Av

GOVERNMENT OF PAKISTAN

NATIONAL HIGHWAY AUTHORITY

GNCR RT SPCCIFICRTIONS(DECEMBER - 1998)

Prepared & Presented By:

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102.3.2

The falsework drawings shal l show any pedestr ian openings, which arerequired through the falsework.

Anticipated total settlements of falsework and forms shall be indicated bythe Contractor on the falsework drawings. These should include falseworkfoot ing sett lement and joint take-up. Ant ic ipated sett lements over two (2)cms wi l l not be al lowed unless otherwise permit ted by the Engineer. Deckslab forms between girders shall be constructed with no allowance forsettlement relative to the girders

Detai led calculat ions by the Contractor showing the stresses. def lect ions,and camber necessary to compensate for said def lect ions in al l loadsupport ing members shal l be included in the worktng drawings.

After approving the Contractor's falsework deflection camber, the Engineerwill furnish to the Contractor the amounts of camber necessary tocompensate for vedical al ignment or ant ic ipated structure def lect ion, i f th isis not shown on the drawings. The total camber used in construct ingfalsework shal l be the sum of the afore mentioned cambers.

False rvork Construction and Dran'ings

The falsework shall be constructed to conform to the falseworr drawings.The mater ials used in the falsework construct ion shal l be of the quant i ty andqual i ty necessary to withstand the stresses imposed. The workmanshipused in falsework construction shall be of such quality that the falsework willsupport the loads imposed on it without excessive settlement or take-upbeyond that shown on the falsework drawings.

Falsework shal l be founded on foot ings, capable of support ing the loadsimposed on i t .

When falsework is supported on piles, the piles shall be driven to a bearingvalue, equal to the calculated pi le toading as shown on the falseworkdrawings.

Suitable jacks or wedges shall be used in connection with falsework to setthe forms to their required grade and to take up any excessive sett lement inthe falsework either before or during the placing of concrete.

The Contractor shall provide tell-tales attached to the soffit forms easilyreadable and in enough systematical ly-placed locat ion to determine the totalsettlement of the entire portion of the structure where concrete is beingplaced.

Should events occur, including settlements that deviate more than + 2 cmsfrom those indicated on the falsework drawings, which in the opinion of theEngineer would prevent obtaining a structure conforming to therequirements of these specifications, the placing of concrete shall. bediscontinued until corrective measures are provided to entire satisfaction ofthe Engineer. In the event, sat isfactory measures are not taken tocorrectness of excessive settlements, the contractor shall not be relieved ofresponsibility for conforming to the requirements of these specifications.

402-3

{02.3.3

402.-l

Itemoving Falsc*'orlr

Unless otherwise shown on the drawings, or permit ted by the Engineer,falsework support ing any span of a simple span br idges shal l not bereleased before 14 days after the last concrete, excluding concrete abovethe br idge deck, has been placed. Falsework support ing any span of acontinuous or rigid frame bridge shall not be released before 14 days afterthe last concrete, excluding concrete above the bridge deck, has beenplaced in that span and in the adjacent portions of each adjoining spanwhere falsework is to be released.

Falsework supporting deck overhangs and deck slab between girders shallnot be released until seven (7) days after the deck concrete has beenplaced.

In addition to the above requirement, no falsework for bridges shall bereleased until the supported concrete has attained a compressive strengthof atleast eighty (80) percent of the required twenty eight (2g) days strength.

Falsework for cast-in-place prestressed portions of structures shall not bereleased unt i l af ter the prestressing steel has been tensioned.

All falsework materials shall be completely removed. Falsework piling shallbe removed atleast sixty (60) cms below the surface of the original groundor stream bed. when falsework piling is driven within the limits of ditch orchannel excavation areas, the falsework piling within such areas shall beremoved to atleast sixty (60) cms, below the bottom and side slopes of saidexcavated areas.

All debris and refuse resulting from work shall be removed and the premisesleft in a neat and presentable condition.

MEASUREMENT AND PAYMENT

For all concrete structures, prestressed concrete structures or oortionsthereof, no separate measurement or payment shall be made for falseworksupporting such structures. All falsework costs shall be considered asincluded in the contract prices paid (cost/cM or LM of structural members orlump-sum) for the various items of concrete work and no additionalcompensation will be allowed thereof..

402-4

ITEM 403 FORMWORK

403.1

403.2

403.3

403.3.r

403.3.2

DESCRIPTION

The work shall consist of providing, erecting and removing concrete forms ofsufficient strength with all necessary bracings, fasteners, etc. and inconformity with the requirements hereinafter specified.

MATERIAL REOUIREMENTS

Forms shall be of wood, metal or other approved materials and shall be builtmortar tight and of sufficient rigidity to prevent distortion due to the pressureof the concrete and other loads incident to the construction operations.

CONSTRUCTION REOUIREMENTS

Formwork Design and Drawines

The contractor shall prepare working drawings, backup calculations andmaterial data for the form work and shutters to be submitted to the Engineerfor approval unless otherwise directed.

The requirements for design of formwork are the same as described underItem 402.3.1 - Falsework Design and Drawings.

Formwork Construction

concrete forms shall be constructed and maintained so as to preventwarping and the opning of joints due to the shrinkage of the lumber andshall be true to the dimensions, lines and grades of the structure and withthe sufficient strength, rigidity, shape and surface smoothness as to leavethe finished works true to the dimensions shown on drawings or required bythe Engineer and with the surface finish as specified.

Forms for exposed surfaces shall preferably be lined with metal, plywood, orother approved material, or may with the Engineer's permission, be made ofdressed lumber of uniform thickness. Forms shall be filled at all sharpcorners(Minimum two (2) cms triangular fillets) and shall be given a level ordraft in the case of all projections, such as girders and copings, to ensureeasy removal.

Form fasteners consisting of form bolts, clamps or other devices shall beused as necessary to prevent spreading of the forms during concreteplacement. The use of ties consisting of twisted wire loops to hold forms inposition will not be permitted. Metal ties or anchorage within the forms shallbe so constructed as to permit their removal to a depth of at least five(s)cms from the face without injury to the concrete.

403-1

Fitting for metal ties shall be of such design that, upon their removal, thecavities that are left will be of the smallest possible size. The cavities shallbe filled with cement mortar and the surface left sound, smooth, even, anduniform in colour. Anchor devices may be cast into the concrete for later usein supporting forms or for lifting precast members. The use of driven types ofanchorages for fastening forms or form supports to concrete will not bepermitted.

The inside surfaces of forms shall be cleaned of all dirt, mortar and foreignmaterial. Forms, which will later be removed, shall be thoroughly coated withform oil prior to use. The form oil shall be a commercial quality form oil orother approved coating which will permit the ready release of the forms andwill not discolour the concrete. All exposed surfaces of similar portions of aconcrete structure shall be formed with the same forming material or withmaterials which produce similar concrete surface textures, colour andappearance.

Concrete shall not be deposited in the forms until all work in connection withconstructing the forms has been completed, all materials required to beembedded in the concrete have been placed for the unit to be poured, andthe Engineer has inspected and approved said forms and materials.

The rate of depositing concrete in forms shall be such as to preventdeflections of the forms or form panels in excess of the deflections permittedby these specifications. Maximum deflection allowed due to prop settlementis 5 mm and due to bending of shutters is 3 mm, when measured with 3meter straight edge.

Forms for all concrete surfaces, which Will not be completely enclosed orhidden below the permanent ground surface, shall conform to therequirements herein for forms for exposed surfaces. Interior surfaces ofunderground drainage structures shall be considered to be completelyenclosed surfaces.

Formwork for concrete placed under water shall be watertight. When lumberis used, this shall be planed and tongued and grooved.

Forms for exposed concrete surfaces shall be designed and constructed sqthat the formed surface of the concrete does not undulate excessively in anydirection between studs, joists, form stiffeners, form fasteners, or wales.Undulations exceeding either two (2) mm or 11270 of the center to centerdistance between studs, joists, form stiffeners, form fasteners, or wales willbe considered to be excessive. Should any form or forming system, eventhough previously approved for use, produce a concrete surface withexcessive undulations, its use shall be discontinued until modifications,satisfactory to the Engineer have been made. Portions of concretestructures with surface undulations in excess of the limits herein may berejected by the Engineer.

403-2

403.3.3

Forms shall be set and maintained true to the line designated until theconcrete is sufficiently hardened. Forms shall remain in place for periods,which shall be determined, as herein specified. When forms appear to beunsatisfactory in any way, either before or during the placing of concrete,the Engineer will order the work stopped until the defects have beencorrected.

The shape, strength, rigidity, watertightness, and surface smoothness ofreused forms shall be maintained at all times. Any warped or bulged lumbermust be resized before being reused. Forms that are unsatisfactory in anyrespect shall not be reused.

For narrow walls and columns, where the bottom of the form is inaccessible,the lower form boards shall be adjustable so that they may be removed forcleaning out extraneous material immediately before placing the concrete.

