NHDP FUNDING, FLEXIBLE AND RIGID PAVEMENT

8/11/2019 NHDP FUNDING, FLEXIBLE AND RIGID PAVEMENT

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Q1. How much funding was allocated to the NHDP phases initially and what is the present

expenditure now?

Ans.

Phase Details Funding allocated Present

expenditure

length

Phase I Golden Quadrilateral `42,000 crore `52,434 crore 5846

Phase II NS-EW corridor 981

Phase

III

Upgradation of High traffic

density NHs

`55,000 crore `65,197 crore 10,000

Phase

IV

Widening of NH (excluding

Phase I, II, III)

`25,000 crore `27,800 crore 20,000

Phase V Six laning of selected

highways

`17,500 crore `41,210 crore 6,500

Phase

VI

Development of expressways `15,000 crore `16,680 crore 1,000

Phase

VII

Improvement of City road

network

`15,000 crore `16,680 crore _

Q2. What were the sources of funding for NHDP projects?

Ans.

The main sources of funding for the NHDP projects are stated below:

Government of Indias Gross Budgetary Support (GBS) and Additional Budgetary

Support (ABS)


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SEAL COAT:

Functions:

To water-proof the surface

To provide skid resistance.

Type A seal Coat:Liquid seal coat comprising of an application of a layer of bituminous binder

followed by a cover of stone chips.

Composition:

The quantity of bitumen per 10 m2 should be 9.8 kg; when bituminous emulsion is used as a

binder quantity required is 15 kg.

The stone chips should consist of angular fragments of clean, hard rocks. Stone chips should be

6.7 mm size defined as 100% passing through 11.2 mm sieve and retained on 2.36 mm sieve.

The quantity used for spreading should be 0.09 m3per 10 m

2area.

Construction:

Bitumen should be heated to 1500

to 1630

C and sprayed. Immediately after its application, stone

chips should be spread by means of mechanical grit spreaders. After that, rolling is done with a

8-10 tonne smooth wheeled roller.

Type B seal coat: Premixed seal coat comprising of a thin application of fine aggregate

premixed with bituminous binder.

Composition:

The quantity of bitumen per 10 m

2

should be 6.8 kg; when bituminous emulsion is used as abinder quantity required is 10.5 kg.


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The aggregate should be sand or grit and should consist of clean, hard rocks. The aggregates

should pass 2.36 mm sieve and be retained on 180 micron sieve. The quantity used for spreading

should be 0.06 m3per 10 m

2area.

Construction:

The binder should be heated in boilers of suitable design. The aggregates should be dry and

heated to 1500

to 1650

C in a mixer. The mix is then transported to the site and spread uniformly

on the bituminous surface followed by rolling with smooth wheeled roller of 8-10 tonne weight.

TACK COAT:

Function:

To ensure proper bonding between the new construction and old surface

Composition:

The binder used for tack coat should be bitumen emulsion complying with IS 8887 of a type and

grade as specified in the contract. Cutback bitumen can also be used per IS 217 for places with

sub-zero temperatures.

Construction:

The surface on which tack coat is applied should be swept clean with a mechanical broom in

order to make it free from dust and clean. The rate of application of tack coat generally varies

from 0.20 to 0.40 kg/m2. The normal range of spraying temperature for bitumen emulsion should

be 200to 70

0C and for cutback, 50

0to 80

0C if RC-70/MC-70 is used. The tack coat should be

left to cure until all the volatiles have evaporated before any subsequent construction is started.

PRIME COAT:

Functions:

To seal the pores by penetrating into it

To water-proof the underlying layer


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To coat and bond dust and loose mineral particles

To provide adhesion between the base and superimposed layer

Composition:

As per the porosity characteristics of the surface to be primed, the choice of the bituminous

primer is made. The type and viscosity of the primer should comply with the requirements of IS

8887. The quantity of liquid bituminous material per 10 m2varies from 6 to 9 kg for low porous

surface, 9-12 kg for medium and 12-15 kg for surfaces with high porosity. The use of MC

cutback should be restricted only for sub-zero temperature conditions.

Construction:

The surface is first prepared by sweeping clean of dust and loose particles without disturbing the

interlocking of aggregates. The rate of application is cited at the contract although the method of

application will depend upon the type of equipment to be used, size of nozzles etc. A primed

surface should be allowed to cure for at least 24 hours or such other period as is found to be

necessary to allow all the volatiles to evaporate before any subsequent surface treatment.

SURFACE COURSE/WEARING COURSE:

Functions:

It provides characteristics such as friction, smoothness, drainage, etc. Also it will prevent

the entrance of excessive quantities of surface water into the underlying base, sub-base

and sub-grade,

It must be tough to resist the distortion under traffic and provide a smooth and skid-

resistant riding surface,

It must be water proof to protect the entire base and sub-grade from the weakening effect

of water.

Bi tuminous concrete:

Composition:


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Bitumen: It should be paving bitumen of penetration grade complying with IS: 73 Paving

Bitumen. As per requirement the bitumen can be modified bitumen also.

