introduction to steel fiber reinforced concrete
DESCRIPTION
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.TRANSCRIPT
An introduction to
Steel Fiber Reinforced Concrete
Fiber Reinforced Concrete
Fiber Reinforced Concrete is a composite
material consisting of cement, aggregate
and discontinues, discrete, uniformly
dispersed suitable fibers
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.
Ahsanullah University of Science and TechnologyDepartment of Civil Engineering
Classification of Fibers
Steel Fiber Reinforced Concrete (SFRC)
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.
Different Types of Fiber
Steel Fiber Reinforced Concrete (SFRC)SFRC is concrete made of hydraulic cements containing
fine and coarse aggregate and discontinuous discrete steel
fibers.
Classification of Steel Fibers
ASTM A 820 provides a classification of
four general types of steel fibers.
Type I - Cold-drawn wire
Type II - Cut sheet
Type III – Melt-extracted
Type IV – Other fibers
The Japanese society of civil engineers
(JSCE) has classified steel fibers based on
the shape of their cross-section.
Type I – Square section
Type II – Circular Section
Type III – Crescent Section
Cross Section of Steel Fibers
Steel Fiber cutting machine
Property
3/8- in. maximum
sized aggregate
¾- in. maximum
sized aggregate
1½- in. maximum
sized aggregate
Cement
(kg/m3)350-600 300-550 250-450
w/c ratio0.35-0.45 0.35-0.5 0.35-0.55
Percent of fine to
coarse aggregate (%)45-60 45-55 40-55
Entrained Air Content
(%) 4-8 4-6 4-5
Deformed
Fiber (%)0.4-1.0 0.3-0.8 0.2-0.7
Smooth
Fiber (%)0.8-2.0 0.6-1.6 0.4-1.4
Mix design of SFRC
Fiber Content, (% of total volume)
Properties of Concrete Improved
Compressive Strength
In compression the ultimate strength is onlyslightly affected by the presence of Steel
Fibers. The presence of steel fibers increasescompressive strength from 0 to % for up
to 2% of volume of fibers.
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.
Flexural Strength
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.
Application of SFRC
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.
INNOVATIVE BUILDERS
Zubayer Ibna Zahid (Group Leader) -- 12.02.03.061
Hasan Jubair Siam -- 12.02.03.037
Soaib Imran Abir -- 12.02.03.003
Abdullah Al Mamun -- 12.02.03.019
Jarin Tasnim Hiya -- 12.02.03.039
Eden Chakma -- 12.02.03.001
Md Omar Faruk Rupak -- 12.02.03.010
Sohan Ahmed Tonmoy -- 12.02.03.016
Kanak Chakma -- 12.01.03.003
Steel Fiber
Natural Fiber
Glass Fiber
Synthetic Fiber
Some SFRC Constructions