General
This Method Statement outlines the construction procedures for the substructure of bridge structures, adhering to section 06100 - Concrete and Concrete Structures and section 06400 - Reinforcing Steel Bars from Division 6 – Concrete Work of the General Specifications, following the excavation of the structure The substructure will include components such as the pile cap, pier column, pier head, and abutment walls Details regarding the construction of the bearing seat and the installation of anchor bars will be provided in a separate submission A typical drawing of the structure referenced in this method statement is included as Appendix I.
Details of working drawing and Design Calculation of Form will be submitted separately as Addendum.
Locations
Refer to below table for the Substructure Locations Detailed and specific locations will be shown on shop drawing.
No Bridge Name Station Span arrangement
A7/06 Xom Danh Bridge Km 198+438.05 1x24 + 2 x 33m 2 4 A7/07 Thin Thung I Bridge Km 199+050.50 2x 24m 24 32 A7/08 Thin Thung II Bridge Km 199+131.40 2x 24m2x 24m 2 2
No Bridge Name Station Span arrangement
A7/08 Thin Thung II Bridge Km 199+131.40 2×24M 2 1
Construction Schedule shall be referred to latest approved Overall Schedule and construction process of subcontractor shall be indicated on the monthly and weekly schedule
The below list of materials that should be approved by the Engineer shall be used for the construction of substructure
1 Reinforcing Steel Bar CB400-V, CB24004-T Approved in accordance with
The list of equipments for the construction of Substructure is shown below.
No Equipments Using for NoteRem arks
Above stated schedule of equipment shall be increased in quantity if required and necessary.
Actual equipment mobilized shall be subject to inspection and approval by the Engineer in accordance with Guide Form No BBMMNL
1) 1) The Whole Substructure Works for one Pier/Abutment
Confirmation and approval of working drawing
Establish reference and marking points
Check and inspection for location, spacing and
Check and inspection of shape and dimension Fabrication
Installation of rebar for pile cap Survey marking for limit
"Action to be taken" and Column/Wall starter rebar of fabricated rebar and arrangement of installed rebar in accordance
Exposure of clean aggregates for construction joint Check and inspection of dimension, location
Structure Excavation of rebar Confirmation of material testing for rebar
Concrete casting for Pile Cap Confirmation of layer height to be cast
Check concrete quality,temperature (T < 32 C) Check resources for concrete casting and verticality of forms
Removal of forms and curing of concrete
Confirmation of time elapsed (24 hours after Check surface of concrete
(8) for pile cap with shorings of pile cap
Ensure the casting speed is monitored, verify the stability and tightness of the formwork, and confirm the correct arrangement of installed rebar Additionally, check the formwork's suitability for removal and assess the concrete slump on site, aiming for a measurement of 7.5 cm, in accordance with the shop drawings and the specified tolerances for the concrete structure.
Check and inspection of concrete covering (A) Pile Cap
Concrete sampling for compressive test
Installation of vinyl sheet for curing
+ 2.5cm) Approval by the Engineer
Check surface of concrete Confirmation of time elapsed (48 hours after Exposure of clean aggregates for
Check and inspection of verticality, location
Removal of forms and curing Treatment for construction joint
(8) of concrete (7) construction joint Concrete casting for column/wall
Installation of forms and embedded for first/next lift Installation of column/wall rebar
"Action to be taken" scaffolding height, railing and support
Establish reference and marking points
Survey marking for location of
Pier column/wall pier column/wall on pile cap Check condition of scaffolding frames,
Check splice length and location items for pier column/wall first lift/next lift Survey and inspection of shape, dimension
Confirmation of arrangement and layout of scaffoldings
Extend scaffoldings for next lift
Safety procedures for working on elevated platform
Splicing and fixing rebar Confirmation of approved working drawing for next lift
Move to next lift until reach top elevation Pier column
Surface shall be free from depressions
Finishing of column/wall surface and projections
(B) elevated platform Safety procedures for working on and location
Check arrangement of installed rebar and form Check stability and tightness of form Check casting speed
Check resources for concrete casting Confirmation of layer height to be cast casting for removal of form) Approval by the Engineer
Check and approval by the Engineer
Check and approval by the Engineer
Installation of vinyl sheet for curing
Concrete sampling for compressive test
Check concrete quality,temperature (T < 32 C) and slump on site (7.5cm + 2.5cm)
Check and inspection for location, spacing and with shop drawing and tolerance of con structure and arrangement of installed rebar in accordance
