07 2 iok g5 ABUTMENT AND PIER

MOBILIZATION OF EQUIPMENT FOR CONSTRUCTION OF ABUTMENTS AND PIERS CHAPTER II: CONCRETE WORK, REINFORCEMENT, FORMWORK, FALSEWORK I.. - Details of construction plan show in the drawings o

CONSTRUCTION METHOD STATEMENT FOR

ABUTMENTS AND PIERS

TABLE OF CONTENTS

CHAPTER I: PREPARATION WORKS

I CONSTRUCTION LAYOUT

II ARRANGEMENT OF WORKING TEAMS

III MOBILIZATION OF EQUIPMENT FOR CONSTRUCTION OF

ABUTMENTS AND PIERS

CHAPTER II: CONCRETE WORK, REINFORCEMENT, FORMWORK, FALSEWORK

I FORMWORK AND FALSEWORK

II REINFORCEMENT

III CONCRETE WORK

IV INSPECTION AND ACCEPTANCE

CHAPTER III: CONSTRUCTION METHODS FOR ABUTMENTS AND PIERS

I GENERAL

II CONSTRUCTION SEQUENCES FOR ABUTMENTS AND PIERS

NGAI SECTION

CHAPTER I: PREPARATION WORKS

I CONSTRUCTION LAYOUT

Expressway/Linking Road Cross

2 OP09 Phu Tho

•

Km035+479.

0 Girde PC-I

r 1@21

1 Construciton Sequence

NGAI SECTION

at the positions of apporach roads on the left side , facilitate themovement of machinery or supply equipment

high

- Details of construction plan show in the drawings of constructionmethod for each bridge

II ARRANGEMENT OF WORKING TEAMS

1 ORB07 - Km34+151 (1 span I33m - 10 girders)

Arranging construction teams as follows:

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

2 OP09 - Km35+497 (1 span I21m - 14 girders)

Arranging construction teams as follows:

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

3 ORB08 - Km36+431.4 (1 span I33m - 14 girders)

Arranging construction teams as follows:

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

4 ORB09A - Km38+377.5 (3 spans I24m - 30 girders)

Arranging construction teams as follows:

- Team 2: Construction of abutments, piers and approach slabs

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

5 LRB08 - Km39+645.85 (6 spans I33m - 60 girders)

Arranging construction teams as follows:

- Team 2: Construction of abutments, piers and approach slabs andretaining wall

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

6 CB09 - Km40+110.15 (1 span I33m - 10 girders)

Arranging construction teams as follows:

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

7 OP09a - Km40+880 (1 span I27m - 14 girders)

Arranging construction teams as follows:

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

8 OP10 - Km41+235 (1 spans I24m - 13 girders)

Arranging construction teams as follows:

Construction of desk slabs, parapet and handrail, expansion joints andmiscellaneous

in the Site, based on actual situation, the Contractor will suitably organizeconstructions teams to meet the construction schedule

Item

CHAPTER II: CONCRETE WORK, REINFORCEMENT, FORMWORK,

FALSEWORK

All specifications for this work item will be in accordance with Division 7:Concrete and Bridge Works of the Specification

I. FORMWORK AND FALSEWORK

The Contractor shall submit a method statement for formwork andfalsework, including design calculations, shop drawings, working drawingsand details of all materials and manufactured goods included in theformwork and falsework to the Engineer for his approval at least two monthsbefore the start of construction work on Site Work shall not start untilapproval has been given

Formwork shall be made of steel to ensure rigidity, stability and removable,and will not cause difficulties for installation of reinforcement steel, placingand compacting concrete

Formwork and falsework shall be designed for vertical load and lateralpressures in accordance with Vietnamese Standard TCVN 4453-1995 andwhere appropriate, any increased or readjusted loading that may result fromprestressing forces If retarding admixtures are used their effect shall beduly considered during the calculation of the lateral pressures of the freshconcrete The formwork and falsework shall be designed and constructed toensure completed concrete surfaces comply with the tolerances specified inVietnamese Standard TCVN 4453-1995 or relevant Specification

All joints in shuttering or moulds must be tight to avoid water loss whenpoured and compacted cement concrete, at the same time protect the freshconcrete from weather influences

Fabricating and installation of formwork must be accurate as in accodancewith the correct shape and size Formwork will be the appropriate designand durable construction The contractor will adjust to get the exactconcrete structures to ensure small chamfer, camber, etc

It is neccessary to limit formwork joints, the joints should not be arranged onthe same cross section and at the position of big loads The bracing, strutand supports should be calculated and arranged appropriately to the overallstability of formwork

