Technical Specifications of Roads_part4

8/12/2019 Technical Specifications of Roads_part4

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All rivet and boltholesshall be edge-sealed

with clear lacquer

after the application of

the plastics sheeting.

Rivets shall be spacedat not more than 150

mm apart, around the

outside edge of the

sign plate and on

cross braces the

spacing shall be not

more than 300 mm.

Any rivet broughtthrough the sign face

shall be colored to

match the sign face.

Any rivet or other

device fixing sign

plates to their

framework shall have

protective washer of

nylon or other

approved insulating

material inserted

where they would be

in contact.

8. All materials shall be supplied innew and unused condition except in

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4.7

ExecutionAll operations shall be performed in accordance with the specification, and in conformity

with the lines, grades, thickness and typical cross Section shown on the plans or established

by the Engineer. Only approved material shall be used in the construction. The embankment

and sub grade in fill shall be constructed utilizing only suitable material obtained from

roadway excavation or imported fill material from sources previously approved by the

competent authority.

4.7.1 Placement of fill1. Prior to the placement of any fill

materials, the Contractor shall

conduct trial compaction tests as

directed by the Engineer.

Fill material used in the trials shall be with the proposed borrow orexcavated material.

Compaction equipment to be used shall be that specified andacceptable to the Engineer.

The object of these trials shall be to determine the optimum moisturecontent and the relationship between the number of compaction

equipment passes and density for the proposed borrow materials.

2. Compaction of fills shall be carriedout at the moisture content

determined by the trials.

Fill material, which does not contain sufficient moisture to obtain therequired compaction, shall have additional water incorporated therein

by the use of approved sprinklers and mixing.

Material containing an excess of the amount of moisture required toobtain the necessary compaction shall not, without written approval of

the Engineer, be incorporated in the fill until it has been allowed to dry

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During construction of the roadway, the roadbed shall be maintained insuch a condition that it will be well drained at all times.

The Contractor shall make allowances in the height and width of thework for any swelling or shrinkage.

3. Fill materials shall be placed inhorizontal layers of uniform

thickness.

Work shall be carried out to adhere to the designated slopes, levels anddepths.

After adjustment of the moisture content to that required to attainmaximum density, the loose material shall be compacted to obtain the

specified density.

Maximum layer thickness shall be 150mm, unless otherwise agreed bythe Engineer.

4. Placement of fill materials at pointsinaccessible to normal compaction

equipment shall be made in

horizontal layers of loose material

not exceeding 100 mm in depth and

thoroughly compacted by the use of

mechanical tampers.

5. When fill materials are to be placedand compacted on slopes steeper than

1H : 3V the following shall apply,

unless otherwise approved by the

Engineer. If the embankment shall

be benched in steps or prepared as

directed by the Engineer. The width

of the benching shall be enough to

permit the operations of placing

equipment.

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6. If the original surface upon which theembankment is to be placed is an old

roadbed, the surface shall be

ploughed, scraped and broken upregardless of the height of the

embankment and compacted as

directed by the Engineer.

7. G. If backfill is to be placed belowstanding water, only approved

granular material meeting the

requirements of free draining

material shall be deposited. Placing

of aggregates may be with or without

the associated use of compaction

plant.

8. H. If the foundation on which theembankment or the subgrade

materials are to be laid is unstable,

crushed aggregate or stabilizing rock

fill meeting the requirements of

stabilizing material shall be placed

and compacted as directed by the

Engineer.

9. Density to which suitable fill layersshall be compacted is 95% MDD,

unless other wise approved by the

Engineer.

10.When an embankment or filled areahas achieved settlement and requires

additional material to bring it up to

the required formation level, the top

of the borrow or fill shall be

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4.7.2

Subgrade preparation1. After site clearing the upper portion

(300mm below formation level) of

the existing subgrade (cut area) shall

be sampled and tested to confirm

suitability of the material.

If the upper portion of the subgrade is found to be unsuitable, suchsubgrade material shall be removed and replaced with suitable

subgrade material as directed by the Engineer. The ground after

cutting shall be treated and prepared as existing ground.

