1. ALUMINIUM SHUTTERING COMPONENTS
WALL COMPONENTS:
a) Wall Panel: - It forms the face of the wall. It is an Aluminum
sheet properly cut to fit the exact size of the wall.
WALL PANEL
b)
Rocker: - It is a supporting component of wall. It is L-shaped panel
having allotment holes for stub pin.
ROCKER
c) Kicker: - It forms the wall face at
the top of the panels and acts as a ledge to support.
KICKER
d) Stub Pin: - It helps in joining two
wall panels. It helps in joining two joints.
STUB PIN
e) Wall Tie:
- - It
helps in joining two parallel wall panels and it helps to maintain the spacing
of walls.
WALL TIE
5.2. BEAM
COMPONENTS:
a) Beam Side
Panel: -
It forms the side of the beams. It is a rectangular structure and is cut according to the size of the beam.
BEAM SIDE PANEL
b) Prop Head for Soffit Beam: - It forms the soffit beam. It is a V-shaped head for easy dislodging of the formwork.
PROP HEAD FOR SOFFIT BEAM.
c) Beam
Soffit Panel:
- It supports the soffit beam. It is a plain rectangular structure of
aluminum.
BEAM SOFFIT-PANEL
d) Beam Soffit Bulkhead: - It is the bulkhead for beam. It
carries most of the bulk load.
BEAM SOFFIT BULKHEAD
5.3. DECK COMPONENT:
a) Deck
Panel:
- It forms the horizontal surface for casting of slabs. It is
built for proper safety
of workers.
DECK
PANEL
b) Deck Prop: - It forms a V-shaped prop
head. It supports the deck and bears the load coming on the deck panel.
DECK PROP
c) Prop
Length:
- It is the length of the prop. It depends upon the length of the slab.
DECK PROP LENGTH
d) Deck
mid – Beam:
- It supports the middle portion of the beam. It holds the concrete.
DECK MID-BEAM
e) Soffit Length: - It provides support to the edge of the
deck panels at their perimeter of the room.
SOFFIT LENGTH
f) Deck
Beam Bar:
- It is the deck for the beam. This component supports the deck and beam.
DECK BEAM BAR
5.4.
OTHER COMPONENTS:
a) Internal
Soffit Corner:
- It forms the vertical internal corner between the walls and the beams,
slabs, and the horizontal internal cornice between the walls and the beam slabs
and the beam soffit.
INTERNAL SOFFIT CORNER
b) External
Soffit Corner:
- The external soffit corners forms the vertical external corner between
walls and / or beam faces and horizontal external corners between wall / beam
face and soffit of slabs.
EXTERNAL SOFFIT CORNER
c) External Corner: - The external corner connects vertical or horizontal form work together at right angles.
EXTERNAL CORNER
d) Internal
Corner:
- It connects two pieces of vertical formwork pieces at their internal
intersections.
INTERNAL
CORNERS
5.5.
FORMWORKS ASSEMBLE:
a)
WALL ASSEMBLY DETAILS
FIG:- WALL ASSEMBLY DETAILS
b) BEAM &
DECK PANEL ASSEMBLY DETAILS
FIG: - BEAM & DECK PANEL ASSEMBLY DETAILS
METHODOLOGY FOR FORM WORK
6.1
DESIGN
CONCEPT
During
the designs of form work the following points shall be considered:-
Ø
Unit weight of concrete
Ø
Type of structure
Ø
Rate of pouring of concrete
Ø
Pouring sequence of concrete
Ø
Tolerance of deflection
Ø
Vertical and lateral load including live and
vibrating loading.
The design
calculation and drawing for the different structure like slab, beam, column,
retaining wall etc. shall be made by in-house form work departments. The same
calculation and drawings shall be submitted to the client for information /
Records / Approvals.
6.2. CONSTRUCTION
ACTIVITIES WITH ALUMUNNNIUM SHUTTERING AS FORMWORK;
The construction activities are divided as Pre Concrete activities, During Concreting and Post Concrete activities.
They are as follows:
6.2. A. PRE-CONCRETE
ACTIVITIES:
i) RECEIPT OF MATERIALS ON SITE:
Ø Unload components from transport
and where possible, stack by code and size panels can normally be stacked
safely up to 25 panels high on skids or pallets.
Ø When stacked, hole in the
formwork should be aligned allowing easy identification by code.
Ø Ensure the first panel at the
bottom of the stack has the contact face upwards.
Ø All pins, wedges, wall ties,
sleeves, and special tools to be put into proper storage.
