1. FORMWORK for Civil Engineering Construction Works
Dr V Srinivasa Reddy
Professor of Civil Engineering
GRIET
Lecture 2

2. Formwork v. Falsework Formwork includes Falsework
Formwork and Falsework are separate
Formwork is the Mould that holds fresh concrete
False work supports formwork and other structures (such as precast girders)
There are two types of Formwork:
1. Vertical Forms
2. Horizontal Forms
Vertical Forms are used to hold pressure
Horizontal Forms are used to hold weight

3. Vertical Forms Vertical Forms are used to form: Walls Columns Piers
Abutments
Beamsides
Other Vertical Concrete Surfaces

4. Vertical Form: Wall Form

5. Vertical Form: Shear Wall

6. Vertical Form: Retaining Wall

7. Vertical Form: Sidewall/Abutment

8. Horizontal Forms Bridge Decks Floors Overhangs
Horizontal Forms are used to form:
Bridge Decks
Floors
Overhangs
Other Horizontal Concrete Elements

9. Horizontal Form: Metal Bridge Deck

10. Horizontal Form: Bridge Overhang

11. Horizontal Form: Bridge Overhang
(Cantilevered Beams)

12. Pressure
Vertical Forms are designed to resist pressure. Form Pressure is affected by:
The Concrete Mix
The Rate of Placement
The Temperature of the Concrete
The Weight of the Concrete

13. Weight
Horizontal Forms are designed to hold the weight of the concrete. The design weight is determined by:
The Depth of the Concrete
The Unit Weight of Concrete
The Amount of Reinforcing

14. Manufactured Forms
What is the Pressure Capacity?

15. Job-Built Forms
Is it designed according to specification?
Is it constructed according to the design?

16. The Perfect Wall??
Bad Joint
Blemish

17. What do you think?

18. Is the concrete being placed properly?

19. Falsework Supporting Pier Cap Formwork

20. Falsework Supporting Precast Concrete Girders

21. NORMAL DEFECTS IN FORM WORK1.
The props or supports of form work were not in plumb and were not cross braced. 2.
The ground supports (sills) to props or shores were poor and therefore the formwork settled. 3.
Wedges were not tightened properly to the shores. 4.
There was insufficient thickness of shuttering unable to bear lateral pressure imposed by wet concrete, specially in columns. 5.
Shuttering plates were not cleaned and oiled or oiled with dirty oil. 6.
There were many insufficient and loose connections in centering and shuttering. 7.
Form work was removed before time. 8.
Form work was not planned and designed properly. 9.
In the case of beam forms, proper provision for retaining the side was not made. Hence, the concrete beam bulged on the sides.
10.
The shuttering was poorly made with cracked and warped timber planks having lot of holes and knots.
11.
Through bolts for the R.C.C. walls form work for an underground tank were used. Later the holes made by the bolts could not be plugged.
12.
'Ballis' were resting on bricks or brick pillars.
13.
'Ballis' were not in one piece and were having joints in between. Joints were also improperly made and no additional cross bracing was provided at the joint.

23. Formwork for Foundations
Wall foundations
It consists of
Plywood Sheeting
Struts

24. Formwork for Foundations
Column Foundations
It consists of
Side Supports
Side Planks
Cleats
Cleats
Side Support
Side Planks

25. Formwork for Wall It consists of
Vertical Posts
It consists of
Timber sheeting
Vertical posts
Horizontal members
Rackers
Stakes
Wedges
After completing one side of formwork reinforcement is provided at the place then the second side formwork is provided.
Struts

26. Formwork for Column It consists of the following
Side & End Planks
Yoke
Nut & Bolts
Two end & two side planks are joined by the yokes and bolts.

27. Formwork for Slabs & beams
It consists of
Sole plates
Wedges
Props
Head tree
Planks
Batten
Ledgers
Beam formwork rests on head tree
Slab form work rests on battens and joists
If prop height are more than 8’ provide horizontal braces.

28. Formwork for Stairs It consists of Vertical & inclined posts
Inclined members
Wooden Planks or sheeting
Stringer
Riser Planks
Riser Planks

29. Removal of formwork
Time of formwork removal depends on the following factors
Type of Cement
Rapid hardening cements require lesser time as compared to OPC (Ordinary Portland Cement)
Ratio of concrete mix
Rich ratio concrete gain strength earlier as compared to weak ratio concrete.
Weather condition
Hydration process accelerates in hot weather conditions as compared to cold and humid weather conditions.

30. Time of Removal of formwork
Structural Member
OPC
(Ordinary Portland Cement)
Rapid Hardening Cement
Beam sides, walls & Columns
2-3 Days
2 Days
Slab (Vertical Supports remains intact)
4 Days
3 Days
Slab (Complete Formwork removal)
10 Days
5 Days
Beams (Removal of Sheeting, Props remains intact)
8 Days
Beams & Arches (Complete formwork removal) (up to 6 m span)
14 Days
5-8 Days
Beams & Arches (Complete formwork removal) (more than 6 m span)
21 Days
8-10 Days

31. Maintenance of formwork
Due to continuous use wooden planks & steel plates surfaces become uneven and require maintenance.
For wooden formwork use cardboard or plastic fiber board. Bolt hole places must also be repaired.
For steel formwork plates must be leveled by mallet and loose corners must be welded.

32. Cost of formwork
For normal works cost of formwork is about 30%-40% of the concrete cost.
For special works cost of formwork is about 50%-60% of the concrete cost.
Formwork cost is controlled by the following factors
Formwork Material cost
Formwork erecting cost
Formwork removal cost
Formwork jointing cost (Nails and Cables)
Labor charges.

