2. a broad category of coarse
particulate material used
in construction, including sand, gravel, crus
hed stone, slag, recycled concrete and geo-
synthetic aggregates.
used as a stable foundation or road/rail
base with predictable, uniform properties, or
as a low-cost extender that binds with more
expensive cement or asphalt to form
concrete.
7. 1. As compacted aggregates in bases, sub-
bases and shoulders
2. As ingredients in hot mix asphalt
3. As ingredients in Portland cement
concrete
8. composed of compacted aggregate and
bitumen
the aggregate transmits the load from the
surface to the base and the bitumen
(bituminous binder) holds the aggregate
together
for bituminous construction, aggregate is
classified according to particle size
9. “The aggregate shall consist of hard,
durable particles of fragments of stone or
gravel and sand or other fine mineral
particles free from vegetable matter and
lumps or balls of clay and of such nature it
can be compacted readily to form a firm,
stable layers. It shall conform to the
grading requirements shown in table 3
when tested by AASHTO T-11 and 27”.
10. SIEVE DESIGNATION MASS PERCENT PASSING
Standard Alternate US
Grading A Grading B Grading C Grading D
(mm) Std.
25 1" 100 100 100 100
10 3/8 50-85 60-100
5 No. 4 35-65 50-85 55-100 70-100
2 No. 10 25-50 40-70 40-100 55-100
0.5 No. 40 15-30 25-45 20-50 30-70
0.075 No. 200 5-20 5-20 6-20 8-25
11. The coarse aggregate material
retained on the 2.00 mm (No.10)
sieve shall have a mass per cent
of wear by the Los Angeles
Abrasion Test (AASHTO T-96) of
not more than 45.
12. When crushed aggregate is
specified, not less than 50 mass
per cent of the particles retained
on the 4.75 mm (No. 4) sieve shall
not have at least one fractured
face.
13. The fraction passing the 0.75
mm (No. 200) sieve should not be
greater than two thirds of the
fraction passing the 0.425 mm (No.
40) sieve.
14. The fraction passing 0.425 mm
(No.40) sieve shall have a liquid limit
of not greater than 35 and a
plasticity index range of 4 to 9 when
tested by AASHTO T-89 and T-
90respectively.
16. AGGREGATES FOR PORTLAND
CEMENT CONCRETE
IMPORTANT PROPERTIES FOR
AGGREGATES THAT ARE USED IN
CONCRETE PAVING MIXTURES:
17. Gradation
The size distribution of the
aggregate particles affects the relative
proportions, cementing materials and
water requirements, workability, pump
ability, economy, porosity, shrinkage,
and durability. The size distribution of
the aggregate particles should be a
combination of sizes that results in a
minimum of void spaces.
18.
19. Absorption
The absorption and surface
moisture condition of aggregates must
be determined so that the net water
content of the concrete can be
controlled.
20. Particle Shape and Surface Texture
• Rough textured, angular, or elongated particles
require more water to produce workable concrete.
• Smooth, rounded, compact aggregates require more
cementing materials to maintain the same water-
cement ratio.
Angular or poorly graded aggregates may result
in the production of concrete that is more difficult
to pump and also may be more difficult to finish.
The hardened concrete strength will generally
increase with increasing coarse aggregate
angularity, and flat or elongated coarse aggregate
particles should be avoided.
23. Abrasion Resistance
The abrasion resistance of an
aggregate is often used as a general
index of its quality.
Abrasion resistance applies only to
coarse aggregates. Aggregates vary in
their resistance to fracturing under
impact (toughness); and breaking down
into smaller pieces from abrasive action
(hardness).
25. Durability
Aggregates must be resistant to
breakdown and disintegration from
weathering (wetting/drying and
freezing/thawing) or they may break
apart and cause premature pavement
distress.
Durability and soundness are
terms typically given to an aggregate’s
weathering resistance characteristic.