When the existing ground in the cut (within 300mm of the formationlevel) is found to be suitable, the subgrade surface shall be completely

broken up by scarifying, watered and mixed to achieve a uniform

moisture content between 2% of the OMC for the full depth of

150mm.

The top 300mm below formation level in fill area shall be constructedwith approved sub grade material and each layer shall be compacted to

98% of the MDD. The moisture content shall be within 2%of the

OMC.

2. After the foregoing work has beenaccomplished, the entire subgrade

shall be shaped to a smooth uniform

surface. Excess material which

cannot be disposed of by normal

drifting to the low spots during

shaping operations shall be removed

and placed in other areas deficient in

materials or disposed of in an

approved manner.

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3. Once prepared, the subgrade shall bemaintained in the finished condition

until the first succeeding course of

subbase or base material has beenplaced.

Contractor shall take all precautions necessary to protect subgradefrom damage.

Hauling over finished subgrade shall be limited to that which isessential for construction purposes.

Contractor shall protect the prepared subgrade from both his own andpublic traffic.

Contractor shall maintain the subgrade by rolling as frequently as maybe necessary to preserve the subgrade in a completely satisfactory

condition.

The Contractor shall be responsible for reinstatement (to thesatisfaction of the Engineer) of any layer damaged or disturbed after

the compaction and approval, before placing the next layer.

Finished surface of the formation level shall not vary at any point bymore that 10 mm above or 30mm below the grade shown on the

drawing or established by the Engineer.

An inspection request shall be sent to the Engineer prior to proceedingto the next operation.

4.7.3 Compaction1. Contractor shall carry out the compaction of fills as specified after grading

and leveling the surface to be compacted.

In areas to be filled, compaction shall include adding necessary fill,water, and other materials as required, and compacting the first layer in

addition to subsequent layers up to the proposed levels.

In areas already excavated down to the required level, compactionshall include adding the necessary water, etc., and compacting the

surface, in accordance with the procedure outlined hereinafter.

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Procedure outlined below shall not relieve the Contractor of his dutiesto determine the most suitable procedure for compaction. All such

procedures shall be subject to the approval of the Engineer.

2.

After carrying out the grading, leveling, scarifying, pulverizing, and otherwork as required, the Contractor shall add the necessary amount of water

(within 3% of the MDD) to obtain a suitable moisture content for

compaction. Fill shall be thoroughly turned over after adding each lot of

water so as to achieve a homogeneous moisture content throughout the

whole thickness of the layer.

3. Before compacting, samples from the pulverized fill will be taken andtested according to standard procedures in order to establish the moisture

content.

Field testing using "Speedy Moisture Device" or similar instrumentgiving direct readings for the field moisture content may be used for

guidance only.

In the event that moisture is more than Optimum Moisture Content, thearea represented by the sample shall be scarified and aerated until the

moisture content is within 3% of the optimum moisture content.

The fill shall then be leveled for compaction.

4. After primary leveling, compaction shall be commenced by means ofapproved rollers depending on the type of material being compacted in

order to obtain the required dry density.

Placement and compaction of materials shall be in layers notexceeding 150 mm compacted thickness, unless otherwise approved by

the Engineer.

Each layer of fill material shall be compacted to 95% of the MDD.

5. Rolling shall be carried out in the direction of the road axis until the fillreaches the required density.

In crowned sections, rolling shall start from both edges of the road inthe direction of the axis.

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If the road is super elevated, rolling shall commence from the lowerside and continue to the higher side.

In order to compensate for the amount of water lost in evaporation inthe course of compaction, additional quantities of water shall be addedas required.

6. The surface shall thereafter be leveled longitudinally and transversely bymotor graders and finally rolled to achieve uniform compaction, free from

undulations, soft spots and depressions.

7. No layer shall be covered by the next layer until it has been tested,inspected and approved by the Engineer.

8. Saline water for earthworks shall only be permitted if the percentage ofwater soluble salts in the compacted fill does not exceed 3% by weight of

dry soil.

4.7.4 Installation of precast concrete curbsPrecast curbs shall be set to the lines and grades as shown on the Drawings, unless otherwise

agreed with the Engineer.

Under no circumstances will it be permitted for levels to be set bydirect measurement from pavement layers.

