typical road cross section typical cross section typical pavement cross section gravel road cross section detail cross section of a road typical road section detail typical cross section of road road cross section details fdot typical road cross section roadway cross section drawings highway cross section typical roadway section typical pavement cross section roadway cross section cross section of a road typical pavement road section

1. TYPICALROAD STRUCTURE
CROSS SECTION
PRESENTED BY
AGLAIA

2. Typical Road Structure Cross Section Details
Composition of Road Structure:
Road Structure Cross Section is composed of the following
components
1. Surface/Wearing Course
2. Base Course
3. Sub Base
4. Sub Grade
typical road structure cross section

3. typical road structure cross section

4. Surface/Wearing Course
• The top layers of pavement which is in direct contact with the
wheel of the vehicle.
• bitumen is used as binder materials.
a. Bituminous Pavement
• Consists of combination of mineral aggregate with bituminous
binder ranging from inexpensive surface treatment ¼ in or less
thick to asphaltic concrete.
• For good service throughout the full life bituminous pavement
must retain following qualities.
1. Freedom from cracking or raveling.
2. Resistance to weather.
3. Resistance to internal moisture.
4. Tight impermeable surface or porous surface
typical road structure cross section

5.  Heat a viscous bituminous binder to make it fluid, then in a plant mix it
with heated aggregate place and compact the mixture while it is hot.
 Use fluid bituminous binder, mix it with aggregate at normal
temperature.
 Mixing may be done at a plant or on the prepared roadway.
 Spread and compact the mixture at normal temperature.
 Add solvent to a viscous bituminous binder to make it fluid with
aggregate at normal temperature.
 Spread and compact at normal temperature before solvent evaporates.
 Use fluid emulsion of viscose bituminous binder in water, mix it with
aggregate at normal temperature.
 Spread and compact at normal temperature before the emulsion breaks
down with its components.
typical road structure cross section

6.  Spread and compact clean crushed aggregate as for water bound
macadam.
 Over it spray heated dissolved or emulsified bituminous binder
which penetrates open areas of the rock and binds the aggregate
together. Thus is commonly called “Penetration Method”.
 Spread bituminous binder over the roadway surface then cover it
with properly selected aggregate. This is commonly called the
“Inverted Penetration Method”.
 Selections based on the requirements and economy, large volume
of heavy vehicles, low traffic volume etc.
typical road structure cross section

7. 2. Base course
• It is the layer immediately under the wearing surface (Applies
whether the wearing surface is bituminous or cement concrete and
or more inch thick or is but a thin bituminous layer).
• As base course lies close under the pavement surface it is
subjected to severe loading.
• The material in a base course must be of extremely high quality
and its construction must be done carefully.
Types of Base Course
1. Granular Base Course
2. Macadam Base
3. In-water bound Macadam
4. Treated Bases
typical road structure cross section

8. 3. Sub Base
• It is layer of granular material provided above sub grade generally
natural gravel.
• It is usually not provided on sub grade of good quality.
• It is also called granular sub base.
a. Function of Sub base in Road Cross Section
 It enables traffic stresses to be reduced to acceptable levels in sub-
grade in the Road Cross Section.
 It acts as a working plate form for the construction of upper pavement
layers.
 Acts as a drainage layer, by protecting the sub grade from wetting up.
 It intercept upward movement of water by capillary action.
 It acts as a separating layer b/w sub grade and road base. By this it
prevent the two layers from mixing up.
typical road structure cross section

9. b. Characteristics of materials used in Sub Base:
The sub grade material should be clean and free from organic matter
.
The material should have following characteristic.
 Well graded uniformity coefficient should not be less than 3.
 Fraction passing sieve #200 shall not be greater than 2/3rd of the
fraction passing sieve #40.
 Should have a L.L not greater than 25%.
 P.I not greater than 6
 CBR should not be less than 25.
 In coarse grain, aggregate retained by #10 sieve, %age of wear
shall not be greater than 5%.
 The max diameter of any particle shall not be greater than 2/3ed
of the layer thickness of sub-base.
typical road structure cross section

10.  Typical particle size distribution for the sub-base (granular) when will meet
strength requirement are
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11. • To avoid intrusion of silt and clay material in sub-base from sub
grade
• D15 (sub base) < 5 D15 (sub grade)
 Recommended plasticity characteristic for granular Sub Base
(Road Note 31) are;
typical road structure cross section

12. Sub Grade
• Consists of the naturally occurring material on which the road is
built, or the imported fill material used to create an embankment
on which the road pavement is constructed.
• Sub grades are also considered layers in the pavement design,
with their thickness assumed to be infinite and their material
characteristics assumed to be unchanged or unmodified.
• Prepared sub grade is typically the top 12 inches of sub grade.
typical road structure cross section

13. Thank you
For more…. Mail to aglaiaconnect2018@gmail.com
typical road structure cross section