Installation of formwork should ensure the following requirements:

non-stick oil The anti-adhesive oil is applied according to themanufacturer's instructions and do not touch either reinforcingsteel or prestressed strand and anchors The Contractor shall useonly one type of anti-adhesive oil for the concrete structure toensure uniformity of color concrete

formwork without affecting to the quality

NGAI SECTION

 Formwork must be placed firmly on concrete or a hard ground,smooth, non-slip and no deformation when the bearing the loadand the impact of the construction process

points or the appropriate measures to check the centre line

 Tolerances for installing formwork must be in compliance withproject standards

Formwork is only be removed when the concrete have reached the strengths

of each type of structures indicated by the technical instructions of theproject

Removal of formwork should be avoided without causing sudden stress orstrong collision:

F ormwork/Falsework Time / % of Design

Strength of Concrete

To enable finishing, forms used for parapets, barriers, and

exposed vertical surfaces may be removed between 24

hours and 48 hours after casting, depending on weather

Before fabrication of reinforcement steel and before placing concrete shouldensure:

 The surface is clean, no sticky dirt, grease, no flakes and rustlayers on steel

cover

 Reinforcement steel were crushed, loss in cross section due tocleaning or other reasons shall not exceed the permitted limit of2% in diameter If this limit is exceeded that limit reinforcementsteels shall be used in actual remained cross section

2. Cutting and bending of reinforcing steel.

NGAI SECTION

The fabrication of reinforcing steel is in compliance with project standardsCutting and bending reinforcing steel shall be conducted only by mechanicalmethods

Reinforcing steel is bent to fit the shape, size of the design Steel products to

be cut and bent must be inspected and approved by the Engineer

Bar reinforcement shall be cut and bent to the shapes shown on theDrawings Fabrication tolerances shall be in accordance with ACI 315 Allbars shall be bent cold, unless otherwise permitted Bars partially embedded

in concrete shall not be field bent except as shown on the Drawings or asspecifically permitted

The dimensions of hooks and the diameters of bends measured on the inside

of the bar shall be as shown on the Drawings When the dimensions of hooks

or the diameter of bends are not shown, they shall be in accordance withArticle of Vietnamese Standard 22TCN 272-05 Bridge Design Standard

rows of outer perimeters, the remaining points in between by awelding alternating order;

Electrical arc welding is used in the following cases:

than 8 mm

 Welding all the in-situ details, the component structures andbonding of joints in the assembly

The welding joints must meet the following requirements:

are no bubbles

 Make sure the length and height of welding seams as requireddesign

Reinforcing Steel Components

Lap joint:

Lapped splices shall be of the lengths shown on the Drawings If not shown

on the Drawings, requirements for lapped slices shall be in accordance withArticle 5.10.3 of the Vietnamese Standard 22TCN 272-05 Bridge DesignStandard The bars in lapped splices shall be placed and wired in such asmanner as to maintain the minimum concrete cover and the minimumspacing between the bars as detailed in the Specification

In Lap Joints, tied with steel wire rods that maintain the minimum distance tothe surface of the concrete as shown in the drawing

Mechanical Joint (Coupler Type)

Splices made with mechanical couplers shall be used only if detailed on theDrawings or previously approved by the Engineer in lieu of welding Suchcouplers shall develop in tension or compression as required, at least 125percent of the specific yield strength of the bar

When requested by the Engineer, up to two field splices out of each 100, orportion thereof, placed in the work and chosen at random by the Engineer,shall be removed by the Contractor and tested to 125 percent of thespecified yield strength

Tensile failure must be occur in the bar away from the joint

There must be no reduction of the nominal cross section area of the parentbar

Couplers must be marked to allow full traceability of the material

Couplers connecting bar reinforcement embedded in existing structures toother bar reinforcement should meet the performance criteria set out insubsection 3.6.3(a) above

Mechanical Joint by threaded coupler splice shall be applied to rebar morethan D36

Splicing of Mesh or Mats

Sheets of mesh or bar mat reinforcement shall be spliced by overlappingsufficiently to maintain a uniform strength and shall be securely fastened atthe ends and edges The lap shall not be less than one mesh in width plus

on the Drawings Only one brand of cement shall be used for all concreteworks throughout the Works unless otherwise authorized by the Engineer.Cement shall be delivered to the Site in sealed bags or in bulk TheContractor proposed source of supply of cement shall be submitted to theEngineer for his approval All deliveries of cement to Site shall includeappropriate test certificates, certified by an independent agency in thecountry of origin, confirming that the material delivered complies with thespecification.