26. Soundness Test
The soundness test
repeatedly submerges
an aggregate sample in a sodium
sulfate or magnesium sulfate
solution. This process causes salt
crystals to form in
the aggregate’s water permeable
pores. The formation of these
crystals creates internal forces
that apply pressure
on aggregate pores and tend to
break the aggregate.
27. Deleterious Materials
Aggregates should be free of
potentially deleterious materials such as
clay lumps, shales, or other friable
particles, excess dust and vegetable
matter are not desirable because they
generally affect performance by quickly
degrading, which causes a loss of
structural support and/or prevents
binder-aggregate bonding.
29. Particle Strength
For normal concrete
pavements, aggregate strength is rarely
tested. However, aggregate
characteristics other than strength, such
as the size, shape, surface
texture, grading and mineralogy are
known to affect concrete strength in
varying degrees. Particle strength is an
important factor in high-strength
concrete mixtures.
31. Purpose of mineral fillers in asphalt mixes:
• The portion of the mineral filler that is finer than the
thickness of the asphalt film and the asphalt cement
binder form a mortar or mastic that contributes to
improved stiffening of the mix.
• The particles larger than the thickness of the asphalt
film behave as mineral aggregate and hence
contribute to the contact points between individual
aggregate particles.
The gradation, shape, and texture of the mineral
filler significantly influence the performance of hot
mix asphalt.
32. MINERAL FILLERS
IMPORTANT PROPERTIES OF
MINERAL FILLER USED IN ASPHALT
CONCRETE APPLICATIONS
33. • Gradation – mineral fillers should have
100 percent of the particles passing 0.60
mm (No. 30 sieve), 95 to 100 percent
passing 0.30 mm (No. 40 sieve), and 70
percent passing 0.075 mm (No. 200
sieve).
• Plasticity – mineral fillers should be
nonplastic so the particles do not bind
together.
• Deleterious Materials – the percentage
of deleterious materials such as clay and
shale in the mineral filler must be
minimized to prevent particle breakdown.
35. Testing Methods:
a. Penetration graded bitumen
b. Viscosity graded bitumen
c. Oxidised bitumen grades
36. Penetration Graded Bitumen
Bitumen is classified by the depth to
which a standard needle will penetrate
under specified test conditions.
This “pen” test classification is used
to indicate the hardness of
bitumen, lower penetration indicating a
harder bitumen.
37. Viscosity graded bitumen
Bitumen is also graded and
specified by their viscosity at a standard
temperature (typically 60°C).
Specifications for viscosity graded
bitumen normally give the nominal
viscosity prefixed by a V, e.g. V1500.
38. Oxidised bitumen grades
The degree of oxidation can range
from very small, often referred to as air-
rectification, or semi-blowing, which only
slightly modifies the bitumen
properties, through to “full”
blowing, whereby the properties of the
bitumen are significantly different to
penetration grade bitumens.
39. Nomenclature and grading for
the oxidised bitumen products is
based on a combination of the
temperature at which the bitumen
reaches a certain “softness” when
being heated up as expressed by
the ring and ball softening point
test, and the penetration value.
41. Cut-back bitumen
Cut-backs are bitumen
preparations in which the viscosity of
the binder has been reduced by the
addition of a volatile
solvent, normally derived from
petroleum. Typically the solvents used
are white spirit and kerosene. Cut-
back products are typically used for
spraying and some mixing
applications.
42. Fluxed bitumen
Fluxed bitumens are bitumen
preparation where the viscosity of the
binder has been reduced by the
addition of relatively non-volatile oils.
Typical fluxants include gas oil and
vegetable based oils.
43. Modified bitumen
Modified bitumens are bituminous
binders whose performance
properties, such as elasticity, adhesive or
cohesive strength, have been modified by
the use of one or more chemical agents.
These agents may be polymers, crumb
rubber, sulphur and polyphosphoric
acid, among other materials. Modified
bitumens are widely used in the
production of roofing felt and in paving
applications.
44. Bitumen emulsion
Bitumen emulsions are products in
which tiny droplets (the dispersed phase)
of bitumen or bituminous binder are
dispersed in an aqueous medium (the
continuous phase).