Removal of Formwork

ln the determination of the time for the removal of falsework and forms,consideration shall be given to the location and chara;ter of the structure,the weather, and other conditions influencing the setting of the concrete,and the materials used in the mix.

lf field operations are not controlled by beam or cylinder tests, the followingperiods, exclusive of days when the temperature is below five (5) degree C,for removal of forms and supports shall be used as a minimum subject tothe approval of the Engineer and to the requirements of ltem 402.3.3.Removing Falsework.

Arch CenterCentering Under BeamsSupports under Flat SlabsFloor SlabsVerticalWall SurfacesColumnsSide of BeamsTop Slabs R.C. Box Culverts

14 Days14 Days14 Days14 Days24 Hours24 Hours12 Hours14 Days

Side forms for cast-in-place beams, girders, columns, or other memberswhere the forms do not resist dead load, bending shall remain in place for atleast forty (40) hours after placing concrete for the members. Side forms forprecast members may be removed the next day after placing concretetherein.

lf high early strength cement is used or by the use of additional cement,these periods may be reduced as directed.

\Men field operations are controlled by cylinder tests, the removal of forms,supports and housing, and the discontinuance of heating and curing (whereapplicable) may begin when the concrete is found to have the requiredcompressive strength, provided in no case shall supports be removed inless than seven (7) days after placing the concrete.

403-3

403.4

All forms shall be removed, except when no permanent access is availableto the cells, the forms supporting the deck of box girders and the forms inhollow abutments or piers may remain in place. prior to completion offorming for the deck forms, the inside of box girders shall be cleared of allloose material and swept clean.

Methods of form removal likely to cause overstressing of the concrete shallnot be used. In general, the forms shall be removed from the bottomupwards. Forms and their supports shall npt be removed without approval.supports shall be removed in such a manner as to permit the concrete touniformly and gradually take the stresses due to its own weight.In general, arch centering or falsework shall be struck and the arch madesetf-supporting before the railing or coping is placed. This precaution isessential in oider to avoid jamming of the eipantion loints jnd' variations inalignment. For filled spandrel arches, such portions of the spandrel wallsshall be left for construction subsequent to the striking of centeis, as may benecessary to avoid jamming of the expansion joints.centers shall be gradually and uniformly lowered in such a manner as toavoid injurious stresses in any part of the structure. In arch structures of twoor more spans, the sequence of striking centers shall be approved by theEngineer.

MEASUREMENT AIID PAYMENT

For all concrete structures, . prestressed concrete structures, precastconcrete elements or portions thereof, no separate measurement orpayment shall be made for formwork supporting such structures. Allformwork costs shall be considered as included in the contract prices paid(cosucM or LM of structural members or lump-sum) for the various items ofconcrete worli and no additional compensation will be allowed thereof.

403-4

ITEM 404 STEEL REINFORCEMENT

404.2

404.1

404.3

4043.r

DESCRIPTION

This work shall consist of furnishing, fabricating and placing of steelreinforcement of the type, size, shape and grade required in accordancewith these specifications, and in conformity with the requirements shown onthe Drawings and Special Provisions or as directed by the Engineer.

IUATERIAL R.E,OUIRE]UENTS

All materials shall conform to the requirements hereinafter given. Testreports from approved sources shall be submitted to the Engineer for allsteel reinforcement used. These reports shall show the results of chemicaland physicaltests made

Deformed BilletSteel Bars (Grades 40 and 60) for ConcreteReinforcement AASHTO M-31 (ASTM 4-615)Deformed Steel Wire for Concrete Reinforcement-AASHTOM-225 (ASTM A-496)Welded Steel Wire Fabric for Concrete Reinforcement-AASHTOM-55 (ASTM A-185)Steel Bar Mats for Concrete ReinforcementAASHTO M-54(ASTM A-184)Cold-Drawn Steel Wire for Concrete Reinforcement-AASHTOM-32 (ASTM A-82)Welded Deformed Steel Wire Fabric for ConcreteReinforcement-AASHTO M-221 (ASTM A-497)Structural Shapes for Concrete Reinforcement ASTM A-36

CONSTRUCTION REOUIREMENTS

Fabrication of Bent Bars

a) Order Lists

Before materials.are ordered all order lists and bending diagrams shall befurnished by the Contractor, for the approval of the Engineer. The approvalof order lists and bending diagrams by the Engineer shall in no way relievethe Contractor of responsibility for the correctness of such lists anddiagrams. Any expenses incident to the revisions of material furnished inaccordance with such lists and diagrams to make it comply with thedrawings shall be borne by the Contractor.

r)i i)

i i i)

iv)

v)vi)

vli)

404-1'

b) Storins and Surface Condition of Reinforcement

Steel reinforcement shall be stored above the surface of the ground onplatforms, skids, or other supports and shall be protected as far aspracticable from mechanical injury and surface deterioration caused byexposure to conditions producing rust. When placed in the work,reinforcement shall be free from dirl, detrimental rust, loose seals, paint,grease, oil, or other foreign materials. Reinforcement shall be free frominjurious defects such as cracks and laminations. Surface seams, surfaceirregularities, or mill scale will not be cause for rejection, provided theminimum dimensions, cross-section area, and tensile properties of a hand-wire brushed specimen meets the physical requirements for the size andgrade of steel specified.

c) Fabrication

Bent bar reinforcement shall be cold bent to the shapes shown on thedrawings or required by the Engineer. Bars shall be bent around a pinhaving the following diameters(D) in relation to the diameter of the bar (d):

Stirrups & column tie bars

Other bars having

d

stir.rups and ties shall always pass around. the outside of main bars and be,""ur"fy attached thereto. Att ieinforcing steel shall be securely held at the;rp";'d;t""ce from steel forms, which remain in place by means oflatvanizeo steel bars or chairs placed on the forms. All reinforcing steel,E*""pt as mentioned above, shall be securely held at the proper distancefrom the forms by means of templates, concrete b|ocks or galvanized steel"f.r"i6.

Metal chairs shall not be used against formed surfaces, which will be

"*p"i"O in the finished structure aftei tne forms are stripped. Blocks for

troiOing reinforcement away from contact with the forms shall be precast

"on"rJt" blocks of approved shape, and dimensions and shall have 16-

g""g" br"il annealed'tie wires embedded in them. The precast concreteblock shall have a compressive strength equal to that specified for the classof concrete to be placed in the work. Layers of bars shall be separated byapproved metal chairs or bolsters.

Any broken or damaged concrete spacer blocks shall be removed before

"lii"r"t" iS placed. T"he use of pebbles, pieces of broken. stone or brick,

r"t"r pip" or wooden blocks as spacers will not be permitted' Reinforcingsteef wn'en placed in the work shail be free from flake rust, dirt and foreignma te r i a l andbe fo reanyconc re te i sp |aced ,anymor ta rwh i chmaybeaonering to the reinforcing steel shall be removed. No concrete shall beJ"p".it,iO until the Engin6er has inspected the placing of the reinforcingsteel and given permisJion to place the concrete. The Contractor shall allowtne enginler four hours time after the reinforcement and forms are in placeto condluct the inspection. Any bar of incorrect size, length or shape shall beilmoueo and replaced wi*i correct bars. Any bar located or spacedincorrectly shall be relocated or spaced correctly before permission is givento place toncrete and such replacements and corrections shall be at thecontractor's expense. All concrete placed in violation of these provisionsshall be rejected and removed'

c) SplicineAll reinforcement shall be furnished in the full lengths indicated on theoi"*ing, unless otherwise permitted. splicing of bars, except where shownon the

-drawings, will not be permitted without the written approval of the

;;g;;;";. SptiJei snatt be staggered as far as possible and with a minimumseiaration of not less than fort' (aO) times bar diameters. Not more thanon! tnirO (1/3)of the bars may be spliced in the same cross-section, exceptwhere shown on the drawings.

Unless otherwise shown on the Drawings, bars shall .be lapped with a,ini*rrn overlap of forty (40) times the bir diameter. In lapped splices' thebars shall be placed in tontict and wired together. Lapped splice-s will.notbe permitted at locations where the concrete section is insufficient tofrouiO" a minimum clear distance of one bar diameter or one and one thirdir_ila1 the maximum size of coarse aggregate between the splice and the_i""r"rt adjacent bar..Welding of reintorclng steel shall be done only ifdetailed on the Drawings or if-authorized by ihe Engineer.in writing' Spiralreinforcement shall belpliced by lapping ai least oneand one half (1-112)irrn, ot" by butt welding unless otherurise shown on the Drawings.

404-3

d) Lanning of Bar Matsheet of mesh or bar-mat reinforcement shall overlap each other sufficienflyto maintain a uniform strength and shall be secureiy fastened at the endsand edges. The overlap shall not be less than one mesh in width.

e) Covering

The minimum covering, .measured from the surface of the concrete to theface of any reinforcement bar shail, unress otherwise shown on theDrawings or directed by the Engineer, be not ress than s cms except asfollows:

404.4

404.4.1

In the_footings of abutments.and retaining wails the minimum covering sharlbe 7.5 cm. In work exposed to the action 6f sea water ine mini.n* covenngshal l be 10 cm.

