English abstract
Concrete is considered as a brittle material in absence of reinforcement. To promote and implement
the sustainability concept in construction, it is important to investigate and study the properties of
available resources of materials in order to utilize them as reinforcement materials in concrete.
Nowadays, and considering the sustainable development context, worldwide researches have been
devoted to the use of different types of fibers in concrete.
This study aims to investigate and examine the mechanical behavior of fiber reinforced concrete
(FRC) by using three types of waste fibers: steel fibers from used tire, waste soda bottle plastic
and waste fishing net at different contents and lengths. A proper experimental work was designed
and conducted for this research to assess the behavior of concrete reinforced with waste fibers.
The experimental work consists of fresh properties of FRC, compressive strength, flexural
strength, splitting tensile strength, load vs. deflection and porosity tests.
The workability of all (FRCs) was reduced when adding waste fibers and this reduction found to
be more significant when fiber`s length and volume increases. FRC with steel (SFRC) showed the
highest reduction in workability compared to all other FRCs. A relative compressive strength loss
up to 45% was recorded when introducing different types of fibers. The mean tensile strength loss
and gain is ranging from 3% to 27% and 1% to 15%, respectively. The FRC with polypropylene
fibers (PPF) performs better than other FRC with more tensile strength improvement. Fiber
inclusion has resulted in an increase in the flexural strength up to 26%. Thick SFRC showed the
highest improvement whereas fishing mesh (FM) FRC had the lowest flexural strength
improvement. Energy absorption under flexural loading was greatly enhanced for all FRCs with a
relative energy absorption gain ranging from 7% to 800%. The SFRCs were found to reach the
maximum post peak load-deflection and ductility compared to the FMF & PPF. Moreover, hybrid
fibers reinforced concrete (HFRC) has not only improved the post-cracking behavior of the
multimodal composites but also its flexural strength by around 12% compared to the single fiber
composite. The porosity of FRCs increased compared to the unreinforced control concrete.
Porosity also increased as the content and length of fibers increase.
