GRBCC MS BXCV a1( box culvert)

As to safety control activities on site, please refer to Section 9.3 and 9.4 2 Installation of Reinforcement Bar and Cut-off Plate for Concrete Base 2.1 Survey marking layout shall be ca

1 General - 3

2 Scope of Work and Locations - 3

3 Construction Schedule - 4

4 Site Organization Chart - 4

5 Material - 5

6 Equipment and Tools - 6

7 Construction Procedure - 7

8 Quality Control - 16

9 Safety Control - 17

10 Environmental Control - 18

APPENDIX

Appendix 1 - Construction Schedule (03 paged Attached)

Appendix 2 - Construction Sequence for Box Culvert (01 page Attached)

Appendix 3 - Typical Drawing of Formworks (01 page Attached)

Appendix 4 - Inspection and Testing Plan (01 page Attached)

Appendix 5 - Inspection Sheet and Checklist (12 pages attached)

Total: 41 pages

1 General

This Method Statement is to describe the work procedures for the construction of Underpass BoxCulvert and Drainage Box culvert This work item shall be done in accordance with Section

06950 of the General Specifications

Detailed Drawings indicate Detour/Temporary Waterway, Layout of site and ConstructionSchedule for each location of Box Culvert shall be submitted separately

2 Scope of work and Locations

The scope of work and locations of Underpass Box Culverts are as follows:

The scope of work and locations of Drainage Box Culvert are as follows:

4 Site Organization Chart

Organization Chart for management and construction of box culverts is as follows:

5 Material

List of required material for construction is shown below:

S06100

7 Cut off Plates (Water stop)

8 Joint filler

10 Gavanized Wire Mesh

Mimimum Diameter of 3.05mm, Tensile Strength of 4200~5980Kg/cm2, Opening shall not exceed 100mm

For Gabion Basket

Detail Refer to Submmited MS of Structure Excavation (GRBCC-MS-STEX-A7- EN)

Material proposal shall be submitted

separately

When stored at site, materials such as rebar and PVC pipes must be kept off the ground and shall

be covered by vinyl sheet Other materials used for backfilling and blinding stone shall be timelytransported to the site

6 Equipment and Tools

List of required equipment and tools for construction is shown below:

7 Construction Procedure

7.1 Typical Construction Flow

Typical Construction Flow (Continue)

7.2 Work Sequence

Typical work sequence sketch is shown in Appendix 2

Box Culvert shall be divided into several segments (as indicated on approved shopdrawing) and each segment shall be constructed one by one The description of eachsegment work item is shown as follows:

2) Making Detour/ Temporary water way, Soft soil replacement

For underpass box culvert located at existing road Detour must be made to ensure trafficduring construction of Box culvert

Detour shall be designed and constructed with suitable width and curve Connectionbetween detour and existing road must be smooth Safety signboard and turning lampshall be installed at both ends of detour

For Irrigation / Drainage box culvert that located at existing waterway, temporarywaterway shall be made during construction of new box culvert.

Cross section of temporary waterway shall ensured that drainage and irrigation to besimilar to previous situation

Detail of Detour/Temporary waterway shall be shown on the working drawing and thistemporary work shall be followed approved working drawing

Soil replacement shall be followed approved shop drawing and approved methodstatement of road earthwork

I- Construction of Base Slab

1) Excavation, Trimming Works, Blinding Stone, Lean Concrete

Excavation and trimming works shall be carried out based on approved WorkingDrawing Survey marking shall be established prior for placing blinding stone BlindingStone shall be placed following the Approved Shop Drawing and shall be compactedthoroughly to the satisfaction of the Engineer using portable compacting equipment orequivalent

After placing blinding stone, Lean concrete shall be placed and casted as indicated in theApproved Shop Drawings Placing concrete shall be carried out either by direct pouring,using excavator or crane and concrete bucket

For more detail of above works refer to Submitted Method Statement of StructureExcavation

Note: Stability of slopes 1:0.5 shall be checked and approved by the Engineer prior tocommencement of works The Contractor either shall perform an on-site test to validatestability or shall justify adopted slope angle by any means approved by the Engineer

As to safety control activities on site, please refer to Section 9.3 and 9.4

2) Installation of Reinforcement Bar and Cut-off Plate for Concrete Base

2.1) Survey marking layout shall be carried out prior to rebar and formwork installationfor concrete base

2.2) Rebar used for structures shall be in accordance with Specification of the Project andapproved by the Engineer

2.3) Rebar, before and after fabrication, shall not be placed directly to the ground butfirmly chocked and covered by nylon canvas to minimize all the external effects

2.4) Rebar shall be fabricated by cutting and bending machine at fabrication yard andshall be transported to construction site

2.5) Rebars shall be installed and fixed with wires in workmanship manner based onApproved Shop Drawings Rebar protection thickness shall be ensured by installation

of pre-cast concrete spacer

2.6) Starting rebars for wall shall be installed and carefully protected from corrosion.starting rebar shall be fixed during concreting of Base Slab.

