CONSTRUCTION
4.1 Placement of Sub-base
Courses
4.1.1 The granular sub-base (GSB) material shall be placed and spread evenly on the prepared formation to a
compacted thickness as shown on the drawings or as directed by the COMPANY. The preparation of the
formation shall be completed at least 200mm ahead of the placing of sub-base material. The maximum
compacted thickness of any one layer shall not exceed 150mm. When the specified compacted thickness
exceeds 150mm the material shall be laid in two or more approximately equal layers, each not exceeding 150mm.
4.1.2 The sub-base materials shall be thoroughly compacted with suitable and adequate compaction equipment
approved by COMPANY.
4.1.3 Rolling operation shall be from the outer edge towards the centre and proceed gradually in a longitudinal direction except on super elevated curves where rolling shall proceed from the low side and
move towards
the high side.
4.1.4 The finish sub-base
level shall not vary more than +/-20mm from the grade or level shown on the drawings.
4.2 Placement of
Road Base
4.2.1 All work on the portion of the granular sub-base on which the wet mix macadam base is to be laid shall be properly shaped
and compacted at least 180mm ahead of the placing of the road base
material.
4.2.2 All materials shall be placed and spread evenly over the full width of the required layer by spreader or grader
as approved by COMPANY. Compaction to the thickness as shown on the drawings, or as directed
by COMPANY, shall be completed as soon as possible after the material has been spread. The maximum
compacted thickness of any one layer shall not exceed 150mm. When the specified compacted thickness
exceeds 150mm the material shall be laid in two or more approximately equal layers each not exceeds
150mm.
4.2.3 Each layer shall be thoroughly compacted with suitable compacted. Rolling operations shall begin along the edges and progress towards the centre gradually in a longitudinal direction except on super-elevated curves where rolling
shall
proceed from the low side and
progress towards
the high side.
4.2.4 The surface of the layer shall, on compaction, be well closed, free from movement from compacted planes, ridges, cracks or loose material. All loose, segregated or otherwise defective areas shall be made good to the
full thickness of the layer and
re-compacted.
4.2.5 The finished wet mix macadam base surface base surface shall not vary in level more than +10mm, or -15mm from the levels shown on the drawings. Surface irregularities shall be measured;
both longitudinally and transversely, by a 3m long straightedge placed either parallel with, or right angle to, the centreline of the road. The maximum deviation
of the road base surface shall be 8mm. Where irregularities in excess of
8mm
occur, the surface shall be rectified by scarifying, reshaping with material added or removed as
necessary.
4.2.6 After placing but before compacted of any layer of road base commences a partial width of the shoulder,
not less than 450mm wide, shall be constructed adjacent to the road base to act as a haunch to the edges
of the layer. This
material shall
be compacted along with the
road base.
4.2.7 The wet mix macadam base material shall be maintained at the correct moisture content necessary for
proper compaction by drying
out as required.
4.2.8 When a base is spread adjacent to concrete curbs or gutter sections, extreme care shall be exercised so
as not to damage the kerbs or gutters. Any damaged curbs or gutters shall be removed and replaced at
the CONTRACTOR’s own expense.
4.2.9 The wet mix macadam surface shall be well brushed with mechanical sweepers or stiff brush and swept clean of all loose materials, dust and debris in preparation to receive the tack coat and premix. The
brushing and sweeping shall be done at least 2 hours before premix is laid. Once the surface is brushed
and swept, no traffic shall be allowed to use that portion of the road unit the surfacing of the portion is
completed.
4.3 Preparation of Formation to Receive Road Pavement
4.3.1 CONTRACTOR shall ensure sub-grade is at required
elevation.
4.3.2 The subgrade material in the road formation shall be compacted to a 95% maximum dry density over the upper 600mm layer
of the
formation.
4.3.3 Soft sport and unsuitable materials encountered in the pavement subgrade shall be removed and
backfilled with approved suitable material and compacted by not less than four (4) passes of a smooth
wheeled roller weighting not less than 10 tonne or an equivalent vibratory roller. The formation shall be
checked and the final trimmed surface shall be rolled by one pass of a smooth wheeled roller of not less
than 5 tonne.
