This document provides details on various aspects of road construction including: 1) Classification of excavated materials such as soil, ordinary rock, hard rock, and marshy soil. 2) Requirements for embankment construction including physical requirements of materials, compaction and moisture content, layer thickness, and quality control tests. 3) Details on road drainage systems including types of aggregate drains and their grading requirements.

1. IMPORTANT ASPECTS OF ROAD
CONSTRUCTION
Presented by:
Subir Kumar Sharma
Assistant Professor
Department of Civil Engineering

2. Classification of Excavated Material
1) Soil :This shall comprise top soil, turf, sand, silt, loam, clay, mud ,peat, black cotton soil,
soft shale or loose moorum a mixture of these and similar material which Yield to the
ordinary application of pick, spade and/or shovel, rare or other ordinary digging implement .
Removal of gravel or any other nodular material having dimension in any one
direction not exceeding 75mm occurring in such strata shall be deemed to be covered under
this category.
2) Ordinary Rock (not requiring blasting) This shall include:
i) Rock types as laterites, shales and conglomerates, varieties of limestone and sand stone
etc., also including any rock which in dry state may be hard, requiring blasting but which,
when wet, becomes soft and manageable by means other than blasting
ii) Macadam surfaces such as water bound and bitumen / tar bound; soiling of roads, paths
etc. and hard core; compact , moorum or stabilized soil requiring grafting tool or pick or both
and shovel, closely applied gravel; and cobble stone having maximum dimension in any one
direction between 75mm and 300mm.
iii) Lime concrete, stonemasonry in lime mortar and brick work in lime/cement mortar below
ground level, reinforced cement concrete which may be broken up with crow bars or picks
and stone masonry in cement mortar below ground level.

3. iv) Boulders which do not require blasting having maximum dimension in any direction of
more than 300mm, found lying loose on the surface or embedded in river bed , soil, talus,
slope wash and terrace material or dissimilar origin.
3) Hard Rock (requiring blasting) This shall comprise:
i) Any rock or cement concrete for the excavation of which the use of mechanical plant and
/or blasting is required;
ii) Reinforced cement concrete (reinforcement cut through but not separated from the
concrete) below ground level; and
iii) Boulders requiring blasting.
4) Hard Rock (blasting prohibited): where blasting is prohibited for any reason and
excavation has to be carried out by chiseling, wedging or any other agreed method.
5) Marshy soil :This shall include soils like soft clays and peats excavated below the
original ground level of marshes and swamps and soils excavated from other areas requiring
continuous pumping or bailing out water.

4. EMBANKMENT CONSTRUCTION
1) Physical Requirements: The following materials such as (a) materials from marshes,
swamps and hogs, (b) Peat, log, stump perishable materials, (c) clay with L.L. exceeding
70% and P.I. exceeding 45%, (d) expansive soils with free swelling index exceeding 50%
and (e) materials with salts are unsuitable for embankment
2) The Size of the coarse material in earth shall ordinarily not exceed 75mm when placed
in the embankment and 50mm in sub grade. However the Engineer may at his discretion
permit the use of larger size material, which shall not be more than two thirds of the
compacted layer thickness.
3) Density requirements: The M.D.D. (lab) shall not be less than 1.52 g/cc for
embankments upto 3 M height and 1.6 g/cc for embankments exceeding 3m height. It shall
not be less than 1.75 g/cc (17.5 KN/cum) for sub grade, earthen shoulders, and verges or
back fill.
4) Borrow materials: Borrow pits along the roadside shall be discouraged. If permitted by
the Engineer, these shall not be dug continuously. Ridges not less than 8m width should be
left at intervals not exceeding 300M. Small drains should be cut through the ridges to
facilitate drainage. The depth of the pit shall be limited to 1.5M and its edge shall not fall
within the offset width from the toe of the embankment.
5) Compaction Requirements: The relative compaction shall not be less than 95% of lab
MDD for embankment and not less than 97% for sub grade and earthen shoulders.

