This research studies the effect of the addition of polypropylene
fibers (PF) on the properties of the swelling clayey soil. The effect
of PF on the shear strength of the clayey soil has been studied
and the results show that adding PF, up to spec
ific value,
increases the shear strength. Beyond this value of addition, the
shear strength decreases. The increase in shear strength was
about (100-110) % and the optimal addition ratio was determined.
