TABLE OF CONTENTS
1.0
INTRODUCTION
2.0
REFERENCES
3.0
RESOURCES
4.0
METHODOLOGY
4.1 Flowchart for concreting
of floor slab & Lift wall
4.2 Reinforcement
4.3 Formwork
4.4
Concrete placing, compaction and finishing
5.0 RESPONSIBILITIES
6.0
QUALITY ASSURANCE / INSPECTIONS AND TESTING
6.1 Material
6.2 Inspection for Construction
7.0 SAFETY
PLAN
8.0
ANNEXURE
Details of Slab and Beam Supporting
Data Sheet of Nitrobond SBR Emulation
1.0
INTRODUCTION
This
method statement specifies the sequence and methodology to be followed for Concreting
of Floor slab & Lift wall.
2.0
REFERENCES
Structural
Construction Drawings
Approved
Shop Drawings
Project
Specification
3.0
RESOURCES
3.1
Material
1. Timber
– 50 x 50 ,25 X 50 , 100 x 100 mm
2. 15
mm thk. Plywood sheets
3. GI
Pipes / acro jacks
4. Reinforcement
5. Ready-mix Concrete ( as per approved mix design )
The mix proportions are designed by mix
design and verified by Trial mix and trial workability tests.
1. Batching plant
2. Truck
Mixers
3. Pump
Cars
4. Concrete
Distributor
5. Shovel/Mamoty
6. Porker/Shutter
Vibrator
7. Level
Bar
8. Level
Machine and staff
9. Concrete
Chute
10. Tower
Crane with Bucket
11. Mason
Trowel
12. Power
Trowel
13. Plumb
bob
14. Water
pressure gun m/c
15. Wire
brush
16. Compressor
17. Scaffolding
3.3
Man Power
1. In charge
Engineer (Structural)
2. Concrete In charge Engineer
3. Assistant Engineer
4. Construction Supervisor
5. Safety Officer
6. Survey Helper
7. Concrete Forman
8. Masons
9. Skilled Workers
10. Unskilled Workers
11. Standby Carpenter
12. Standby MEP Service Workers
13. Machine Operators
4.0
WORK PROCEDURE
4.1 Flowchart for concreting
floor slab & Lift wall
|
Cleaning, Setting Out and
Marking
|
Formwork for Beam, Slab, Lift
Wall
|
Formwork for Beam, Slab, Lift
Wall
|
|
If not approved
|
|
Fixing of Rebar and MEP items
for Beam, Slab, Column, and Lift Wall
|
|
·
No of Trucks
·
Method of Pouring (Pump Car/Tower Crane)
·
Concreting group
·
Compaction method & Equipment
·
Sampling & Testing
|
|
Approval for concreting
|
|
Arrangement for Concrete
|
|
If Approved
|
|
Sampling &
Testing
|
|
Concreting
|
|
Curing
|
|
Surface finish
|
4.2
Reinforcement
·
The rebar diameter, number, spacing and
lap length are to be as per the approval drawing and bar bending schedule.
·
Adequate concrete cover to be maintained
on all rebars.
·
Reinforcement should be installed as
given in the drawings being careful to maintain the specified cover, Lap
length, Spacing.
·
The line and level of rebar is to be
checked prior to casting
·
The rebar will be fixed in such a manner
that its stability is assured in all respect.
·
After the installation they should be
check and approved by the consultant engineer before placing the concrete.
·
The area will be cleaned thoroughly by
handpicking debris, blowing out sand if any with a compressed hose.
4.3 Formwork
·
For fixing bottom formwork of beams,
beam bottom levels shall be measured from offline to structural floor level
marked on column and position of beam shall be measured from the grid line
marked on columns faces & on floor slab.
·
All material use for temporary form
works should be cleaned and clear from any deflection
·
Shutters will be treated with shutter
releasing agent to enable easier stripping.
·
Place formwork and supports to its
dimensions correctly and ensure that lines and levels are within the
tolerances.