5. 6) Trimming: The embankment / sub grade shall be built sufficiently wide (0.6m on
either side for 2: 1 slope) than the design dimension to allow good compaction of
edges. The surplus material shall be trimmed to proper slope and permitted to reuse.
7) Layer thickness: The embankment and sub grade materials shall be spread in
layers of uniform thickness not exceeding 200mm compacted.
8) Moisture content: At the time of compaction, the moisture content shall be in the
range of 1 percent above to 2 percent below the optimum moisture content obtained
from lab tests.
9) Breaking clods: Clods or hard lumps of earth shall be broken to have a maximum
size of 75mm when being placed in the embankment and a maximum size of 50mm
when being placed in the sub grade.
10) Drainage: The surface of the embankment / sub grade at all times shall be carried
out at all times during construction shall be maintained at such a cross fall as will
shed water and prevent ponding.
11) Benching: Whenever fill is to be deposited against the face of a natural slope or
sloping earthworks face including embankments, cuttings, other fills and excavations
steeper than 1 vertical on 4 horizontal, such faces shall be benched continuously. The
horizontal benches each at least 300mm wide, shall be cut into the old slope for
ensuring adequate bond.

6. 12) Repairing of damages caused by rain/spillage of water:
The soil in the affected portion shall be removed in such areas before the next
layer is laid and refilled in layers and compacted using appropriate mechanical means.
13) Necessary Quality Control tests:
(1) Sieve Analysis
(2) Atterberg’s limits
(3) Procter’s Test to find out OMC and MDD
(4) Laboratory CBR Tests on 4 day soaked samples
(5) Field Density Tests to find relative compaction.

7. Earthwork for widening existing road embankment:
When an existing embankment and/or sub-grade is to be widened and its
slopes are steeper than 1 vertical on 4 horizontal, continuous horizontal benches, each
at least 300mm wide, shall be cut in to the old slope for ensuring adequate bond with
the fresh embankment/sub-grade material to be added.
The material obtained from cutting of benches could be utilized in the
widening of the embankment/sub-grade. However, when the existing slope against
which the fresh material is to be placed is flatter than 1 vertical on 4 horizontal, the
slope may be only be ploughed or scarified instead to benching.
Embankment and sub-grade around structures:
To avoid interference with the construction of abutments, wing walls or
return walls of culvert/bridge structures, the Contractor shall, at points to be
determined by the Engineer suspend work on embankment forming approaches to
such structures, until such time as the construction of the latter is sufficiently
advanced to permit the completion of approaches without the risk of damage to the
structure.

8. Road Drainage IRC: SP 42
The main objective of road drainage is to prevent early damage of the pavement
due to entry of excess of water and preventing saturation up to a depth of 1 meter below
the top of sub grade
Various types of damages arising due to inadequate drainage
1) Reduction in bearing capacity of sub grade soil
2) Pavement failures like potholes, rutting, waviness and corrugation in flexible pavement
3)Reduction in strength of many pavement materials like stabilised soil, WBM and BT
surfacing
4) Damages to shoulder and pavement edges from surface water
5) Considerable erosion of soil from sub strata, slopes ,cut and hill side due to surface water
Aggregate drains:
Aggregate drains shall be place within the verge/shoulders after completion of the
pavement. Depth, thickness and spacing of the aggregate drains shall be as shown on the
plan.

9. Table 300-4. Grading Requirements for Aggregate Drains
Sieve size
Percent passing by weight
Type A Type B
63 mm ─ 100
37.5 mm 100 85 ─ 100
19 mm ─ 0 ─ 20
9.5 mm 45 ─ 100 0 ─ 5
3.35 mm 25 ─ 80 ─
600 micron 8 ─ 45 ─
150 micron 0 ─ 10 ─
75 micron 0 ─ 5 ─

10. GRANULAR SUB BASE
Requirements: The materials to be used for the work shall be natural sand, moorum,
gravel, crushed stone, or combination thereof to satisfy the following requirements:
a) The mix shall be as per the specified grading. The Engineer has to specify a particular
grading from the six gradings given in Table 400-1 and 400-2. In some special cases, the
Engineer may specify a modified grading other than the above six gradings.
b) The material in the mix shall have a 10 percent fines value of 50 KN or more (for
sample in soaked condition) when tested in compliance with BS: 812(part III).
c) The material passing 425 micron (0.425mm) in the mix when tested according to 1S:
2720 (Part 5) shall have liquid limit and plasticity index not more than 25% and 6%
respectively.
d) The mix shall produce the required laboratory CBR values on 4 day soaked samples.