Bitumen emulsions are used largely in
road surfacing applications, such as
surface dressing, cold mixtures and slurry
seals.
45. Asphalt
Asphalt is a mixture of a bituminous
binder with mineral aggregate
(stone), sand and filler, typically
containing approximately 4-7%m
bitumen.
47. Bituminous concrete
- is a type of construction material used
for paving roads, driveways, and
parking lots
- made from a blend of stone and other
forms of aggregate materials joined
together by a binding agent. This
binding agent is called “bitumen”
48. - has a thick, sticky texture like tar
when heated, then forms a dense
solid surface once it dries.
- is also widely known
as asphalt in many parts of the
world.
49. Bituminous concrete is
quite different than
standard concrete, and contains
no cement.
Bituminous concrete is
known for its distinctive black
appearance.
50. Asphalt paving is also fully
recyclable.
Some manufacturers add
recycled tires or glass
aggregate to recycled asphalt to
increase its strength and
resilience.
51. Bituminous concrete is strong
enough to handle years of vehicle
traffic, and is relatively easy to repair
or refinish.
It also provides a smoother and
quieter ride than cement
surfaces, which helps to reduce noise
pollution around highways and other
busy roads.
52. G. Asphalt Concrete Pavement
-composite material used in the
construction of roadways and
parking lots
- mixture of a petroleum
byproduct, asphalt bitumen and
aggregate materials
53. Methods of mixing asphalt
1. Hot mix asphalt concrete, HMAC
- produced by heating the asphalt binder to
decrease its viscosity, and drying the
aggregate to remove moisture from it prior
to mixing
** Mixing is generally performed with
the aggregate at about 300 °F (roughly
150 °C) for virgin asphalt and 330 °F (166 °C)
for polymer modified asphalt, and the
asphalt cement at 200 °F (95 °C)
54.
55. 2. Warm mix asphalt concrete, WMA
- produced by adding
either zeolites, waxes, asphalt emulsions,
or sometimes even water to the
asphalt binder prior to mixing
**This allows significantly lower mixing
and laying temperatures and results in
lower consumption of fossil fuels, thus
releasing less carbon dioxide, aerosols and
vapors
56.
57. 3. Cold mix asphalt concrete
- produced by emulsifying the
asphalt in water with
(essentially) soap prior to mixing
with the aggregate
- commonly used as a patch for
road surfaces
58.
59.
60. 4. Cut-back asphalt concrete
- same process as in cold
mix, but instead of soap and
water, kerosene or light
petroleum products are
employed to emulsify the
asphalt binder
61. 5. Mastic asphalt concrete
- produced by heating hard grade
blown bitumen (oxidation) in a green
cooker (mixer) until it has become a
viscous liquid after which the
aggregate mix is then added, and
then to be cooked again for another 6
to 8 hrs.
- used for footpaths, roofing, flooring
and other light-use paving projects
62. 6. Natural asphalt concrete
- occurs as the result of upwelling
bitumen
- exist below the Earth’s surface, but
can seep its way up through porous
sedimentary rocks and stones
65. • Caused by excessive loads.
• Heavy loads creates deflection on the
road surface, with insufficient
underlying strength.
• Repetitious underlying of the excessive
load with roughen and crack the road
pavement will ultimately result to
complete failure of the roadway.
66. 1. Bleeding or Flushing
-this distress is caused by excess asphalt in
the surface layer.
67. …cont’n
Major bleeding can be corrected by cutting
off excess asphalt with a motor grader or
removing it with a “heater planer”.
69. …cont’n
To repair corrugations in an aggregate base overlain with a thin surface
treatment, scarify the pavement, add aggregate as needed, mix well, re-
compact, prime, and then resurface. Where the surface has 2 inches or more of
asphalt plant mix, corrugations can be removed with a “heater planer”. After
removal of corrugations, cover with a new surface treatment or new asphalt
overlay. To repair shoved areas, remove surface and base as necessary and
replace with a more stable material to prevent a recurrence. For out-of-season
inclement weather repairs, smooth shoved areas with patching if the surface
unevenness is hazardous to traffic.