Any excavated surface for the concrete bedding shall be watered andcompacted to a minimum of 95% MDD.

Unless otherwise indicated, elements shall be laid either directly onto awet concrete base or on to a cement/sand (1:3) mortar bedding, 25 mm

thick placed on a previously laid concrete base on approved sub-grade.

Dimensions of the base and backing shall be as shown on theDrawings.

Concrete base shall be constructed with Grade 20 Concrete. Unless otherwise indicated, after curb units have been laid a

continuous backing of Grade 20 Concrete shall be poured for the

elements using steel forms.

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No pavement layers shall be laid against curbing until such time as thebacking is complete, back filled and approved by the Engineer.

Joints between radius curbs, shall have a width not greater than 4mmand be filled with a cement / sand (1:3) grout with 1/5 part hydratedlime and sufficient water to make the mixture plastic and easily

smoothed.

A grooving tool shall be used to produce a smooth, circular sectiongroove not more than 3 mm deep in all joints.

Grouted joints shall be cured by an approved method to the Engineerssatisfaction.

Joints between straight curbs shall have a width of 4mm and be filledwith the above specified grout, unless otherwise directed by the

Engineer.

Immediately after any concrete is in place and for 7 days thereafter thecurbs, base backing and mortared joints shall be fully cured and

protected from drying out and against the harmful effects of weather,

including rain and rapid temperature changes.

Method of protection shall be subject to the Engineers approval. Use of colored curing membranes will not be permitted. Concrete not properly cured and protected will be rejected and shall be

removed from the works.

Expansion joints shall be placed as shown on the Drawings, unlessotherwise approved by the Engineer.

Every 9 meters (or as directed by the Engineer) the joint between curbsshall be filled with an approved joint filler 10mm thick. The filler

shall extent through the curbs, bed, backing and channel and shall be

trimmed to the finished slope of the curb and channel.

At access points the curbs (including the bed backing) shall be droppedto shown a face of 75mm or as shown on the drawing.

At the end of any curb run, the end element shall be sloped down toground level and angled away from the road at 30 degrees.

Curbs shall be level within a tolerance of 3mm at each end of theelement, to the designated lines and grades.

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4.7.5 In-situ concrete curb layingIn-situ curbs shall be laid to the lines and grades as shown on the drawings.

In-situ curbs shall be laid by an approved automatic curbing machine,unless otherwise approved by the Engineer.

The curbs shall be dense with regular sides, arises and chamfers andfinished to a fine surface free from blow holes.

The concrete used for the curbs shall be grade C40, except as modifiedby the Engineer.

Curbs shall be cut to form expansion and contraction joints as shownon the drawings or as directed by the Engineer.

The joints shall be filled with suitable compressible board or othersuitable material as approved by the Engineer.

The maximum deviation of the top of the curb under a straight edgeshall be not greater than 3mm in 3m.

The vertical alignment of the finished curb shall not depart from thetrue level more than 6mm at any point.

The horizontal alignment shall not depart from that shown on thedrawing by more than 13mm nor deviate from the straight by more

than 3mm in 3m.

4.7.6 Granular sub-base1. After the formation has been inspected and accepted by the Engineer,

granular sub-base shall be placed, as shown on the drawings.

Material shall be delivered to the roadbed as a uniform mixture. Shall be spread in layers. Segregation shall be avoided. Shall be free from pockets of coarse or fine materials. Spread by finisher, or grader or other approved mechanical methods as

approved by the Engineer.

Watered, shaped to a compacted thickness not exceeding 150 mm andcompacted to the required grade and cross-section.

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Compaction procedure and plant shall be to the satisfaction of theEngineer. At the time of compaction the moisture content of the laid

material shall not vary by more than + 2% of the optimum moisture

content. The grading of the placed materials shall be checked bytaking samples from an area 0.5m x 0.5m from the full depth of the

layer for every 1000m3of material laid.

No road mixing of subbase shall be permitted. Before using in the works subbase material shall be stockpiled in a

manner to prevent segregation.

2. Sub-base shall be compacted to not less than 98% of the maximum drydensity as determined in accordance with BS 1377: Part 4 : Method 3.6,

unless otherwise agreed by the Engineer.

