2. CreatedBy:
Jay S. Singhania (14….6107)
Pratik Sisodiya(14….6108)
VirenTrivedi (14….6115)
Ajit Shiyal (14….6105)
Civil-B V-Sem
3. ¶ Formwork is the temporary structure used as a mould to caste structural
members at site.
¶ These are also knownas farmas or false work or shuttering.
¶ It is erectedat its correct positionbefore concrete is poured in it.
¶ This poured concrete is then consolidated and allowed to harden to give desired
strength.
¶ It is allowed to remain in position till the poured concrete gains sufficient strength
to withstandthe stresses coming on it in absence of formwork.
¶ After this the formwork is removedand this process is knownas stripping.
4. Costly item and its proper design and maintenance can affect
economic considerations considerably.
It costs almost as much as 20-25% of the total construction cost
of the structural members in building works and even more in
the case of bridges.
5. For construction of lot of similar elements, formwork is designed in
such a way that stripping and erection involves least possibilities of
damages and least labor, and also this is made out of separate panels
with provisions of adjustments.
For this type of formwork, during erection or stripping, only bolts or
pins are to be inserted or removed.
Such type of formwork should preferably be of structural steel but
timber formwork may also work with being economical, considering
disadvantages of warping, swellingand shrinkage effects.
6.
7. ¥ Requirements of timber formwork:
i. Be well seasoned.
ii. Be light in weight.
iii. Be easily workable with nails without splitting.
iv. Be free from knots.
¥ Standard formworks can be adopted for different components of formwork
for shuttering of different sections of 4.5m span and 3.5m height.
¥ For structures not meeting the above demands, special design of formwork
should be done based on the dead loads and live loads acting on the structure
and also some relevant factors.
¥ For normal constructional work with same dimensions of formwork,
shuttering can be also formed in such a way that it can be moved to the other
location without dismantling and fixed there in the new position.
¥ Each set of formwork can be used 10-12 times for normal constructional
works.
8. ¥ For shuttering of concrete surfaces to be
exposed, smooth and even surfaced
formwork should be used to obtain directly
smooth exposed surface of concrete and
thus eliminating the need of finishing to the
concrete members.
¥ For surfaces that are not exposed directly,
uneven or undressed timber planks can be
used.
¥ The formwork should be jointed using the
grooved and tongued joints.
9.
10. ╬ Consists of panels fabricated of thin steel plates stiffened
along the edge by small steel angles, which can be held
together by clamps and bolts along each edge, and kept in
alignment using vertical or horizontal timber or steel
centring.
╬ Usual size of wall or slab panels vary from 60cm * 60cm to
60cm * 120cm (2’ *2’ to 2’ * 4’).
╬ These type of formwork is mostly used in large
constructional projects and where repeated use is possible.
╬ These are extensively used for pre-cast concrete members
and also the most suitable for shuttering of circular or
curved sections such as tanks, columns, chimneys etc. and
for large structures like large sewer, tunnels, retaining
walls etc.
11.
12.
13. Use of plywood is getting more popular these days,
and these are attached to the timber frames to
make up panels of desired shapes and sizes.
These types of shuttering can be easily assembled
with the use of bolting, riveting etc.
These types of shuttering is highly suggestive in
the large constructional projects where exposed
concrete surface is large in area such as faces of
retaining walls, concrete dams, floor slabs etc.
14. These type of formwork can be used
economically in following considerations:
i. Perfectly smooth and finished external
surface can be obtained and thus expense of
external finishing (plastering) can be saved.
ii. Large sized panels can be formed thus saving
the labour charges for assembling and
dismantling.
iii. Number of re-uses can be increased to 20-25
times.
15. Easy in erection and stripping.
Can be used repeatedly for many times.
Comparatively stronger.
No possibilities of shrinkage, warping or
swelling.
17. Formwork material must be cheap and easily available in local market.
It must be sufficiently rigid to avoid excessive deflections while
concreting.
Must be strongenough to effectively resist all loads comingon it.
Easy to erect and strip.
Must rest on strong and un-yielding supports.
Joints should be stiff and strong and water-tight.
Surface in direct contact (internal surface) must be enough smooth to
give finishedsurface.
It must be water tight and non absorbing to maintain w/c ratio avoiding
leakage/absorbingof water fromthe concrete.
18. Dead load of green concrete
Hydrostatic pressure of green concrete
Live load of working labors
Impact effect at the time of pouring concrete into the
formwork.
Vibrations in concrete during pouring concrete into
the formwork.
19. Temporary live load due to labors
and equipments including impact
may be taken as 370 kg/m2.
Planks for formwork of vertical
facing of columns etc. are known
as sheathing.
Planks for formwork of floor
slabs are known as decking.
20. of concrete, in initial stages of pouring
depends upon amount of water, size of
aggregates, rate of pouring etc.
Hydrostatic pressure is maximum at
the time of pouring, but gradually
decreases with setting of concrete
and hardening.
Hydrostatic pressure mainly depends
on the depth of concrete poured
before starting of setting.
Hydrostatic pressure considerations
may include height of concrete which
21. Equivalent fluid weight of concrete up to 1.5m height may be
assumedas2300 .
Equivalent fluid weight of concrete may be reduced to 1200
when poured for 6mheightin one hour.
For pouring heights between 1.5-6.0m and setting time ¾-1 hour,
equivalent fluid weight may be calculated by linear interpolation
between 2300-1200 .
Maximum deflection of sheathing and joists must be limited to
2.5m.
3
m
kg
3
m
kg
3
m
kg
27.
Sr.
No Structural Member
OPC
(Ordinary Portland
Cement)
RapidHardening
Cement
1 Beamsides,walls & Columns 2-3Days 2 Days
2 Slab (Vertical Supports remains intact) 4 Days 3 Days
3 Slab (CompleteFormworkremoval) 10 Days 5 Days
4 Beams(Removal of Sheeting, Props
remains intact)
8 Days 5 Days
5 Beams& Arches (Completeformwork
removal) (upto 6 m span)
14 Days 5-8 Days
6 Beams& Arches (Completeformwork
removal) (more than 6 m span)
21 Days 8-10 Days