Check and inspection of concrete covering in accordance with Tolerance of con structures Approval by the Engineer
Confirmation of 80% of designed Removal of bottom form
Finishing of pier head surface (10) (9)
Confirmation of time elapsed (48 hours after
Check arrangement of installed rebar and form Checking displacement of forms
Check elevation, dimension and location
Check arrangement and layout of scaffoldings Check elevation and adequacy of compaction
Removal of side forms and curing
Concrete casting for pier head
Installation of pier head rebar
Pier Head Backfilling and preparation for
(1) foundation of support for pierhead
Confirmation of period of curing and support
Surface shall be free from depresssions and projections Removal of scaffoldings
Cleaning up site of bottom form
(C) concrete strength casting for removal of side forms) and support for pier head Check condition, stability and adequacy of brace for scaffolding and support for pier head
Check stability and tightness of form Check casting speed
Exposure of clean aggregates for construction joint at bearing location
Treatment of construction joint at bearing location (8)
Check stability of foundation and base of support Removal of Cofferdam (if any)
Check and approval by the Engineer Check concrete surface
Check concrete quality,temperature (T < 32 C) Concrete sampling for compressive test and slump on site (7.5cm 2.5cm) +
Ensure thorough inspection and verification of the location, spacing, and arrangement of installed rebar in concrete structures, adhering to working drawings and specified tolerances Confirm the splice length and location, along with the tolerances for concrete structures, and obtain approval from the Engineer Conduct checks on concrete cover and perform surveys to inspect the shape and dimensions of the structures.
Check and inspection of verticality, location and stability of form and location
The Contractor shall maintain an adequate number of trained and experienced supervisors and foremen at site to supervise and control the work.
Experienced steel fixers must be present during concrete placement to prevent any displacement of reinforcement If any dislocation occurs, the reinforcement should be repositioned before continuing with the concrete pouring process.
All concrete shall be placed within 1.5 hours from finishing of mixing (as proposal of the Contractor and approved from the Engineer).
The excavation area not occupied by the concrete structure must be backfilled and compacted using acceptable materials, following the approved Method Statement for Structure Excavation (GRBCC A7-MS-STEX-A2-EN).
Reinforcing steel bars must be inspected by the Engineer immediately after placement If a significant amount of time passes before concrete is poured, the steel bars should be cleaned and re-inspected by the Engineer to ensure quality and compliance.
Prior to pouring concrete the following should be strictly complied:
- Pouring request has been approved by the Engineer.
- Tightness and stability of formworks shall be checked carefully.
- Thorough checking of rebars, concrete covering, elevation and location.
- Water shall be sprayed on forms, rebars (and surface of lean concrete if any).
- Resources check such as supply of concrete, back-up equipment, pouring guards, standby carpenters, steel man, welder, lighting system, etc…
Before commencing work, it is essential to confirm the working drawings and prepare the work area The location of construction joints must be indicated on the approved working drawings The surrounding ground should be as level and stable as possible to ensure smooth equipment mobility; steel plates will be utilized in moist or muddy conditions to facilitate equipment movement Additionally, all necessary materials and machinery should be organized and ready for use.
Approved shop drawings must clearly depict the arrangement, location, dimensions, and shapes of reinforcing steel bars, commonly known as rebar.
Rebar fabrication must adhere to the shapes and dimensions specified in the approved shop drawings Prior to fabrication, a material test of the rebar should be conducted following the Inspection and Test Plan Proper equipment, such as bar cutters, is required for cutting rebar, while bar bending can be performed using either specialized equipment or manual methods to achieve the specified shapes The process of rebar fabrication should primarily involve cold cutting and cold bending, with any heat application during fabrication carried out only as directed by the Engineer.
3) Survey Marking for Limit of Pile Cap
3.1) Survey marking for layout of pile cap shall be carried out and marked clearly on the surface of the lean concrete.
Rebar installation must adhere to the approved shop drawings, utilizing concrete blocks with whip as spacers to ensure proper concrete cover Spacers should be positioned at the bottom and sides of the rebar, with the bottom rebar of the pile cap secured first using a concrete block spacer underneath Additionally, a sample of the concrete spacer must undergo inspection and a compressive strength test, receiving approval from the Engineer before use.