·
All formwork shall be erected and placed
in accordance with the construction drawings. The placement of the formwork
should be accurate. U jack ,T jack and Acro Jack arrangements shown in drawing
shall be properly manage to avoid deflection in beams, slab and near to
construction joints. (Refer SKRD /SK/SBS/09)
·
Top levels of Jacks shall be places +5mm
to require level and it shall be checked and adjusted to required level while
concreting for avoid deflection.
·
Formwork for walls and elsewhere shall
be arranged for height of as instructed by the consultant for a single pour.
Where necessary panel openings are to be provided in the forms for cleaning,
inspection, access of vibrators etc.
·
Before placing of concrete ties and
fixings shall be positioned and all openings, holes, pockets shall be fixed to
the formwork carefully.
·
Before placing concrete make sure the
formwork joints and the minor gaps are properly sealed by checking Level of bottom forms , Spacing of support,
Sectional dimensions, Gaps between form panels , Cleaning of forms panels &
construction joint , Tightening of support and bracing
·
Formwork should be removed in such a
manner that no shock or damage shall result to the concrete.
·
Construction joint shall be formed
vertically, horizontally using plywood, 2”x 2”and 1”x 2” timber. Loose
aggregate and cement grout will be chipped off after removing stopped boards. Nitobond
SBR emulation Which is equivalent emulation to Barra Emulation, shall be used
for all the vertical construction joints according to manufactures
Specification (Due to unavailability of Barra Emulation in Finco Stocks.
Manufactures Data Sheet of Nitobond SBR
is attached herewith.)
·
Shear keys will be provided at
construction joints where slab thickness greater than 200m.
·
Formwork Shall not be removed until the concrete
has acquired sufficient strength to support safely its own mass and any
superimposed load without exceeding acceptable deflection
·
Formwork stripping without admixtures shall
be done according to following table to avoid thermal cracks ,shrinkage cracks
and cracks due to deflection while removing formwork support
|
Member Type
|
Member
|
Effective Span (m)
|
Minimum Stripping Time (days)
|
|
Vertical & Unloaded
|
Wall, Column, Beam Side
|
-
|
2
|
|
Vertical & Loaded
|
Wall, Column or Load bearing structure
|
-
|
5
|
|
Horizontal
|
Slab
|
< 3 m
|
7
|
|
3m-6m
|
10
|
||
|
>6m
|
14
|
||
|
Horizontal
|
Beams
|
< 3 m
|
10
|
|
3m-6m
|
14
|
||
|
>6m
|
21
|
·
Formwork stripping of Member type
Vertical & Unloaded (Wall, Column, and Beam Side) shall be done in 12 hours
using admixtures.
·
Re stripping formworks within the
tolerance limits of gradual irregularities and abrupt irregularities shall be sampling
as Class S1, S2, S3 and S4 according to Project Specification.
4.3 Concrete placing,
compaction and finishing
·
All surfaces shall be cleared
thoroughly.
·
Appropriate arrangement and approval for
pouring concrete shall be obtained from consultant.
·
Pump car or Tower crane will be used as
per site condition.
·
Target slump will be maintained as per
the approved mix design.
·
Concrete, during and immediate after
depositing, shall be thoroughly compacted. The compacting shall be done by
mechanical vibrator.
·
Pouring height should not exceed more
than 1.5m to prevent segregation.
When this height exceeds the 1.5m there
are two procedures need to be practiced.
Ø Lowered
the concrete pump car boom outlet into the concrete element.
Ø Make
a pocket in a lower height than 1.5m in concrete element. Once concrete filled
up to that close the pocket and pour the concrete for remaining height.
·
Concrete shall be placed in the forms as
close as possible to its final position in a single operation to the full
thickness of slabs and beams.
·
The Concrete in-charge shall organized
the pouring of concrete in such a manner that once concreting of a section has
started the operation shall be continuous and each operation shall be completed
prior to a stoppage.