The surface on completion of compaction shall be well-closed, freefrom movement under compaction plant and free from ridges cracks or

loose material.

Finished surfaces of the road sub-base shall not vary at any point morethan 10 mm above or below the grade established by the drawings.

The surface shall be maintained in a condition satisfactory to receiveany subsequent base or surfacing material.

Any sub-base, which does not conform to the specified requirementsshall be reshaped, removed or reworked, watered and thoroughly re-

compacted to conform to the specified requirements.

At any stage in the mixing, transportation, spreading or compactionprocess the Engineer may instruct specified tests to be carried out.

An inspection request shall be sent to the Engineer prior to proceedingwith the next operation.

4.7.7 Aggregate road-basea. Compaction Trials

If directed by the Engineer, prior to the commencement of theaggregate road base operations, the Contractor shall construct trial

lengths as directed by the Engineer. Materials used in the trials shall

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Trial lengths may not form part of the permanent works but may be

permitted in the construction of temporary detours of sufficient length.

Object of these trials is to determine:a. Adequacy of the Contractors equipment.

b. Loose depth measurements necessary to determine suitable compacted

layers depths.

c. Field moisture content.

d. Relationship between the number of compaction passes and the resulting

density of the material.

Contractor may proceed with the aggregate road-base work only afterthe methods and procedures established in the compaction trials have

been approved by the Engineer.

2. After the previous work has been inspected andaccepted by the Engineer, approved road-base material

shall be placed as shown on the drawings.

Road-base material shall be delivered to the road as a uniform mixturecomplying with the specific requirements.

Method of mixing and laying of road base material shall be subject tothe approval of the Engineer.

Layers shall not exceed 150 mm in compacted thickness. Material shall be handled in a manner, which avoids segregation. Segregated materials shall be remixed until uniformity is obtained. Suitable precautions shall be taken to prevent rutting during the

spreading.

No hauling or placement of material will be permitted when, in thejudgment of the Engineer, the weather or road conditions are such that

the hauling operations will cause rutting or contamination of granular

road-base material.

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Road-base, which has been placed without approval of the Engineershall be removed at the Contractors expense.

Moisture content of the aggregate road-base material shall be adjustedby watering with approved sprinkler trucks or by drying out, to bewithin 2% of the OMC prior to compaction.

Road base shall be compacted to not less than 100% MDD by meansof approved compaction equipment progressing gradually from the

outside of the road towards the center with each succeeding pass

uniformly overlapping the previous pass.

a. Rolling shall continue until entire thickness of each layer is thoroughly

and uniformly compacted to the specified density.

b. Rolling shall be accompanied in a manner approved by the Engineer, to

ensure a smooth surface free from ruts or ridges is obtained with the

proper section and crown.

Surface of the material shall on completion of compaction:a. Be well closed.

b. Free from movement under the compaction plant.

c. Free from compaction planes, ridges, cracks, or loose material.

Any areas inaccessible to normal compaction equipment shall becompacted by means of mechanical tampers, until satisfactory

compaction is obtained.

The gradation of the placed material shall be checked by takingsamples from an area 0.5m by 0.5m from the full depth of the layer of

every 1000m3 of laid material.

Contractor shall program his operations to avoid the drying out of thesub-base during construction.

a. At any stage in the mixing, transportation, spreading or compaction process

the Engineer may instruct the Contractor to carry out the specified tests.

b. If any layer of aggregate road-base material, or part thereof, is permitted to

dry out after compaction, or does not conform to the specified

requirements or finish, the Contractor shall, at his own expense, remove

water, rework or re-compact the material, as directed by the Engineer,

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before the next layer of aggregate road-base or subsequent pavement

layers are placed.

3. Finishing

Before the commencement of each activity an inspection request shallbe sent to the Engineer for inspection and tests.

Surface of the finished aggregate road base will be tested with a 3 mstraightedge by the Engineer at selected locations. Variations of the

surface from the testing edge of the straight edge between any two

contacts with the surface shall at no point exceed 10 mm when placed

on or parallel or perpendicular to the centerline of the roadway. All

humps and depressions and thickness deficiencies exceeding the

specified tolerance shall be corrected by removing the defective work

or by adding new material as directed by the Engineer. Any work

necessary to reshape the surface shall be at the contractors expense.