Concrete to be used for the fabrication of concrete spacer shall be Class C Typical detail of concrete spacer is shown on Appendix II.
Rebar fixing and splicing must utilize iron wire with a diameter of 0.9mm or larger, following the specifications outlined in the shop drawings Adequate ties at rebar intersections are essential to prevent dislocation during casting, and all intersections must be securely tied Welding for fixing is permitted only if specified in approved working drawings or directed by the Engineer Additionally, all installed rebar must be clean and free from rust, dirt, oil, or any substances that could impair bonding.
4.3) Rebar spacing and arrangement of main bottom rebar will be adjusted at site due to existing
GUANGXI ROAD AND BRIDGE CONSTRUCTION CO, LTD
Noi Bai-Lao Cai Highway Construction Project
Method Statement For Substructure of Bridge Structure GRBCC-MS-SUBSTR-A2-EN
GUANGXI ROAD AND BRIDGE CONSTRUCTION CO, LTD
Noi Bai-Lao Cai Highway Project
This method statement outlines the substructure requirements for bridge construction, specifically focusing on the GRBCCA7-MS-SUBSTR-A1A2-EN rebar used in cast-in-place concrete piles The Engineer will accept over-tolerance spacing of rebar, ensuring flexibility in installation A typical rebar installation sequence is provided in Appendix II for reference.
After installing the bottom and top rebar of the pile cap, the starter main bars for the column or wall must be positioned according to the approved shop drawings It is crucial to protect exposed column main rebars from bending due to strong winds, as well as from injury and corrosion, especially if they are intended for the first or subsequent lifts Prior to concrete casting, an adequate number of column stirrup rebars should be temporarily installed above the finished pile cap level and securely tied to the main rebars for stability Once the concrete casting is complete, the stirrup rebars must be promptly installed in their designated locations, with temporary supports fixed to maintain stability Refer to Appendix II for the typical drawing.
To ensure proper rebar installation for the pile cap, top rebar must be supported with temporary chair bars to prevent sagging, while all other rebar, including hoops for the pile head, should be installed as indicated in Appendix II Additionally, temporary embedded rebar is required at the top of the pile cap to support the formwork for columns or walls, with specific locations and quantities detailed in the working drawing Once the installation is complete, these temporary bars must be cut to a minimum of 30mm below the pile cap surface, which should then be finished neatly with a cement mortar mixture of cement and fine aggregates in the same ratio as Class C, as illustrated in Appendix III.
4.7) Inspection and approval by the Engineer shall be carried out prior to setting of forms.
Metal formworks must adhere to the shapes, lines, and dimensions specified in the working drawings, ensuring structural integrity They should be constructed robustly to prevent deformation under load.
- The contractor shall carry out placing concrete of pile cap without formworks
7) 6) Concrete Casting for Pile cap
6.1) In order to place concrete, the Contractor will use concrete mixerconcrete pump and the standby alterntive is to use crane and basket
Concrete pumps are essential for placing concrete within structures, with one pump sufficient for layers up to 80 cubic meters For layers exceeding 80 cubic meters, two pumps should be utilized simultaneously Prior to casting, water must be sprayed on forms, rebar, and the surface of lean concrete To prevent free drops of concrete from heights greater than 1.5 meters, pipes and short chutes should be used Concrete should be cast layer by layer and in accordance with the specified casting speed, starting from one end and progressing to the opposite end For detailed procedures, refer to the Typical Setup Plan for Concreting Works in Appendix Va and the Typical Concrete Casting Sequence in Appendix VIa.
Materials
The below list of materials that should be approved by the Engineer shall be used for the construction of substructure
1 Reinforcing Steel Bar CB400-V, CB24004-T Approved in accordance with
Equipment
The list of equipments for the construction of Substructure is shown below.
No Equipments Using for NoteRem arks
Above stated schedule of equipment shall be increased in quantity if required and necessary.
Actual equipment mobilized shall be subject to inspection and approval by the Engineer in accordance with Guide Form No BBMMNL.