Ø Check to be carried out against
the packing list ensuring all items stated are received.
ii) LEVEL SURVEYS:
Ø A concrete level survey should be
taken on all sites and remedial work carried out prior to the erecting of
formwork.
Ø All level surveys should be taken
from T.B.M (Temporary Bench Mark).
Ø High spots along the wall line to
be chipped off to the proper level. Low
spots along the wall line should be packed to the required level,
using plywood or timber.
Ø Packing the corner and the Centre
of the wall length to the required level will be normally be adequate, as the
formwork when pinned together will bridge across low spots.
Ø Concrete (+10mm) and above must
be chipped to the correct level.
Ø After concreting, level surveys
should also be carried out on the top of the kickers.
Ø Kickers are manufactured with a
26mm slotted hole on the face to allow for adjustment after concreting.
iii) SETTING OUT:
Ø Only approved shell drawings
supplied by Formwork Design will be used for setting out.
Ø Setting out lines will continue
through openings, external corners etc., by a minimum of 150mm. This makes it
easier to fix formwork in position prior to concreting.
Ø The reference points and the
setting out points will be protected against accidental movement or damage.
Ø Transferring of reference points
from the level below requires to be done quite accurately.
Ø Survey Equipment will be used for
transferring the points through openings provided in the slab.
iv) CONTROL/CORRECTING
OF DEVIATIONS:
Ø A study of the deviation and
kicker level survey will confirm if any corrective action is required.
Ø If the kicker requires adjustment
for level, loosen the holding in bolt by turning anti-clockwise, adjust kicker
to the required position and retighten the bolt.
Ø Once the vertical formwork is
fixed in position, the external corners will be checked for plumbness. This
will determine if further action is required to control the deviation.
Ø In addition to the kicker levels,
the formwork can be pulled by using bottle screws and chain blocks; if the
formwork requires to be pushed adjustable props can be used.
v) ERECT FORM WORK:
Ø For the initial set up only
50mm*25mm timber stays can be nailed to the concrete slab, close to the
internal and external corners, to ensure the formwork is erected to the setting
out lines.
Ø All formwork begins at a corner
and proceeds from there. This is to provide temporary lateral stability.
Ø A single panel at a corner will
give sufficient lateral support to a very long section of wall.
Ø Ensure all edges of the formwork
and contact face are properly cleaned ad oiled prior to fixing in place.
Ø When satisfied the corner is stable
and the internal corner is positioned to the setting out lines continue
erecting the formwork to one wall.
Ø Initially only 2 no of pins and
wedges will be used to connect the formwork at this stage the pins and wedges
will have to be removed later to insert the wall ties.
Ø Alternatively the wall ties can
be positioned as the formwork is erected.
Ø For ease of striping, pin the
wall panels to the internal corners with the head of pin to the inside of the
internal corner if possible.
Ø Wall ties will be coated with the
approved releasing agent provided before fixing to the formwork.
Ø Fit the wall ties through slots
in the wall formwork and secure in position with pins and wedges.
Ø Prior to closing the formwork,
pre-wrapped corrugated PVC sleeves are placed over the wall ties.
Ø Sleeves installed with one end
fixed between the side rails of two adjoining panels, exposes the wall tie at
the opposite end, therefore impossible to retrieve the wall tie after
concreting.
Ø If any deviation of external
walls occurs, wall will be brought back to the correct plan location as quickly
as possible. This is done by slightly tilting the external wall forms in one
plane.
Ø If any deviation from plumb has
occurred in two directions, then this will be improved over two floors, one for
each direction. Realignment in two directions will not be attempted on a single
lift.
Ø A maximum of 10mm in vertically
improvement in one lift is sufficient.
vi) METHOD
OF ERECTING FORMWORK:
Ø One side is erected using only on
upper and lower pin and wedge connection. Later, ties are inserted at the
connection and fixing with pin and wedge.
Ø Then previously installed pins
are removed and those ties inserted and pinned. Subsequently, panels for the
other side are inserted between the existing ties and fixed with pins and
wedges.
The advantages of this Erection Method are as Follows:-
Ø Rooms can be closed and squared
by assembling only one side of wall panels. If misaligned, it is easier to shift
rows of single panels.
Ø If steel reinforcement is likely
to interfere with the placement of the ties, it can be seen and corrected
without delaying the pane erection.
Ø Enables fast start up of deck
teams as the first rooms can be closed quickly.
Ø Continuous steel reinforcement
for the walls creates a barrier between the two sides of the formwork, so the
work proceeds at the pace of single erector.