11. IS Sieve
Designation
Per cent by weight passing the IS sieve
Grading I Grading II
Grading
III
75.0 mm 100 -- --
53.0 mm 100
26.5 mm 55-75 50-80 100
9.50 mm
4.75 mm 10-30 15-35 25-45
2.36 mm
0.425 mm
0.075 mm < 10 < 10 < 10
CBR Value (Minimum) 30 25 20
Table 400-1. Grading for Close-Graded Granular Sub-Base Materials

12. IS Sieve
Designation
Per cent by weight passing the IS sieve
Grading I Grading II Grading III
75.0 mm 100 -- --
53.0 mm 80-100 100 --
26.5 mm 55-90 70-100 100
9.50 mm 35-65 50-80 65-95
4.75 mm 25-55 40-65 50-80
2.36mm 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 (Minimum) 30 25 20
Table 400-2. Grading for Coarse Graded Granular Sub-Base Materials
A minimum Aggregate Impact value of 50% and maximum Water Absorption
value of 6% is stipulated in table 4.8 of Rural Roads Manual (IRC: SP20-2002)

13. 1) Aggregate Impact Value IS: 2386(Part-4) or IS: 5640 30% (Max)
2) Flakiness Index 15% (Max)
3) Combined Flakiness And
Elongation Indices (Total)
For coarse Aggregates
IS: 2386 (part-1) 30% (Max)
Layer Max AIV % Max FI %
Max Water
Absorption
Sub Base Course 50 % 40 % 6 %
Base Course 40 % 30 % 3 %
Climate Range Max Liquid Limit Plasticity Index
Moist Temp and Wet Tropical 35 % 4 - 9 %
Seasonal Wet Tropical 40 % 6 -15 %
Arid 55 % 15 – 30 %
WATER BOUND MACADAM SUB-BASE/BASE.
Plasticity Requirement for Binder for WBM as Wearing Course
Physical Requirements of Coarse Aggregates
TABLE 4.8 of RURAL ROADS MANUAL IRC: 20-2002,
PHYSICAL REQUIREMENTS OF MATERIAL FOR WBM

14. Sl.
No.
Size Range IS Sieve Designation
Percent by weight
passing.
1. 90 mm to 45 mm
125 mm
90 mm
63 mm
45 mm
22.4 mm
100
90-100
25-60
0-15
0-5
2. 63 mm to 45 mm
90 mm
63 mm
53 mm
45 mm
22.4 mm
100
90-100
25-75
0-15
0-5
3. 53 mm to 22.4 mm
63 mm
53 mm
45 mm
22.4 mm
11.2 mm
100
95-100
65-90
0-10
0-5
Grading requirement of Coarse aggregates:
.
Table 400-7 Grading Requirements of Coarse Aggregates
Note: The Compacted thickness for a layer with Grading 1 shall be 100mm while for layer
with other gradings ie.2 & 3 it shall be 75 mm.

15. Screenings
Screenings to fill voids in the coarse aggregate shall generally consist of the
same material as the coarse aggregate. However, where permitted, predominantly
non-plastic material such as moorum or gravel (other than rounded river borne
material) may be used for this purpose provided liquid limit and plasticity index of
such material are below 20 and 6 respectively and fraction passing 75 micron sieve
does not exceed 10 percent.
Binding material
Binding material to be used for water bound macadam as a filler material meant
for preventing raveling, shall comprise of a suitable material approved by the Engineer
having a Plasticity Index (PI) value of less than 6 as determined in accordance with IS:
2720 (Part-5).
The quantity of binding material where it is to be used, will depend on the type of
screenings. Generally, the quantity required for 75 mm compacted thickness of water
bound macadam will be 0.06-0.09 Cum/10 Sq. m and 0.08-0.10 m3/10 m2 for 100 mm
compacted thickness.
Spreading coarse aggregates
The coarse aggregates shall be spread uniformly and evenly upon the prepared
sub grade/sub-base/base to proper profile by using templates placed across the road
about 6 M apart, in such quantities that the thickness of each compacted layer is not
more than 100 mm for Grading 1 and 75 mm for Grading 2 and 3.

