civil engineers must

1. FORMWORKFORMWORKFORMWORKFORMWORK

2. FormworkFormwork
Concrete being plastic material in fresh state, is kept in a
moulds till it gain reasonable strength, this temporary
structure is called “Formwork”.
It is closed from all sides and can carry the hydrostatic load
of fluid concrete, additional load due to vibration, and load
of men and machinery.of men and machinery.
Formwork should be such that it can be easily removed after
hardening of concrete.
Timber, plywood panels or steel sheets are used for
formwork. The initial cost of steel forms may be high but
they can be repeatedly used for a number of times.

4. ShutteringShuttering
Shuttering is a temporary platform constructed with the help
of wooden planks, wooden logs, steel rods or bamboos over
which formwork is supported and ultimately pouring of
concrete is done.

5. scaffoldingscaffolding
Scaffolding is a grid of bamboos, wooden planks or circular
steel pipes by which labour can have access to any point of
the structure to be constructed and further formwork and
shuttering can rest over it .
Steel scaffolding is most commonly used as it is easy to
dismantle and reassemble.dismantle and reassemble.

10. ShoringShoring
Shoring is the temporary support given to the existing
structure for repair purposes. When dismantling any central
building, the surrounding building is also temporarily
supported.

15. Basic Requirements of a Good
Formwork
Basic Requirements of a Good
Formwork
Formwork must be strong enough.
Formwork should be smooth to get a smooth surface
of the required member.
Formwork should be true.Formwork should be true.
Formwork should be such that it can easily be
removed without damaging the surface.
Deflections is the most important considerations.
Formwork must be water tight.
Formwork should be as economical as possible.

16. Formwork CostFormwork Cost
Cost of Formwork for RCC
Concrete 35%
Reinforcement 35%
Formwork 30%
The exact proportions of cost are, however, affected be the
following factors:
(i). The simplicity or complexity of the structure.
(ii). The availability of the repeated formwork.
(iii). The specified surface appearance of the concrete.

17. Formwork CostFormwork Cost
Cost of Formwork for Building Structures
Formwork cost is a major part of the total cost and normally
varies from 30% to 65% for building works; however, for
complicated works or with special surface finishes such as
helical stair cases or for the construction of minars, it mayhelical stair cases or for the construction of minars, it may
increase up to as much as 80%.

18. Formwork CostFormwork Cost
Cost of Formwork for Huge C.E. Works
The cost of formwork varies from 5% to 25% of the total
cost for bridges, highway, and dam construction, etc.
Such jobs are bigger in magnitude and again lot of money isSuch jobs are bigger in magnitude and again lot of money is
required for formwork necessitating careful design.

19. Wooden Formwork for R.C.C.
Walls
Wooden Formwork for R.C.C.
Walls
It includes sheathing, studs, wales, ties and braces.
Sheathing is the layer which constitutes the inner surface of
the form and is immediately in contact with the concrete.
If solid timber is used for sheathing, it may be 1", 11/4", 11/2",
2" thick, the opposite sides of the wall form are held in
correct positions by steel form ties, which resist the lateral
pressure of the concrete and serve as spacers to govern
width of the space between the forms.

20. Wooden Formwork for R.C.C.
Walls
Wooden Formwork for R.C.C.
Walls
The form ties usually have a safe working strength of 3000
lbs.
Sheathing is supported by closely spaced vertical timber
studs which are further supported by the horizontal wales.
The sizes of studs and wales may be 2" x 4", 2" x 6", 3" x 4",The sizes of studs and wales may be 2" x 4", 2" x 6", 3" x 4",
3" x 6" and 4" x 4", etc.
Steel ties are fixed with the help of ties clamps to the wales
and these are cut to remove the formwork when concrete is
hardened.
The form, as a whole, is stabilized by inclined braces
consisting of wooden battens or bamboos etc. Braces are
held rigidly in position by cleats on the form and by properly
driven stacks at the ground.

23. 9’6”
Wall
tie
3/4” plywood sheathing2”x 4”x 10’- 0 “ stud2- 2”x 4”
wale
2”x 4” x 10’- 0”
brace @ 6’- 0”
Concrete Footing
9’6”
2”x 4” sill
25’4”
Side ElevationSection through the Wall
2”x 4”x 3’- 0”
Stake @ 6’- 0”

26. Pressure on the FormworkPressure on the Formwork
Maximum pressure of fresh concrete on the formwork is
mainly influenced by the following factors.
1) Rate of pouring of concrete which is generally 4 to 5 ft per
hour.
2) Temperature of concrete. If temperature is lower, the2) Temperature of concrete. If temperature is lower, the
concrete will remain in fluid form for longer time.
3) Workability of concrete. Workable concrete will have more
fluidity and hence will exert more pressure.
4) Thickness of concrete wall. Pressure will be lower in thin
walls because of the arching action in the cross-section.
5) Vibration of concrete.

29. Floor Slab Formwork or Deck
Formwork
Floor Slab Formwork or Deck
Formwork
Following points are important for deck formwork.
1) It should be properly designed to withstand the imposed
loads.
2) Loads are taken directly by plywood/ steel/solid timber
soffit sheathing. The sheathing and joists (secondarysoffit sheathing. The sheathing and joists (secondary
beams) must be water tight to prevent any leakage or
grout.
3) Normally the size of panels used for sheathing is 8 x 4 in.
and these are placed side by side.
4) Plywood sheathing, if used, is normally thick otherwise
thick commercial wooden planks may be used for the deck
formwork.

