The main target of the present research is to study the possibility of utilizing used (recycled) polypropylene (PP) packages in the reinforcement of concrete as an alternate for the virgin mono-filament and mesh PP currently in use in Fiber-Reinforced Concrete (FRC). The over-arching benefits of loading concrete with used PP may be summarized as: reducing the cost of FRC as a step towards wider range of applications, as well as utilizing a solid waste as a step towards a cleaner environment. In the present work PP fibers of different geometry (mesh, monofilament and recycled) are added to concrete in different concentrations namely: 0.1% by volume, equivalent to 900 gm fiber/m3 concrete and 0.2% by volume equivalent to 1800 gm fiber/m3 concrete. The concrete specimens are subjected to both normal (soaking in water) and severe (soaking in acids at various concentrations) conditions, for periods of time: 7, 14 and 21 days. Compressive strength test was applied for all prepared blocks after soaking for 7, 14 and 21 days and the average values are recorded. The results obtained for the FRC are compared with those of the blank sample. Results showed that incorporating PP to concrete blocks leads to an enhancement in the compressive strength with increasing the incorporated-fiber concentration up till 0.1%, above which the compressive strength decreased significantly. On soaking in H2SO4, the highest strength for the three types of PP fibers was recorded after 14 days, after which the strength deteriorated rapidly until it reached the lowest value after 21 days. X-Ray analysis was applied in an attempt to interpret the obtained results.