i io i
l i i l o

68. E l i i l o i
i o io i l l i
oi o i A
l i i l o o i ol
o i li i i l i l
oll io l i i l
lo i o i i
i ll
i o i io l T o
o l i i l o
i i l o l l

70. AS HALTI MATERIALS

71. AS HALT EME T
A l ll oil l o
i o i li i l
i oli l o
l i ol I ll o
i i i o i
i i i l i ill io o o l o l o
i ll o o o
o

72. A l ll l i i
io i o
i o o o
AASHT o l ll
o o o i o i
T l
T o l o ll i
o i S i i io o
S i l o i io o i
E i

73. E IR ME TAL A T RS
I i l o i l oil
lo o i io
o i o o
l oil i l o o
o o io io o
o io I l o li
l i o l i o i
i i i i i

74. l i i l
i i o
i l
i o i io il
T l lo i o l
o io
o i io

76. o i i MS lo i SS
l i i l i l i i l
i T i o o io i ASTM
o AASHT M o io i ASTM o
AASHT M S l i o o o ll
o o o i i
T o l i i l i l i il o
i o i ili o i o il o
T i i i o i ili
ASTM AASHT T o
i o i l io il ili
o i i i i o
o io i i o o
i