4.7.8 Placement of asphalt paving course1. Equipment

Method statement and equipment list shall be according to the type andnumber outlined in the Contractors detailed Program of Work, as

approved by the Engineer. The Contractor shall furnish to the Engineer

the manufacturers technical data for each equipment and no

equipment shall be used without the approval of the Engineer.

Trucks used for hauling bituminous mix shall have tight, clean, smoothmetal beds which have been coated with a minimal amount of paraffin

oil, lime solution, or other approved material to prevent the mix from

adhering to the beds. Excess release agent must be drained from the

bed prior to loading bituminous materials.

Each vehicle shall be equipped with a canvas cover or other suitablematerial of such size as to protect the mix from the weather and the

trucks must be clearly numbered for easy identification.

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The pavers shall be self propelled and equipped with hoppers anddistributing screws of the reversing type to place the mixture uniformly

in front of the electronic controlled screeds.

If during construction it is found that the spreading and finishingequipment in operation leaves surface tracks in the pavement or

indented areas or other object able irregularities that are not

satisfactorily corrected by scheduled operations, the use of such

equipment shall be discontinued and other satisfactory spreading and

finishing equipment shall be provided by the Contractor.

Rolling equipment shall be self-propelled.a. Wheels on the rollers shall be equipped with adjustable scrapers.

b. Rollers shall have water tanks and sprinkling apparatus, which shall be

used to keep the wheel wet and prevent the surface material from sticking.

c. Rollers shall be of steel-wheel and pneumatic tire type and shall be in good

condition.

d. Rollers shall be capable of reversing without backlash.

e. Rollers shall be operated at speeds slow enough to avoid displacement of

the bituminous mix.

f. Number and weight of rollers shall be sufficient to compact the mix to the

required density while it is still in a workable condition.

g. Use of equipment, which results in excessive crushing of the aggregate,

will not be permitted.

h. A minimum of three (3) rollers, two (2) steel-wheel and one (1)

pneumatic-tire type, shall be used with each spreading operation for each

lane.

Contractor shall provide adequate back-up equipment for use in theevent of mechanical failure, all to the satisfaction of the Engineer.

The Engineer reserves the right to stop the use of any equipment orplant which he deems to be detrimental to the work required and

instruct its removal and replacement with suitable equipment.

The Contractor shall not be allowed to use any plant without thepermission of the Engineer.

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The Engineer shall have the right to expel any operators, mechanics orlabor and to instruct suitable replacement thereof at any time he deems

such action is necessary.

2. Surface Preparation When the Bituminous Mix is placed on a prepared area, (whether or

not a prime coat is designated on the Drawings) the area shall be even

and firm and within the construction tolerances specified.

When the paving layer is constructed on an existing bituminoussurface, the surface shall be cleaned of all foreign material and boomed

free of dust.

a. Any loose, broken or shattered bituminous material along the edges of the

existing surface shall be removed.

b. Any exposed sub-grade or shoulder adjacent to the edge of the existing

surface to receive the new bituminous mix shall be shaped, bladed,

compacted and boomed and primed to provide a uniform firm sub-grade

for the new surface course.

Existing bituminous surface, base, or sub-grade shall be removed ifbroken, shattered, or unstable. Areas shall be excavated to a depth as

directed by the Engineer, and refilled with the Bituminous Mix.

Prior to the placing of the mix, when designated on the Drawings ordirected by the Engineer, a prime coat or tack coat shall be applied to

the surface in accordance with the Specification for Prime Coat or

Tack Coat.

3. Placing of the mix All bituminous mixes shall be introduced to the paver at a temperature

not less than 140 C and not more than 163 C. Mixes outside this

temperature range shall be discarded.

Bituminous mix shall be spread and finished to crown and grade byautomatically controlled bituminous paves unless otherwise approved

by the Engineer.

