Construction method statment

REMOVAL OF TOPSOIL: Removal of topsoil shall include excavation to remove the top organic layer, hauling todesignated locations and stockpilling or removing as instructed, to permit cons

CONSTRUCTION METHOD STATEMENT

2 Excavation and backfilling

(a) Excavation should be suited to the situation in surrounding areas, geology andgroundwater conditions, and slope surface protection or landslide protection shall beemployed in accordance with the relevant laws so as to prevent the collapse of sediment.(b) Where buildings adjacent to the excavation area are likely to be collapsed or broken,adequate measures shall be taken in advance to prevent such occurrences

(c) Where underground water supply or drain pipe, gas pipe or cables are likely to bediscovered, a survey shall be conducted In the event that a buried object is found, itshall be carefully handled so as not to cause damage All necessary emergency measuresshall be taken, and the final outcome shall be determined through discussing with theEngineer and/or the authority concerned

(d) All minor obstacles to construction work shall be removed The treatment of majorobstacles shall be discussed with the Engineer

(e) The bottom of cutting shall be excavated without disturbing the ground, and inspected

by the Engineer upon completion of the excavation

3 Drainage

(a) Rainwater, spring water, stagnant water, etc that may hinder construction shall beremoved via drain ditches, catching basins or pumps Where unusual freshet is seriouslyaffecting the execution of the work, this matter shall be brought to the attention of theEngineer

(b) Appropriate measures shall be taken before draining water from the excavated area so asnot to influence the bottom of the cutting, the surface of slope, construction site orneighboring areas

4 Backfilling and Fill

(a) Prior to Backfilling, remove formwork and other objects located in the area to bebackfilled Consult the Engineer in the event that formwork shall remain as they are

(b) Consult the Engineer if the excavated soils are not suited to the backfilling and fill.(c) Extra fill settlement or allowance may be required depending on the soils.

(d) Material filling is met technical requirement stipulated on term 11.2 in 0009

3550-8310-SP-5 Grading

Grading (leveling) shall be performed for a width of approximately 2m around the building inorder to drain away water

6 Disposal of Earth Generated during Construction

(a) Earth generated from the construction work shall be transported outside the premises anddisposed of in a suitable manner in accordance with local regulations,

(b) In the event that some of earth generated from the construction work can be reused,under consultation with the Engineer and/or the local authority

SECTION 2 EARTH WORK SUPPORT

1 Structure and Other

(a) Earthwork shall be supported safely and securely in accordance with the localregulations and/or the Engineer’s directions

(b) Earthwork supporting system shall be submitted to the Engineer for approval withcalculation sheet

(c) During execution due attention should be given to the stress and deformation with aview to potential disasters

(d) The use of measuring instruments such as earth pressure gauges shall be provided

(e) When installing earthwork support works, constantly check and measure the adjacentground for potential landslides Should any abnormal state be detected, adequate stepsshall be immediately taken and a report made to the Engineer

(f) Removal of earthwork support structures shall be performed in a careful manner afterverifying the safety level The holes left after steel sheet piles are pulled out shall beimmediately backfilled with sand or other suitable material directed by the Engineer,thereby preventing deformation of the ground

(g) Use open excavation method when excavation depth <=2.5m, and when excavationdepth>2.5m, use support system for slop protection (refer attached drawing)

SECTION 3 METHOD OF EXECUTION

1 REMOVAL OF TOPSOIL:

Removal of topsoil shall include excavation to remove the top organic layer, hauling todesignated locations and stockpilling or removing as instructed, to permit construction of theWorks, all as indicated on the Drawings or as instructed by the Engineer and as specified.Prior to commencement of removal of topsoil, the subcontractor shall obtain the Engineer’swritten instructions regarding work area and depth limits, and approval for the equipment andmaterials are to be used and the method of work execution

A survey team shall be stationed on site to monitor and control each stage of work All themajor setting out works will be carried out jointly with the Engineer’s Surveyor

Before commencement of massive cut/fill, the haul roads shall be constructed with two laneswidth for to traffic and to ensure smooth flow of the plant

The construction of berm drain shall follow closely to the slope trimming and surface watershall be regulated to the temporary earth drains and eventually discharged to the slit traps

2 EMBANKMENT AND BACKFILL METHOD

Construction sequence:

 Fill material is transported by dump truck to the site anddumped into each heap at the calculated interval and suitablevolume with length and thickness of the section to beconstructed within a day to secure leveling and compactingwork at least and most effectively to avoid encounteringinconvenient weather when leveling and compacting work is notfinished within day

 Use bulldozer and grader to level fill material into even layersalong the length of the section to be constructed Formsmoothness, crown, longitudinal slope and horizontal slope tothe design

 The thickness of each layer is 20cm, otherwise instructed by theEngineer

Compacting fill material:

- Rolling is performed along the laid section, from edge to thecenterline, from lower point to higher point Successive passes

shall overlap the previous passes from 25cm to 50cm (in paralleldirection to centerline)

- Successive passes shall overlap the previous passes from 50cm

to 100cm (in perpendicular direction to centerline)

- Rolling at the super-high section shall be carried out from thecurved-road lower point to the curved-road higher point

- Layers are compacted to the required density in theSpecifications, and then the Engineer will be invited to check thedensity by sand cone method at site Subsequent layers will only

be carried out when previous layers are approved by theEngineer Compaction work will be complied with theSpecifications

- Completion of embankment and slope: Embankment slope will beshaped to the required slope and density by suitable tools Thesurface of embankment shall be smooth, free from crack meetingthe requirements shown on drawings or as instructed by theEngineer

- Acceptance work will be executed following the sequence:

 Check elevation of fill embankment by level machine

 Check geometry dimensions by steel tape

 Check smoothness by 3m straight edge

 Check density by sand cone method at site

- Prior to construction on a large scale is commenced theContractor will perform a trial section with the area of not lessthan 500m2 (the length of 50m, the width of 10m) The results oftrial section to be submitted to the Engineer are included:

 Construction equipments

 Design of rolling diagram, rolling sequence: rolling speed ofvarious stages, number of passes on one point with the bestmoisture for trial section

 Test results of density attained with the designed rollingdiagram for sand material used.

- The parameters attained from the trial section, if satisfied therequirements, it will be applied to construct on a large scale onsite

- Other requirements for embankment fill are complied by theContractor with the Specifications, Section 3550-8310-sp-0009

3 EXCAVATION

All excavation shall be carried out to the required lengths, depths, inclinations and curvatures

as may be necessary for the constructions of the work or as shown on the drawings inwhatever material that may be found, including top soil and the surplus soil shall be disposed

of as Main Contractor engineers may instruct

Excavation for foundation shall extend a sufficient distance from the footing (approximately

30 cm) to create appropriate space for placing and removal of forms

The bottoms of all excavation shall be leveled carefully, unless otherwise on the drawing or

by Main Contractor’s engineers’ instruction

4 EXCAVATION PROCESS

1 MACHINE EXCAVATION

The purpose of machine excavation is to speed up the process Follow this procedure,excavation machine can not break the under ground soil structure which according to thedesign of foundation Excavator will not be able to excavate the small space, but that soil will

be excavated by hand Anyway, after excavator has finished its work, the excavation pit is to

be repaired by hand

2 HAND EXCAVATION

Hand-excavation can keep the ground surface of excavation pit evenly and the under groundsoil not to be broken Hand excavation is the only choice in the areas where excavator couldnot work The purpose of hand excavation is to make the surface of excavation pit to besmooth with small tolerance

Checking-level pole will be used to correct the level of ground during excavation byhand

5 INSPECTION OF EXCAVATIONS

All excavations are to be inspected and must be approved by Main Contractor’s engineerbefore gravel and lean concrete is laid (in case the work is carried out by a sub contractor ofVINACONEX) The sub contractor shall inform Main Contractor’s engineer in time to allowVINACONEX’s inspector to make the visual inspection of the excavation works (Seeattached check list )

6 ADDITIONAL EXCAVATION

If it is necessary for any reason to form, extend and/or deepen foundations under or aroundany part of the work, the additional excavation shall be processed

7 INSPECTION BEFORE FILLING IN

No filling in shall be commenced until the concrete foundations have been inspected by MainContractor’s engineer in charge

8 UPHOLDING SIDES OF EXCAVATION

When it is necessary, upholding the sides of excavations shall be processed to prevent anydamage to adjacent structure and buildings caused by collapsing of sides and embankments

of excavations

9 TIMBER, Etc LEFT IN EXCAVATIONS

Timbering, dust, debris, rubbish, etc Shall not be left in when excavations are being filled

10 REMOVAL OF SURPLUS SOIL

All surplus excavated material, rubbish and waste matter shall be removed from the site The

place for disposal shall be selected by site manager or by sub contractor.