4.3.4 When sufficient moisture content exists, water and thoroughly mix the subgrade until optimum moisture content is obtained. When excess moisture content exists, rework and aerate the sub-grade until optimum
moisture content is obtained.
4.3.5 Before final rolling, shape the entire section, add additional subsoil as required, and compact the
subgrades, elevation and cross sections as indicated on the drawings. All points of finished
subgrade section
shall be within 25mm of the required section.
4.4 Bituminous Surfacing
4.4.1 Pavement Section
a. This consists of,
from the wet mix macadam road base and upwards:
Prime Coat
Bituminous Base Course
Tack Coat
Dense Bituminous Wearing
Course
4.4.2 Prime Coat Application
a. The CONTRACTOR shall apply the prime coat on the completed portion of the road base as soon as
practicable. However, CONTRACTOR shall not apply the tack coat if the moisture content in the top 50mm of the wet mix macadam road base exceeds the higher of either, the average of the optimum moisture content as determined by the standard compaction test and the absorption of the plus 5mm
sieve fraction or two third of the optimum moisture contents as determined by the standard compaction test.
b. The Surface of the road base shall be cleaned immediately and shall be free of all loose material,
foreign matter and standing water, prior to the application of the prime coat. The bituminous material
shall be applied by means of a distributor at the rates of 0.435 litre/m2 and within the temperature range
requirement by IS-73, IS-217, IS-3117 and IS-8887.
4.4.3 Tack
coat Application
a. The surface of the Bitumen Macadam Base course shall be cleaned immediately prior to the
application of the tack coat.
b. The bitumen material shall be applied by means of a distributor at the rates directed by COMPANY, but shall not be less than 0.326 litre/m2 within the temperature
range requirement by IS-73, IS-217, IS-3117
and
IS-8887.
c. The Sprayed
surface shall be
allowed to
cure for at least 8 hours prior
to any surfacing being laid.
4.4.4 Transporting
a. The premix shall be expeditiously transported from manufacturing plant to the site of the works in
clean vehicles adequately covered by canvas or tarpaulins to minimize the loose of temperature and protect the premix from rain, dust or spilling on top the road surface. The temperature
of the work mixed material as delivered to the work site should not be less than 1040C, at the time of rolling not
less than 970C.
4.4.5 Laying
a. The bitumen macadam shall be laid by machine. Laying shall not proceed under unsuitable weather conditions. The machine used for laying shall preferably be a self-propelled type and capable of
laying bitumen automatically to an even, smooth and compact surface to the required widths,
thickness and cross falls without segregation of the
bitumen macadam.
4.4.6 Compaction
a. As soon as rolling can be affected without causing displacement, the bitumen macadam shall be
uniformly compacted by rolling. Compaction shall be carried out with a roller or rollers of weight not
less than 6 tons nor exceeding 10 tons and the width of the roll shall not be than 450mm. The bitumen macadam shall be rolled in a longitudinal direction working from the sided to the centre of the
carriageway, overlapping on successive passes by at least one half of the width of the rear roll. The
roller shall be fitted with a quick reverse and smooth acting clutch. Rollers shall not be allowed to stand on
newly laid bitumen
macadam when there is a risk
that the surface will
be deformed thereby.
b. Finished
road surfaces are to remain without traffic for two days after
laying of the wearing course.
4.4.7 Laying
Interval
a. The wearing course shall be laid on the bitumen macadam base course as soon as practicable. No part of the base course shall be left uncovered by the wearing course for longer than three (3) days
unless extension of this period is approved by COMPANY due to suitable weather for laying. During
this intervening period unless the work consists of resurfacing, no traffic, other than used in connection with the provision
of
the wearing course, shall be permitted
on
the surface of the base course.
4.4.8 Joints
a. All joints shall be cut back to a vertical face and painted with hot binder before the adjoining surfacing is laid.