16. Rolling
Immediately following the spreading of the coarse aggregate, rolling shall be
started with three wheeled power rollers of 80 to 100 KN capacity or tandem or
vibrator rollers of 80 to 100 KN static weight.
The type of roller to be used shall be approved by the Engineer based on trial run.
Rolling shall be discontinued when the aggregates are partially compacted
with sufficient void space in them to permit application of screenings. However, where
screenings are not to be applied, as in the case of crushed aggregates like brick metal,
laterite and kankar, compaction shall be continued until the aggregates are thoroughly
keyed.
During rolling, slight sprinkling of water may be done, if necessary. Rolling
shall not be done when the sub-grade is soft or yielding or when it causes a wave-like
motion in the sub-grade or sub-base course.
•Application of Screenings
•Sprinkling of water and grouting
•Application of binding material
•Setting and drying

17. WET MIX MACADAM
The thickness of a single compacted Wet Mix Macadam layer shall not be less than
75mm. when vibrating or other approved types of compacting equipment are used,
the compacted depth of a single layer of the sub base course may be increased to
200mm upon approval of the Engineer.
Physical requirements of Aggregates for Wet Mix Macadam Sub-Base and
Crusher Run-Macadam Base: Coarse aggregates shall be crushed stone. If
crushed gravel/shingle is used, not less than 90 per cent by weight of the
gravel/shingle pieces retained on 4.75 mm sieve shall have at least two fractured
faces. The aggregates shall conform to the physical requirements set forth in Table
given below.
Test Test Method Requirements
1. Aggregate impact value
IS 2386(Part-4) or IS-
5640
30 per cent (Max).
2.Combined flakiness and
Elongation indices (Total)
IS 2386(Part-1) 30 per cent (Max).
3. Water absorption test IS 2386(Part-3) 2 per cent (Max).
4. Liquid Limit of material
passing 425 micron
IS 2720(Part-5) Not more than 25
5. Plasticity Index of material
passing 425 micron
IS 2720(Part-5) Not more than 6
Table 400-10. and 400-13

18. IS Sieve Designation Per cent by weight passing the IS Sieve
53.00 mm 100
45.00 mm 95-100
26.50 mm ---
22.4 mm 60-80
11.20 mm 40-60
4.75 mm 25-40
2.36 mm 15-30
600.00 micron 8-22
75.00 micron 0-8
Note: The final gradation approved within these limits shall be well graded from coarse to fine and
shall not vary from the low limit on one sieve to the high limit on the adjacent sieve or vice versa.
Layer Thickness: Maximum if smooth wheeled roller is used = 100mm compacted
Maximum if vibrated roller is used= 200mm
Table 400-11. Grading Requirements of Aggregates for the Wet Mix Macadam

19. BT. SURFACING
501. GENERAL REQUIREMENTS FOR BITUMINOUS PAVEMENT LAYERS
Materials
•Binder: The binder shall be an appropriate type of bituminous material
complying with the relevant Indian Standard (IS), as defined in the
appropriate Clauses of these specifications, or as otherwise specified
herein.
•Coarse Aggregates: The coarse aggregates shall consist of crushed rock,
crushed gravel or other hard material retained on the 2.36mm sieve. They
shall be clean, hard, durable, of cubical shape, free form dust and soft or
friable matter, organic or other deleterious matter.
•Fine Aggregates: Fine aggregates shall consist of crushed or naturally
occurring material, or a combination of the two, passing 2.36mm sieve and
retained on the 75micron sieve. They shall be clean, hard, durable, dry and
free from dust, and soft or friable matter, organic or other deleterious
matter.

20. •Source of material: The source of all materials to be used on the project
must be tested to the satisfaction of and be expressly approved by the
Engineer. The Engineer may from time to time withdraw approval of specific
source, or attach conditions to the existing approval.
•Mixing: Premixed Bituminous Materials, including Bituminous Macadam,
Dense Bituminous macadam, Semi Dense Bituminous Concrete and
Bituminous Concrete, shall be prepared in a Hot Mix Plant of adequate
capacity and capable of yielding a mix of proper and uniform quality with
thoroughly coated aggregates.
The difference in temperature between the binder and aggregate
should at no time exceed 140C. In order to ensure uniform quality of the mix
and better coating of aggregates, the Hot Mix Plant shall be calibrated from
time to time.

21. Requirements of a pavement
An ideal pavement should meet the following requirements:
•Sufficient thickness to distribute the wheel load stresses to a safe value on the sub-
grade soil,
•Structurally strong to withstand all types of stresses imposed upon it,
•Adequate coefficient of friction to prevent skidding of vehicles,
•Smooth surface to provide comfort to road users even at high speed,
•Produce least noise from moving vehicles,
•Dust proof surface so that traffic safety is not impaired by reducing visibility,
•Impervious surface, so that sub-grade soil is well protected, and
•Long design life with low maintenance cost.