11 KEEPING EXCAVATION FREE FROM WATER

Powered pumping, drainage or otherwise shall be used to keep the whole of the excavationfree from water arising from rain, flood, drain, springs or any other cause If the work iscarried out by a sub contractor of VINACONEX, he shall convince VINACONEX engineer

in charge before he starts with the excavation works that suitable equipment, in good workingcondition is available on the project site

II ROAD AND PAVEMENT WORK:

B Construction of road AND PAVEMENT system:

1 Clearing and grubbing:

The entire road reserve and platform area shall be cleared as described above,unless otherwise shown on the Drawings and I or directed by the EmployerRepresentative

b Setting out:

The right of way (ROW) shall be surveyed and set out before any site clearance iscarried out Wooden pegs usually indicate the surveyed right of ways

c Plant and equipment:

Sites clearing of trees, vegetation, undergrowth, bushes and minor structures arecarried out by bulldozers and or hydraulic excavators Trees that cannot be felled bythe aforesaid equipment shall be felled by using chainsaws

Major structures that cannot practicably be cleared by hydraulic excavators and/ orBulldozers, these demolitions can be carried out using pneumatic tools and/ or otherspecialised equipment depending on the size and type of structures

- Photographs shall be taken of structures, landscaping trees and shrubs,fences, telephone and electrical poles and others that are payable underindividual measured item apart from the general site clearance in the bill ofquantities.

- The above site clearance items shall be measured according to themethod of measurement jointly with the Employer’s Representatives Thelocations of these items shall be identified according to the surveyedcoordinates or offsets from the centerline of the proposed alignments inroad construction

- Prior to demolition of existing buildings, liaison with the respectiveauthorities to terminate the utilities supplies to the buildings

- Prior to removal of landscaping trees end shrubs, a joint inspection shall

be carried out with the local authority

- Fencing or others that are to be relocated or salvaged shall be carried outaccording to the drawings or as per instructions given by the EmployerRepresentative

- Ensure that the right of way lands have been acquired by the Employer orrelevant authorities

- Access roads to the site shall be constructed if required to enablevehicles, equipment and plants to be brought into the site

- Solid waste dump sites shall be predetermined within or outside the sitefor the dumping of the site clearing materials These dumping sites shall

be approved by the Employer's Representatives or the relevantauthorities

The site clearance shall then proceed to clear the trees, vegetation, undergrowth,bushes and minor structures by hydraulic excavators and or dozers

All unwanted materials shall be piled up and disposed off in a safe tidy manner at thedesignated dumping areas

All burning shall be subject to the prior approval of the relevant GovernmentAuthorities, and shall be carried out in conformance with all pertinent regulations.Material designated in the Contract or direct by the Engineer to be salvaged, shall becarefully removed and stored, and shall be the property of the Employer orGovernment whichever is specified in the contract

Saleable timber if any shall be trimmed and stacked in accordance with therequirements of the specification or appropriate Government Agency, in accessibleplaces within the right of ways.

The above engineers shall ensure that all items payable under measured items shall

be measured and recorded in the joint measurement sheets by these supervisorswith the Employer’s Representative

2 Construction of Subgrade, subbase, Base, Asphalt concrete:

Content of works:

- Construction of embankment

- Construction of Subbase course

- Construction of Base course

- Asphalt concrete pavement

At the same time we carry out construction of the lighting system, drainage system

Proposed equipment used for embankment construction

Trial area location

Used roller type

Site Records

Rolling plan

Number of Roller passes, site density, embankment thickness relationship.This report will be prepared and submitted by subcontractor to Engineer for reviewand approval Embankment construction in large area only be carried out whenabove report approved by Engineer in writing

 Embankment will be formed in accordance with the approved drawings and to thewidths, slopes, levels and heights shown thereon and construction method will beprogrammed so that any embankment during to the construction period will notovertopped by flood water after completed

 Benching will be required when embankment is placed on hillsides or againstexisting embankment with slopes that are steeper than 6:1 when measured at theright angle to the roadway and will be continuously benched in loosen lift not toexceed 30 cm Benching will be wide enough to permit the operations ofplacement and compaction equipment All horizontal cuts will begin at theintersection of the natural ground line and the vertical side of the previous bench