70. 3. Cracking, Alligator
Interconnected cracks
forming a series of small polygons
resembling an alligator’s skin are
called alligator cracks.
71. Types of Alligator Cracks
a. Alligator Cracking without Surface Distortion
80. 5. Cracking Joint
Joint cracks occur where the
shoulder or paved wedge separates
from the mainline pavement or along
weak seams of adjoining pavement
spreads in the surface layers.
83. 6. Random Cracking
The causes of random cracking are
numerous and, in its early stages,
difficult to determine. Consequences
range from severe, such as deep
foundation settlement, to slight, such
as a construction error or mishap.
90. 7. Polished Aggregate
Although uncrushed gravels often have surfaces
that are initially smooth and potentially
hazardous, crushed rock initially has a rough, skid-
resistant texture. Under the action of
traffic, however, some aggregates - including many
limestones - become polished and slick, especially
when wet. The likelihood of aggregate become
polished increases with the volume of traffic. Because
polished aggregate results in a loss of skid resistance, it
is potentially hazardous. The most economical repair is
to apply a skid-resistant surface treatment.
91.
92. 8. Potholes
Potholes are caused by water
penetrating the surface and causing the
base and/or subgrade to become wet and
unstable. They also may be caused by a
surface that is too thin or that lacks
sufficient asphalt content, lacks sufficient
base, or has too many or too few fines.
93.
94. Potholes in Surface Treatments over
Aggregate Base
To repair potholes in surface
treatments, take the following actions:
• Clean out hole.
• Remove any wet base.
• Shape hole so that it has vertical sides.
• Prime hole.
• Fill hole with Asphalt Concrete.
95. Potholes in Asphalt Concrete
To repair potholes in Asphalt Concrete,
take the following actions:
• Clean out hole.
• Remove any wet base.
• Square up pothole so that it has neat lines
both perpendicular and parallel to the center
line and have vertical sides.
• Prime the pothole.
• Fill the pothole with Asphalt Concrete.
96. 9. Raveling
Raveling is caused by a dry brittle surface; dirty,
dusty, or soft aggregate; patching beyond base
material; lack of compaction of surface during
construction; too little asphalt in mix; or
excessive heating during mixing.
Note: If the raveling is not a part of the paved
surface, no action should be taken. In other
words, don’t patch beyond the edge of the
pavement.
97.
98. 10. Channels or Rutting
Channels are caused by heavy
loads and high tire
pressures, subgrade settlement
caused by saturation, poor
construction methods, or asphalt
mixtures of inadequate strength.
99.
100. 11. Intact Surface
Where the depression is 1 inch or less
and the surface is cracked but still
largely intact, skin patch the area.
Where the depression is more than 1
inch and the surface is cracked but still
largely intact, repair with asphalt
concrete.
101. 12. Disintegrated Surface
Where the surface is badly cracked
and loose (regardless of amount of
depression), remove the old surface. If the
area shows signs of mud being pumped to
the surface, remove all wet material,
replace base material, compact, prime, and
build up with Asphalt Concrete.
102. 13. Upheaval or Frost Boil
Upheaval is caused by expansion of
freezing moisture in the lower courses of
the pavement or subgrade or by the
swelling effect of moisture in expansive
soils. When this distress occurs, repair by
installing combination drains as necessary
and replacing base and surface.
103.
104. I. Macadam Asphalt
- pioneered by Scottish engineer John
Loudon McAdam in around 1820
** he discovered that massive foundations
of rock upon rock were unnecessary, and
asserted that native soil alone would
support the road and traffic upon it, as
long as it was covered by a road crust that
would protect the soil underneath from
water and wear
105. • The lower 200-millimetre (7.9 in) road
thickness was restricted to stones no
larger than 75 millimetres (3.0 in).
• The upper 50-millimetre (2.0 in) layer of
stones was limited to 20 millimetres
(0.79 in) size and stones were checked
by supervisors who carried scales
106.
