It is the presentation based on precast concrete construction which includes each and every point and scope which may be useful to civil engineering students

1. PRECAST CONCRETE
CONSTRUCTION

2. What isPrecast Concrete?
Precast concrete means a concrete
member that is cast and cured at a
location other than its final designated
location. The use of reinforced concrete
is a relatively recent invention, usually
dated to 1848 when jean- Louis Lambot
became the first to use it.
Joseph Monier, a French gardener,
patented a design for reinforced
garden tubs in 1868, and later patented
reinforced concrete beams and posts
for railway and road guardrails.

3. CONCRETE
CUBE TESTING

4.  INTRODUCTION :
4
+ +/- Additives
= +Concrete +
CONCRETE MIX DEPENDS ON :
Workability
5 categories:
•Very high
•High
•Medium
•Low
•Very low
Strength
Finished surface
Consistency
Durability = Quality of material, environmental effect
Compactibility
Mobility
Stability or cohesiveness
Water content in concrete mix
Nature of aggregate particles
(shape, surface, porosity)

5.  SPECIFICATION OF CONCRETE :
Environmental
effect
Mixing Compacting Batching Transporting Placing Cement
content
Strength Water - cement ratio Aggregate - cement ratio
New site
•No old track record is available
•Requires at least 30 test strength results of
same grade of concrete
Old site
•Old track records
is available
Fly ash
GGBFS
 TARGET MEAN STRENGTH OF CONCRETE:
Methods – determined by following situation
4

6.  Formula to calculate TARGET MEAN STRENGTH (Fm) –
Fm = Fck + t X s
Where,
Fm = target mean strength
Fck = strength of concrete
( Strength achieved in 28 days )
t = constant
( probability of no. Of results fall below Fck )
s = standard deviation
( 30 hourly test results collected & tested daily using all 24hr samples mixed together )
 AGGREGATES
Types --------------------------
Coarse Aggregates
Particles greater than
4.75mm.
E.g.- Gravel and
crushed rock
Downgraded Coarse Aggregates
Size may be either 40mm CAN and
20mm CA1 or 30mm CAN and
15mm CA1
Fine Aggregates
Particles passing
through 9.5mm sieve
E.g. - Natural sand
5

7. Properties ---
7
Physical
• Texture
• Structure
• Composition
Chemical
•Solubility
•Reactivity
•Weathering
resistance
S. Properties of
No. Aggregate
Influence on Concrete
property
1. Porosity Strength / absorption
2. Chemical stability Durability
3. Surface texture Bond grip
4. Shape, size Water demand, strength
Shape of Aggregates ---
Rounded gravel Irregular gravel Crushed rock

8. Fineness of Aggregates :
Influence the water demand of concrete mix
or strength.
8
Classified in 4 zones –----
Zone 1
Coarse sand
Zone 2
Normal sand
Zone 3
Fine sand
Zone 4
Very Fine sand
The selection of proportion of FA is given
by Department of Environment (DOE), UK
Maximum size of the Aggregates
(MAS) :
Mostly MAS is 10mm, 20mm or 40mm
is used.
For massive work, MAS is 150mm or
above is used.
Limitation of MAS :
Minimum dimension of concrete section to be cast is < 4 X MAS
Zone 1
Zone
2
Zone 3
Zone 4

9. Determination of Aggregate to Cement Ratio (A/C):
A/C ratio can be calculated if following factors are known or determined:
Shape of the aggregate
Maximum aggregate size (10mm,20mm,40mm)
Zone of aggregates (1,2,3,4)
Degree of workability
Water-to-cement ratio
If concrete ingredients consist of coarse crushed and natural fine aggregates then A/C is
adjusted as follows :
Determine A/C for crushed aggregates for the MAS fixed for the Mix (Say Aca)
Determine A/C for rounded or irregular gravel aggregates for MAS fixed for the Mix
(Say Afa)
Calculate A/C of the concrete mix (Say A’) as per formula
A’ = Aca (%of CA1+%of CA2) + Afa (%of FA1)
100 100
Where,
Aca = Actual coarse aggregate
Afa = Actual fine aggregate
FA1 = Fine aggregate (zone 1)
CA1 = Coarse aggregate (zone 1)
CA2 = Coarse aggregate (zone 2)
8

10. Age to strength relation – chemical compositions and fineness
Higher early strength
content of Tricalcium cilicate > Dicalcium cilicate
Finer ground cement > coarse ground cement
10
Concrete strength are generally specified by compressive
strengths and the structural design is worked out on that basis.
Exact information
of compressive strength
of concrete depends
on quality control
Parameters affecting
compressive strength
•Cement (quality and grade)
•Water (water-cement ratio)
•Cement storage andtransportation
•Cement packaging
•Aggregates
•Concrete workability
•Concrete placement
•Concrete compaction
•Curing of concrete