MEASUREMENT AND PAYMENT

Measurement

The .quantity -to be paid for shail be the carculated theoreticar number ofmetric tons of reinforcement steer bars, mesh or mats as determined fromthe approved bar bending diagrams and incorporated in the concrete andaccepted, except when reinforcement is paid foi under ot

"i pay-it"rs.

The weight of prain or deformed bars or bar mat wiil be computed from thetheoretical weight of plain round bars of the same nominal size as shown inthe following tabulation :

Size Weight in Sizemm Kilograms mm.

per Meter

6 0.222 208 0.395 2210 0.616 2512 0.888 3213 1.042 3516 1.578 40

clips, ties separators, and other material used for positioning and fasteningthe. reinforcemenJin prace and structurar steer shail not be incruoed in thJyreiojrt calcutated for payment under this item. rf bars are substituted uponthe contractor's request and as a result more steer is used than specified,on|ytheamountspecif iedsha||bemeasuredforpayment

Top of slabBottom of SlabStirrups and ties in T-beams

4.0 cm3.0 cm3.5 cm

Weight inKilogramsper Meter

2.4662.9843.8536 . 3 1 37.5539.865

404-4

404.4.2

When laps are made for splices, other than those shown on the Drawings orrequired by the Engineer and for convenience of the Contractor, the extrasteelshall not be measured nor paid for.

When continuous bars are shown on the Drawings, without the splices beingshown the necessary steel in the splices will be paid for on the basis of theindividual bars not being shorter than twelve(12)meters.For bent bars, the length along centre-line of bar will be paid.

Payment

The accepted quantity measured as provided above shall be paid for at thecontract unit prices respectively for the pay items listed below and shown inthe Bill of Quantities which price and payment shall be full compensation forfurnishing materials, labour, equipment and incidentals necessary tocomolete the item.

Descript ion.Pay ltemNo.

Unit ofMeasurement

404a

404b

404c

404d

404e

404f

4049

404h

Reinforcement as per AASHTO M 31Grade 40

Reinforcement as per AASHTO M 31Grade 60

Reinforcement as per AASHTO M-225

Reinforcement as per AASHTO M-55

Reinforcement as per AASHTO M-54

Reinforcement as per AASHTO M-32

Reinforcement as per AASHTO M-221

Reinforcement (Structural Shapes)as per ASTM A-36.

Ton

Ton

Ton

Ton

Ton

Ton

Ton

Ton

404-5

ITEM 405 PRESTRESSED CONCRETE STRUCTURES

405.1

405.2405.2.7

DESCRIPTION

This work shall consist of prestressing precast or cast-in-place concrete byfurnishing, placing and tensioning of prestressing steel in accordance withdetails shown on the plans, and as specified in these specifications or asdirected by the Engineer.

This work shall also include the furnishing and installation of anyappurtenant item necessary for the particular prestressing system to beused, including but not limited to ducts, anchorage assemblies and groutused for pressure grouting ducts.MATERIAL REOUIREMENTSPrestreSSinE Reinfoicement Steel

Prestressing steel shall be hightensile wire conforming to ASTMSpecification 4-421 or AASHTO Designation M-204; strand or ropeconforming to ASTM specification A-416 or AASHTo Designation M-203 orhigh tensile alloy bars as follows:

High{ensile-strength alloy bars shall be stress relieved and cold stretched toa minimum of 9,100 Kg/sq.cm. After cold stretching the physical propertiesshall, be as follows:

Minimum Ultimate tensile strength 16,5T0 Kg/sq.cmMinimum yield strength, measuredby the 0.7 percent extension underload method shall be not less than g,100 Kg/sq.cmMinimum mgdulus of elasticity 1.75 x 10 Kg/sq.cmMinimum elongbtion in 20 bar dia meter 4 percJnt

'

Diameters after rupture - 0.75 mmDiameters tolerance - 0.25 mm

The steel shall be free from injurious defects and shall have a smoothsurface. Material, which shows injuries defects during or prior to itsinstallation in the work, shall be rejected.wire and strand shall be supplied in coils of sufficient diameter to ensurethat they lie out straight.

The Engineer may call for a relaxation test on prestressing steel in case, heis not satisfied with the source of manufacture. Relaxation for prestressingsteel shall be measured over a period of thousand (1000) hours stressed atseventy (70) percent of its ultimate tensile strength giving less than six (6)percent elongation.a) Testins

All wires, strands, or bars to be shipped to the site shall be assigned a lotnumber and tagged for identification purposes. Anchorage assemblies to beshipped shall be likewise identified.

r)i i )

i i i )iv)v)vi)

405-1

405.2.2

405.2.3

All samples submitted shall be representative of the lot to be furnished.

All of the materials bpecified for testing shall be furnished free of cost andshall be delivered in time for tests to be made well in advance of anticipatedtime of use.

The contractor shall furnish for testing the following samples selected fromeach lot as ordered by the Engineer. The selection of samples shall bemade at the manufacturer's plant by the Engineer or his representative'

Pretensioninq Method Samples at least 2.10 M long shall be furnished ofeach wtrepr strand size. A sample shall be taken from each and every coil'

Post-Tensioninq Method Samples of the following lengths shall befurnished:

For wires, sufficient length to make up one parallel-lay cable one and half(1.5) M long consisting of the same number of wires as the cable to beiurnistred. For strands, one and half (1.5) M length shall be furnished.

For bars to be furnished with threaded ends and nuts, one and half (1.5) Mbetween threads at ends.

Anchorage Assemblies Two anchorage assemblies of each size ofanchorage to be used shall be furnished, complete with distribution plates.

Concrete

The materials for concrete shall conform to the requirements of item 401.The concrete shall be Class D as shown in table 401-1 unless otheruviseshown on the Plans.

Reinforcement Steel

Reinforcement steel shall conform to the requirements of item 404.

CONSTRUCTION REOUIREMENTS

General

Unless otherwise ordered by the Engineer, the Contractor shall certify forthe Engineer's approval that a technician skilled in the approvedprestressing method will be available to the Contractor to give aid andinstruction in the use of the prestressing equipment to obtain the requiredresults.

The tensioning process shall be conducted so that the tension beingsupplied and the elongation may be measured at alltimes.

During the prestressing operations, standing behind or under jack will not beallowed in order to ensure that no one is injured by the flying spindle, tendonor the jack in the event of a break occurring.

405.3

405-2

40s.3. t Prestressing Method

The method of prestressing to be used shall be optional with the contractor,provided he introduces no change in the position of centroid of the totalprestressing force over the length of the member and in the magnitude ofthe final effective prestressing force as prescribed in the Drawings. Theprestressing system chosen by the Contractor shall have been indicated inthe tender. This option shail be subject to arr requirements hereinafterspecified.lndependently from the prestressing system to be applied, the foilowingpoints have to be ensured.

(i) The safety.g.f t!" anchorage of the prestressing tendons andtheir suitability for the transmission of forces t6 tne concreteunder all loads whatsoever.

(ii) That the actual losses due to friction coincide with the calculatedones for the prestressing.

(iii) The suitability of the proposed steel for the chosen prestressingsystem.

(iv) The length of transmission of the force to the concrete and theminimum strength of the ratter necessary for prestressing insystems, where the prestressing.erementi are fuily or partiailyanchored to the concrete through bond and friction.

(v) The suitability of measures taken to protect prestressing tendonsfrom corrosion untir the finartensioning is carried out.The contractor shail submit well in advance to the Engineer for approvalcomplete details of the methods, materials, and equipmEnt he proposes touse in the prestressing operations. such detail shail oufline the method andsequence of stressing, complete specifications and details of theprestressing steer and anchoring devices proposed for use, anchoringstresses, type of encrosures, and ail oirrei data p"rtrining to theprestressing operation, incruding the proposed arrangement of theprestressing units in the members.

An agreement certificate for the prestressing system shall be submitted andapproved by the Engineer before any structuril member to be prestressedmay be tensioned; this agreemeni certificate must ne issrleo by anauthorised testing laboratory otherwise the Enginee, ,"y oioer such anagreement certificate lrom a laboratory of hislnoice at'tfre cost of thecontractor. All rules rgferrlng to this agieement certificate here in after aresubject to the approval of the Engineer.Prestressing Equipment

Hydraulic jacks shail be equipped with accurate pressure gauges. Thecontractor may elect to. substitute screw jacks or ot'her types ior nyoraulicjacks. ln that case, proving rings or other ipproved devices shall be used in

405.3

405.3.2

connection with the jacks. All devices, whether hydraulic jack gauges orother wise, shall be calibrated so as to permit the stress in the prestressingsteel to be computed at all times. A certified calibration curve shallaccompany each device. Safety measures shall be taken by the contractorto prevent accidents due to possible breaking of the prestressing steel or theslipping of the grips during the prestressing process. All equipments shall bethoroughly washed with clean water at least once every three (3) hoursduring the grouting operations and at the end of use for each day.