Coarse aggregate:It consists of crushed rock, crushed gravel or other hard material retained on

2.36 mm sieve. They should be clean, hard and durable.

Fine Aggregate:They should be clean, hard and durable. They consist of crushed or naturally

occurring material or a combination of the two, passing through 2.36 mm sieve and retained on

75 micron sieve and should have following properties-

Property Test Specification

Cleanliness Grain Size Analysis Max 5% passing 0.075 mm

sieve

Particle shape Flakiness and elongation

index

Max 30%

Strength Loss Angels Abrasion Value Max 30%

Agg. Impact Value Max 24%

Polishing Polished stone value Min 55

Durability Soundness: Sodium Sulphate Max 12%

Magnesium Sulphate Max 18%

Water absorption Water absorption Max 2%

Stripping Coating and stripping of

bitumen aggregate mixture

Maximum retained coating

95%

Water sensitivity Retained tensile strength Min 80%

Requirement of the mixture:

Minimum Stability (kN at 60 C) 9.0

Minimum Flow (mm) 2

Maximum flow 4

Compaction Level (no. of blows) 75 blows on each of the two faces of the

specimen


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Percent of air voids 3-6

%VMA 10-16

%VFB 65-75

Loss of stability on immersion in water at

600C

Min 75% retained strength

Construction:

The pre-existing surface should be thoroughly swept clean by a mechanical broom, and the dust

removed by compressed air. Except in areas where a mechanical paver cant access, bituminous

material shall be spread, leveled and tamped by an approved self propelled paving machine. The

bituminous material, with a temperature greater than 1450C, should not be laid on deposited on

bridge deck.

BASE COURSE:

Function:

To provide additional load distribution

To contribute to the sub-surface drainage

Dense graded bituminous macadam:

Composition:

Bitumen: It should be paving bitumen of penetration grade complying with IS: 73 Paving

Bitumen. As per requirement the bitumen can be modified bitumen also.

Coarse aggregate:It consists of crushed rock, crushed gravel or other hard material retained on

2.36 mm sieve. They should be clean, hard and durable.

Fine Aggregate:They should be clean, hard and durable. They consist of crushed or naturally

occurring material, or a combination of the two, passing through 2.36 mm sieve and retained on

75 micron sieve and should satisfy the physical requirements as stated below-


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Property Test Specification

Cleanliness Grain Size Analysis Max 5% passing 0.075 mm

sieve

Particle shape Flakiness and elongation

index

Max 30%

Strength Loss Angels Abrasion Value Max 35%

Agg. Impact Value Max 27%

Durability Soundness: Sodium Sulphate Max 12%

Magnesium Sulphate Max 18%

Water absorption Water absorption Max 2%Stripping Coating and stripping of

bitumen aggregate mixture

Maximum retained coating

95%

Water sensitivity Retained tensile strength Min 80%

Filler: It should consist of finely divided mineral matter such as rock dust, hydrated lime or

cement.

The combined grading of the coarse and the fine aggregates and added filler for a particular

mixture should fall within the limits of grading 1 and grading 2.

Requirement of the mixture:

Minimum Stability (kN at 60 C) 9.0

Minimum Flow (mm) 2

Maximum flow 4

Compaction Level (no. of blows) 75 blows on each of the two faces of the

specimen

Percent of air voids 3-6

%VMA 10-16

%VFB 65-75


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Construction:

The pre-existing surface should be thoroughly swept clean by a mechanical broom, and the dust

removed by compressed air. When the material on which the DBM is to be laid is other than a

bitumen bound layer, a prime coat shall be applied. The mixture is prepared in a hot mix plant

and carried to the site and is spread over followed by rolling of smooth wheeled roller.

SUB-BASE COURSE:

Functions:

To provide structural support, improve drainage,

To reduce the intrusion of fines from the sub-grade in the pavement structure

If the base course is open graded, then the sub-base course with more fines can serve as

filler between sub-grade and the base course

Composition:

The material to be used for the work shall be natural sand, gravel, crushed stone or their

combination depending on the grading required. The material should be free from organic or

other deleterious constituents and should conform to one of the three gradings given in table:

IS Sieve Percent by weight passing the IS sieve

Designation Grading I Grading II Grading III

75 mm 100 - -

53 mm 80-100 100 -

26.5 mm 55-90 70-100 100

9.5 mm 35-65 50-80 65-95

4.75 mm 25-55 40-65 50-80

2.36 mm 20-40 30-50 40-65

0.425 mm 10-25 15-25 20-35

0.075 mm 3-10 3-10 3-10

CBR value 30 25 20


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(Minimum)

Construction:

Immediately prior to the laying of sub-base, the subgrade shall be prepared by removing all the

vegetations, lightly sprinkled with water and rolled with two passes of 80-100 kN smooth

wheeled roller.

The materials selected as per the table are mixed either manually or in mechanically. Moisture

content of the loose material is checked with IS: 2720 (Part 2) and suitably adjusted by

sprinkling water so that it remains 1% above to 2% below the OMC during compaction.