11. Equipments
 Only steel or cast iron
 Made up of three parts
1.two side flanges
2.base plate
3.nut bolts
 Inside faced must be planed and machine
finished


All internal angles has to be accurate
Edges and joints must be cleaned
 Surfaces should be coated by mould oil
 Prevent mould from rusting
 All parts should be bolted and then stored
in close room
 Steel bar of 16mm dia.
 600 mm length
 Bullet head

12. Process for filling & compacting cube
mould
must be done into three layers
each app. 50mm
Must be placed using scoop
each layer is compacted using tamping rod
needs 35 stroke for 150mm &
25 stroke for 100mm
surface level should be planed
No air gaps in between or
scratches on surface
22

13. Process for identification , curing &
testing
On the surface level some
identification mark, number and
date has to be scratched and
same noted on paper
after removal from mould it should
immediately covered with damp jute
Transfer to a room having
humidity90% and temperature 27^
Keep the cube in curing pond of
clean water for 28 days
automatic compression
machine is better than manual
load application
Machine has a control on rate of
loading, we can apply various
loading while testing its strength
23

14. Precautions need to be taken while
testing
14
allow skilled workers only
Fresh water within 7 days only used for curing pond
Cubes has to be deep completely
Storage space has to be without any vibrations
Temperature control from 22 to 30 ^c.
There should not be loss in moisture while travelling from site to testing lab.
Afloat should be used to push the excess concrete after pouring third layer.
If the mix is too wet, allow water to drained out from mould.

15. Requirement of compression testing
15
machine
TOP PLATEN :
Harden and smooth faces
Fitted on cylinder concentric
with central point
must be accurate
Well calibrated, well certified
Having capacity to crush cube
Load applying rod
Concrete cube placing space
BOTTOM PLATEN :
Plain finished
Rigidly fixed on bearing block
Size more than cube size
Selection of machine depends
on size of cube and load
application

16. Acceptance criteria for compressive
Note the reading by applying
different loads from machine till the
cube crashes
Compressive strength should not be
less than the characteristic value
26

17. Modes of failures
USUAL FAILURES :
Equal cracking on all four sides
No damage to top and bottom faces
Cracks are vertical zigzag pattern
vertical faces breaks away leaving one
pyramid between
UNUSUAL FAILURES :
Crushed only at one side
Tensile or horizontal cracks only at one side
This indicates lower compressive strength
Reasons
Defects in machine
Faulty manual operation
Faulty casting of cube
Improper curing 27

18. Features
 The division and specialization of the human
workforce.
 The use of tools, machinery, and other
equipment, usually automated, in the
production of standard, interchangeable parts
and products.
 Compared to site-cast concrete, precast
concrete erection is faster and less affected by
adverse weather conditions.
 Plant casting allows increased
efficiency, high
quality control and greater control on
finishes.
4

19. Comparison
Site-cast
 no transportation
 the size limitation is
depending on the
elevation capacity only
 lower quality because
directly affected by
weather
 proper, large free space
required
Precast at plant
 transportation and
elevation capacity limits
the size-
 higher, industrialized
quality – less affected by
weather
 no space requirement on
the site for fabrication
 unlimited opportunities of
architectural appearance
 option of standardized
components
5

20. Design concept for precast
concrete buildings
 The design
concept of
the precast
buildings is
based on
 1.build
ability.
 2.economy
3.standardization of
precast
components.
6

21. Precast concrete structural
elements
7
Precast slabs
Precast Beam & Girders

23. 8
Precast Columns
Precast Walls

24. 9
Precast stairs
Precast
concrete Stairs
Steel plates supported on 2 steel
beams

25. Designconsiderations
 final position and loads
 transportation requirements – self load and
position during transportation
 storing requirements – self load and position
during storing – (avoid or store in the same
position as it transported / built in)
 lifting loads – distribution of lifting points –
optimal way of lifting (selection of lifting and
rigging tools)
 vulnerable points (e.g. edges) – reduction of
risk (e.g. rounded edges)
10

26. Types of pre cast system
1. Large-panel systems
2. Frame systems
3. Slab-column systems with walls
4. Mixed systems
11

27.  box-like structure.
 both vertical and
horizontal elements are
load-bearing.
 one-story high wall panels
(cross-wall system /
longitudinal wall system /
two way system).
 one-way or two way
slabs.
12
1. Large-panel systems

28. 2. Frame systems
 Components are usually
linear elements.
 The beams are seated
on corbels of the pillars
usually with hinged-
joints (rigid connection
is also an option).
 Joints are filled with
concrete at the site.
13