2.7) After installation, rebar must be inspected by the Engineer

2.8) Illustration of Cut-off Plate (Water stop)

As to safety control activities on site, please refer to Section 9.3 and 9.5

3) Installation of Side Formwork for Concrete Base

3.1) Side forms shall be installed based on the line marking at the surface of leanconcrete

3.2) Forms support and bracings shall be installed and properly fixed Formwork andsupporting system shall be ensured so that formwork is even without distortion anddeformation during concreting

3.3) Installed formwork shall even and tighten to avoid water leakage during concretingwhich may influence the quality and appearance of the structure So the gaps on form

SIDE FORM TIMBER SUPPORT FOR

CUT-OFF PLATE & J OINT FILLER DETAIL

FIXING OF CUT-OFF PLATE DETAIL

2 1

CONCRETE WALL SEGMENT NO.1 SEGMENT NO 2

Clip fastened to a rebar with a tie wire

1

joint shall be treated and filled by cleat.

3.4) Prior to concrete, entire surface of formwork shall be oily coated for easydismantling in the next stage

3.5) After installation, form alignment shall be carefully checked by survey works

As to safety control activities on site, please refer to Section 9.3, and 9.4

4) Casting for Concrete Base of Box Culvert

CASTING CONCRETE OF BAS E SLAB

4.1) Supply of concrete, auxiliary equipments and tools shall be carefully considered to

ensure continuous performance

4.2) Concrete shall be mixed at plant and shall be transported to site by concrete mixertrucks Mixer Truck’s tank must be rotated during transportation so that concrete shallnot be segregated

4.3) Concrete slump and temperature shall be checked at site prior to concreting

concrete bucket depending on site condition

layer During concreting, concrete shall be continuously compacted by vibrator toensure concrete quality While compacting, end of vibrator shall be 10 cm embedded

in the previous concrete layer to ensure adhesion between old layer and the new one

to prevent problems if any.

9.7

5) Concrete Curing, Removal of Forms and Treatment of Construction Joint

5.1) Curing shall be done after concrete surface start dry Concrete surface shall becovered by wet burlap or vinyl sheets These burlaps or vinyl sheets shall be keptmoisture during curing period Curing shall be at least 7 days from finishing

5.2) Formwork removal can only be done at least 1 day after completion of concretecasting for vertical structure After remove forms, concrete shall be covered by vinylsheet for curing

5.3) Construction joint shall be chipped by steel brush and water to ensure loose concreteshall be removed until sound aggregate is exposed

CONCRETE

Surface of concrete Wet burlap

Chipping of surface of construction joint

Rebar of wall Bottom slab

5.4) Prior to casting of the next lift, the previously cast concrete top surface must becovered with a pure cement mortar layer

5.5) As to safety control activities on site, please refer to Section 9.3, 9.4, and 9.7

II- Construction of Vertical Wall and Top Slab

1) Survey Marking for Vertical Wall of Box Culvert

Survey layout for vertical wall of box culvert shall be marked on top surface of concretebase

2) Installation of Working Platform and Scaffolding for Vertical Wall and Top Slab

Vertical wall and top slab shall be cast together For this casting procedure, stability andrigidity of formwork and scaffolding shall be checked carefully

Scaffolding and working platform shall be installed prior to install rebar and formworkfor vertical wall and top slab of box culvert

As to safety control activities on site, please refer to Section 9.3, 9.4, 9.7 and 9.8

3) Installation of Rebars and Cut-off Plate for Vertical Wall of Box Culvert

Reinforcing bar for vertical wall shall be installed and properly fixed with wires inappropriate position according to Approved Shop Drawing Concrete spacer shall beinstalled to ensure thickness of concrete cover Cut-off plate shall be installed and set onits proper position based on the submitted Shop Drawings

4) Installation of Inner Side Forms for Vertical Wall and Bottom Forms of Top Slab

4.1) Panel forms shall be set to its proper position using the lines marked on top surface

of the box culvert base Bottom formworks for top slab shall be installed based ondesign elevation as referred to the Approved Shop Drawings.