405.3.3 Enclosures

405.3.4

405.3.5

Enclosures for prestressing steel shall be accurately placed at locationsshown on the plans or approved by the Engineer.

All enclosures shall be of ferrous metallic material and shall be completelymortar-tight with the exception that the contractor, at his option, with theapproval of the Engineer, may form the enclosures by means of cores orducts composed of rubber or other suitable material which can be removedprior to installing the prestressing reinforcement. Enclosures shall be s[rongenough to maintain their shape under such forces as will be imposed uponthem. They shall be six (6) mm. larger in internal diameter than the bar,cable, strand or group of wires, which they enclose. Where pressuregrouting in specified, cores or ducts shall be provided with the pipes or othersuitable connection for the injection of grout after the prestressingoperations have been completed.

Pl?cine Steel

All steel units shall be accurately placed in the position shown on theDrawings or required by the Engineer and firmly held during the placing andsetting of the concrete.

Distance from the forms shall be maintained by stays, blocks, ties, orhangers approved by the Engineer. Blocks for holding units from contactwith the forms shall be precast mortar blocks of approved shape anddimensions. Layers of units shall be separated by mortar blocks or otherequally suitable devices. Wooden blocks shall not be left in the concrete.

Suitable horizontal and vertical spacers shall be provided, if required, to holdthe wires in place in true position in the enclosure.

Placing Concrete

Concrete shall be controlled, mixed, and handled as specified in otherarticles of this section unless otherwise specified herein.

Concrete shall not be poured in the forms until the Engineer has inspectedthe placing of the reinforcement, conduits, anchorages, and prestressingsteel and has given his approvalthereof.

The concrete shall be vibrated internally or externally, or both, as ordered bythe Engineer. The vibrating shall be done with care in such a manner as toavoid displacement of reinforcement, conduits, or wires.

405-4

405.3.6

405.3.7

Pretensioning

The pretensioning elements shall be accurately held in position andstressed by jacks. A record shall be kept of the jacking force and theelongation produced thereby. Several units may be cast in one continuousline and stressed at one time. Sufficient space shall be left between ends ofunits, if necessary, to permit access for cutting after the concrete hasattained the required strength. No bond stress shall be transferred to theconcrete, nor end anchorages released, until the concrete has attained acompressive strength, as shown by cylinder tests, of at least two hundredsand eighty (280) kg/sq.cm and as approved by the Engineer. The elementsshall be cut or released in such an order that lateral eccentricity of prestresswi l lbe min imum.

Post-Tensioning

Tensioning shall be carried out only in the presence of the Engineer or hisrepresentative unless permission has been obtained to contrary.lmmediately before tensioning, the contractor shall prove that all tendonsare free to move between jacking points and that members are free toaccommodate the horizontal and vertical movements due to the applicationsof prestress.

Tensioning of prestressing reinforcement shall not be commenced untiltestson concrete cylinders, manufactured of the same concrete and cured underthe same conditions, indicate that the concrete of the particular member tobe prestressed has attained a compressive strength of at least 280Kg/sq.cm.

After the concrete has attained the required strength, the prestressingreinforcement shall be stressed by means of jacks to the required tensionand stress transferred to- the end anchorage(s). Stressing shall be from bothends unless otherwise required in the Contract or agreed by the Engineer.The tensionihg process shall be so conducted that the tension being appliedand the elongation of the prestressing elements'may be measured at alltimes. The friction loss in the elements, i.e., the difference between thetension at the jack and the minimum tension in the prestressing steel shallbe determined by the formula:

F , = 2 ( F n - a c E )d

Where

t r -I t -

p , =- t

a =

total friction loss

Observed tension at the jackcross-sectional area of the prestressing element.

observed elongation of the element when the forceat the jack is F.,.

405-5

40s.3.8

E = secant modules of elasticity of the element for thestress F1 as determined from the stress-straindiagram of the element.

d = distance from the jack to the point of lowest tensionin the element. Where jacking is done from both endsof the members, the point of minimum tension is thecenter of the member. Where jacking is done from oneend only, d is the distance to the other end of themember.

Any surplus length of tendon shall be cut off by an approved method whichwill not affect the strength of the stressed tendon, with particular care if theuse of spark erosion or oxyacetylene burning methods of cutting areapproved by the Engineer.

A record shall be kept of gauge pressures and elongation at all times andsubmitted to the Engineer for his approval with in twenty four (24) hours ofeach tensioning operation. The tendons shall be maintained in such acondition that they can be re-stressed until the Engineer has given finalapproval after inspecting the tensioning log.

Groutins of Bonded Steel

Post{ensioned prestressed bridge' members preferably shall be of thebonded type in which the tensioned steel is installed in holes or flexiblemetal ducts cast in the concrete and bonded to the surrounding concrete byfilling the tubes or ducts with grout. The grout shall be a mixture of cementand fine sand (passirig a No.30 sieve) in the approximate proportion of onepart cement to 0.75 part sand, the exact proportions to be adjusted to form agrout having the proper consistency and under no circumstances, shall thewater cement ratio exceed 0.45. The compressive strength of the hardenedgrout shall not be less than one hundred and seventy (170) Kg/sq.cm afterseven (7) days at a temperature of eighteen (18) degree C, when makingpreliminary trials for quality. The grout shall be mixed for a minimum of two(2) minutes and until a uniform consistency is obtained.

All prestressing reinforcement to be bonded shall be free of dirt, loose rust,grease, or other deleterious substances. Before grouting, the ducts shall befree of water, dirt or any other foreign substance. The ducts shall be blownout with compressed air until no water comes through the duct. For longmembers with draped strands an open tap at the low point of the duct maybe necessary.

The grout shall be fluid (consistency of thick paint) but proportioned so thatfree water will not separate out of the mix. Unpolished aluminum powdermay be added in an amount per sack of cement as approved by theEngineer. Commercial plasticisers used in accordance with themanufacturer's recommendation may be used provided they contain noingredients that are corrosive to steel. Sufficient pressure shall be used ingrouting to force the grout completely through the duct, care being takenthat rupturing of the ducts does not occur.

405.3.9

40s.3.10

405.3.1r

Handlins

Precast prestressed concrete members shall be transported in an uprightposition and the points of support with respect to the member shall beapproximately the same during transportation and storage as when themember is in its final position. In the event that the contractor deems itexpedient to transport or store precast girders in other than this position itshould be done at his own risk.

care shall be taken during storage, hoisting, and handling of the precastingunits to prevent cracking or damage. Units damaged by improper storing orhandling shall be replaced by the Contractor at his expense.

Prestressed structural members shall be constructed in conformrty with thedrawings governing the particulir type of structure to oe ouitt or as requiredby the Engineer.

Manufacture of Prestressed Members off the Site

i) The details of the method of manufacture shall be approved by theEngineer before work is started. When the method has been approved,no changes shall be made without the consent of the Engineer.

ii) The contractor shall inform the Engineer in advance of the date ofcommencement of manufacture and the dates when tensioning oftendons, casting of members and transfer of stress will be undertaken forthe first time for each type of beam.

iii) The contractor shall send to the Engineer not more than seven (7) daysafter the transfer.of stress, a certificate showing the force and strain inthe tendons immediately after they were anchored, the strength and ageof the test cubes cast in accordance with specified procedure and theminimum age in hours of the concrete at the time the stress was appliedto the member. A copy of all twenty eight (28) days cube test resultsrelating to the work shall be sent to the Engineer as these becomeavailable. Records shall be kept so that the identity of those who stressthe tendons, cast the concrete and transfer the stress on any member orline of members can be traced.

iv) where the Engineer's Representative requires tests to be carried out, nobeams to which the test relate shall be dispatched to the site until thetests have been satisfactorily completed.

Comnosite Slab Bridses

a) The manufacturing tolerances for the precast members shall no-vrhereexceed those given for the length, cross-section and straightness in BScode of Practice cP116(1969). The structural use of precast concrete. lnaddition, where beams are laid side by side in a deck:

(i) The difference in soffit level between adjacent units before the insitu concrete is placed shall no-where exceed five (5) mm forunits up to five (5) meters nor ten (10) mm for longer units.

405-7

b)

c)

(ii) The width of the deck soffit shall be within plus twenty five 1+25;mm of that described in the Contract.

(ii i) In adjacent spans, the continuity of line of the outside beamsshal l be maintained.

(iv) The width of the gap between individual beams shall not exceedtwice the nominal gap described in the contract.

(v) The alignment of transverse holes shall permit the reinforcementor prestressing tendons to be placed without distortion.

The in-situ concrete shall be placed in such a sequence that theadvancing edge of the freshly deposited concrete over the full width ofdeck or between longitudinal construction joints is approximately parallelto the deck supports.

Beams shall be prevented from moving laterally during the placing of thein-situ concrete.