Bagged cement shall bear the manufacturer’s name, cement type and thedate of manufacture and shall be stored in waterproof sheds or other suchtemporary buildings used exclusively for the storage of cement Cementshall be stored in dry conditions on areas raised above ground level Storagecapacity shall be sufficient to hold enough cement for the largest units to becast Bags shall not be stored more than 8 high and a free passage of atleast one meter shall be left between the cement and the side walls of thesheds

Cement delivered by bulk carriers shall be stored in silos made for cementstorage All handling shall be by methods that prevent contamination of thecement The silos shall be provided with interior moisture control devicesthat keep the cement dry and prevent premature hydration The silos shall

be provided with access ladders and access points to enable samples to betaken from various levels of each silo for testing purposes

Access ways shall be provided between storage containers such that everycontainer can be visually inspected Each delivery shall be stored separatelyfrom previous deliveries Deliveries shall be used in the order in which theywere delivered Any delivery which has become caked or otherwiseadversely affected shall be removed from the Site at the Contractor’sexpense

The Contractor shall provide weighing machines which shall be keptpermanently in each shed for checking the weight of the bags

2.2 Water for Concrete Mixing and Curing

The Contractor’s proposed water source shall be submitted to the Engineerfor his approval together with test results confirming that water from thesource complies with this Specification Section

Water for concrete mixes, curing concrete and other products containingcement shall be clean water free from oil, salt, acid, sugar, vegetable or anyother substance injurious to the concrete in according with VietnameseStandard TCVN 4506:2012

2.3 Aggregates

Aggregates shall be free of substances that react deleteriously with alkali inthe cement sufficiently to cause unacceptable expansion of the concrete.The Engineer’s approval of aggregate sources will be based on satisfactoryevidence furnished by the Contractor that the aggregate is free from suchmaterials This evidence shall include certified records of tests by a testinglaboratory that the aggregates meet the requirements of VietnameseStandard TCVN 7570:2006 and may include service records of concrete ofcomparable properties placed under similar conditions of exposure Testsshall be made in accordance with Vietnamese Standard TCVN 7572:2006All aggregates shall consist of tough, hard, durable uncoated particles TheContractor shall be responsible for processing aggregates to meet therequirements of this Specification Section The Contractor’s proposedsources of aggregates shall be submitted to the Engineer for his approval.Samples shall be taken in the presence of a representative of the Engineerand the Contractor for testing and approval before materials are brought tothe Site

Aggregates shall be stored in stockpiles that ensure the materials remainfree draining and are adequately separated to prevent cross contamination.Stockpiles shall be placed on a properly prepared surface to ensure nocontamination occurs when materials are re-handled Materials shall behandled in a manner which avoids segregation All stockpiles are to belabeled with markers indicating the material type in the stockpile

Materials previously approved but rendered unacceptable due to inadequatestorage or handling will be rejected Aggregates shall be stored in sufficientquantity to ensure that there is no interruption of concreting work at anytime Aggregates shall be stored near the mixing plant and shall be checkedand approved by the Engineer prior to use by the Contractor

Fine and coarse aggregates shall be tested in accordance with VietnameseStandard TCVN 7572:06 Source approval shall be withdrawn if aggregates

do not meet the requirements of this Specification Section during routinetesting

Fine aggregates

Fine aggregate shall consist of natural sand with hard, strong, durableparticles or other inert materials with similar characteristics Fine aggregateshall be clean and free from extraneous materials, clay balls, organic matter

or other detrimental material in accordance with Vietnamese Standard TCVN7570:06

Fine aggregate shall be reasonably graded and shall meet the gradingrequirements as in the Specifications

NGAI SECTION

Fine aggregate shall be of such uniformity that the fineness modulus asdefined in Vietnamese Standard TCVN 7570:06 shall not vary more than 0.20

in either way from the fineness modulus of the representative samples used

in the mix designs

Content of silt, dust andclay, % quantity, notgreater than

From 15MPa to30MPa

2,0

The compressive strength of rock used for coarse aggregate in concreteshall be ascertained from the original rock sample or shall be determinedthrough press test inside the cylinder In the latter case (1) igneous andmetamorphic rock shall have a compressive strength 2 times higher thancompressive strength of the concrete and (2) sedimentary rock shall have a

compressive strength 1.5 times higher than the compressive strength of theconcrete.

The wearability of coarse aggregate when impacting is tested by the LosAngeles machine, it is not greater than 50 % of quantity

Content of flat particle in the coarse aggregate shall not exceed 15% forconcrete compressive strength > 30MPa and shall not exceed 35% forconcrete compressive strength <=30MPa

Organic contaminant in gravel is determined by the method of colourcomparison, it is not darker than the standard colour

Content of iron Cl- (acid-soluble) in the coarse aggregate, is not exceeded0.01%

Reactivity of alkali - silica for the coarse aggregate is stipulated same as forfine aggregate

2.4 Admixtures

The use of any admixtures will require the approval of the Engineer Eachtype and each location or purpose shall be approved individually Approvalwill be dependent upon the submission of mix designs and satisfactory trialmixes to demonstrate the function of the admixture

The use of any admixtures will require the approval of the Engineer Eachtype and each location or purpose shall be approved individually Approvalwill be dependent upon the submission of mix designs and satisfactory trialmixes in according with Vietnamese Standard TCVN 8826:2011 or ASTMC1017 to demonstrate the function of the admixture