 Roadway embankment material will be placed in each layer with loose thicknessnot exceed 20 cm Each layer will be extended more than specified width ofembankment and will be compacted to required density before the next layer isplaced to ensure uniform density of embankment achieved

 Embankment will be constructed in layers of uniform thickness approximately

parallel to the finished grade of the road with compaction by heavy vibratingrollers with capacity of 13.5-17 tons and by wheel rollers with capacity of 16 ton.Proceeding in the direction of the alignment and gradually over the width ofembankment or by overlapping passes Successive layers of the embankmentwill graded with motor graders or by other means in conjunction with compactionoperation A smooth surface grade having an adequate crown slope or cross-fallwill be maintained to provide for de-watering at all time of rain-falling.

 Placing and compaction of embankment material may proceed in light rainprovided that compaction in accordance with the density requirements given here

is achieved

 It will be ensured that the compact effort is uniformly spread over each layer

 Compaction by construction traffic will not be permitted

 Material approved for the use in the embankment from whatever source will beuniform when spread If, in the opinion of the Engineer, unacceptable non-uniformity, exist in the delivered materials either within individual loads orbetween successive loads, We may be directed that compaction he suspendedwhile non-uniform materials is blended by motor graders or by apprised labormethods We may also be directed to suspend the delivery of further materialwhile blending of non-uniform material is proceeding If, in the opinion of theEngineer, the uniform embankment will not result from blending by motor grader,the non- form material will be removed from works

 Prior to start of compaction of any layer of embankment on the road, the materialwill be watered to distribute required moisture evenly Compaction will beundertaken at moisture content of not less than 85% nor greater than 110% ofoptimum moisture content determined by the Engineer and specified degree ofcompaction

 We will at all time have on the embankment a sufficient number of water tankers

to watered the embankment material at the requited rate and to control dust.Where sand is used, the material will be saturated with water during compaction.Where de-watering is required We will ensure that sufficient pumps are provided

to enable the works to proceed without damage or delay due to unnecessary orprolonged inundation

 Where embankment is to be constructed across low swampy ground that will notsupport the mass of trucks or other hauling equipment, the lower part of the fillmay be constructed, when approved by the Engineer, by dumping successive

loads in a uniformly distributed layer of thickness not greater than necessary tosupport the hauling equipment while placing subsequent layers.

 Where placing or compaction of material under saturated or flood conditions cannot be avoided, We will submit his proposal methods to ensure adequatecompaction to the Engineer for approval

 Except otherwise or directed by Engineer, the layer in embankment areas shall

be compacted to at least 95% of the maximum dry density as determinedaccording to AASHTO T99 method D, except for the 1000 mm below subgradelevel compaction degree of 98% of maximum dry density according to AASHTOT99 method D is required

b Construction of Subbase layer:

Scopes of work

The works procedure for sub-base work will be shown as following:

This work will be consist of supplying, processing, hauling, spreading, watering, andcompacting aggregate subbase on a prepared subgrade in accordance withspecification, lines, grade and cross sections shown on the drawing or as directed bythe Engineer

Processing will include where necessary crushing screening separation,blending and any other operation necessary to produce a material conforming to therequirements of the Technical Specification

Material

- The sub-base materials will be crusher-run materials which will not containunsuitable objects and substances such as vegetable and deleterious substancesand they will conform with the requirements stated in the General Specification

- Prior to subbase, We will submit a sample of material proposed to use as base material, mixing plant type, mixing plant lay-out, test result, hauling way,hauling method to Engineer for his review and approval When Engineer’s approval

Trial section

be informed to Contractor in writing, any changes relating to afore – mentionedmust be informed to and approved by Engineer in writing.

Proposed equipment used for construction

Construction process

Trial section.

Prior to the implementation of sub-base construction, We will spread and compacttrial section as directed by Engineer The purpose trial section construction is todetermine suitability of sub-base material, relationship between number of rollerpasses and site density to various embankment depth, effectiveness of usedequipment type Report including :

Trial area location

Used roller type

Site Records

Rolling plan

Number of Roller passes, site density, embankment thickness relationship.This report will be prepared and submitted by the subcontractor to Engineer for hisreview and approval Embankment construction in large area only be carried outwhen above report approved by Engineer in writing

Placing aggregate materials

- The aggregate sub-base material will be transported from mixing plant to site by

dump truck and be placed on prepared and approved surface When more than onelayer is required, each layer will be shaped and compacted before the succeedinglayer is placed

- Sub-base materials will be placed from trucks especially equipped to distribute thematerial in a continuous uniform layer The layer will be such a size that when spreadand compacted the finished layer will be reasonably close conformity to the normalthickness show on the plan

Spreading and Compacting.