Construction Procedure
1) 1) The Whole Substructure Works for one Pier/Abutment
Confirmation and approval of working drawing
Establish reference and marking points
Check and inspection for location, spacing and
Check and inspection of shape and dimension Fabrication
Installation of rebar for pile cap Survey marking for limit
"Action to be taken" and Column/Wall starter rebar of fabricated rebar and arrangement of installed rebar in accordance
Exposure of clean aggregates for construction joint Check and inspection of dimension, location
Structure Excavation of rebar Confirmation of material testing for rebar
Concrete casting for Pile Cap Confirmation of layer height to be cast
Check concrete quality,temperature (T < 32 C) Check resources for concrete casting and verticality of forms
Removal of forms and curing of concrete
Confirmation of time elapsed (24 hours after Check surface of concrete
(8) for pile cap with shorings of pile cap
Ensure the casting speed is optimal, verify the stability and tightness of the formwork, and confirm the proper arrangement of installed rebar Additionally, check the form's readiness for removal and measure the slump on-site, aiming for 7.5 cm in accordance with shop drawings and the specified tolerances of the concrete structure.
Check and inspection of concrete covering (A) Pile Cap
Concrete sampling for compressive test
Installation of vinyl sheet for curing
+ 2.5cm) Approval by the Engineer
Check surface of concrete Confirmation of time elapsed (48 hours after Exposure of clean aggregates for
Check and inspection of verticality, location
Removal of forms and curing Treatment for construction joint
(8) of concrete (7) construction joint Concrete casting for column/wall
Installation of forms and embedded for first/next lift Installation of column/wall rebar
"Action to be taken" scaffolding height, railing and support
Establish reference and marking points
Survey marking for location of
Pier column/wall pier column/wall on pile cap Check condition of scaffolding frames,
Check splice length and location items for pier column/wall first lift/next lift Survey and inspection of shape, dimension
Confirmation of arrangement and layout of scaffoldings
Extend scaffoldings for next lift
Safety procedures for working on elevated platform
Splicing and fixing rebar Confirmation of approved working drawing for next lift
Move to next lift until reach top elevation Pier column
Surface shall be free from depressions
Finishing of column/wall surface and projections
(B) elevated platform Safety procedures for working on and location
Check arrangement of installed rebar and form Check stability and tightness of form Check casting speed
Check resources for concrete casting Confirmation of layer height to be cast casting for removal of form) Approval by the Engineer
Check and approval by the Engineer
Check and approval by the Engineer
Installation of vinyl sheet for curing
Concrete sampling for compressive test
Check concrete quality,temperature (T < 32 C) and slump on site (7.5cm + 2.5cm)
Check and inspection for location, spacing and with shop drawing and tolerance of con structure and arrangement of installed rebar in accordance
Check and inspection of concrete covering in accordance with Tolerance of con structures Approval by the Engineer
Confirmation of 80% of designed Removal of bottom form
Finishing of pier head surface (10) (9)
Confirmation of time elapsed (48 hours after
Check arrangement of installed rebar and form Checking displacement of forms
Check elevation, dimension and location
Check arrangement and layout of scaffoldings Check elevation and adequacy of compaction
Removal of side forms and curing
Concrete casting for pier head
Installation of pier head rebar
Pier Head Backfilling and preparation for
(1) foundation of support for pierhead
Confirmation of period of curing and support
Surface shall be free from depresssions and projections Removal of scaffoldings
Cleaning up site of bottom form
(C) concrete strength casting for removal of side forms) and support for pier head Check condition, stability and adequacy of brace for scaffolding and support for pier head
Check stability and tightness of form Check casting speed
Exposure of clean aggregates for construction joint at bearing location
Treatment of construction joint at bearing location (8)
Check stability of foundation and base of support Removal of Cofferdam (if any)
Check and approval by the Engineer Check concrete surface
Check concrete quality,temperature (T < 32 C) Concrete sampling for compressive test and slump on site (7.5cm 2.5cm) +
Ensure thorough inspection and verification of the location, spacing, and arrangement of installed rebar in concrete structures, adhering to working drawings and tolerance specifications Check the splice length and location, ensuring compliance with the concrete structure's tolerance requirements Obtain approval from the Engineer and conduct inspections of concrete cover Additionally, survey and inspect the shape and dimensions of the concrete structures for accuracy.
Check and inspection of verticality, location and stability of form and location
The Contractor shall maintain an adequate number of trained and experienced supervisors and foremen at site to supervise and control the work.