4.2) Shoring, bracing and form support shall be properly installed and fixed Gaps onform joint shall be treated and filled by cleat

4.3) Prior to concrete, entire surface of formwork shall be oily coated for easydismantling in the next stage

5) Installation of Rebars and Cut-off Plate for Top Slab

Rebar shall be installed in workmanship manner, arrangement and location of rebar shall

be referred on Shop Drawings Cut-off plate and joint bar shall be installed and set on itsproper position based on the submitted Working Drawings

6) Installation of Outer Side Forms for Vertical Wall of Box Culvert

6.1) Panel forms shall be installed following the survey layout

6.2) Shoring, bracing and form support shall be fixed properly

6.3) Concrete covering shall be checked

6.4) All forms shall be cleaned and free from dirt, dust, grease or other foreign substanceand shall be applied with the form-release-oil

6.5) All gaps between the forms shall be treated and filled with cleat

6.6) Prior to concrete, entire surface of formwork shall be oily coated for easydismantling in the next stage

6.7) Typical drawing of formwork is attached as Appendix 3

7) Concrete Casting for Vertical Wall and Top Slab of Box Culvert

7.1) Prior to casting concrete, the below items shall be strictly followed:

- Mobile pump shall be used for casting concrete Plastic hose shall be provided andattached on the tip of mobile pump pipe to avoid the concrete segregation duringcasting

- Cleaning inside the form and water shall be sprayed on construction joint

- Resources of materials shall be checked such as supply of concrete and equipments

- Concrete casting equipment shall be set-up and check its condition before castingconcrete

- Pouring guide level shall be established for finishing the top slab surface Pouring

guide level shall be placed at the centerline transversely and a maximum distance of

2 meter longitudinally

7.2) During casting, the below items shall be strictly followed:

- Vibrators shall be used in workmanship manner in order to consolidate and compactthe concrete properly Vibrator shall be applied to area of concreting on a verticalposition at 5 to10 sec at one place

- Regularly check the verticality of forms and necessary adjustment shall be madeimmediately if displacement or movement on forms is found

- Discharging concrete on wall shall be done layer by layer with a max of 50cm / lift

- Concrete supply shall be closely monitored to avoid cold joint

- Tightness of the formworks shall be inspected regularly by the pouring guards tomake sure that there is no deformation or displacement of forms and rebar and leaks

at the formworks

If displacements occur, immediate adjustment shall be done to reposition the forms orrebar before concrete placing continues

7.3) After placing concrete, top slab surface shall be hand finished by trowel

CASTING CONCRETE OF WALL AND TOP SLAB

7.4) As to safety control activities on site, please refer to Section 9.3, 9.4, 9.7 and 9.8

8) Curing and Removal of Forms

8.1) Just after removal of formwork and completion of finishing work, the entire exposedsurface of the newly cast structure must be covered with vinyl sheet for curing

concrete strength

8.3) As to safety control activities on site, please refer to Section 9.3, 9.4, 9.7 and 9.8

9) Finishing works for Concrete Surface

Just after formwork removal, exposed wires and rebars used to support formworks in

right positions shall be removed or cut off at least 2.5cm beneath the concrete surface.Any edges or grout stains and all false work shall be treated Any minor voids,depressions and honeycombs shall be filled with cement mortar mixed in the sameconcrete proportions of the structure but without coarse aggregate Any excessivelyhoneycombed structure portions shall be rejected, and then, upon receipt of theEngineer’s written instructions, shall be removed and constructed again at theContractor’s expense

10) Removal of Working Platform

Working platform shall be removed, after inspection and approval for the finishingworks of concrete surface

As to safety control activities on site, please refer to Section 9.3, and 9.4

III) Construction of Wing Wall and Apron

Wing wall and Apron shall be commenced after finishing of all segment of box culvert.

This method is similar to method statement of Substructure So that Construction ofWing Wall shall be refer to Method Statement for Construction of Substructure (submitseparately)

IV) Backfilling and Compaction

Refer to Submitted Method Statement for Construction of Pipe culvert

V) Construction of Approach Slab

Refer to Method Statement for Construction of Approach Slab (Submit separately)

VI) Cleaning Up Site

All excess materials and rubbish shall be removed and disposed leaving the site neat,tidy and acceptable to the Engineer

 In Case of Emergency

15.1) If it is necessary to stop placing concrete before a casting is completed, make thesurface flat until the last available batch of concrete, and make proper constructionjoint In case of rainfall, pooling water shall be removed from concrete surfacebefore making the surface flat

15.2) Extra specimens for concrete compression test shall be taken from emergencystopped concreting area in order to confirm the strength of concrete at the correspondingsection

15.3) In case of rainfall, all areas of concreting shall be covered by plastic vinyl sheet.15.4) If casting equipment breakdown, a standby casting equipment shall be utilized forconcrete casting Casting concrete shall follow the direction initially poured

8 Quality Control

The whole procedure shall be thoroughly checked by the Engineer in charge for operation.Quality control shall be carried out in accordance with this Method Statement and otherapplicable specifications Inspection and Test Plan and Inspection Checklist are attached asAppendix 3 Inspection and Test Plan and Inspection Checklist are subject to revision inaccordance with the instruction by the Engineer