High strength concrete (HSC) has been widely applied worldwide, in
recent years, due to its favorable strength and dense microstructures.
HSC shows some characteristic and engineering properties different from
those of normal strength concrete even they utilize similar raw materials.
Great use of the HSC is found in application where durability is
important as high way bridge decks, parking structures, industrial,
facilities and off-shore structures special structure such as high rise
building and bridges with very long span would not have been possible
without the development of HSC. However, the applications of HSC are
still hindered by its relative brittleness or lack of ductility such a
drawback can be overcome by the addition of discontinuous fibers.
The present work investigates the effect of addition of two types of fibers
with different ratios; pure polypropylene and steel fibers to high strength
concrete in order to diminish some poor performances particularly in
case of tensile strength. The effect of the addition of the two types of
fibers on the mechanical properties of HSC is studied. The polypropylene
fibers and the steel fibers were added at concentration of 0.0, 0.25, 0.5
and 1.0% by volume. Compression and bending tests were carried out to
determine the mechanical properties such as maximum compressive
strength, modulus of elasticity, splitting strength and modulus of rupture.
On the basis of the experimental results, it can be concluded that,
addition of fibers either steel or polypropylene to HSC mixes slightly
increases the modulus of rapture 0.5% of polypropylene improves the
modulus of rapture by 10% while the same value of steel fibers increases
it by 15%. Meanwhile, the polypropylene fibers have no influence in the
value of the calculated modulus of elasticity. However, steel fibers
increases the modulus of elasticity by about 28%.