Samplinq and Testins

a) Testing of Pretensioned Beams

(i) Any beam required by the Engineer to be subjected to a load testwill be selected after transfer and wherever possible before thebeam has been removed from the casting yard to the storagearea. The Contractor shall not proceed with a load test until hehas obtained the approval of the Engineer to the detailedarrangements. Except where otherwise agreed by the Engineer,the load test shall be carried out not less than twenty eight (28)days after casting. The cost of the load test shall be born by theContractor.

(ii) The beam shall be supported at its design points of bearing. Thespecified test loads shall be applied equally at the third points ofthe span in not less than ten (10) approximately equal stages.The maximum load shall be sustained for five (5) minutes andthen removed in not less than five (5) approximately equalstages. The mid-span deflection relative to a straight referenceline joining the points of support shall be measured for eachvalue of the load and five (5) minutes after removal of the load.

(iii) Loads shall be measured with an accuracy of + two (2) per centor 50kg and deflections with an accuracy of + decimal five (0.5)millimeter.

(iv) The load-deflection graph shall be plotted from these values andshall show no appreciable variation from a straight line. lf afterfive (5) minutes of removal of the load the beam does not show arecovery of at least ninety (90) per cent of the maximumdeflection recorded during the test, the test loading shall berepeated. The beam shall be considered to have failed the test ifthe recovery five (5) minutes after removal of the test load for thesecond time is not at least ninety (90) per cent of the maximumdeflection recorded during the second test.

405.3.12

405-8

The result of the test shall be deemed to apply to the otherbeams cast in the same production line but in the event of failureany additional beam may be separately tested at the contractor'soption.The contractor shall supply to the Engineer record sheets of thetest showing the age of the beam at the time of the test, loads,deflections, load-deflection curves and calculated value ofYoung's Modules of Elasticity (E).In addition, the record sheets supplied by the contractor to theEngineer shall show the temperatures of the top and bottomsurfaces of the beam measured at the time of the test.

b) Testing of Prestressing Anchorages

Anchorages for post-tensioning shall be tested in accordance with theprocedure described in 854447 or as approved by the Engineer. For eachanchorage system used in the works, the characteristic value for anchoraqeefficiency shall be not less than ninety (90) percent.

Curing Concrete

a) GeneralFor all prestressed concrete operations the curing procedures shall be wellestablished and properly controlled. Curing shall be commencedimmediately following initial set or completion of surface finishing. Membersshall be kept wet during the entire period of curing.

b) Method of CurinsThe curing methods shall conform to those detailed under item 401.3.g.

MEASUREMENT AND PAYMENT

Measurement

Measurement and payments for the various items in prestress concretework shall be made in accordance with appropriate items of relevantsections, as depicted in the drawings.

Pavment

The quantity to be paid for shall be the number of prestressed concretestructural members of the several types and sizes, constructed and installedin place, as per drawings completed and accepted. Each member shallinclude the concrete, reinforcement and prestressing steel, enclosures forprestressing steel, anchorage, plates, nuts, formwork, shuttering andcentering if required, and other such material contained within or attached tothe unit .

(v)

(vi)

(v i i )

40s.3.13

405.4

405.4.r

405.4.2

405.4.2.1

405-9

405.4.2.2 Cast-in-Place Prestressed Concrete

The work to be paid for under this item will be only the prestressing work asspecified here and shown on the Drawings or required by the Engineer andshall include supply and installation of prestressinQ steel, spacers,enclosures, anchorages plates, nuts and other such material deemednecessary to complete the work. Steel reinforcement, concrete, falsework,and formwork will, unless otherwise prescribed, be measured and paid foraccording to item No.401and 404 respectively.

Pay item No. Description and Unit of Measurement for Precast PrestressedConcrete Members and Castin-Place Prestressed Concrete will becovered, under specified BOQ item number provided in special provisions,as per drawings and other related documents for following item separately.

(a) Concrete Member (including grouting)(b) Prestressed ropes/strands, Size .....(c) Prestressed Wire Size .....(d) Prestressed Hardware, including Sheets,

Male/Female Cone and Anchors etc.

CM.Ton.Ton.

Ton.

405-1 0

ITEM 406 JOINTS AI\D BEARING DEWCES FOR CONCRETESTRUCTURES

406.1

406.2

406.2.1

406.2.2

406.2.3

DESCRIPTION

The work covered in this item shall consist of furnishing all plant, equipment,materials and labour in performing all operations in connection withfurnishing and placing (in concrete structures) all deck expansion joints andseals, metal bearing pads and elastomeric bearing pads complete and inaccordance with the specifications, the Drawings, and or as required by theEngineer.

MATERIAL REQUIREMENTS

Concrete Joint Filler

a. Preformed Expansion Joint Filler

Unless otherwise directed by the Engineer preformed joints filler shallconform to the requirements of AASHTO M-213.

b. Neonrene Rubber Sheet with Bitumastic Seal

Unless otherwise directed by the Engineer, neoprene rubber sheets six(6)mm in thickness, meeting the requirements of ltem 406.2.3, shall be usedas a joint fil ler covered with a bitumastic seal as shown in the Drawings.

Steel for Deck Exnansion Joint Seals

Plates, angles or other structural shapes including anchor bolts required forthe expansion joint seals shall conform, unless otherwise directed by theEngineer, to the requirements of AASHTO M-160 and shall be hot zincsprayed (galvanized) with the exception of the nuts and washers which shallbe in stainless steel.

Elastomer for Deck Exnansion Joint Seals

Elastomer shall be of the component as neoprene or of polyvinyl chloride(PVC), at the option of the Contractor. Neoprene shall be manulacturedfrom a vulcanized elastomeric compound containing neoprene as the soleelastomer and shall have the following physical characteristics inaccordance with ASTM Method D15. Part B.

406-1

Hardness, Durometer A,ASTM D 2240.

Tensile Strength,ASTM D 412min.

Elongation at Break

Compression Set, 22 Hours at70 degree C. ASTM D 395, Method B.

Low Temperature, ASTM D 746

Ozone Resistance, Exposure to100 PPHM OZone for 70 hours at38 degree C. Sample under20 percent. ASTM D 1149.

Oil Deterioration - Volume increaseafter soaking in ASTM oil No. 3 for70 hours at 100 degree C. ASTM D 470

406,2.4 Metal Bearins Derices

45 + 5 points

127 Kgs/square centimeter

400 percent min.

20 percent max.

Not brittle at 40 degree C.

No cracks

120 percent max.

Unless othemrise directed by the Engineer or provided in the SpecialProvisions, the requirements for metal bearings shall conform to thefollowing:

a) AASHTO M 107 for bronze ueai-iirg.

b) AASHTO M 108 for rolled copper alloy bearings.

c) ASTM B 438 for sintered metal powder bearings.

d) AASHTO M 160 for galvanized steel bearings.

406.2.5 Elastomeric Bearins Pads

General

Elastomeric bearings as herein specified shall include plain bearings(consisting of elastomer only) and laminated bearings (consisting of layersof elastomer restrained at their interfaces by bonded laminates.

The reinforcing steei plates laminations for bearing pads shall conform tothe requirements of AASHTO M 183.

Elastomeric bearing pads shall conform to the requirements in thesespecifications and the Special Provisions.

406-2

Pads twelve (12) mm'and less in thickness may be either laminated or allelastomer.

Pads over twelve (12) mm in thickness shall be laminated.

Laminated pads shall consist of alternate laminations of elastomer andmetal or elastomer and fabric bonded together.

The thickness called for an elastomeric bearing pad is deemed to be thetotal effective thickness of the elastomeric laminations.

The outside laminations shall be metal or fabric. The outside edges of metallaminations shall be coated over with elastomer not more than three (3) mmin thickness.

The edges of the steel reinforcing plates of the bearing pads shall becarefully treated to prevent notch effects.

Steel plates shall be fully enclosed in elastomer so that there is no danger ofcorrosion.

Laminations of elastomer shall be 12 mm + 3 mm thickness. Variation inthickness of an individual elastomer lamination shall not exceed three (3)mm within the width or length of a pad and the variation in thickness of allelastomer laminations within a pad shall be such that each metal or fabriclamination will not vary by more than three (3) mm from a plane parallel tothe top or bottom suface of the pad.

The total overall thickness of a pad shall not be less than the thicknessshown on the plan nor more than six (6) mm greater than that thickness.Variation of total thickness within an individual pad shall not exceed three(3) mm.The length and width of a pad shall not vary more than three (3) mm fromthe dimensions shown on the Drawings.

Where elastomeric bearing pads over twelve (12) mm, in thickness areshown on the Drawings or required by the Engineers, such pads may bemanufactured as a molded laminated pad, or at the option of the Contractor,may be made up by stacking individual laminated pads.

When laminated pads are stacked, their contact surfaces shall be cleanedprior to stacking and an approved method shall be used to hold theindividual pads in the stack in proper alignment. Pads of all elastomer orwith fabric laminations may be cut from large sheets. Cutting shall beperformed in such a manner as to avoid heating of the material and toproduce a smooth edge with no tears or other jagged areas and to cause aslittle damage to the material as possible.

Corners and edges of molded pads may be rounded at the option of theContractor. Radius at corners shall not exceed ten (10) mm and radius ofedges shall not exceed three (3) mm.