·
Construction joints shall be provided
and the concrete shall be poured continuously between two adjacent joint.
·
Adequate
illumination shall be provided during night concreting.
·
Wet curing with water shall be carried
out to keep the concrete in contact with water once the concrete has set.
Concrete curing shall be carried out as specified and wet gunny bags shall be
used for curing vertical concrete surfaces and continuous wetting with water
shall be done for floor slab curing.
·
Curing shall be continued for minimum of
7 days according to Project Specification.
·
Surface
defects if any corrected as per the engineer instruction.
Batching plants
1. Sanken
Construction (Pvt) Ltd.
2. City
concrete (Pvt) Ltd.
5.0 RESPONSIBILITIES
|
Position
|
Responsibility
|
|
Engineer in charge (structural)
|
1. Get
approved for Concreting (i.e. for R/F,
F/W and for Services)
2. Cleaning
of debris in the form work.
3. Sealing
the joints of formwork to avoid the grout leaks.
4. Arranging
all infrastructures for Concreting.
5. Monitoring
of slab deflection during concreting.
6. Curing
of Concreted elements.
|
|
Concrete
In charge Engineer
|
1. Estimating
the required Concrete volume and order from the batching plant.
2. Testing
and Sampling the Concrete.
3. Keeping
records of concreting.
4. Handling
the traffic of the Concrete truck mixers.
5. Quality
controlling of Concreting.
|
|
Assistant
Engineer
|
Assist
to the Tower In charge.
|
|
Construction
Supervisor
|
1. Assist
to the Concrete In charge.
2. Handling
the Concrete gang.
|
|
Concrete
Forman
|
Handling
the Concrete gang.
|
|
Survey
Helper
|
Maintaining
the verticality and required levels of the concrete elements.
|
|
Admin
Officer
|
Providing
the welfare facilities for Concreting staff and for workers.
|
|
Safety
Officer
|
Maintain
Safety and Health in the working area.
|
Table
5.1 Responsibilities
6.0 QUALITY ASSURANCE /
INSPECTIONS AND TESTING
6.1.1
Concrete
Slump Value : 150mm +-
Or
Grades of Concrete : 30N/mm2
for Superstructure
Concrete Sampling &
Testing Plan
One sample shall be taken from any batch, selected
randomly to represent an average volume of not more than 20 cubic meters
The Test Plan
6 cubes (7days 3nos, 28days 3nos)
Test Results
At least two test specimens from sample shall form a
single result;
The difference between the strength of two specimen
prepared from the same sample shall not exceed 15% of the mean strength.
The allowable range (maximum minus minimum value) of
the strength of 3 cubes made from the same sample shall not exceed the 20% of
the average value of the 3 cubes.
Seven days strength may be taken to be 75% of the 28
days cube strength (approximately)
Curing period for test specimen
(a)
28 days
(b)
Any other curing method as a structural design
Engineer’s recommendation.
6.1.2
Reinforcement
Sample
Three
bars from each diameter shall be taken for one sample. Three samples shall be
taken for one test.
Frequency
of Sampling
Every
500 tons of steel one sample of each bar shall be tested for mechanical
properties according to BS 4449.
6.2 Inspection for Construction
All kinds of inspection for
construction shall be carried out by the site Engineers along with Engineers
representative and QA/QC Engineer of SANKEN as per the standards and
specifications.
However, prior information shall be given to
Consultant representative at site to proceed necessary checking’s periodically
& make final comments.
Inspection shall be carried out while progressing of
the work & approval shall be granted without affecting to the progress of
the work.
7.0.SAFETY PLAN
Safety of the
personnel and properties is to be given prime importance and al the works to be
carried out without causing any accidents or property damages.
·
Adequate access and egress should be
provided to the site for work
·
All workers should wear basic personnel
protective equipments.
·
All the equipment, tools being used for
the work should be in good working condition and maintained.
·
Adequate
illumination shall be provided during night concreting.
·
First aid facilities and vehicles for emergency
cases shall be available at site.
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