Construction of road is important topic of infrastructural developement

1. CHP 4:CONSTRUCTION OF
ROADS
BY: R.V. K

2. TYPES OF PAVEMENTS
•Un Surfaced
–Earthen roads
–Gravel roads
•Surfaced
–Bituminous Road
–Cement Concrete Road
•Un Conventional
–Block Pavement

3. Further classification
Flexible Pavements
– Earthen Roads
–Gravel Roads
–Bituminous Roads
Rigid Pavements
–Reinforced Concrete
– Plane Concrete Roads

4. FLEXIBLE PAVEMENT RIGID PAVEMENT

5. Types of Pavements

6. Wheel Load Distribution

7. Flexible Rigid

8. Properties Flexible Rigid
Design
Principle
Empirical method
Based on load distribution
characteristics of the
components
Designed and analyzed by using the elastic
theory
Material Granular material Made of Cement Concrete either plan,
reinforced or prestressed concrete
Flexural
Strength
Low or negligible flexible
strength
Associated with rigidity or flexural strength
or slab action so the load is distributed over
a wide area of subgrade soil.
Normal
Loading
Elastic deformation Acts as beam or cantilever
Excessive
Loading
Local depression Causes Cracks
Stress Transmits vertical and
compressive stresses to the
lower layers
Tensile Stress and Temperature Increases
Design
Practice
Constructed in number of
layers.
Laid in slabs with steel reinforcement.
Temperature No stress is produced Stress is produced
Force of
Friction
Less. Deformation in the
sub grade is not transferred
to the upper layers.
Friction force is High
Opening to
Traffic
Road can be used for traffic
within 24 hours
Road cannot be used until 14 days of curing
Surfacing Rolling of the surfacing is
needed
Rolling of the surfacing in not needed.

9. LOAD DISTRIBUTION

10. PAVEMENT MATERIALS
Different materials are used in different
types
of pavements
• Soil
• Aggregates (natural, artificial)
• Bitumen, Tar, Emulsion, Cutbacks
• Modified bituminous binders
• Bituminous mixes
• Cement
• Cement concrete (plain, reinforced,
prestressed)
• Stabilized materials
• Recycled materials

11. Tests
• Tests on soil-CBR test
• Tests on agg- Abrasion,Impact,Shape test
• Tests on bitumen-Penetration,Softening,flash
n fire point etc

12. EARTHEN ROADS

13. General Terms used in Earthwork
of Roads
1. Borrow Pits
2. Balancing Earthwork
3. Lead & Lift
4. Spoil Bank

14. Borrow Pits
• Small pits dug parallel to the road alignment
on both sides of the road formation to draw
extra earth required to fill in embankment.

15. Spoil Bank
• Extra earth excavated and to be dumped on
the road sides in road in cutting.
• Dumped in regular shape for future use.

16. Balancing Earthwork
• While constructing road, it is desirable for a
segment of road, that the quantity of earthwork
in cutting and embankment should be nearly
equal if the soil available is good for the use.
• If possible, keeping in mind the limiting values of
gradients and curves, the alignment is so fixed to
have the equal quantity of earthwork in cutting
and banking.
• This is known as balancing earthwork.

17. Lead & Lift
• Lead: Horizontal distance travelled by the
earth to be moved for banking or dumping.
• Lift : Vertical distance travelled by the
earthwork after excavating.

18. Construction Procedure for Earthen Road
• Preparation of Sub-Grade: Arranging sub-grade in
proper gradient & camber.
• The sub-grade is rolled & watered to have OMC &
compacted to MDD.
• Over it, a layer of soil 10cm thick is sprayed,
rolled, & finished to have required camber &
gradient.
• 4-5 days curing.
• Opening to traffic.
• Watering for 10 days after opening to traffic.
Sub-Grade
Soil Layer 10 cm Thick

19. Marking Road Levels & Boundaries
• Marking the centre line of alignment on
ground with the help of theodolite.
• Marking carriageway, shoulder, berms, borrow
pits & road boundaries.
• Putting pegs & clearing stakes in the sides &
cleaning the area within the clearing stakes.