Special care must be taken at the lift shafts as
Follows:-
Ø The interior panels will align
properly on their own because they are set of the kicker from the formwork
below.
Ø Ensure the kickers are level and
will not affect the vertically of the lift shaft. However, the matching panels
are set on the concrete that may not be level.
Ø The ends of walls and door
openings will be secured in position by nailing timber stays to the concrete
slab.
Ø Walls require to be straightened
by using a string line and securing in place by nailing timber stays to
concrete slab.
Ø Vertically of door openings also to
be checked for plumb.
vii) ERECT
DECK FORMWORK:
Ø Normally deck panels can be
struck after 72 hours.
(Striking times should be confirmed by Client /
Consultant).
Ø The striking begins with the
removal of deck beam. Remove the 132mm pin and the beam bars from the beam
which has been identified for removal.
Ø This is followed by removing the
pins and wedges from the deck panels adjacent to the deck beam to be removed.
Ø The deck beam can now be taken
out.
Ø As the first panel in are rests
on the support lip of the soffit length, the adjacent panel will be removed
first.
Ø After removing the pins and
wedges from the panel to be removed, a panel puller can be used to beak the
bond from the adjacent formwork.
Ø Where there is no deck beam
support and the panels span from wall to wall, one wall will have the
supporting lip of the soffit length removed.
Ø Pins and wedges only to be
removed on the identified component that is to be struck.
Ø Deck panels remains in place
longer than wall panels and will not come away easily unless proper cleaning
and oiling is done during the erection process. Panels should confirm to the
sequence of erection.
Vii) PROP LENGTHS
(PL):
Whenever the PL's is to be removed, wooden mallet will be
used to strike the bottom of the PL in the same direction as the beam and holding
the PL with other hand.
6.2. B. DURING CONCRETE ACTIVITIES:
At least one supervisor & two Skilled Carpenters will
be on standby during concreting for checking pins, wedges and wall ties as the
pour is in progress. Pins, wedges or wall ties missing could lead to a movement
of the formwork and possibility of the formwork being damaged. This effected
area will then require remedial work after striking of the formwork.
Things to
look for during concreting;
i.
Dislodging of pins / wedges due to vibration.
ii. Beam
/ deck props adjacent to drop areas slipping due to vibration.
iii. Ensure
all bracing at special areas slipping due to vibration.
iv.
Overspill of concrete at window opening etc.
6.2. C. POST CONCRETE ACTIVITIES:
i) CLEANING:
All components should be cleaned with scrapers and wire
brushes as soon as they are struck.
Wire brush is to be used on side rails only.
The longer cleaning is delayed, the more difficult the
task will be. It is usually best to clean panels in the area where they are
struck.
ii) Transporting:
There are basic three methods recommended when
transporting to the next floor:
a. The heaviest and the longest, which is a
full height wall panel, can be carried up the nearest stairway.
b. Passes through void areas.
c. Rose through slots specially formed in the floor slab
for this purpose. Once they have served their purpose they are closed by
casting in concrete filter.
iii) Striking:
Once cleaned and transported to the next point of erection,
panels should be stacked at right place and in right order.
Proper stacking is a clean sign of a wall – managed
operation greatly aids the next sequence of erection as well as prevents
clutters and impend other activities.
INSTRUCTIONS:
To be imposed
on every worker, are the following things not to be done:
Ø
Do not lay bottom panel contact
face down, when starting a stack
Ø
Do not drop equipment from any
height
Ø
Do not use panels as ramp,
bridges or scaffold
Ø
Do not use hammer and wedges to
pull panels together
Ø
Do not drive wedges until full
length of panels are butted together
Ø
Do not use extreme hammer force
when installing wedges
Ø
Do not erect elements which are not
properly cleaned and oiled
(Deck panel
faces are oiled after erection)
It is the
minimum time before which formwork of freshly laid concrete structure should
not be removed. It depends on various factors like ambient temperature, type of
cement, type of structure etc. For ambient temperature of more than 150C
and concrete made with OPC cement and crushed stone aggregate stripping time
may be followed as a general guideline as per Clause 11.3 of IS: 456-2000.
|
Sr. No: |
Description |
Stripping Time |
|
1 |
Vertical
formwork for Cols, walls and sides of beams |
16
to 24 hours |
|
2 |
Slabs
( Props Remaining ) |
3
days (Subject
to 3days cube results ) |
|
3 |
Beam
soffit( Props remaining ) |
7
days |
|
4 |
Removal
of props to slabs: |
|
|
|
a.
Spanning up to 4.5 m |
7
days |
|
|
b.