107. Tar-bound macadam or tarmac
-The area of low air pressure
created under fast-moving vehicles
sucks dust from the road surface,
creating dust clouds and a gradual
unravelling of the road
material. This problem was
approached by spraying tar on the
surface to create tar-bound
macadam.
109. SURFACE TREATMENT
•A surface treatment is an application of
asphalt materials to any type of road surface
with or without a
cover of mineral aggregate.
•This application produces an increase in
thickness usually less than 1 inch.
•Have a variety of uses
110. PURPOSES
1. Waterproof the surface.
2. Provide a wearing surface.
3. Make the surface nonskid.
4. Prevent hydroplaning.
5. Rejuvenate an old road or runway.
6. Make permanent improvements
111. TYPES
Surface treatments may be applied to the base
course of a new road or to the surface of an old road
as a method of repair. Surface treatments are
grouped into these categories:
1. Sprayed Asphalt Surface Treatment
2. Aggregate Surface Treatment
112. v
Sprayed Asphalt Surface Treatment
Sprayed asphalt treatments contain no aggregates.
They are simply applications of different types of
asphaltic materials to a prepared surface.
Three types of sprayed asphalt surface treatment:
a. FOG SEAL
b. DUST LAYING
c. ROAD OILING
113. FOG SEAL
• a fog seal is a light application of diluted slow-setting asphalt
emulsion, used to renew old asphalt surfaces and seal small
cracks and surface voids. Fog seals are especially useful for
pavements carrying a low volume of traffic.
• Other uses:
To seal surface voids in new asphalt plant mixes
To prevent dust on sprayed asphalt with cover
aggregate surface treatments
To increase aggregate retention
To provide a uniform dark color
114. FOG SEAL
The asphalt emulsion is diluted with an equal
amount of water, and the diluted material is
sprayed at the ROA of 0.1 to 0.2 gallon per
square yard, depending on the texture and
dryness of the old pavement. In normal
conditions, the separation and evaporation of
the water is rapid, permitting traffic within 1 or 2
hours.
115. DUST LAYING
- consists of spraying an untreated surface with a low-viscosity
liquid asphalt, such as SC-70, MC-30, MC-70, or a diluted slow
setting asphalt emulsion. The asphalt and dilutant
penetrate and coat the fine particles and temporarily relieve
the nuisance of dust. The material is sprayed at a ROA of 0.1 to
0.5 gallon per square yard.
- When emulsion is used, it should be diluted with 5 or more parts
of water by volume. Diluted emulsion dust-laying treatments
usually require several applications. The dust stirred by traffic
between applications eventually conglomerates and no longer
rises.
- This is an effective treatment in a very dusty environment where
one application of asphalt is insufficient.
116. ROAD OILING
- differs from dust laying in that it is usually accomplished as part of a
planned build up of low-cost road surfaces over several years. Each
application may be mechanically mixed with the material being treated, or
it may be allowed to penetrate. The light oils in the road oil penetrate into
the subgrade and tend to repel moisture absorption.
- The objective in all roads oiling work is to form a dustless wearing
surface, combined with a strong water-repelling subgrade.
Because soils vary widely, procedures for oiling area matter for local trial
and error, rather than scientific analysis.
- The amount of road oil, required in the first year of work will vary from
0.75 to 1.0 gallon per square yard. The first application is applied at the
ROA of about one half of the total; succeeding applications are made in
equal amounts. Road oiling treatments are placed several weeks apart,
depending upon the character of the asphalt soil mat.
117. Aggregate Surface Treatment
The sprayed asphalt with aggregate cover surface
treatments are applications of liquid asphalt, followed by
an application of aggregate. This can be done in one or more
layers of construction.
• Two types of sprayed asphalt with covered aggregate
surface treatments :
-SINGLE-SURFACE TREATMENT
-MULTIPLE-SURFACE TREATMENT
118. SINGLE-SURFACE TREATMENT
Single-surface treatments are thin, bituminous-aggregate
toppings, applied to existing bases or surfaces, such as
concrete or asphalt. Construction involves applying a
bituminous prime or tack coat to the base or surface.