20. Construction Steps
• Clearing & Grubbing: It includes removing any
unwanted material i.e. tree roots, grass, loose
soil, Preparing the leveled surface
• Stripping off the top of soil to avoid the plant
growth on the road.
• Excavation: if the existing material is not
suitable for the road, other suitable material is
dumped in the excavated portion.
• Embankment preparation

21. Sheep Foot Roller

22. SOIL STABILIZED ROADS

23. soil stabilized roads
• Step1 Stabilization
Soil stabilization is the process whereby soil and related
materials are made stronger and more durable by mixing
with stabilizing agents. The common method to achieve soil
stabilization are:
a) Stabilization by compaction
b) Mechanical stabilization
c) Stabilizing by the use of stabilizing additives like cement,
lime, bitumen and many other stabilizers available in the
market. Alternatively, you may use TopSeal-SoilStabilizer a
Soil Stabilizer & Strengthener.
• 100% Environmentally safe
Non-toxic, non-flammable non-corrosive, non-allergenic
Water-based liquid form

25. Step 2 SeaIing
•
The stabilized soil surface is then sealed with TopSeal SOIL
SEALANT, providing a waterproof layer to prevent rain water
penetration into the soil and keep the road in condition at all times.
A stabilized soil road in dry condition will perform in its best
condition with TopSeal Soil Sealant covered on soil surface, making
it dust free and mud free at all times.
• Waterproof.
No erosion by rainwater & traffic
Maintain soil/gravel road strength even during rainy seasons
Dust & mud free
Minimum maintenance
Not slippery, overcoming hilly road problems
Seal stabilized soil surface using Top Seal Soil Sealant

27. Step 3Maintenance
• Patching any pothole or depression by mixing
roadside soil with TopSeal-SoilStabilizer,
followed by sealing a layer of TopSeal Soil
Sealant on the affected area. Maintenance
can be done as and when required for long-
lasting road.
Pothole & Depression Maintenance

29. WBM Roads
Definition: The pavement base course made of
crushed or broken aggregates mechanically
interlocked by rolling and voids filled by screening
and binding material with the assistance of water

30. Salient Features of WBM Roads
• WBM means Water Bound Macadam.
• The word Macadam comes from the name of
Scottish Engineer John L. Macadam.
• Wearing surface is formed by cleaned,
crushed aggregates which are spread and
rolled by sprinkling water.

31. Salient Features of WBM Roads
• Low cost
• Thickness range: 8cm to 30 cm
• Camber : 2.5% to 3% OR 1:36 to 1:48
• Surface is better than earthen road but rough
as compared to bituminous or Concrete roads
• Can be used as Base Course for Bituminous or
Concrete roads.

32. Salient Features of WBM Roads
• Low cost
• Thickness range: 8cm to 30 cm
• Camber : 2.5% to 3% OR 1:36 to 1:48
• Surface is better than earthen road but rough
as compared to bituminous or Concrete roads
• Can be used as Base Course for Bituminous or
Concrete roads.

33. IRC Recommendations for Course
Aggregate Grading for WBM Roads
Grading No Size Range (mm) Sieve Size (mm) % Passing the sieve by
weight
1
2
3
90 to 40
63-40
50-20
100
80
63
40
20
83
63
50
40
20
63
50
40
20
100
65-85
25-60
0-15
0-5
100
90-100
30-70
0-15
0-5
100
95-100
35-70
0-10

34. IRC Recommendations for Grading of
Screenings
Classification
Grading
Size of Screenings
mm
Sieve size
mm
% by weight
passing the sieve
A
B
12.5
10.0
12.5
10.0
4.75
0.15
10.0
4.75
0.15
100
90-100
10-30
0-8
100
85-100
10-30

35. Construction Procedure of WBM
Roads
• 1. Preparation of Sub Grade
• 2. Preparation of Base Course
• 3. Intermediate Layer
• 4. Wearing Surface
• 5. Shoulders
Sub Grade
Base Course
Intermediate Course
Wearing Course Shoulder
Shoulder

36. Precautions in Rolling WBM Roads
• Roller to be used- 8-10 Tonnes
• Rolling should be done from edges to the centre
• The successive rolling strips should be overlapped
• Length of each rolling should be <=200m.
• Water should be sprinkled and not poured by
buckets
• The rolling should be done for 80 passes or until
the aggregates are broken.

37. RIGID PAVEMENTS :
Pavements usually constructed using plain
or unreinforced cement concrete slabs
having high flexural strength.
It serves as good and durable wearing
surface as well as an effective and strong
base course of highway pavements.