Experienced steel fixers must be present during concrete placement to prevent any displacement of reinforcement Should any dislocation occur, the reinforcement should be properly repositioned before continuing with the concrete placement.
All concrete shall be placed within 1.5 hours from finishing of mixing (as proposal of the Contractor and approved from the Engineer).
The excavation area not occupied by the concrete structure must be backfilled and compacted using acceptable materials, following the approved Method Statement for Structure Excavation (GRBCC A7-MS-STEX-A2-EN).
Reinforcing steel bars must be inspected by the Engineer immediately after placement If a significant amount of time passes before concrete is poured, the steel bars should be cleaned and re-inspected by the Engineer to ensure compliance with safety standards.
Prior to pouring concrete the following should be strictly complied:
- Pouring request has been approved by the Engineer.
- Tightness and stability of formworks shall be checked carefully.
- Thorough checking of rebars, concrete covering, elevation and location.
- Water shall be sprayed on forms, rebars (and surface of lean concrete if any).
- Resources check such as supply of concrete, back-up equipment, pouring guards, standby carpenters, steel man, welder, lighting system, etc…
Pile Cap
Before commencing any work, it is essential to confirm the working drawings and prepare the working area The working drawings must clearly indicate the location of construction joints for approval To ensure optimal mobility of equipment, the surrounding ground should be as level and stable as possible; in cases of moist or muddy conditions, steel plates will be used to facilitate equipment movement Additionally, all necessary materials and machinery must be properly set up in the working area.
Approved shop drawings must clearly indicate the arrangement, location, dimensions, and shapes of reinforcing steel bars, commonly referred to as rebar.
Rebar fabrication must adhere to the approved shop drawings regarding shape and dimensions, with material tests conducted as per the Inspection and Test Plan before fabrication begins Appropriate bar cutter equipment is required for cutting, while bar bending can be performed using specialized equipment or manually to achieve the specified shapes All rebar fabrication should utilize cold cutting and cold bending techniques, unless otherwise directed by the Engineer for heat application.
3) Survey Marking for Limit of Pile Cap
3.1) Survey marking for layout of pile cap shall be carried out and marked clearly on the surface of the lean concrete.
Rebar installation must adhere to the approved shop drawings, utilizing concrete blocks with whip as spacers to ensure proper concrete coverage Spacers should be positioned at both the bottom and sides of the rebar The bottom rebar of the pile cap should be secured first, with a concrete block spacer placed underneath for adequate coverage Additionally, a sample of the concrete spacer must undergo inspection and compressive strength testing, receiving approval from the Engineer.
Concrete to be used for the fabrication of concrete spacer shall be Class C Typical detail of concrete spacer is shown on Appendix II.
Rebar fixing and splicing must utilize iron wire with a diameter of 0.9mm or larger, following the specifications outlined in the shop drawings It is essential to ensure that ties at rebar intersections are adequately installed to prevent dislocation during casting, with all intersections requiring proper tying Welding for fixing is permitted only when specified in approved working drawings or directed by the Engineer Additionally, all installed rebar must be clean and free from rust, dirt, oil, or any substances that could compromise the bond.
4.3) Rebar spacing and arrangement of main bottom rebar will be adjusted at site due to existing
GUANGXI ROAD AND BRIDGE CONSTRUCTION CO, LTD
Noi Bai-Lao Cai Highway Construction Project
Method Statement For Substructure of Bridge Structure GRBCC-MS-SUBSTR-A2-EN
GUANGXI ROAD AND BRIDGE CONSTRUCTION CO, LTD
Noi Bai-Lao Cai Highway Project
The method statement for the substructure of the bridge structure, referenced as GRBCCA7-MS-SUBSTR-A1A2-EN, outlines the installation of rebar in cast-in-place concrete piles It is important to note that any over-tolerance in rebar spacing will be accepted by the Engineer For detailed guidance, the typical rebar installation sequence can be found in Appendix II.
After installing the bottom and top rebar of the pile cap, the starter main bars for the columns or walls must be positioned according to the approved shop drawings It is essential to protect exposed column main rebars from bending due to strong winds, as well as from injury and corrosion A sufficient number of column stirrup rebars should be temporarily placed above the pile cap's finish level and securely tied to the main rebars to ensure stability Once the concrete casting is completed, the stirrup rebars must be installed promptly in their designated locations, with temporary supports fixed in place to maintain stability A typical drawing is included in Appendix II.