33. Types of Scaffolding Needle Scaffolding or Cantilever Scaffolding
Following are the types of scaffolds
Brick layer’s Scaffolding or Single Scaffolding
Mason’s Scaffolding or Double Scaffolding
Ladder Scaffolds
Needle Scaffolding or Cantilever Scaffolding
Suspended Scaffolds
Steel or Tubular Scaffolds

34. Definition
Scaffold
It is the temporary support system provided for the construction & maintenance purposes.
It consists of supports and a working platform for workers and Materials.
Scaffolding
Method of construction of scaffolds is called scaffolding.

35. Single Scaffolds It consists of Standards (v posts)(10 cm)
Putlogs (7.5 x 7.5)
Ledgers (
Wooden boards
Braces
Used for ordinary buildings
1.2 m

37. The distance in between two standards is generally kept within 2
The distance in between two standards is generally kept within 2.4 to 3 m.
These standards are connected to each by a longitudinal horizontal member (named as Ledgers).
Ledgers are tied with standards at every rise of 120 cm to150 cm (i.e. 4 ft to 5 ft).
Rope lashing is used to tie the standard with ledgers.
The putlogs (or transverse horizontal members) are placed at a horizontal spacing of 120 cm such that one end is supported on the ledgers and the other end is held in the holes made in the wall. Rope lashing is used to fasten the putlogs with ledgers.
If the height of the scaffolding is very high, to maintain its stability, sometimes diagonal members (named as Braces) are provided. Braces are cross diagonally fitted with the standards using rope lashing.

38. Double Scaffolds It consists of Two rows of standards. 15 cm, 1.5 m
Shores are provided.
Used for superior works

40. This type of scaffolding is commonly used in case of stone masonry
This type of scaffolding is commonly used in case of stone masonry. It is stronger than brick layer’s scaffolding.
The primary differences between brick layer’s scaffolding and mason’s scaffolding are as follow:
In case of brick layer’s scaffolding single row of standard is fixed into the ground. But in case of mason’s scaffolding two rows of standards are fixed into the ground.
First row of standards is fixed close to the wall and second row of standard is fixed at a distance of 1.5 m from the first row. This is why it is named as double scaffolding.
In case of brick layer’s scaffolding one end of putlog is fixed with wall. But in double scaffolding, putlogs are not fixed with the wall. Put logs are supported at both ends on ledgers. Therefore mason’s scaffolding is completely independent of the wall surface. And there is no need to make any hole on the wall surface.
Sometime raking shores are provided to prevent the slipping of scaffolding away from the wall.

41. Ladder Scaffolds
It consists of
Brackets for Plate form.

42. Cantilever Scaffolds It consists of Cantilever Struts Standards
Putlogs
Plate forms
It is used above ground level

44. Needle scaffolding or cantilever scaffolding is required in the following cases
When it is not possible to fix standard into the ground
When construction is done on the side of a busy street
When construction work is carried out at very high level in case of tall building
In this type of scaffolding instead of fixing the standard into the ground, it is placed at some height above the ground level. The platform on which stands are placed is called needle. A needle is a cantilever structure, made of timber, projected out from the holes in wall.

45. Suspended Scaffolds It consists of Ropes Working platforms
Ropes can be raised Manually or mechanically
Used for light construction and finishing works of multistory buildings.

47. Steel or Tubular Scaffolds
It consists of
Steel tubes (1-1/2” – 2-1/2” diameter)
Coupler or Clamps (to hold pipes in different positions)
Prop nuts (to hold single pipes)
Bolts, Nuts & washers
Wedge & Clip

48. Scaffold pipes

49. Coupler or Clamps

50. Scaffold fittings Double Coupler It joins ledgers and standards.
Swivel Coupler
Composed of two single couplers and used to join two scaffolds at any angle.
Putlog Coupler
Used to join putlogs with transom.
Base Plate
Used at the base of the standards.
Split joint Pin
It’s a connection fitting used to join scaffold tubes.
Reveal Pin
It fit in to the end of a tube to form an adjustable strut.
Putlog end
A flat plate used at the end of a scaffold to convert it in to a putlog.

51. Prop nuts, clamp and fasteners

52. Wedge & Clip

53. The method of construction of steel scaffolding is similar to that of brick layer’s and mason’s scaffolding. The primary differences are
Instead of using timber, steel tube of diameter of 40 m to 60 mm are used
Instead of using rope lashing, special types of steel couples are used for fastening
Instead of fixing the standards into the ground, it is placed on base plate
The gap between two standards in a row is generally kept within 2.5 m to 3 m. These standards are fixed on a square or round steel plate (known as Base Plate) by means of welding.
Ledgers are spaced at every rise of 1.8 m. Length of the putlogs are normally 1.2 m to 1.8m.

54. Advantages of the Steel Scaffolds are as follow:
It can be erected or dismantled more rapidly in comparison to timber scaffolding. This helps in saving construction time.
It is more durable than timber. Therefore it is economical in long run.
It has more fire resisting capacity
It is more suitable and safe to work at any height.

55. Shoring
Definition
It is the method of providing temporary support (shores) to an unsafe structure.
Types of Shoring
Horizontal shoring or flying shoring
Vertical shoring or dead shoring
Inclined Shoring or flying shoring

56. Horizontal shoring It consists of Horizontal beam or strut Wall plates
Cleats
Straining beams
Used to support two adjacent buildings.

57. Single Flying Shoring

58. Double Flying Shoring

59. Vertical shoring It consists of Dead shores Sole plates Needles Props
Used for rebuilding of walls.

60. Dead or Vertical Shoring

61. Inclined Shoring It consists of Rackers Needles Cleats Braces
Sole plate
Used to strengthen a wall.

62. Inclined or Raking Shoring

63. Inclined or Raking Shoring (unsymmetrical)