406-3

The bond between elastomer and metal or fabric shall be such that, when a,urpr" is tested for separation, failure shall occur within the elastomer andnot between the elastomer and metal or fabric'

Metal laminations shall be rolled mild steel sheets not less than twenty (20)gauge in thickness.

Fabric laminations shall be either, (1) a long chain synthetic polymer

"on t , in ingat |eas te igh ty f i ve(85)percento fpo |yes ter f romethy |eneg|yco |uno i"r"inthalic acii ir Q) i tong chain synthetic po-lym.eric amid fromfrexametnyene diamine and adipiC acid. Each ply of fabric shall have abreaking ltrength of not less ihan 125 Kg' per cm' of width in bothdirections. Fabric laminations shall be single ply ai top and. bottom surfacesot t r repaoande i therdoub|ep |yordoub|es t rengthwi th in th -epad '

The sole potymer rn the elastomeric compound shall be neoprene and shallbe not less than sixty (60) percent by volume of the total compound'

T h e e | a s t o m e r , a s d e t e r m i n e d f r o m t e s t s p e c i m e n s , s h a | | c o n f o r m t o t h efollowing:

Test

Tensile strength, Kgs/sq.cm

Elongation at break, PercentCompression set, 22 hrs. at 67degree C, Percent (Method B)

Tear Strength, Kgs Per cmt

Hardness (Shore A)Ozone resistance 20% strain, 100hrs. at 38 degree C 1 100 1 20parts I degree C

Low tem Perature stiffness,Young's Modulus at 35 degree C

Low temPerature brittleness' 5hours at - 40 degree C

ASTMtion

D 412D 412

D 395D 624 (Die C)

D 2240

D 1149

Kgs per cm (2) D 797

D 736

Requirements

160 Min.350 Min.

25 Max.13 M in .6015 points

(except NoCracks per100,000,000)

350 Max.

Passed

406-4

406.3

406.3.I

106.3.2

After accelerated aging in accordance with ASTM Designation D s73 for 70hours at 100 degree c, the elastomer shall not show deterioration changesin excess of the following:

Tensile strength, percent

Elongation at Break, percent

Hardness, points

+ 1 5

- 50 (but not less than 300% totalelongation of the material)+ 1 0

Shear Test (without vertical load) 7 Kg/sq.cm (Min)

sampling.shall be performed in accordance with AASHTO M2s1-74 asappropriate for the tests required during or immediately after manufacture.

The contractor shall furnish to the Engineer a certification by themanufacturer that the elastomer, and fabric (if used), in the elastomericbearing pads to be furnished conforms to all of the above requirements. Thecertification shall be supported by a certified copy of the results of testsperformed by the manufacturer upon samples of the elastomer and fabric tobe used in the pads.

The Engineer will take a sample of not less than 15 x 30 cm in size fortesting from each lot of pads or batch of elastomer to be furnished,whichever results,in the greater number of samples. The samples will beselected at random at the point of manufacture or, at the option of thecontractor at the job site. samples taken at the job site shail consist ofcomplete pads as detailed on the plans, and the contractor shall furnishadditional complete pads to replace those taken for testing. pads shall beavailable'for sampling three (3) weeks in advance of intended use. Allsample pads for testing shall be furnished by the contractor at his expense.

CONSTRUCTION REQUIREMENTS

Onen Joints

open joints shall be constructed at the locations shown on the Drawings orrequired by the Engineer using a suitable material, which is subsequenilyremoved. when removing the material, care shall be exercised to avoidchipping or breaking of concrete. Reinforcement shall not extend across anopen joint, unless shown on the Drawings.

Filled Joints

when joints of preformed type are required on the Drawings or by theEngineer, the fil ler shall be placed in correct position beforJ concrete isbeing placed against the fil ler. preformed Filler with holes and cracks shallnot be permitted and shall be reiected.

406-5

406.3.3 Steel Joints

Plates, angles or other structural shapes shall be accurately shaped at theshop, to conform to the section of the concrete floor as per drawings. Thefabiication shall conform to the requirements in Special Provisions. Careshall be taken to ensure that the surface in the finished plane is true andfree of warping. Methods approved by the Engineer shall be employed inplacing the joints to keep them in correct position during the placing of theconcrete. The opening at expansion joints shall be that to avoid impairmentof the clearance in any manner.

Water Stops {Joint Seals)

Water-stops shall be furnished and installed in accordance with the detailsshown on the Drawings or where required by the Engineer and inaccordance with the provisions in these specifications.

Water-stops shall be furnished in full length for each straight portion of thejoint, without field splices Manufacturer's shop splices shall be fullyvulcanized.

Reinforcing bars provided to support the water-stops shown on theDrawings or as required by the Engineer shall be securely held in positionby the use of spacers, supporting wires, or other approved devices. suchreinforcing bars shall be considered, for payment purposes, as a part of thewater-stop. lf, after placing concrete, water-stops are materially out ofposition or shape, the surrounding concrete shall be removed, the water-stop reset, and the concrete replaced, all at the contractor's expense.

Field splices for neoprene water-stops shall be either vulcanized, ormechanical, using stainless steel parts, or made with a splicing union of thesame stock as the water-stop, at the option of the Contractor. All finishedsplices shall have a full size tensile strength of eighteen (18) kg per cm ofwidth.

Field splices for polyvinyl chloride water-stops shall be performed by heatsealing the adjacent surfaces in accordance with the manufacturer'srecommendations. A thermostatically controlled electric source of heat shallbe used to make all splices. The heat shall be sufficient to melt but not charthe plastic.

Water-stops when being installed shall be cut and spliced at changes indirection as may be necessary to avoid buckling or distortion of the web orf lange.

Metal Bearing Devices

steel bearing plates, bars, rockers, assemblies, and other expansion orfixed devices shall be constructed in accordance with the details shown onthe plans and shall be hot-dip galvanized after fabrication.

-t06.3.,1

.106.3.5

406=6

d06.3.6

406..1

106.1.r

Bronze or copper alloy plates, if specified, shall conform to the requirementsof the Special Provisions.

The bearing plates shal l be set level and the rockers or other expansrondevices shall be set to conform to the temperature at the time of erection orto the setting specified.

when bearing assemblies or masonry plates are shown on the Drawings tobe placed (not embedded) directly on colcrete, the concrete bearing areashal l be constructed sl ight ly above grade and shal l be f in ished by gr indingor other approved means to a true level plane which shall not varyperceptibly from a straight edge placed in any direction across the area. Thef inished plane shal l not vary more than three (3) mm from the etevat ionshown on the Drawings or that required by th,e Engineer.

Elastomeric Bearing Pads

when elastomeric bearing pads are shown on the Drawings, the concretesurfaces on which pads or packing are to be placed srrait be wood floatf in ished to a level plane which shal l not vary more than one and a half (1.5)mm from a straightedge placed in any direction across the area. Thefinished plane shall not vary more than three (3) mm from the elevationshown on the Drawings or that required by the Engineer.

MEASUREMENT AND PAYMENT

Measurement

a) Filled Concrete Joints

The quantity to be paid for shall be in square meters of either expansionjoint -with preformed joint fil ler or expansion joint with neoprene rubber sheet

six (6) mm thick and covered with bitumastic seal, completed and acceptedin work.

b) Steel Joints

The quantity to be paid for shall be the number of kilograms of steel for steeljoints fabricated, galvanized and placed in the work completed andaccepted.

c) Water Stotrs

The quantity to be paid for shall be the number of linear meters of water-stop placed in the work, completed and accepted.

d) Bearing Devices

The quant i ty to be paid for shal l be the number of cubic cent imeter ofbearing devices either steel bearing or elastomeric bearing pads installed inthe work completed and accepted.

406-7

406.1.2

e) Asphaltic Felt

The quantity to be paid shall be in square meter of 3 ply rating-Fibre/Fabricnaseo asphaltic felt weighing forty one 41 kg to forty five (45) kg per 20square meter including ltr,ifing coat/paint coat and flood coat of specialindustr ial bi tumen and sand OtinOing as approved by the Engineer, la id inplace as directed bY the Engineer.

Payment

The accepted quantity measured as provided a-bove shall be paid for at thecontract unit price respectively for the pay items listed hrelow and shown inthe Bill of Quantities which price and payment shall be full compensation forfurnishing all materials, labour, equrpment, tools and incidentals and anywork pertaininE tO joints and bearings and which is not paid for separately'necessary to comPlete the item'

Pay ltemNo.

Descript ion. Unit ofMeasurement

406a

406d

406e

406f

4069

Premoulded Joint fil ler12 mm thick with BitumasticJoint Seal.

Nebprene Rubber Joint Filler12 mm thick with BitumasticJoint Seal.

Steel Expansion Joints.

Water Stops 6" Size

Elastomeric Bearing Pads (Accor-ding to size and thickness)

Asphalt Fdlt (3 Ply)

Steelor metal Bearing Devices

SM

406b

406c

SM

Kg

M

Cubic cm.