38. WHERE ARE RIGID PAVEMENT PROVIDED ?
Rigid pavements are usually provided
when road stretch is subjected to adverse
conditions:
1. Very heavy rainfall.
2. Poor soil conditions
3. Poor drainage
4. Extreme climatic conditions
5. Combinations of some of these
conditions which may lead to
development of cracks in pavements.

40. MATERIALS FOR CONSTRUCTION OF CC
PAVEMENTS :
Portland cement :
--OPC of grade 43.
--OPC of grade 53.
--Portland pozzolona cement with fly ash (20 per cent)
Portland slag cement.
2. Coarse aggregates :
Los angeles abration value < 35 %
Combined flakiness and Elongation
index
<35%
Water absorption <3%
soundness For Na2So4 <12%
For MgSo4 <18%

41. Fine aggregates :
clean natural sand / crushed stones /combination of both.
It should be free of clay ,coal and ignite. Well graded with
100% passing 10 mm sieve.
WATER: Water used for mixing and curing of concrete shall be
clean and free from injurious amount of oil, salt, acid,
vegetable matter or other substances harmful to the finished
concrete. It shall meet the requirements stipulated in IS:456.
Chemical Admixtures : conforming to IS:9103 and IS:6925
shall be permitted to improve workability of the concrete
and/or extension of setting time, on satisfactory evidence that
they will not have of any adverse effect on the properties of
concrete with respect to strength, volume change, durability
and have no deleterious effect on steel bars.

42. Reinforcement:
• steel dowel bars (rounded) with yield
strength 240 MPa are used for the load
transfer across in expansion and
construction joints.
• Plain or twisted steel bars are used as
tie bars are used as tie bars at
longitudinal joints.

43. • Basic Components of CC Pavements:
• --soil subgrade.
• --drainage layer.
• --sub-base course generally constructed
using lean cement concrete or ‘dry lean
concrete’
• --separation membrane laid on top of base
course.
• --CC pavement slabs Using ‘ paving quality
concrete’ (PQC)
• --construction of different types of joints in
CC pavements.

45. • DIFFERENT TYPES OF CC PAVEMENTS:
 Jointed Plain Concrete Pavement (JPCP)
• – does not use any reinforcing steel
 Jointed Reinforced Concrete Pavement (JRCP)
• – Reinforcing steel placed at mid height and discontinued at
the joints.
 Continuously Reinforced Concrete Pavement (CRCP)
• – This method is very costly and generally not used in India.
 Pre-stressed Concrete Pavement (PCP)
• – Comprises new and innovative construction methods
Among these Plain CC pavements are most commonly used.

46. Equipments required for the different phases of concrete
road construction:
 Three wheeled or vibratory roller for compaction purpose
 Shovels, spades and Sieving screens
 Concrete mixer for mixing of concrete
 Formwork and iron stakes
 Watering devices - Water Lorries, water carriers or watering cans
 Wooden hand tampers for concrete compaction
 Cycle pump/pneumatic air blower for cleaning of joint
 Mild steel sections and blocks for making joint grooves for finishing
purpose

47. • METHODS OF CONSTRUCTION OF CC PAVEMENTS :
1. Construction by Slip Form Paver
2. Construction by Fixed Form Paver.
3. Construction by Fixed Form and labour oriented method of
paving.
• Basically different operation involved in construction of CC
pavements slabs are :
a) spreading prepared concrete mix to desired thickness,
grade and cross profiles.
b) Compacting.
c) Finishing the surface to desired surface profile.
d) Texturing.
e) Curing
f) Cutting of construction joints and longitudinal joints.

48. TYPES OF JOINTS IN CC PAVEMENTS:
A) Longitudinal joints ( parallel to traffic
flow).
B) Transverse joints ( perpendicular to
traffic flow)
-- Contraction joints
-- Expansion joints.
-- construction joints.

50. • Longitudinal joints
• During initial period of curing ,shrinkage
cracks usually develops in CC pavements
,when length or width of the slabs
exceeds 4.5 to 5 m width or more.
• Hence longitudinal joints are provided
whose spacing depends on width of
traffic lane . For instance if width is 3.5
or3.75 , then spacing of longitudinal
joints is also 3.5 or 3.75m respectively.

51. CONTRACTION JOINTS :
• These are purposely made weakened planes
which relieve the tensile stresses in the concrete
Caused due to changes in the moisture content
(Drying shrinkage) and/or temperature and
• Prevent the formation of irregular cracks due to
restraint in free contraction of concrete .
Purpose of joints in Concrete Roads
1. To absorb expansion & contraction due to variation in
temperature.
2. To avoid warping of slab edges
3. To grant facility in construction .

