الفهرس 
REVIEW OF FRACTURE TOUGHNESSOnly 14 pages are availabe for public view
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Abstract
Fiber reinforced concrete is characterized by its high ability to resist
fracture by static strains due to dynamic or impact loads.
In this research, toughness was determined in terms oftbe area under
the load-deflection curve, which changes according to the type of fiber used,
and its volume fraction, by means of advanced computerized testing mach ine.
It was reviewed previous researches dealing with the determination of
toughness parameters, according to distinct standard methods. Also, the effect
of several factors affecting toughness parameters was discussed.
In this experimental study; Load-deflection curves were drawn
simultaneously for different concrete grades (250, 400 and 500 kg/ern’)
reinforced with three distinct fiber types, (steel, glass and polypropylene) and
various volume fractions of fibers, namely (0.55, 1.0%, 1.5% and 2% for
steel and glass fibers and 0.1 %, 0.2% and 0.3% for polypropylene fibers).
Toughness parameters were determined by applying three different
standard methods; which are:
- The American Society for Testing Materials (ASTM C-1 018).
- TIle Japanese Standard for Civil Engineering (JSCE - SF4).
- The RILEM Method (50-fMC).
Parameters obtained according to these standards were used for
determining the ideal volume fraction for each type of fiber which improves
toughness property for fiber reinforced concrete (FRC).
It was introduced a detailed comparison showing” the influence of
fiber type, volume fraction of fibers, grade of concrete and presence of notch
on the obtained fracture toughness values. Experimental data representing
toughness parameters by these three methods were reported and compared.Besides, other properties for FRC were calculated for all concrete
mixes with different types of fibers, volume fractions and concrete grades.
Compressive and tensile strengths and modulus of rupture were also
determined.
General observations and conclusions indicate that toughness value
for FRC was extensively increased compared to plain concrete. TI,e amount
of increment depends main lyon both volume fractions of fiber and fiber type.
Steel fiber reinforced concrete (SFRC) showed higher toughness
resistance than the other studied types; glass fiber reinforced concrete
(GFRC) and polypropylene fiber reinforced concrete (PFRC). Besides, the
improvements of toughness parameters for lower concrete grade are better
than that for higher grades for SFRC. On the contrary for GFRC and PFRC.
Recommended practical volume fractions of fibers as testified in this
research in order to moderate FRC ability to resist fracture was suggested. It
was found that the Japanese Standard method (JSCE-SF4) is easier in
application, than American method (ASTM C 10 18) for measuring toughness
parameters, especially for uri-notched specimens.