Spanning over to 4.5 m |
14
days |
|
5 |
Removal
of props to beam and arches |
|
|
|
a.
Spanning up to 6.0 m |
14
days |
|
|
b.
Spanning over 6.0 m |
21
days |
Note:
Deshuttering
of panels can be started after achieving 10Mpa compressive strength of
concrete. Reproping should be maintained.
Or. Formwork removal will be based on 3days
cube strength.
6.4. PROPING AND
REPROPING:
Slab to be Casted (N)
ii. 70 % Props remaining @ N- 2
iii. 30 % Props remaining @ N- 3
6.5.
TOLERANCES
Tolerances
are the specified permissible variation from lines, grade or dimensions given
in the drawings. Unless otherwise specified, the following tolerances will be
permitted:
|
Sr.
No. |
DESCRIPTION |
PERMISSIBLE
DEVIATIONS |
|
1 |
Deviation
from specified dimension of cross section of column and beams |
-6
mm +12
mm |
|
2 |
Deviation
from dimension of footing. |
± 10
mm |
|
a) |
Dimension
in plan |
-12
mm +50
mm |
|
b) |
Eccentricity |
0.02
times the width of footing in the direction of deviation but not more than 50
mm. |
|
c) |
Thickness |
±
0.05 times specified thickness. |
|
3 |
Departure
from level shown on the drawing. |
± 6
mm |
|
4 |
Deviations Abrupt
irregularities/offsets caused by displaced or misplaced formwork lining or
supports. |
±10
mm |
|
5 |
Inserts Variation
in position along concrete surface In
plane position (flush with concrete face) |
±
10 mm ± 5
mm |
1.
ACTIVITIES BEFORE CONCRETING
Ø All formwork activities will be carried out in accordance with the
specification & drawings, structural reinforcement work will commence once
formwork is completed above 50% of plane area. MEP sleeves in beams &
insert plates can be started before starting beam side formwork.
Ø
Lay the main reinforcement bars of bottom
layer of the slab spaced evenly according to design or drawings, once
sufficient progress (around 50% area) is achieved in slab reinforcement bottom
layer, parallel MEP activities like electrical conduiting, insert plates, MEP
sleeves, MEP cut outs are started from bottom layer completed end to work in
progress end, so as there will be synchronization between civil & MEP activities.
Ø
Install bar chairs acting as spacers between
top and bottom reinforcements.
Ø
Lay the top reinforcements with distribution
bars fixed on first and the main reinforcements on the upper layer (transverse
direction).
Ø
After completing the slab top reinforcements,
clean and blow away the dust by using compressed air/hand held blowers.
Ø
Meantime, the surveyor must check the
formwork level and install the markings for the concrete level using auto level
instrument & leveling staff.
Ø
After the formwork level measurements are
done, furnish the copy from the surveyor and locate the area which varies from
the correct level.
Ø
After the adjustment is done, do a routine
formwork inspection to check the stability of the frames and runners.
Ø
Ensure the slab level markers are fixed nice
and tight so that it will not move during the concrete pouring operation.
Ø
Check all the formwork gaps and ensure that
they are plugged before concrete placement. Concrete slurry will flow through
the gaps and will lead to grout loss if not rectified.
Ø
Spray water to the formwork and
reinforcements to lower down the temperature.
Ø
Prepare the vibrator machine / check its
availability while waiting for the concrete truck to come. It is always good to
have a back-up vibrator if in case something goes wrong, so we have Diesel
operated vibrator in addition to electrical high frequency vibrator.
Concrete Mix Proportion
Ø The Mix Design shall be established for various grade of concrete to determine proportion of cement, aggregate, water and Admixtures to attain the required strength shall be either preparation of design Mix.
Ø For Design Mix concrete proportion of raw material shall be finalized as per IS 10262 “Recommended guidelines for concrete mix design”.
Ø
Minimum
Cement content, Water cement ratio shall be followed as per specification &
IS standards.
Ø
The compliance of a design mix for structural
concrete shall be judged by the strength of hardened concrete in comparison
with the specified characteristic strength.
Ø
Final Mix design of concrete shall be
submitted to for approval from client.
7.2 Batching of Concrete.
Ø Availability of all approved material shall be ensured by approved RMC
Vendor.
Ø In proportioning concrete, the quantity of both cement and aggregate
shall be determined by weight and as per approved Mix Design.
Ø The water-cement ratio shall be maintained as a constant at its correct
value. As per approved Mix design
Ø Determination of moisture content in both fine and coarse aggregate
shall be done on daily basis for required water correction.