52. Construction of contraction joints :
• They are formed initially by sawing a
groove of 3-5 mm with up to about one-
fourth to one-third the slab which facilitates
the formation of a natural crack at this
location extending to the full depth.
Two methods of construction of contraction
joints:
1. As ‘plain joints without dowel bars’.
2. With dowel bars.

54. Expansion joints
• There are full-depth joints provided transversely
into which pavement can expand, thus relieving
compressive stresses due to expansion of concrete
slabs, and preventing any tendency towards
distortion and buckling.
• They are allows expansion of slabs due to
temperature.
• A joint filler board of compressible material is
used to fill the gap between the adjacent slabs at
the joint.
• The height of the filler board is such that its top
is 23-25mm below the surface of the pavement.
• The joint groove is filled by a sealant .

56. CONSTRUCTION OF EXPANSION JOINT WITH LOAD TRANSFER
DOWEL BARS
1. A steel bulk head with drilled holes at desired intervals is
provided to support end of slabs adjoining expansion joint such
that dowel bar can be inserted up to mid-length and held in
correct position.
2. Concreting is done , filler board is inserted through gap of
expansion joint ,so that dowel bars are properly placed in
position .
3. Now filler board will be 25mm below the surface of slab.
4. Wooden strips of 20x25 size and 25 mm depth are placed on
top of filler to fill gap during concreting .
5. After concrete is cured for a period of 14 days ,wooden strips
are removed and gap is thoroughly cleaned .
6. The sealant is heated ,poured in gap of joint, above filler board.
Top of sealant shall be at same level as adjoining pavement
surface.

58. EFFECT OF REINFORCEMENT IN CONCRETE PAVEMENTS

60. WORKING OF EXPANSION
JOINTS :
• During hot climate CC
slab expands towards
the gap provided at
expansion joint, due to
which filler board and
joint sealer gets
compressed and
pushed up.
• Dowel bars also move
along with the slab,
occupying the space in
the metal cap attached
at the end of each
dowel bar.

61. • AND, During cold
climate slabs
contracts and gap
increases and
dowel bars also
move along with
slab.
• The compressed
filler board may
partly recover and
joint sealer moves
down.

62. JOINT SEALER
Top portion of gap at expansion joint above the joint filler is sealed to
prevent entry of water and grit into pavement through expansion joint
The sealer should be impermeable and flexible to accommodate slab
movements , sealant should not flow in hot season or become brittle in
winter.
Rubberized bitumen is commonly used.
Hence, for effective sealing of joint for a long period, it is essential that
sealing compounds posses these properties :
1. Adhesion to cement concrete edges.
2. Extensibility without fracture.
3. Resistance to ingress of grit.
4. Durability.
Some sealants are:
• Hot poured rubberized Asphalts (Thermoplastic type)
• • Cold applied poly sulphide sealants( performs well for 5 to 7 years).
• Cold silicone Sealants(performs well for 10 years.)

63. QUALITY CONTROL DURING CONSTRUCTION:
1. CA samples collected should be tested to specified tests in the
laboratory to decide suitability.
2. Grading of CA and FA for mix is checked and compared with
specified gradation.
3. Samples of fresh CC mix are collected ,cube and beam
specimen prepared and tested according to standard test and
checked with acceptance criteria.
4. Side slabs of pavements is checked to find
hungry/honeycombed surface such surfaces are finished with
cement mortar.
5. Regularity of finished pavements is checked with a 3m straight
edge, 6 to 12 hours after laying , maximum permissible number
of irregularities of 4 mm and 7 mm sizes in a 300 m stretch are
20 and 2mm.

64. • Unevenness index or roughness index is
measured using bump indicator, along
the wheel path of each lane; the
average value of unevenness index shall
not exceed 2200 mm/Km length of
highway.

65. OPENING TO TRAFFIC
The entire surface of newly laid pavement is
carefully examined for :
1. Fine cracks have developed on surface
2. Non-uniform settlements of CC slabs has
taken place near abutments or along high
embankments.
If any such defect is noticed ,then corrective
measures may be taken up.
A newly constructed CC pavement stretch
shall be opened to traffic only after a
minimum curing of 28 days.