03-01-2013, 03:03 PM
Fiber Reinforced Concrete (FRC)
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INTRODUCTION
Concrete is relatively brittle, and its tensile
strength is typically only about one tenths
of its compressive strength.
Regular concrete is therefore normally
reinforced with steel reinforcing bars.
For many applications, it is becoming
increasingly popular to reinforce the
concrete with small, randomly distributed
fibers.
Their main purpose is to increase the
energy absorption capacity and toughness
of the material, but also increase tensile
and flexural strength of concrete.
FRC - Historical Perspective
BC horse Hair
1900 asbestos fibers, Hatscheck process
1920 Griffith, theoretical vs. apparent strength
1950 Composite materials
1960 FRC
1970 New initiative for asbestos cement
replacement
1970 SFRC, GFRC, PPFRC, Shotcrete
1990 micromechanics, hybrid systems, wood
based fiber systems manufacturing
techniques, secondary reinforcement, HSC
ductility issues, shrinkage crack control.
2000+ Structural applications, Code integration,
New products.
Strength
The most important contribution of fiberreinforcement
in concrete is not to strength but
to the flexural toughness of the material.
When flexural strength is the main
consideration, fiber reinforcement of concrete
is not a substitute for conventional
reinforcement.
The greatest advantage of fiber reinforcement
of concrete is the improvement in flexural
toughness (total energy absorbed in breaking a
specimen in flexure).
Durability
Fiber-reinforced concrete is generally made
with a high cement content and low
water/cement ratio.
When well compacted and cured, concretes
containing steel fibers seem to possess
excellent durability as long as fibers remain
protected by cement paste.
Ordinary glass fiber cannot be used in
portland cement mortars and concretes
because of chemical attack by the alkaline
cement paste.