4.4.9 Tolerance
in Surface Level and
Minimum Compaction
Thickness
a. The bitumen macadam wearing course shall be laid by machine in single course and the average compacted thickness of the course shall be as shown on the drawings. The accuracy of finish on the longitudinal direction shall be determined by measuring the gap under 3m straight edge placed in any
position of the road surface parallel to the centre line, the gap at any place between the points at
which the road should not exceed +/-6mm. The transverse profile shall also confirm to a similar
standard or accuracy using a correct shaped template instead of a straight edge. The compacted
thickness of the two macadam courses shall nowhere be less than the specified thickness as shown on the drawings after
compaction.
4.5 Bituminous Pavement Mix
a. The mineral
constituents
shall
be combined to the following graduation.
b. For
Bitumen macadam base Course with binder content 3.8%-4.8%:
Metric Sieve
25mm - 100
20mm - 90-100
12.5mm - 50-80
6.3mm 15-35
3.15mm mm 5-20
0.075mm mm 2-6
c. For Dense
Bitumen Macadam wearing
Course with
binder content 4%-5%:
Metric Sieve
20mm - 100
12.5mm - 90-100
6.3mm - 20-40
3.15mm - 10-20
0.075mm - 2-6
4.5.1 The aggregate shall be surfaced dry, and the aggregate and binder separately heated to within the following ranges before entering the mixer:
a. Aggregate
b. Binder
660C-1490C
(1500F-3000F)
940C-1630C (2000F-3250F)
4.5.2 It is particularly important to avoid overheating of the binder and excessively high temperatures of the
aggregate at the time of mixing, as these will adversely affect the quality of the resultant Macadam.
Materials including any added filler shall be weighed or measured
before being put into a mechanical mixer
and thoroughly mixer
until all particles of the aggregates
are completely and
uniformly coated.
4.6 Wet mix Macadam Road
Wet
mix macadam roads shall consist of a layer of compacted granular sub-base material
followed by
a layer of compacted wet mix macadam materials. Refer to drawings for material thickness.
4.7 Crushed Gravel
Surfacing
Crushed gravel surfacing shall consist of clean, hard natural gravel or crushed stone conforming to gradation of 100 mm nominal gravel size, as per specification. Crushed gravel surfacing shall be spread after installation of services and cables and suchlike, it shall be spread where indicated on a properly levelled or graded
surface, free from weeds, to a compacted thickness on 100mm and lightly rolled.
5.0 CONCRETE ROAD PAVING
5.1 Concrete paving shall have 30MPa reinforced concrete.
5.2 In areas where heavy maintenance cranes are anticipated around equipment, the concrete paving shall be specially designed to take such crane loads.
5.3 In areas where heavy maintenance cranes are anticipated around equipment, the concrete paving shall be
specially designed to take such crane loads.
6.0 FIELD TEST
6.1 The number and frequency of the field density tests of the control of the compaction of the placed shall be as
follows:
a. A minimum of one test per lift shall
be made.
b. Material
and compaction testing services shall be arranged
and
paid by CONTRACTOR.
7.0 PERMANENT PAVEMENT MARKINGS
7.1 This work shall consist of furnishing all materials equipment labour and applying permanent markings on the compacted road pavement for the delineation of shoulders and parking lots.
7.2 Traffic paint shall conform to AASHTO M248 Type F. Stripes shall be a minimum of 10cm wide, for which the
minimum rate of paint application shall be 1 litre per 25m length.
8.0 RESURFACING
AND REINSTATING EXISTING ROAD
8.1 All materials and workmanship required for resurfacing and reinstating roads shall comply with the
requirements as specified therein before for the new roads.
8.2 Where existing roads are required to be resurfaced all the weak areas in the existing pavement shall be repair
with proper patches using bituminous macadam base course adequately compacted. Where the surface is
distorted regularly course of bituminous macadam base course material shall be laid in
horizontal layers, each
not exceeding 75mm in thickness.
8.3 The existing bituminous surfacing shall be scarified
to
a depth of 15mm and tack coat shall be applied
before laying new bituminous
surfacing.
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