29. 3.Lift-slab systems
 - partially precast in plant
(pillars) / partially precast on-
site (slabs).
 - one or more storey high
pillars (max 5).
 - up to 30 storey high
constructions.
 - special designed joints and
temporary joints.
 -slabs are casted on the
ground (one on top of the
other) – then lifted with crane
or special elevators.
14

30. Lift-slab procedure
15
1. pillars and the first package (e.g. 5 pieces) of slabs
prepared at ground level
2. lifting boxes are mounted on the pillars + a single slab
lifted to the first floor level
3-8. boxes are sequentially raised to higher positions to
enable the slabs to be lifted to their required
final position - slabs are held in a relative (temporary)
positions by a pinning system

31. Equipments
cranes:
 mobile crane
 tower crane (above
3stories)
lifting tools:
 spreader beams
 wire rope slings
rigging tools:
 eye bolt
 shakles
 hooks
17

32. Slabs:
• b) Hollow Core slab-
• Thicknesses of 4",6",8",10"and12"
• Spansup to 40’-0"
• Standard panel width =4’-0"
• Typical designations =4HC6 (4=panel width infeet, HC=
• Hollow Core, 6=slab thicknessininches)
a) Flat slab -
Standard panel width =4’-0"
Thickness of 4",6"and 8"
Spans up to 25’-0"
Typical designations =FS4(FS=Flat Slab, 4 =thickness of slab

33. Beams:
a) Rectangular Beam (RB)-
Typical beam width =12"or16"
Spans up to 50’-0"
Typical designation =16RB24 (16 =width in inches, 24=
depth ininches)
b) "L"and "IT"(inverted "Tee") beams (LBand IT)-
Typically used tosupport slabs, walls, masonry, and
beams
Typical beam width=12"
Depths of 20",28",36",44",52"and 60"

36. c) Double Tee Beam (DT) -
Combination beam and slab
Spans up to 100’-0"
Typical width=8’-0"
Depths of 12", 18", 24" and 32"
Designation =8DT24+2 (8 =width in feet, 24 =
depth, +2=2"topping)

37. d) Single Tee Beam (ST)-
Combination beam and slab
Spans up to 120’-0"
Typical width =8’-0"
Typical depths of 36"and 48"
Designation =8ST36+2(8 =width in feet, 24 =depth, +2=
2" topping)

38. Walls
Wall panels available in standard 8’-0" widths.
Can be flat, or have architectural features such as
window and door openings, ribs, reveals, textures,
sandwich (insulation built-in), sculptured,etc.

40. Assembling….
18
Column to column connection

41. Beam to column connection
19

42. Beam-slab joints
20

43. 21
Precast concrete structure consisting of
solid wall panels and hollow core slabs.
Wall to slab connection

44. Methods of Attachment of
PrecastConcrete Members:

45. Weld Plates
Themostcommon method of attachment of precast
members isby use of steelweld plates. Typically, the
precast members have embedded plates that can
be used as weldingsurfacesforlooseconnecting
plates orangles (seebelow):

46. Rebar andGrout
Used typically withslabs,reinforcing barsare
splicedintoslabsand grouted inplace (see
below):

47. PRECAS
T,
PRESTRESS
ED
CONCRETE
STRUCTUR
AL
ELEMENTS

48. Precast Concrete
Slabs
• Used for floor and roof decks.
• Deeper elements (toward the right
below) span further than those that
are shallower (toward the left).
• Right: Hollow core slabs stacked at
the precasting plant.

49. Precast Concrete
Beams and Girders
• Provide support for slabs.
• The projecting reinforcing bars will bond with concrete cast
on site.
• Right: Inverted tee beams supported by precast columns.
M

50. Precast
Concrete
Columns and
Wall Panels
Provide support for
beam and slab
elements.
•Since these elements
carry mainly axial loads
with little bending
force, they may be
conventionally
reinforced without
prestressing.
•Or, long, slender
multistory elements
may be prestressed to
provide resistance to
bending forces during
handling and erection
(columns at right).
LEM

51. Precast Concrete
Columns and Wall
Panels
• Precast concrete wall panels
may be solid (right), hollow,
or sandwiched (with an
insulating core).
• Wall panels can be ribbed, to
increase their vertical span
capacity while minimizing
weight, or formed into other
special shapes (below).