Ø The concrete shall be thoroughly mixed to achieve required workability
at the point of pouring.
Ø Approved admixture shall be used in required quantity to achieve
workability and longer setting time. Dosage shall be as per approved Mix
Design.
7.3 Transportation
Ø Concrete transportation shall be done by Transit Mixer from batching
plant to the point of place to ensure that there shall not be any segregation.
Ø With every load of concrete
delivery slip (Batch Sheet) shall be issued mentioning dispatch date &
time, Grade of Concrete, Location, Quantity, Slump & Temperature of
concrete.
Ø Concrete shall be transported from the mixer to the formwork as rapidly
as possible by methods that will
prevent the segregation, loss of any ingredients
or ingress of foreign matter or water and will maintain the required
workability.
Ø Concrete shall be deposited as
close as possible to its final position to avoid segregation & re-handling
of the concrete.
7.4 Placement & Compaction of Concrete.
Ø Concrete Pour shall be commenced after getting approval (Pour card) as
per approved ITP.
Ø Before placing concrete, all equipment for mixing and transporting the
concrete shall be cleaned.
Ø he face of construction joint shall be roughened and all loose material
shall be removed & approved bonding
agent shall be applied prior to concrete.
Ø Sweet water shall be sprinkled on soil, PCC, shutter prior to concrete.
Ø Concrete shall be placed as nearly as practicable in its final position
to avoid segregation due to re-handling or flowing.
Ø Concrete shall be placed while it is sufficiently workable for full
compaction. It shall be worked around reinforcements and embedded items.
Ø The Concrete Shall be Placed and compacted before initial setting of
concrete.
Ø Free fall of concrete shall not be more than 2.0 m or as per IS code
guideline.
Ø Chutes, hopper gates & other points of discharge shall be so
designed or fitted with suitable baffles that concrete passing from them will
not segregate during its free fall into place.
Ø As concrete is placed, it shall be adequately vibrated with internal
vibrators to the point of consolidating into a dense homogeneous mass
thoroughly embedding the reinforcement and filling all corners and angles.
Ø Concrete shall not be moved horizontally by vibration. (Vibration will
be in controlled manners)
Ø Concrete shall be properly worked around the reinforcement, the embedded
fixtures and into the corners of formwork, so as to achieve finished surface of
concrete.
7.5 Finishing
& Curing
Ø All exposed concrete surfaces
shall be left reasonably smooth and free of excessive form marks and
honeycombing.
Ø Top surfaces of concrete in
walls, beams and floors shall be finished to the proper level. No holes or
rough patches shall remain.
Ø Newly placed concrete shall kept wet by the continuous application of
water for the first 7 days.
Ø Casting date shall be marked on all concrete elements for having track
of curing period.
Ø All vertical faces shall be
covered with Hessian cloth and kept wet.
Ø For Horizontal surface like slab, foundation etc. shall be cured by
ponding water.
Ø Curing compound shall also be used after prior approval and shall be
immediately applied after de-shuttering of the concrete element.
Ø Proper Construction joint shall be provided for the further lift.
Ø For construction joint shear key shall be provided throughout length of
wall, at center of column & foundation.
Ø Construction joint in slab & beam shall not be at center of its span
it should be at 1/3rd length of span and should be vertical as per consultant
or Client approval.
7.6
Precautions to avoid Cracks in Mass Concrete
Ø Plant mixed concrete shall have a temperature between 5 deg. C to 40
deg. C.
Ø Thickness of freshly laid
concrete layer shall not exceed 450 mm.
Ø Good compaction of the concrete
shall be secured. Slump of concrete shall be maintained to the minimum possible
to avoid possible shrinkage cracks.
Ø Mass concrete shall be protected from excessive heating and premature
drying by covering it with wet hessian cloth, as soon as the concrete gets a
set, enough to avoid disturbance of finished surface.
Ø Curing shall be done for a
minimum period of seven days.
7.7 Inspection
& Testing
Ø Testing shall include compressive tests of molded concrete cubes and
slump tests for consistency, according to IS 516 & IS 1199.
Ø For Sampling of Compressive
Testing set (6 Specimen) of cubes shall be prepared, which include 3 specimens
each for 7 days & 28 days as per IS 456.
Ø The fresh concrete shall be
sampled in accordance with IS 1199.
Ø Rate of sampling shall be as per
project specification.
Ø Slump test shall be carried out
to check the consistency of concrete.
Ø Inspection shall be carried out as approved ITP and Acceptance criteria
shall be as per applicable codes and specification.
= * =
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