22. Typical layers of a flexible pavement
Typical layers of a conventional flexible pavement includes seal coat,
surface course, tack coat, binder course, prime coat, base course, sub-base course,
compacted sub-grade, and natural sub-grade.
Seal Coat:
Seal coat is a thin surface treatment used to water-proof the surface and to provide
skid resistance.
Tack Coat:
Tack coat is a very light application of asphalt, usually asphalt emulsion diluted with
water. It provides proper bonding between two layer of binder course and must be
thin, uniformly cover the entire surface, and set very fast.
Prime Coat:
Prime coat is an application of low viscous cutback bitumen to an absorbent surface
like granular bases on which binder layer is placed. It provides bonding between two
layers. Unlike tack coat, prime coat penetrates into the layer below, plugs the voids,
and forms a water tight surface.

23. Surface course
Surface course is the layer directly in contact with traffic loads and generally contains
superior quality materials. They are usually constructed with dense graded asphalt
concrete(AC). The functions and requirements of this layer are:
•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.
Binder course
This layer provides the bulk of the asphalt concrete structure. It's chief purpose is to
distribute load to the base course The binder course generally consists of
aggregates having less asphalt and doesn't require quality as high as the surface
course, so replacing a part of the surface course by the binder course results in
more economical design.

24. Base course
The base course is the layer of material immediately beneath the surface of binder
course and it provides additional load distribution and contributes to the sub-surface
drainage It may be composed of crushed stone, crushed slag, and other untreated or
stabilized materials.
Sub-Base course
The sub-base course is the layer of material beneath the base course and the primary
functions are to provide structural support, improve drainage, and 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 a filler between sub-grade and the base
course A sub-base course is not always needed or used.
For example, a pavement constructed over a high quality, stiff sub-grade may not
need the additional features offered by a sub-base course. In such situations, sub-base
course may not be provided.
Sub-grade
The top soil or sub-grade is a layer of natural soil prepared to receive the stresses from the
layers above. It is essential that at no time soil sub-grade is overstressed. It should be
compacted to the desirable density, near the optimum moisture content.

25. Failure of flexible pavements
The major flexible pavement failures are fatigue cracking, rutting, and thermal
cracking. The fatigue cracking of flexible pavement is due to horizontal tensile strain at
the bottom of the asphaltic concrete.
The failure criterion relates allowable number of load repetitions to tensile
strain and this relation can be determined in the laboratory fatigue test on asphaltic
concrete specimens. Rutting occurs only on flexible pavements as indicated by
permanent deformation or rut depth along wheel load path.
Two design methods have been used to control rutting: one to limit the
vertical compressive strain on the top of subgrade and other to limit rutting to a
tolerable amount (12 mm normally). Thermal cracking includes both low-temperature
cracking and thermal fatigue cracking.

26. BITUMINOUS MACADAM
Physical Requirements of Coarse Aggregate for BM DBM, SDBC and BC Of MORT & H
Standard Specification for Road and Bridge Works (4th Revision)
Physical Requirements of Coarse Aggregates: As per Table 500-3. Refer Table Below.
Combined Table from tables 500-3, 500-8, 500-14 and 500-17
Property Test Specification Code Reference
Cleanliness Grain size Analysis Max. 5% passing 0.075mm sieve IS: 2386 part 1
Particle shape
Flakiness and Elongation
Index (combined)
Max. 30% IS: 2386 part 1
Strength
Los Angeles Abrasion Value
(or)
Aggregate Impact Value
Max. 40% for BM, 35% for DBM &
SDBC, 30% for BC
Max. 30% for BM , 27% for DBM &
SDBC, 24% for BC
IS: 2386 part 4
Durability
Soundness:
Sodium Sulphate
Magnesium Sulphate
Max. 12%
Max. 18%
IS: 2386 part 5
Water Absorption Water Absorption Max. 2% IS: 2386 part 3
Stripping
Coating and Stripping of
Bitumen
Aggregate Mixtures
Minimum retained coating- 95% IS: 6241
Water Sensitivity Retained Tensile Strength Min. 80%
AASHTO T283
to be done on samples
failed in stripping test