- The sub-base material shall be spread by bulldozers and motor spreaders to thecompacted thickness not less than 100 mm and not greater than 150 mm.Spreading works will be carried out in the manner that is convenient for compactingworks The applied machines will be approved by the Engineer before implementingthe spreading works

- The moisture content of sub-base material is one of the most important factor thatinfluences seriously the compaction works Therefore, it will be adjusted prior tocompaction by watering with approval sprinklers mounted on trucks or by drying out

if it is relatively low and high respectively, to not less than 85% during compactionand moisture content shall be kept not less than 65% and not greater than 100% ofoptimum moisture content

- Immediately following final spreading and smoothening, each layer will becompacted to the full width by means of approved compaction equipment,compaction method, compaction procedures as described in trial construction reportwhich approved by Engineer Compaction degree of 95% of MDD Any irregularities

or depressions that develop will be corrected by loosening the material at theseplaces and adding or removing material until the surface is smooth and uniform.Along curbs, headers, and walls, and at all places not accessible to the roller, thesub-base material will be compacted thoroughly with approved tampers orcompactors At the end at each shift, the surface of the sub-base will be shaped andsloped to prevent poundage of rain water

Tolerance and finish

 The finished sub-base will not vary more than +10 mm and – 20 mm above orbelow the planned level of pavement indicated on the Drawing, minus the Thesub-base which does not conform to those requirements will be executed again,

watered and thoroughly re-compacted to the satisfaction of the requirementsspecified in the Technical Specification or indicated by the Engineer.

 Irregularities measured by 3 m straight edge is not greater than 20 mm

 Design crossfall or camber:  0.3%

 Design longitudinal grade over 25m in length:  0.1%

c Construction of base layer

Scopes of work

The works procedure for base work will be shown as following:

This work will be consist of supplying, processing, hauling, spreading, watering, andcompacting aggregate base material on a prepared sub–base course in accordancewith specification, lines, grade and cross sections shown on the drawing or asdirected by the Engineer

This work only commence after drainage structures as shown on drawing completedand accepted by Engineer

Processing will include where necessary crushing screening separation,blending and any other operation necessary to produce a material conforming to therequirements of the Specification

At the same time, we carry out construction of median

Material

 The base materials will be crusher-run materials, clean, durable, tough, angle fragment which will not contain unsuitable objects and substances such asvegetable and deleterious substances and they will conform with therequirements stated in the Specification

Trial section

 Prior to base construction, We will submit a sample of material proposed to use

as base material, mixing plant type, mixing plant lay-out, test result, hauling way,hauling method to Engineer for his review and approval When Engineer’sapproval be informed to Contractor in writing, any changes relating to afore –mentioned must be informed to and approved by Engineer in writing

Proposed equipment used for construction

4 Mechanical Tamper

5 Paving Machine 400 – 600 m3/shift

Construction process

Trial section – Proof Rolling.

Immediately prior to placing base material, the complete surface of base shall beproof-rolled as described to satisfaction of Engineer

Prior to the implementation of base construction, We will spread and compact trialsection as directed by Engineer The purpose trial section construction (a section of

100 meter in length recommended by Engineer) is to determine suitability of basematerial, relationship between number of roller passes and site density to variousembankment depth, effectiveness of used equipment type Report including:

Trial area location

Used roller type

Site Records

Rolling plan

Number of Roller passes, site density, embankment thickness relationship.This report will be prepared and submitted by the subcontractor to Engineer for hisreview and approval Embankment construction in large area only be carried out

when above report approved by Engineer in writing.

Placing aggregate materials

 The aggregate base material will be transported from mixing plant to site bydump truck and be placed on prepared and approved surface

 Base materials will be placed from trucks especially equipped to distribute thematerial in a continuous uniform layer The layer will be such a size that whenspread and compacted the finished layer will be reasonably close conformity tothe normal thickness show on the plan

Spreading and Compacting.

