For normal structures we use concrete to build it. But as concrete is a brittle material and it has almost no ductility, it fails in massive load or shock. For giving some ductility to concrete and to fill up the internal micro cracks in concrete we use several fibers. Then the total concrete works as a composite material. Steel Fiber Reinforced Concrete is a composite material having cement, aggregate, and steel fibers.

1. An introduction to
Ahsanullah University of Science and Technology
Department of Civil Engineering
Steel Fiber Reinforced Concrete
Classification of Steel Fibers
ASTM A 820 provides a classification of
four general types of steel fibers.
Different Types of Fiber
Fiber Reinforced Concrete
Fiber Reinforced Concrete is a composite
material consisting of cement, aggregate
and discontinues, discrete, uniformly
dispersed suitable fibers
Steel Fiber
Natural Fiber
Glass Fiber
Synthetic Fiber
Why to use FRC
 Plain concrete is a brittle material with
limited ductility and low tensile strength
and strain capacity. Internal micro-cracks
are present in that concrete. Thus the
concrete leads to heavy brittle fracture.
 The role of randomly distributed fibers is to
bridge across the cracks and to provide
some post-cracking ductility. If the fibers
are sufficiently strong and bonded to
material then FRC will carry significant
stress over a relatively large strain capacity
in the post cracking stage.
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

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Type
Type
Type
Type
III III –
IV –
Cold-drawn wire
Cut sheet
Melt-extracted
Other fibers
 Type I – Square section
 Type II – Circular Section
 Type III – Crescent Section
Application of SFRC
3/8- in. maximum ¾in.
maximum 1½- in. maximum
sized aggregate
sized aggregate
sized aggregate
Property
SFRC is concrete made of hydraulic cements containing
fine and coarse aggregate and discontinuous discrete steel
fibers.
Cement
(kg/m3)
350-600
Percent
of
fine
coarse aggregate (%)
to
250-450
0.35-0.45
w/c ratio
300-550
0.35-0.5
0.35-0.55
45-60
45-55
40-55
4-8
4-6
4-5
Entrained Air Content
(%)
Fiber Content, (% of total volume)
Deformed
Fiber (%)
Cross Section of Steel Fibers
Smooth
Fiber (%)
0.4-1.0
0.3-0.8
0.2-0.7
0.8-2.0
0.6-1.6
0.4-1.4
Classification of Fibers
Properties of Concrete Improved
 Steel Fiber Reinforced Concrete (SFRC)
Compressive Strength
In compression the ultimate strength is only
slightly affected by the presence of Steel
Fibers. The presence of steel fibers increases
compressive strength from 0 to
% for up
to 2% of volume of fibers.
 Glass Fiber Reinforced Concrete (GFRC)
 Synthetic Fiber Reinforced Concrete (SNFRC)
 Natural Fiber Reinforced Concrete (NFRC)
Recently some new FRC named High
Performance
Fiber
Reinforced
Concrete
(HPFRC) and Ultra High Performance Fiber
Reinforced Concrete (UHPFRC) have introduced
which shows significant changes over plain
concrete.
Steel Fiber cutting machine
The changed elastic distribution is importantly plastic
in the tension zone and elastic in the compression
zone, which poses a shift of neutral axis towards the
compression zone. It changes from 20-100% for
addition up to 3% by total volume of fibers.
The Japanese society of civil engineers
(JSCE) has classified steel fibers based on
the shape of their cross-section.
Mix design of SFRC
Steel Fiber Reinforced Concrete (SFRC)
Flexural Strength
 SFRC has been tried on overlays of air-field, road
pavements, industrial floorings, bridge decks, canal
lining, explosive resistance structures, refractory
linings etc.
 It can also be used for the fabrication of precast
products like pipes, boats, beams, stair case steps,
wall panels, roof panels, manhole covers etc.
 SFRC is also being tried for the manufacture of
prefabricated formwork molds of “U” shape for
casting lintels and small beams.
Limitations of SFRC
 Unless steel fibers are added in adequate quantity,
the desired improvements cannot be obtained.
 As the quantity of fibers is increased, the workability
of the concrete is decreased.
 Another problem is the corrosion of the surface
which may influence the appearance of the surface.
 Steel fibers are not cost effective. Due to the addition
of 1% steel fiber of the total volume, there will be a
massive change in the total cost of the construction.
Some SFRC Constructions
Tensile Strength
In direct tension, the improvement in
strength is reported from 30-40% for
addition up to 2% by total volume of fibers.
It is observed that the split tensile strength
increases from 10-45% for addition up to
3% by total volume of fibers.
INNOVATIVE BUILDERS
Zubayer Ibna Zahid (Group Leader) -Hasan Jubair Siam -Soaib Imran Abir -Abdullah Al Mamun -Jarin Tasnim Hiya -Eden Chakma -Md Omar Faruk Rupak -Sohan Ahmed Tonmoy -Kanak Chakma --
12.02.03.061
12.02.03.037
12.02.03.003
12.02.03.019
12.02.03.039
12.02.03.001
12.02.03.010
12.02.03.016
12.01.03.003