27. Mix designation Grading 1 Grading 2
Nominal aggregate size 40 mm 19 mm
Layer thickness 80-100 mm 50-75 mm
IS Sieve
Cumulative % by weight of total
aggregate passing
45 100
37.5 90-100
26.5 75-100 100
19 - 90-100
13.2 35-61 56-88
4.75 13-22 16-36
2.36 4-19 4-19
0.3 2-10 2-10
0.075 0-8 0-8
Bitumen content, % by weight of total mixture 3.1-3.4 3.3-3.5
Bitumen grade 35 to 90 35 to 90
Proportioning of material: The aggregates shall be proportioned and blended to produce a uniform
mixture complying with the requirements of Table 500-4. The binder content shall be within a
tolerance of ± 0.3 percent by weight of total mixture when individual specimens are taken for quality
control tests in accordance with the provisions of Section 900.
Note: Appropriate bitumen contents for conditions in cooler areas of India may be up to 0.50%
higher subject to the approval of the Engineer.
Table 500-4. Composition of Bituminous Macadam

28. Clause 4.2.3.1 of IRC: 37 – 2001
• Bituminous Macadam (BM) has low binder content and high voids and is thus not
impervious to water.
• Effect of high voids is reduced stiffness and an increased stress concentration, From
Fatigue considerations, the detrimental effects of voids is more apparent at low
temperatures.
• During prolonged hot spells, BM mix will operate over a very low stiffness range.
• Hence, use of BM may desirably be restricted only to roads designed to carry traffic
less than 5msa. DBM is recommended for roads designed to carry higher traffic than
5msa (mega standard axles).

29. Minimum stability (kN at 60º C) 9.0
Minimum flow (mm) 2
Maximum flow (mm) 4
Compaction level (Number of blows) 75 blows on each of the two faces of specimen
Percent air voids 3-6
Percent voids in mineral aggregate (VMA) See table 500-12 below
Percent voids filled with bitumen (VFB) 65-75
Mix Design
Table 500-11 Requirement For Dense Graded Bituminous Macadam
The requirements for minimum percent voids in mineral aggregate (VMA) are set out in Table
500-12
Nominal maximum
particle size (mm)1
Minimum VMA percent related to design air voids, percent2
3.0 4.0 5.0
9.5 14.0 15.0 16.0
12.5 13.0 14.0 15.0
19.0 12.0 13.0 14.0
25.0 11.0 12.0 13.0
37.5 10.0 11.0 12.0
Notes: 1.The nominal maximum particle size is one size larger than the first sieve to retain more than
10 per cent.
2. Interpolate minimum voids in the mineral aggregate (VMA) for design air voids values between
those listed.

30. SEMI DENSE BITUMINOUS CONCRETE
Grading 1 2
Nominal aggregate size 13 mm 10 mm
Layer Thickness 35-40mm 25-30 mm
IS Sieve (mm) Cumulative %by weight of total aggregate passing
19 100
13.2 90-100 100
9.5 70-90 90-100
4.75 35-51 35-51
2.36 24-39 24-39
1.18 15-30 15-30
0.6 - -
0.3 9-19 9-19
0.15 - -
0.075 3-8 3-8
Bitumen content % by mass
of total mix²
Min 4.5 Min 5.0
Bitumen grade (pen) 65 * 65 *
Table 500-15 Composition Of Semi Dense Bituminous Concrete Pavement Layers.
Notes: 1. the combined aggregate grading shall not vary from the low limit on one sieve to the high
limit on the adjacent sieve. 2. Determined by the Marshall method.
* Only in exceptional circumstances, 80/100 penetration grade bitumen may be used, as approved by
the Engineer.

31. Description Requirements
Minimum stability (KN at 600C) 8.2
Minimum flow (mm) 2
Maximum flow (mm) 4
Compaction level (Number of
blows)
75 blows on each face of the
specimen
Percent air voids 3-5
Percent voids in mineral
aggregate (VMA)
See table 500-12
Percent voids filled with
bitumen (VFB)
65-78
Table 500-16 Requirements for Semi Dense Bituminous Pavement Layers
508 .3.3 Job Mix Formula:
The procedure for formulating the job mix formula shall be generally as specified in
Clause 507.3.3 and the results of tests enumerated in Table 500-16 as obtained by the
Contractors.

32. THANKS