Retarders shall not be used together with other admixtures in the same mixunless approved by the Engineer The fluid content of admixtures shall beconsidered in the determination of water/cement ratios of the mix-design.Preliminary tests of cylinder strength and any other tests shall be carried outfor all concrete with admixtures When the Engineer approves changing thebrand or type of cement, the Contractor will be required to carry out furthertests and establish a relative mix design

3. Concrete work

The contractor will submit the Consulting Engineer for approval of positionand qualifications of batching plant, and collected yards Contractor shallalso submit details on the type of mixer and mixing plant and transportationplan from concrete batching plant to the Site

Samples of all materials to be used in the mix shall be submitted to theEngineer for testing and such samples shall be tested in the site laboratories

as directed by the Engineer No materials forming any part of this mix shall

be delivered to the Site before the Contractor receives prior approval of theEngineer for such materials

The Contractor shall submit his proposed mix designs to the Engineer for hisapproval Upon approval of the mix designs the Contractor prepare trialmixes for the approval of the Engineer before carrying out mixing concrete

on a large scale The mix design shall include the target mean strength forthe mix and shall be submitted with the results of satisfactory tests from

At construction sites quantities of concrete are not so big and scattered, theContractor propose to use small concrete mixer 500lit or 750 lit

With different structures: measures for placing concrete are shown in thedrawings of the construction methods

3.1 Components of concrete

Material sources as well as concrete mix design shall be in accordance witharticle 3.3.1 “Approved Mix Design” of the Specifications

Calculate and take casting samples in the laboratory

Adjusting concrete components at the site: Adjusting concrete components

at the site are conducted on the principle that does not change the water /cement ratios of design concrete component When moist aggregates shouldreduce the amount of mixing water, keep the required slump

When measuring the amount of water in each batch of concrete, theContractor shall take into account the amount of water contained in theaggregate The total amount of water in each batch must include theamount of water contained in the aggregate and added water

3.2 Batching

Manufacturing concrete mix by batching plant (or concrete mixer)

Cement, fine aggregate, coarse aggregate and liquid admixture to makeconcrete mix is weighted by volume Water and admixture weighed byvolume Allowed error when weighing not exceed the allowed values

The accuracy of measuring equipment must be calibrated prior to placingconcrete During weighing, regular monitoring to detect and correctpromptly

Measurement and batching of materials shall be done at a batching plantand all concrete shall be machine mixed

The Contractor shall submit his method statement for the batching andmixing of concrete to the Engineer for his approval The statement shallinclude the location of the batching and mixing plant, the type or types ofmixers and machines to be used, arrangements for the storage ofaggregates and the batching and mixing of concrete and transportingconcrete from the batching plant to the Site Each material in the storageyard shall be separated by full height partitions The storage yard and theconveyor belts shall be protected from the rain by rain proof covers

The type of mixer shall be a drum mixer Mixers of less than 0.5 cubic metercapacity shall not be used to batch structural concrete The use ofcontinuous mixers will not be permitted.

The batching plant shall include separate bins for the bulk cement, fineaggregate and for each size of coarse aggregate, a weighing hopper, andscales capable of determining accurately the weight of each component ofthe batch Scales shall be accurate to one percent throughout the range ofuse and it shall be calibrated every three months and when so requested bythe Engineer

If there is no prior experience with the approved mix design or if specialhandling procedures, such as pumping, change one or more of thecharacteristics between discharge of the load and placing in the forms, theContractor shall correlate the discharge tests with the placement tests todefine these changes

The Contractor shall also provide documentation, repeat the correlations asoften as necessary or as directed by The Engineer

3.3 Mixing and Delivery

Mixing and delivery of concrete shall be in accordance with the requirements

of Vietnamese standard TCVN 4453-1995 or ASTM C94 except wheremodified in this Specification Section for truck mixing or a combination ofcentral point and truck mixing or truck agitating Delivery of concrete shall

be so regulated that placing is at a continuous rate unless delayed by theplacing operations The intervals between deliveries of batches shall not be

so great as to allow the concrete in place to harden partially and in no caseshall such an interval exceed 45 minutes

Additional mixing water and/or admixture may not be added to the concreteafter leaving the batching plant unless specifically authorized by theEngineer and if the water/cement ratio in the approved job mix is notexceeded and the truck mixer is loaded to no more than 70 percent of itsrated capacity

The volume of concrete mixed per batch shall not exceed the mixer’snominal capacity as shown on the manufacturer’s standard rating plate onthe mixer

Mixing time is determined through the technical characteristics of theequipment used for mixing In case of no precise specifications of aboveequipment, the minimum time for a batch by mixer may be taken from Table

The Minimum Time for MixingMixers having a capacity of 0.5 m3 or less minimum 60 seconds

Mixers having a capacity from 0.5 to 1.0