 The base material shall be spread by propelled paving machine to the compactedthickness not less than 75 mm and not greater than 150 mm Spreading workswill be carried out in the manner that is convenient for compacting works Theapplied machines will be approved by the Engineer before implementing thespreading works

 The moisture content of base material is one of the most important factor thatinfluences seriously the compaction works Therefore, it will be adjusted prior tocompaction by watering with approval sprinklers mounted on trucks or by dryingout if it is relatively low and high respectively, to not less than 85% duringcompaction and moisture content shall be kept not less than 65% and notgreater than 100% of optimum moisture content until successive layer laid

 Immediately following final spreading and smoothening, base course will becompacted to the full width by means of approved compaction equipment,compaction method, compaction procedures as described in trial constructionreport which approved by Engineer Compaction degree of 100% of MDD isrequired for base course Any irregularities or depressions that develop will becorrected by loosening the material at these places and adding or removingmaterial until the surface is smooth and uniform Along curbs, headers, and walls,and at all places not accessible to the roller, the base material will be compactedthoroughly with approved tampers or compactors At the end at each shift, thesurface of the base will be shaped and sloped to prevent poundage of rain water

Tolerance and finish

 The finished base will not vary more than +5 mm and – 10 mm above or belowthe planned level of pavement indicated on the Drawing, minus the The base

which does not conform to those requirements will be executed again, wateredand thoroughly re-compacted to the satisfaction of the requirements specified inthe Technical Specification or indicated by the Engineer.

 Irregularities measured by 3 m straight edge is not greater than 5 mm

 Design crossfall or camber:  0.2%

 Design longitudinal grade over 25m in length:  0.1%

d Asphalt concrete pavement

General

The work of this part is to furnish a firm pavement coated by asphalt concrete mixthat is produced at central plant, including:

 Asphalt concrete base course

 Asphalt concrete wearing course

 Asphalt concrete overlay

The asphalt concrete mix will be placed and compacted on the prepared layeraccording to the specification and cross sections shown on the drawings or asdirected by the Engineer

Proposed equipment used for construction

Asphalt batching Plant 65 Ton/hr

Mechanical TamperAir Compressor 10 m3/ hr

material

Prior to asphalt concrete production, all material used for production, We will submitsample of all material proposed to use , source lay-out, test result, hauling way,hauling method and weekly hauling schedule to Engineer for his review andapproval When Engineer’s approval be informed to Contractor in writing, anychanges relating to afore-mentioned must be informed to and approved by Engineer

in writing

Job Mix design

 Material will be tested as the requirements of the specification

 Before commencing the work, We will design formula of each type of asphaltconcrete mixture and submit to the Engineer for approval Mixing formula in sitelaboratory will be determined and testing quality will be controlled by the designedratio for all aggregates

 The formula submitted shall set definite single values for :

 The percentage of aggregate passing each specified sieve

 The percentage of bituminous material to be added, on the totalaggregate basis

 The temperature of the mixture leaving the mixer

 The temperature of the mixture delivered on the road

 The grade of bituminous material

 Values for mix shall be designed within the limits and grading range asspecification

 If a change in sources of material is made, a new job mix formula shall beestablished before the new materials are used, subject to approval of Engineer

 Samples shall be taken at random times during the day from the mixing plant orbehind the paver prior to compaction and analyzed at least once a day for eachplant in use, or at least once for every 250 ton of materials laid, which ever is morefrequent, to check compliance with the job mix requirements

ASPHAL Construction process

We propose to use asphalt concrete from local batching plants

Trial section construction

 The asphalt concrete course construction will only be commenced after basecourse, drainage structures completed, all material tested in accordance withtechnical requirement, job-mix formula, method statement submitted byContractor and accepted by Engineer

 Before carrying out asphalt concrete course construction in large area, We willprepare trial section (at least 50 linear meter or as directed by Engineer) inpurpose of determination of stability of mixture and the capacity and efficiency ofsubcontractor’s plants and workforce, relationship between number of rollerpasses and site density Report including :

Trial section location

Used equipment type

Site Records

Rolling plan

Number of Roller passes, site density relationship

Test result of non-compacted material on aggregate grading, bitumen content,marshall density, stability, flows and void

This report will be prepared and submitted by the subcontractor to Engineer for hisreview and approval Asphalt concrete course construction in large area only becarried out when above report approved by Engineer in writing