This coating is followed by an application of bitumen
and small-sized aggregate. Single-surface treatments are
sometimes called seal coats, because they seal the surface
of the road or runway.
120. Applying Prime Coat
•The first steps, such as sweeping, priming or
tacking, and curing
•The binder (bituminous material) is applied over
the prime coat with an asphalt distributor
121. Binder Application
when you are applying the binder, it should be hot enough to spray properly and
cover the surface uniformly. After the binder cools and cures, it should bind the
aggregate tightly to prevent dislodgement by traffic. Individual aggregate stones
should be pressed into the binder but must not be covered by the binder.
Approximately one half of the individual aggregate stones should be exposed to
traffic. The ROA for the binder material should be between 0.25and 0.30 gallon of
asphalt per square yard. For a single-surface treatment, the bitumen must be
heated and applied to the surface while hot. The aggregate must be spread and
rolled before the bitumen cools. Under no circumstances is traffic permitted to
travel upon uncovered fresh bitumen. The distributor should NOT apply bitumen
until the aggregate is on hand and ready for application. When the distributor
moves forward to spray the asphalt, the aggregate spreader should start right
behind it. The bitumen should be covered within 1 minute if possible;
otherwise, the increase in asphalt viscosity may prevent
good binding of aggregate.
122. Aggregate Application
The size and amount of aggregate, used for surface treatments, are
important. You must use a size that matches the bitumen application
rate. For a single-surface treatment, one-half inch to sieve number 4 is
needed. The amount of aggregate should be 25-30 pounds per square
yard. When aggregate is distributed properly, very little hand work is
required. At longitudinal joints, the aggregate cover is stopped 8 inches
from the edge of the bitumen to ensure ample overlap of the bitumen
coat. All bare spots should be covered by hand spreading, and any
irregularities of the distribution should be corrected
with hand brooms. Excess aggregate in limited areas should be
removed immediately with square-pointed
shovels. When the aggregate spreader is properly set
and operated, handwork is reduced to a minimum.
123. Rolling
the aggregate is usually rolled by pneumatic-
tired rollers. Steel-wheeled rollers are not recommended
by themselves. If used, they should make only one pass
(one trip in each direction). The rolling operation should then
be completed with the pneumatic-tired rolls. Steel-
wheeled rollers produce maximum compaction but must be
used with care to prevent excessive crushing
of the aggregate particles. Also, these rollers will bridge over
smaller size particles and small depressions in the surface
and will fail to press the aggregate in these places in the
asphalt.
124. Procedures for Rolling
1. Rolling should be parallel to the center line of
the roadway to reduce the number of times the roller
must change direction.
2. Succeeding passes should overlap one half of the wheel width of the roller.
This action ensures that the aggregate becomes well embedded in the
bitumen.
3. Rolling should be completed before the bitumen
hardens. This will ensure that the aggregate becomes
well embedded in the bitumen.
4. Succeeding passes should be made from the low side to the high side of the
surface. This operation maintains the surface crown and prevents feathering
at the edges.
5. Rolling should be done at a slow speed.
6. Rollers should be only wet enough to prevent bitumen from sticking to the
wheels.
7. . The power wheel of the roller should pass over the unrolled surface before
the steering wheel(s) of the rollers. After rolling and curing, the surface is
ready for traffic.
125. MULTIPLE-SURFACE TREATMENT
A multiple-surface treatment is essentially the same as the
single-surface treatment. However, the multiple-surface
treatment consists of two or more successive layers
of binder and aggregate. This type of treatment is done in
stages. Each stage is accomplished in the same manner as
a single-surface treatment. The only difference is
that each additional layer of aggregate should be about one
half of the size of the previous layer. This allows the smaller
aggregate to interlock with the larger aggregate when rolled.
All aggregates are porous, but some are more porous than others. How porous an aggregate is determines how much liquid can be absorbed when soaked in water.