SM

Each

406-8

ITEM 407 PIL ING

407.1 DESCRIPTION

This work shall consist of performing all operations in connection withfurnishing, driving, cutting off and load testing of piles to obtain the specifiedbearing value complete in place and stricfly in accordance with theseSpecifications and as shown on the Drawinos.

The contractor shallfurnish the precast piles in accordance with an itemizedlist, which will be provided by the Engineer, showing the number and lengthsof all piles. when cast-in-place concrete piles are specified on the orawiigs,the Engineer will not furnish the contractor, an itemized list showing thenumber and length of piles. when test piles and load tests are required inconformance with sub-items 407.3.9 and 407.3.9 respectively, the dataobtained from such test loads will be used in conjunction with other avatilablesubsoil information to determine the number and lengths of piles to befurnished. The Engineer will not prepare the itemized'iist of piies for anyportion of the foundation area until all loading tests represeniative of thatportion have been completed.

The contractor shall provide an oufline of his proposed method for:constructing large diameter pile when submitting his tender; the proposedmethod of boring being stated.

Not less than two weeks before the contractor proposes to commencepiling, detailed propos.al for the piling shall be deiivered to the Engineer.These proposals shall include full details of materials, equipment andmethod to be used in the construction of piles.

lf it is proposed to use bentonite slurry, this shall also be describeo.

work on piling shall not commence until the contractor,s proposals havebeen approved by the Engineer and communicated to the contractor.

The requirements herein are minimum. Strict compliance with theserequirements will not relieve the contractor of the responsibility for adoptingwhatever additional provisions may be necessary to ensure the successfulcompletion of the work.

The kind and type of piles shall be as shown on the Drawings and/or asspecified. No alternate types or kinds of piling shall be used, exiept with thewritten approval of the Engineer each time.

407-1

407.2

407.2.1

MATERIAL REQUIREMENTS

Types of Piles

a Untreated Timber Piles

Untreated timber piles shall conform to the requirements of AASHTO M168 .

b. Treated Timber Piles

Treated timber piles shall conform to the requirements of AASHTO M 133and M 168."Unless otherwise called for on the drawings, the timber pilesshall be treated with creosote according to the Standard AWPA Pl of theAmerican Wood-Preservers Association.

c. Reinforced Concrete Cylindr

Diameter of reinforced concrete piles shall be as shown on the Drawingsand may or may not have permanent lining, as shown on the drawing.

Reinforcing Steel shall conform to the requirements under ltem 404 - SteelReinforcement.

Concrete shall meet all the requirements for specified Class as providedunder ltem 401 and shall be of Class-D unless otherwise specified.

d. Structural Steel Piles

Structural steel piles shall be rolled steel sections of the type, weight andshape called for on the Drawings. The piles shall be structural steelconforming to the requirements of ASTM A 7 and ASTM A 36, except thatsteel produced by the Acid-Bessemer process shall not be used.

The steel piles shall be coated with red lead paint conforming to AASHTOM 72 as instructed by the Engineer, unless otherwise specified.

e. Precast Concrete Piles

Concrete for piles shall meet all the requirements for the specified class asprovided under ltem 401 - Concrete. The concrete shall be of Class-Dlunless otherwise specified.

Reinforcing Steel shall conform to the requirements under ltem 404 - SteelReinforcement.

Prestressed concrete piles shall conform to ltem 405Concrete Structures.

407-2

Prestressed

40'7.2.2

407.2.3

407.3

407.3.1

Precast piles shall be made in accordance with the Drawings, .andreinforcement shall be placed accurately and secured rigidly in such manneras to ensure its proper location in the completed pile. The concrete cover asmeasured to the outside face of ties or spirals shall not be less than five (5)cm.

The piles shall be cast separately or, if alternate piles are cast in a tier, theintermediate piles shall not be cast until four (4) days after the adjacent pileshave been poured. Piles cast in tiers shall be separated by tar paper orother suitable separating materials. The concrete in each pile shall beplaced continuously. The completed piles shall be free from stone pockets,porous spots, or other defects, and shall be straight and true to the formspecified. The forms shall be true to line and built of metal, plywood, ordressed lumber. A two and half (2.5) cm chamfer strip shall be formed on alledges. Forms shall be watertight and shall not be removed within twentyfour (24) hours after the concrete is placed. Piles shall be given a surfacefinish according to ltem 401.3.7 - Concrete Surface Finishing.

Pi les shal l be cured in accordance with the requirements of l tem 401.3.8 (e)- Curing Precast Concrete Piles.

Piles shall not be moved until the tests indicate a compressive strength ofeighty (80) percent of the design twenty eight (28) days compressivestrength and they shall not be transported or driven until the tests indicate acompressive strength equal to the design twenty eight (28) dayscompressive strength

When concrete piles are lifted or moved, they shall be supported at thepoints shown on the Drawings or, if not so shown, as instructed by theEngineer.

Pile Shoes

Pile shoes when required shall be of the design as called for on theDrawings or by the Engineer.

Pile Splices

Materials for pile splices, when splicing is allowed, shall be of the samequality and characteristics as the materials used for the pile itself and shallfollow the requirements given on the Drawings unless otherwise directed bythe Engineer.

CONSTRUCTION REOUIREMENTS

Driven Piles

a. Location and Site Preparation

Piles shall be used wherq. indidated on the Drawings or as directed by theEngineer.

407-3

All excavations for the foundation in which the piles are to be driven shall becompleted before the driving is begun, unless otherwise specified orapproved by the Engineer. After driving is completed, all loose anddisplaced materials shall be removed from around the piles by handexcavation, leaving clean solid surfaces to receive the concrete forfoundat ions.

tr. Determination of Pile Length

The criteria for pile length and bearing capacity will be determined by theEngineer according to the results from test piles and load tests. The pilesshal l be dr iven to such depths, that the bearing loads indicated on theDrawings are obtained.

The criterion for pile length may be one of the following:

1) Pi les in sand and gravel shal l be dr iven to a bearing valuedetermined by use for the pile driving formula or as decided bythe Engineer.

2) Pi les in clay shal l be dr iven to the depth ordered by theEngineer. However, the bearing value shall be controlled by theappropriate pile driving formula if called for by the Engineer.

3) Piles shall be driven to refusal on rock or hard layer when soordered by the Engineer.

The contractor shall be responsible for correct pile lengths and bearingcapacities according to the criteria given by the Engineer.

c. Pile Drivins

All piles shall be driven accurately to the vertical or the batter as shown onthe drawings. Each pile shall, atter Orivingj, be within fifteen (15) cm from thetheoretical location underneath the pile cap or underneath thesuperstructure in the case of pile bents. All piles pushed up by the driving ofadjacent piles or by any other cause shall be driven down again.Piles shall be used only in places where a minimum penetration of three (3)meters in firm materials, or five (5) meters in soft materials, can be obtained.Where a soft stratum overlies a hard stratum, the piles shall penetrate tohard material upto a sufficient distance to fix the ends rigidly.

All pile driving equipment is subject to the Engineer's approval. TheContractor is responsible for sufficient weight and efficiehcy of the hammersto drive the piles down to the required depth and bearing capacity.Hammers shall be gravity hammers, single acting steam or pneumatichammers or diesel hammers. Gravity hammers shall not weigh less thansixty (60) percent of the combined weight of the pile and driving head andnot less than 2,000 Kg. The fall shall be adjusted so as to avoid injury to thepi le and shal l in no case exceed one (1) m for t imber and steel pi les and onehalf (0.5) M for concrete piles unless otherwise specified or approved bythe Engineer. The plant and equipment furnished for steam

407-4

hammers shall have sufficient capacity to maintain, under workingconditions, the pressure at the hammer specified by the manufacturer. Theboiler or pressure tank shall be equipped with an accurate pressure gaugeand another gauge shall be supplied at the hammer intake to determine thedrop in pressure between the gauge and the hammer. \A/hen dieselhammers are used, they shall be calibrated with test piling and/or test loadsin accordance with ltem 407.3.9.

Water jets shall be used only when permitted in writing by the Engineer.When water jets are used, the number of jets and the nozzle volume andpressure shall be sufficient to erode the material adjacent to the pile freely.The jets shall be shut off at a depth not less than three (3) M before final tipelevation is reached, and the piles driven solely by hammer to finalpenetration as required by the Engineer.

Piles shall be supported in line and position with leads while being driven.Pile driving leads shall be constructed in such a manner as to affordfreedom of movement of the hammer, and shall be held in position by guysor steel braces to ensure rigid lateral support to the pile during driving. Theleads shall be of sufficient length to make the use of a follower unnecessary,and shall be so designed as to permit proper placing of batter piles. Thedriving of piles with followers shall be avoided if practicable and shall bedone only under written permission from the Engineer.

The method used in driving piles shall not subject them to excessive andundue abuse producing crushing and spalling of the concrete, injurioussplitting and brooming of the wood, or deformation of the steel. Manipulationof piles to force them into proper position, if considered by the Engineer tobe excessive, will not be permitted.