30. Floor Slab Formwork or Deck
Formwork
Floor Slab Formwork or Deck
Formwork
5. Soffit sheathing is supported by timber-joists (secondary
beams), which are further supported by more widely
spaced joists (main beams) at right angles to the secondary
beams. Main beams transfer load to adjustable metal props
and then the load is carried to the foundation.
6. It may be designed for a particular surface-finish if
required.
7. Double system of joists allows the vertical props to be
spaced at reasonable distance in-between to carry full load
but, at the same time, to permit the movement of men and
machinery in-between.
8. Lateral and diagonal bracing of props may be provided for
stability, which prevent side sway.

32. Formwork for Beam & Slab
Floor
Formwork for Beam & Slab
Floor

33. Formwork for ColumnsFormwork for Columns
This type of form-work consists of two end and two side
planks built in one unit or panel.
The height of each panel is built equal to the storey height
less slab thickness and the floor sheeting.
The two end planks are built in width equal to theThe two end planks are built in width equal to the
dimensions of the column plus twice thickness of the
sheeting. The width of the sheeting will be same as the
dimension of the column.
The yokes will project 20 to 25 cm beyond the sheeting at
each end as shown in fig. The spacing of the yokes will be
same on both the sides. Bolt holes are created in the side
yokes, about 3 mm larger than the size of the bolt, for
passing and tightening the bolts easily.

35. Formwork failuresFormwork failures
Generally some unexpected event causes one member to fail,
then others become overloaded or misaligned and the entire
formwork structure collapses.

36. Raft foundation formworkRaft foundation formwork

37. Raft foundation formworkRaft foundation formwork

38. TYPESTYPESTYPESTYPES OFOFOFOF CIVILCIVILCIVILCIVIL ENGINEERINGENGINEERINGENGINEERINGENGINEERING CONTRACTSCONTRACTSCONTRACTSCONTRACTS
Some of the commonly used types are explained
below:
1- Bill of Quantities Contract.
This type of contract which includes a BOQ (billThis type of contract which includes a BOQ (bill
of quantities) priced by the contractor is the most
commonly used form of contract for civil
engineering works.
This type of contract is also known as “Item
rate contract”. Bill of quantities greatly assists in
keeping the tender cost as low as possible because
there is maximum competition among the
contractors. 40

39. 2- Scheduled Contract
In this type of contract the client refers to a
schedule of unit rates covering each item of work
and ask the contractors, when tendering, to quote a
percentage above or below the given scheduled
rates
when it is above, it is called premium
and when below, it is called rebate or discount)and when below, it is called rebate or discount)
When a contract includes both scheduled and non-
scheduled items then the contractors are asked to
quote an overall premium on the total cost of
scheduled items but, as regards the non-scheduled
items are concerned, the contractor will mention the
item-rates and no extra premium would be
permissible.
41

40. 3333---- LumpLumpLumpLump SumSumSumSum ContractContractContractContract
In a Lump Sum Contract, the contractor undertakes to execute
certain specified works for a fixed amount of money.
The nature and extent of the work are normally indicated on
drawings
The nature of materials and workmanship are described in
specifications
But no BOQ is provided.
4444---- LabourLabourLabourLabour ContractContractContractContract4444---- LabourLabourLabourLabour ContractContractContractContract
This is a contract where labour is provided by the
contractor but all the materials are supplied by the client.
It is suitable for those cases where an employer is in a
position to buy large quantities of materials at favourable
prices.
The advantage is that the speed of work will be increased
but, at the same time, there will be more wastage of
materials.
Labour rates for the scheduled items are also given in the
42

41. 5555---- CostCostCostCost PlusPlusPlusPlus PercentagePercentagePercentagePercentage ContractContractContractContract
In the cost plus percentage contract, the accounts are
properly maintained by the contractors showing the actual
expenditure on the work.
This is supported by proper receipts and invoices (bills,
cash memos, etc).
The profit of the contractor is decided as a negotiated
percentage, which may vary from 10 to 25% of the
actual cost of contract.
6666---- CostCostCostCost PlusPlusPlusPlus FixedFixedFixedFixed ProfitProfitProfitProfit ContractContractContractContract
This is similar to the previous type of contract with the
difference that the amount of profit is fixed and will not vary
with increase or decrease of actual cost of the work. Proper
maintenance of accounts by the contractor is must. However,
in this category, the contractor will try to complete the work
as early as possible.
Cost plus percentage and cost plus fixed profit contractors are
together called ‘Reimbursement contracts”.
43

42. 7777---- PackagePackagePackagePackage DealDealDealDeal ContractContractContractContract
If a contracting firm is well-reputed and provides both
design and construction facilities, the project as a whole may
be awarded to this firm; the agreement become a “Package
Deal Contract”.
Special type of buildings such as hotels, picture houses,
shopping plazas, etc., may be built on the basis of package
deal contract. However, the success of such a contract mostlydeal contract. However, the success of such a contract mostly
depends upon the reputation and understanding of the firm
with the client.
8888---- SerialSerialSerialSerial ContractContractContractContract
If a contractor is already working on certain contracts at
a construction site and later on more works are planned on the
same site, these works may be awarded to the same
contractor,
Generally at the same rates, depending upon his previous
performance. This becomes a serial contract
44