To ensure proper positioning and prevent sagging, top rebar must be supported with temporary chair bars, while all other rebar, including hoops for the pile head, should be installed to complete the rebar setup for the pile cap, as illustrated in Appendix II Additionally, temporary embedded rebar is required at the top of the pile cap to support the formwork for columns or walls, with specific locations and quantities detailed in the working drawings This embedded rebar must be removed and cut to at least 30mm below the pile cap surface, which should then be finished neatly with a cement mortar mix of cement and fine aggregates in the same ratio as Class C, as shown in the typical drawing in Appendix III.
4.7) Inspection and approval by the Engineer shall be carried out prior to setting of forms.
Metal formworks must adhere to the shapes, lines, and dimensions specified in the working drawings, ensuring they are constructed to resist deformation under applied loads.
- The contractor shall carry out placing concrete of pile cap without formworks
7) 6) Concrete Casting for Pile cap
6.1) In order to place concrete, the Contractor will use concrete mixerconcrete pump and the standby alterntive is to use crane and basket
To effectively place concrete into a structure, a concrete pump is essential For layers of concrete measuring 80 cubic meters or less, a single pump suffices; however, for layers exceeding 80 cubic meters, two pumps must be utilized simultaneously Prior to casting, it is crucial to spray water on the formwork, rebar, and lean concrete surfaces To prevent excessive drops, pipes and short chutes should be used, ensuring that concrete is not dropped from a height greater than 1.5 meters Concrete should be cast in layers, following the specified casting speed, and placed from one end of the area to the opposite end For detailed procedures, refer to the Typical Setup Plan for Concreting Works in Appendix Va and the Typical Concrete Casting Sequence in Appendix VIa.
The standby alternative utilizes a crane in conjunction with a basket to effectively place concrete into the structure With extensive construction experience, we are committed to ensuring the quality of our concrete placement methods To maintain progress and uphold concrete quality, the Contractor will deploy sufficient cranes and baskets, with a minimum of two cranes and buckets, including a standby pump, for concrete casting Prior to casting, water will be sprayed on the form, rebar, and lean concrete surface Additionally, pipes and short chutes will be implemented to prevent concrete from being dropped freely from a height exceeding 1.5 meters Concrete will be cast layer by layer, adhering to the specified casting speed, and will be placed from one end of the structure to the opposite end For detailed procedures, refer to the Typical Setup Plan for Concreting Works in Appendix Vb and the Typical Concrete Casting Sequence in Appendix VIb.
Concrete consolidation must be achieved using approved mechanical vibrators that operate effectively within the mix When necessary, hand spading with appropriate tools should be employed to ensure adequate compaction The vibrators used should have the correct frequency and be capable of visibly influencing concrete with a 2cm slump over a circular area of 45cm radius A sufficient number of vibrators must be available to properly consolidate the concrete within 10 minutes of placement Additionally, at least three spare vibrators should be kept on standby at the site to ensure immediate continuity in case of equipment failure.
• Vibrator shall be penetrated into the previously cast layer through the new casting layer (see appendix VI)
• Concrete vibrators will not be used to transport concrete like a shovel inside the formwork during casting.
To ensure optimal results in concrete casting, it is essential to closely monitor the concrete condition, preventing it from hardening before the next layer is applied New concrete should be placed within a maximum of two hours after the previous layer has been set.
• Splattered and loose concrete on surface of form shall be removed before placing concrete
Regular inspection and monitoring of formwork tightness during casting are essential to prevent deformation, displacement, and leaks If any displacement occurs, it is crucial to promptly adjust and reposition the forms before continuing with concrete placement.
To ensure structural integrity, it is crucial to handle installed rebar carefully to prevent any dislocation during the concrete casting process Should any dislocation occur, immediate adjustments must be made to reposition the rebar before continuing with the concrete placement.
• Rebar for pier column/wall and any other rebar above the casting level shall be cleaned from splattered concrete during casting and after casting concrete.
6.3) Casting speed shall be monitored not to exceed the designed pressure considered on the design of formwork.
6.4) Casting of pile cap will be done layer by layer up to designed elevation; this will be done from one end to the other end Refer to Appendix VI.