The pile tops shall be protected by driving heads, caps or cushions inaccordance with the recommendations from the manufacturer of the pilehammer and to the satisfaction of the Engineer. The driving head shall beprovided to maintain the axis of the pile in line with the axis of the hammerand provide a driving surface normalto the pile.

Full-length piles shall be used where practicable. Splicing of piles whenpermitted shall be in accordance with the provisions of ltem 407.3.5. Allpiles shall be continuously driven unless otherwise allowed by the Engineer.

d. Pile Drivins Formulae

Pile driving formulas may be used to determine the number of blows ofhammer per unit of pile penetration needed to obtain the specified bearingcapacity for piles driven in the sub-soils at the site. Piles shall be driven to afinal resistance as indicated on the plans determined by the followingformula:

407-5

For drop hammer

Qatt = WH/[6(S+2.5)]For single-acting steam or air hammers.and for dieselHammers havinq unrestricted rebound of rams.

Qatt = wH/[6(S+0.25)]

Qa, = WH/[6{S+0.25(WDA /S)}l

For double-acting steam or air hammersdnd diesel hammers having enclosed rams

Qa l l = E/[6(S+0.25)j

Qarr = E46{S+0.25(WDM/S)}]

In the above formulas:

(Use when drivenweights are smallerthan striking weights)(Use when drivenweights are larger thanstriking weights)

(Use when drivenweightS are smallerthan striking weights).(Use when drivenweights are larggr thanstriking weights)

H

S

Qatt =

I A 'v v

WD

Note: Ratiothree.

Allowable pile load in Kilograms.

Weight of striking parts of hammer in Kilograms.

The height of fall in centimeters for steam, and airhammers, and the observed average height of fall incentimeters, of blows used to determine penetration fordiesel hammers with unrestricted rebound of hammer.

Average net penetration per blow in centimeters for thelast 10 to 20 blows of steam, air, or diesel hammer, orfor the last 15 centimeters of driving for a drop hammer.

The actual energy delivered by hammer per blow inKilogram - centimeter.

Driven weights in Kilograms

of driven weights to striking weights should not exceed

WS = Weight of striking parts in Kilograms.

Modifications of basic pile driving formula:

407-6

407.3.2

a) For piles driven to and seated in rock as high capacity- end-bearing piles: Drive to refusal (approximately four (4) to five (5)blows for the last 0.625 centimeters of driving). Re-drive openend pipe piles repeatedly until resistance for refusal is reachedwithin two and half (2.5) centimeters of additional penetration.

b) For piles.driven through stiff compressible materials unsuitable' for pile bearing to an underlfing bearing stratum:

Add blows attained before reaching bearing stratum to requiredblows attained in bearing Stratum.

c) For piles into limited thin bearing stratum:Drive to predetermined tip elevation, and determine allowable load byload test.

The bearing power as determined by the appropriate formula in theforegoing list will be considered effective only when it is less than thecrushing strength of the pile. other recognized formula for determinigrg pilebearing power may be used when given in special specification. However, itshall be understood that the relative merits and reliability of any of the pileformula can be judged only on the basis of comparisons with the results ofload tests.

Cast-in-Place Piles

Piles, cast-in-place, shall consist of one of the types either shown on thedrawing and/or ds specified. The tbrm shaft wherever used in this section.shall mean either piles or shafts.

a. Woriring i)rawines

At least 4 weeks before work on shafts is to begin, the contractor shallsubmit to the Engineer for review and approvgl, an installation plan for theconstruction of drilled shafts. The submittal shall include the following:

i. List of proposed equipment to be used including cranes, drills,augers, bailing buckets, final cleaning equipment, desandingequipment, slurry pumps, sampling equipment, tremies or concretepumps, casing etc.

ii. Details of overall construction operation sequence and the sequenceof shaft construction in bents or groups.

iii. Details of shaft excavation methods.iv. When slurry is required, details of the method proposed to mix,

circuldte and desand slurry.Details of methods to clean the shaft excavation.Details of reinforcement placement including support andcentralization methods.Details of concrete placement, curing and protection.Details of any required load tests.Other information shown on the plans or requested by the Engineer.

vi .

v i i .v i i i .tx.

407-7

8-10'

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has to be fil led with concrete. The equipment used for execution ofborehole shall be adequate to ensure that each pile penetrates to therequired founding level.. Use of Casinq

Suitable casings shall be furnished and placed when required toprevent caving of the hole before concrete is poured. Casing, if usedin drill ing operations shall be removed from the hole as concrete ispoured unless otherwise specified. The bottom of the casing shall bemaintained not less than fifty (50) cm below the top of the concreteduring withdrawal and pouring operations unless otherwise permittedby the Engineer. Separation of the concrete during withdrawaloperations shall be avoided.

.@!

Reinforcement if called for shall conform to the requirements underitem 404. The steel shells/pipes shall be of sufficient strength andrigidity to permit driving to the required bearing value or depthwithout injury. The steel may be either cylindrical or tapered, steptapered or a combination, plain, circular or fluted. All types shallconform to the corresponding ASTM standards. The minimumaverage tensile strength of steel shall be 3500 Kg/sq.cm (50,000psi) .

When called for on the Drawings or by the Engineer, the steelshells/pipes shall be factory coated on both interior or exterior surfacesby red lead paint conforming to AASHTO M-72 or as stated in the specialspecifications. The coating shall not cause any hindrance whileassembling the pile section during welding operations.

ii) Temnorarv Casins Method

The temporary casing of appropriate diameter for locating the pile andpiloting the borehole shall be pitched at the exact locations as given onthe drawings to ensure that the casing when sunk is within the specifiedtolerances. The casing shall be sunk to sufficient depth by approved

methods. The depth shall be at least sufficient to prevent the ingress ofalluvium or other loose materials into the bore when executed below thebottom level of the casing. In addition, the depth shall be such as thecontractor considers nepessary for the stability of the casing and/ortemporary works system during construction in general and for thefollowing conditions and operations in particular during all conditions ofriver current which may occur during the period of works:

a: Open temporary casing to ensure against blow-in of soil.

b: Concreting of the pile, until temporary casing is extracted.

407-9

. Safetv of Casinq

The contractor shall take all such measures and provide suchstrengthening and bracing as is necessary and to the approval of theenginLer to ensure that the temporary. casing is not disturbed,overturned, over-stressed or under-eroded in any condition oftemporary casing shall be such that it will not disturb the freshly castconcrete and/or permanent lrning and/or reinforcement.

Where the use of temporary casing is approved for the purpose ofmaintaining the stability and over-rapid withdrawal of the boring tools

.which could lead to excessive removal of soil and water anddisturbance of the surrounding ground and when boring through anypermeable stratum (including silt), the water level in the boring shallbe maintained between one (1) meter and two (2) meters above theexternal water level, unleSS the engineer directs otherwise.

The temporary casings shall be free from significant distortion and ofuniform cross sections throughout each continuous length. Duringconcreting they shall be free from encrusted concrete or any internalprojections which might prevent the proper formation of the piles.

Permanent Casins Method

The permanent casing construction method shall be used when requiredby the plans. This method consists of driving or drill ing a casing to apiescribed depth before excavation begins. lf full penetration cannot beattained, the Engineer may require either excavation of material withinthe embedded portion of the casing or excavation of a pilot hole ahead ofthe casing until the casing reaches the desired penetration. In somecases, ovrer-reaming to the outside diameter of the casing may berequired in order to advance the casing.

The casing shall be continuous between the elevations shown on theplans. Unliss shown on the plans, the use of temporary casing in lieu ofor in addition to the permanent casing shall not be used except whenauthorized by the Engineer in writing.

After the installation of the casing and the excavation of the shaft iscomplete, the casing shall be cutoff at the prescribed elevation and thereinforcing steel and shaft concrete placed within the portion of thecasing left in place.

iii) Bentonite Slurrv

Where the use of bentonite slurry is approved for the purpose ofmaintaining the stability of the walls and base of bore, the contractor'sproposals in accordanie with (sub clause vi) hereof shall include detailsof the slurry. These shall include inter-alia:

a. The source of the bentoniteb. The constitution of the slurry.c. Specific gravity, viscosity, sheer strength and PH value of slurry'

407-10

d. The methods of mixing, storing, placing, removal andrecirculating the slurry, and

e. The provision of stand-by equipment.

Tests shall be carried out to ensure that the proposed constitution of theslurry is compatible with the ground water. Proposals for the constitutionand physical properties of the slurry shall include average, minimum andmaximum values. The specific gravity of the slurry shall not be less thanone and three hundredth (1.03) in any case at any time. The contractorshall use additives where necessary to ensure the satisfactoryfunctioning of the slurry.Manufacturers CertificateA manufacturer's certificate showing the properties of the bentonitepowder shall be delivered to the Engineer for each consignmentdelivered to site. Independent tests shall be carried out at labbratoryapproved by the Engineer on samples of bentonite frequenfly.Tests on Bentonite SlurrvThe contractor shall carry out tests during the course of the