52. Other Precast Concrete
Elements
• Precast concrete stairs
(below)
•Uniquely shaped structural
elements for a sports stadium
(right)
PRECAST, PRESTRESSED CONCRETE STRUCTURAL ELEM

53. Assembly Concepts for
Precast Concrete
Buildings
Vertical support can be
provided by precast
columns and beams
(above), wall panels
(below), or a combination
of all three.
•The choice of roof and
floor slab elements
depends mainly on span
requirements.
•Precast slab elements are
frequently also used with
other vertical loadbearing
systems such as sitecast
concrete, reinforced
masonry, or steel.
ELEM

54. Assembly Concepts for
Precast Concrete Buildings
•Above: Precast concrete structure
consisting of solid wall panels and hollow
core slabs.
•Below: A single story warehouse consisting
of double tees supported by insulated
sandwich wall panels.

55. Assembly Concepts for Precast
Concrete Buildings
•A parking garage structure consisting of
precast double tees supported by inverted
tee beams on haunches columns.

56. are manufactured in
casting beds, 800 ft or
more in length.
•High-strength steel
strands are strung the
length of the bed and
tensioned.
•Conventional
reinforcing, weld
plates, blockouts,
lifting loops, and other
embedded items are
added as needed.
•Concrete is placed.
Casting Hollow Core Planks
•Precast elements
Untensioned prestressing strands can be seen in the left-
most casting bed. In the bed second from the right, low-
slump concrete for hollow core slabs is being formed
over tensioned strands using an extrusion process. A
completed hollow core casting is visible at the far right.

57. Prestressing and
Reinforcing Steel
•Many precast elements contain
both prestressing strands and
conventional reinforcing.
•Right: The prestressing strands
for an AASHTO girder are
depressed into a shallow v- shape
to most efficiently resist tensile
forces in the beam. Shear stirrups
are formed from conventional
steel reinforcing.

58. Casting Hollow Core
Planks
•Once the concrete
has cured to sufficient
strength, the castings
are cut into sections
of desired length
(above).
•In some cases,
transverse bulkheads
are inserted to divide
the casting bed into
sections before
concrete is placed. In
this case, only the
prestressing strands
need to be cut to
separate the sections
(below).

59. Casting Hollow
Core Planks
• Individual sections
are lifted from the
casting bed (right) and
stockpiled to await
shipping to the
construction site.

60. Casting
Hollow Core
Planks
• Precast concrete
elements are
shipped to the
construction site by
truck and erected on
site by crane.

61. Casting Hollow CorePlanks
•Sample hollow core slab sections of varying
depths.
•At bottom left, note the insulated sandwich
floor panel.

62. Advantages Of precast
concrete construction
 Quick erection times
 Possibility of conversion, disassembling
and moving to another site
 Possibility of erection in areas where a
traditional construction practice is not
possible or difficult
 Low labor intensivity
 Reduce wastage of materials
 Easier management of construction sites
 Better overall construction quality
 Ideal fit for simple and complex structures
22

63. Disadvantages ofPrecast
Concrete Construction
Somewhat limited building design flexibility
Very heavy members
Camber in beams and slabs
Very small margin forerror
Connections may be difficult
Because panel size is limited, precast concrete can not be
used for two-way structural systems.
Economics of scale demand regularly shaped buildings.
Need for repetition of forms will affect building design.
Joints between panels are oftenexpensive and
complicated.
Skilled workmanship is required in the application of the
panel on site.
Cranes are required tolift panels.

64. Limitations
 size of the units.
 location of window openings has a
limited variety.
 joint details are predefined.
 site access and storage capacity.
 require high quality control.
 enable interaction between design
phase and production planning.
 difficult to handling & transporting.
23

65. Popular UsesofPrecast
Concrete
Concrete curtain walls
As an exterior cladding(may include
exposed aggregate)
For structural walls
Ability to precast in threedimensions
allows precast panels to form parts of
mechanical systems

66. Scheduling
some approximate data for installation
 emplacement of hollow core floor slabs -
300 m2/day
 erection of pillars/columns - 8 pieces/day
 emplacement of beams - 15 pieces/day
 emplacement of double tee slabs - 25
pieces/day
 emplacement of walls - 15 pieces/day
 construction of stair and elevator shafts -
2 floors/day
24

67. Examples….
25
The hospital will feature multi-trade prefabricated racks in the corridors, an
approach that is still new in the U.S.

68. 26
Miami Valley Hospital Dayton,OH

69. Conclusion
27
oThe use of prefabrication and preassembly is
estimated to have almost doubled in the last 15
years, increasing by 86%.
oThe use of precast concrete construction can
significantly reduce the amount of construction waste
generated on construction sites.
o Reduce adverse environmental impact on sites.
o Enhance quality control of concreting work.
o Reduce the amount of site labour.
o Increase worker safety .
o Other impediments to prefabrication and
preassembly are increased transportation
difficulties, greater inflexibility, and more advanced
procurement requirements.

70. 1) Jenil
2) Nalin
3) Sid
4) Riyan
5) Nithin