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a. Bituminous mix may be spread and finished by hand methods only where

machine methods are impractical as determined by the Engineer.

b. Paver shall lay the bituminous mix without tearing the surface and shall

strike a finish that is smooth, true to cross section, uniform in density andtexture and free from hollows, transverse corrugations or other

irregularities.

c. Paver shall be operated at a speed which will give the best results for the

type of paver being used and which co-ordinates satisfactorily with the

rate of delivery of the mix to the paver, to provide a uniform rate of

placement without intermittent operations of the paver.

Mix shall be delivered to the paver in time to permit completion ofspreading, finishing and compaction of the mix during daylight hours.

Longitudinal joints in successive layers shall be offset not less than300 mm. Width of surface or top course placements shall conform to

traffic lane edges as shown on the Drawings.

Leading half of half roadway paving shall not get ahead of the trailinghalf of the pavement by more than one average full-day of paving.

a. In no case, shall the leading half be more than km ahead of the trailing

half without the written permission of the Engineer.

b. If the Contractor fails to comply with this requirement, the Engineer may

suspend paving on the leading half until such time, as the Contractor shall

pave the trailing half to a point approximately even with the leading half.

Unless otherwise directed by the Engineer, where successive layers areto be placed, the surface of the existing layer shall be swept clean with

a power broom, or by other means as approved by the Engineer, and a

tack coat applied. Tack coat may not be required where delay between

laying subsequent courses is less than 48 hours or surface is fresh and

clean at the discretion of the Engineer.

Asphalt concrete mixes (except leveling courses) shall be laid at an un-compacted thickness such that after rolling, the thickness of the

compacted layer shall be :

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a. Minimum 2.0 times the maximum aggregate particlesize.

b. Maximum 4.0 times the maximum aggregate particlesize.

Maximum thickness for layers may be increased slightly when suchincrease is more adaptable to total pavement thickness and when in the

opinion of the Engineer it is not detrimental to placement and rolling

conditions.

Contractor shall erect and maintain an approved reference string lineand operate the paver to conform to the reference string line for the

initial layer and/or any other layers as directed.

a. Elevation control point stakes for the first layer of bituminous paving

course shall be set at a maximum spacing of 20 m.

b. For subsequent layers, control points shall be set at 10 m maximum

spacing.

4. Compaction of Bituminous Layers After spreading and strike off, and as soon as the mix conditions

permit, the rolling shall be performed without excessive shoving or

tearing. If the temperature of the joint falls below 1200C the material

shall be removed by approved methods to ensure the required

compaction at the joint. Rolling procedure for each new job must

consider number of passes, rolling speed, and rolling pattern. Each

mixture must be thoroughly and uniformly compacted.

Rolling will not be prolonged to an extent that cracks appear. When rolling a thin lift use the following sequence.

a. Transverse joints.

b. Outside edge

c. Initial or breakdown rolling, beginning on the low side and progressing

towards the high side.

d. Intermediate rolling (as above)

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e. Finish rolling.

When placing a thick lift, roll the mix in the following sequence.a. Transverse joints

b.

Initial or breakdown rolling,beginning edge 300-380 mm from

the lower unsupported edge and

progressing toward the other edge.

c. Outside edge.d. Intermediate rolling, beginning on the low side and progressing toward the

high side.

e. Finish rolling.

f. When placing thick lifts in echelon, when abutting a previously placed

lane or other lateral restraint, roll the mix in the following sequence;

transverse joint, longitudinal joint, and initial or breakdown rolling

beginning at the longitudinal joint and progressing towards the outside

edge.

g. Outside edge. When within 300mm of an unsupported edge, the roller

should advance toward the edge in approximately 100mm increments in

successive passes.

When the transverse joint is made next to an adjoining lane.a. Make the first pass with a static wheeled roller moving along the

longitudinal joint for a few feet.

b. Straighten the surface and make corrections if necessary.

c. Roll the joint transversely with all except about 150mm of wheel width on

the previously laid material.

d. Repeat the above with successive passes each covering an additional 150-

200mm of the new mix until the entire width of a drive wheel is on the

new mix.

e. Unless precautions are taken, transverse rolling must stop 150-200mm

short of the outside edge and the edge must be compacted later during the

longitudinal rolling.

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Technical Specifications of Roads_part4

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