Transportation of mixtures

 The mixture will be transported from the mixing plant to the location where thework will be performed by vehicles which are approved by the Engineer The beds ofthose vehicles are watertight, clean and made of smooth metal that have beensprayed with a thinned fuel oil or paraffin oil or lime solution to prevent the mixturefrom adhering to the beds The mix on the vehicles will be covered with canvas orother suitable material with suitable size to avoid the contamination and the weather

Spreading

- Prior to spreading asphalt concrete course, aggregate course surface will bethoroughly cleaned, dried out, leveled by approved equipment and manner as trailsection construction carried out A prime coat layer as required in Specification will

be applied on aggregate base course

 Before paving, the screed of the paver will be heated and then the mixture will bespread and struck off to the grades, cross sections shape as shown on the drawings

 We will furnish mechanical, self-powered pavers that are capable spreading themixture to the line, grade, and cross section as shown on the drawings Ready-mixed Asphalt concrete hauled to site by truck always be checked by thermometerand only will dumped in to Paver if it’s temperature not less than 125 0C

 Prior to the commencement of the paving operations, the equipments, labors andother conditions will be prepared in sufficient quantity to provide the speed of theprogress of work not less than 60% capacity of Batching plant

 At the edge of the pavement, timber or other formwork materials will be installedand kept stable at required grades and lines as shown on the drawings when the hotasphalt concrete mixture is placed

 The pavement construction will be operated at the rate which does not cause thesurface cracks, or other irregularities on the surface The rate of spreading will beapproved by the Engineer

 Finishing layer will be adjusted so that the finished pavement will satisfy all therequirements that have been specified in the Technical Specification and its crosssection is close to that as shown on the drawings Paving work will be keptperforming continuously as long as possible

 At the locations where the use of mechanical spreading and finishing equipments

is impracticable, the mixture will be spread and screeded by hand labours On sucharea, the mixture will be handled carefully so as not to be recollected

Compacting

 With each pavement, two 8 - 10 tons capacity steel wheeled rollers and one 16 toncapacity pneumatic tired roller will be required to keep the rate of progress asplanning

 Pneumatic tired roller will be the type that has been approved The roller used inthis project will have more at least seven wheels with smooth tread compactor tires

of equal size and its operating inflation pressure is 8.5 kg/cm2 Each tire will be

inflated to the specified operating pressure so that the pressure difference betweenany two tires will not exceed 350 mg/cm2 In addition, each roller will be equippedwith means of adjusting its own total weight by blasting; therefore, the load per wheelwidth can be varied from l500 to 2500 kg.

 Steel wheel rollers will be capable to develop a compressive loading under rearwheel of not less than 400 kg per 0.1 m over a minimum roller width of 0.5 m Atleast one rollers will be capable to develop a roll pressure of 600kg

 Immediately after the mixture being spread and struck off, the surface will bechecked and any irregularities or mistakes will be corrected and adjusted Thetemperature of the loosen laid mix will be monitored and rolling will be carried outwithin the bitumen viscosity limits and flexibility of asphalt concrete

 After compaction, the specific gravity for the consolidated mixture, as determined

by AASHTO T230 and shall be not less than 95 % of the specific gravity oflaboratory compacted specimens composed of the same material in like proportion

Rolling of mixture will consist of three separate operations as follows:

- Initial rolling: Proceeded in time interval of 0-10 minutes after laying, when thetemperature of asphalt concrete mixture is not less than 120 0C The initial rolling will

be done with steel rollers The initial roller will operate with the drive roll nearest thepaver

- Immediate rolling: Proceeded in time interval of 10 - 20 minutes after laying, when thetemperature of asphalt concrete mixture is 95 0 - 110 0C The immediate rolling will bedone with wheel-tired rollers The immediate roller will operate with the drive rollnearest the paver and will be done while mixture is still at temperature that will result

in maximum compacting

- Finishing rolling: Proceeded in time interval of 20-45 minutes after laying, when thetemperature of asphalt concrete mixture is 80 0 - 95 0C The finishing rolling will bedone while material is still in a sufficiently workable condition for all roller marks to beremoved

- Transverse joints will be rolled first and the initial rolling will be rolled transversely usingboards having the required thickness at the edge of the pavement to provide for off-the-pavement movement of the roller Where the transverse joint is made next to apreviously, paved lane, the first pass will be made along the longitudinal joint for ashort distance