The marked brittleness with low tensile strength of plain concrete can be overcome by the
addition of steel fibres (SF). This paper investigates the mechanical properties of steel fibre
reinforced concrete (SFRC) and spiral steel fibre reinforced concrete (SSFRC). The properties
included compressive and splitting tensile strength, modulus of rupture, and toughness index. The
steel fibres were hook-ended shape with aspect ratio (l/d=50). The introduced shape was spiral steel
fibres (SSF) with diameter of spiral=1.5 cm. The two shapes of steel fibres were added at the
volume fraction of 0.5%, 1.0%,2.0%, and 3.0%. All the mechanica1 properties of SFRC enhanced
up to 2.0% volume fraction of fibers, whereas the mechanical properties of SSFRC enhanced up to
3.0% volume fraction. The compressive strength of SFRC and SSFRC enhanced by 43.4% and 65%
respectively relative to plain concrete. The splitting tensile strength of SFRC and SSFRC enhanced
by 52.6% and 147% respectively relative to plain concrete. The modulus of rupture of SFRC and
SSPRC enhanced by 137.5%, and 62.5% respectively relative to plain concrete. The toughness
index of SPRC improved with increasing the fraction up to 2.0%. The indices I5, I10, and I20
registered values of 10.7, 20.5, and 35.1 at 2.0% fraction. The toughness index of SSFRC improved
with increasing the fraction up to 3.0%. The indices I5, I10, and I20 registered values of 9.76, 18.78,
and 35.8, respectively, at 3.0% volume fraction.