After placing the sub-base materials, rolling should start immediately. If the thickness of the

compacted layer does not exceed 100 mm, a smooth wheeled roller of 80-100 kN can be used.

For thickness upto 225 mm, vibratory roller of 80-100 kN of static weight or pneumatic tyred

roller of minimum 200-300 kN weight having a tyre pressure of 0.7 MN/m2.

Rolling shall be continued till the density the density is at least 98% of the MDD of the material

determined as per IS: 2720 (Part 8).

SUB-GRADE:

To receive the stresses from the layers above

To transfer the entire load coming to it to the earth mass

To provide a good support to the earth structure

Composition:

The materials used in subgrade shall be soil, moorum, gravel, a mixture of these or any other

material approved by the engineer provided the materials are free of logs, stumps, roots or anyother ingredient likely to deteriorate or affect the stability of the subgrade.

Construction:

Any fill material with soluble sulphate content content exceeding 1.9 g/L and total sulphate

content exceeding 0.5% by mass (BS: 1377 test 10, 9) shall not be deposited within 500 mm


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depth of subgrade. The size of the coarse material in the mixture of earth should not exceed 50

mm when placed in subgrade. The materials yielding the maximum laboratory dry unit weight

when tested as per IS: 2720 (part 8) lesser than 17.5 kN/m3 shall not be used in subgrade.

After the site has been cleared the subgrdae, subgrade is generally built sufficiently wider than

the design dimension so that the surplus material may be trimmed, ensuring that the remaining

material is to the desired density and in position, The subgrade material is then compacted to not

less than 97% of the MDD calculated as per IS: 2720 (part 8). The subgrdae materials are

generally spread in layers of uniform thickness not exceeding 200 mm compacted thickness not

exceeding 200 mm compacted thickness over the entire width of embankment by mechanical

means.

Moisture content of each layer of soil shall be adjusted such that at the time of compaction it is in

the range of 1% to 2% below the OMC determined.

The compaction shall be done with the help of vibratory roller of 80 to 100 kN static weight.

RIGID PAVEMENT:

Surface course:

Functions:

To provide characteristics such as friction, smoothness, noise control and drainage

To serve as a waterproofing layer to the underlying base, subbase and subgrade

To carry the load stresses

Composition:

Cement: Preference should be to use at least 43 grade or higher. If the soil around has soluble

salts like sulphates in excess of 0.5% the cement used should be should be sulphate resistant and

should conform to IS: 12330.

Admixtures: Conforming to IS: 6925 and IS: 9103 to improve the workability of concrete.


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Aggregates: Natural aggregates with IS: 383 but with a Los Angels Abrasion Value lesser than

35%

Coarse aggregate: The maximum size should not exceed 25 mm for pavement concrete.

Aggregates should have water absorption value lesser than 2%.

Fine aggregate: Clean natural sand or crushed stone sand or combination of the two.

Water: It should be clean and free from injurious amount of oil, salt, acid etc.

The proportions of these are determined as per the design strength of the pavement.

Dowel bars and tie bars are also provided at the transverse and longitudinal joints respectively.

Construction:

The concrete to be used in pavement is prepared in a batching plant and is transported to the site

without delay by means of trucks. The delay must not exceed 120 minutes when concrete

temperature is less than 250C and 90 minutes when the temperature is in between 25

0C to 30

0C.

The mixing and placing of concrete should progress at such a rate as to permit proper finishing,

protecting and curing of the pavement. While the concrete is still plastic, its surface shall be

brush textured. After 3 hours the pavement, shall be covered by moist hessian and the same shall

be covered by moist hessian and the same shall be kept damp for a minimum period of 14 days

after which the hessian can be removed.

BASE COURSE:

Water bound Macadam:

Functions:

additional load distribution,

contributes to drainage and frost resistance,

uniform support to the pavement

a stable platform for construction equipment

Bases also help prevent subgrade soil movement due to slab pumping.


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Composition:

Coarse Aggregate: It should be either crushed or broken stone, crushed slag etc. Los Angels

Abrasion value should be 30% (maximum) and combined flakiness and elongation indices are

30% (max).

Screenings: Screenings to fill the voids in the coarse aggregate should consist of the same

material as coarse aggregate.

Construction:

The surface of the sub-base to receive the WBM course should be prepared to the specified lines

and camber and made free of dust and other extraneous material. The coarse aggregates should

be spread uniformly and evenly upon the prepared subgrade by using templates placed across the

road. The spreadings should be done from stockpiles along the side of the roadway or directly

from vehicles. Immediately following the spreading of the coarse aggregates, rolling shall be

started with three wheeled power 80 to 100 kN capacity or tandem or vibratory rollers of 80 to

100 kN static weight.

After the coarse aggregate has been rolled, screenings to completely fill the interstices should be

applied gradually over the surface. These should not be damped or wet at the time of applying.

This is followed by sprinkling of water and grouting and the binding material is applied and left

to set and dry.

Documents

NHDP FUNDING, FLEXIBLE AND RIGID PAVEMENT