Influence of waste plastic fibers and strengthening with carbon‐fiber‐reinforced polymer strips on the properties of eco‐efficient reinforced self‐compacting concrete slabs

Plastic waste (PW) is gaining attention due to its low cost, strength, and delayed degradation. This study investigates the effect of PW fibers on the behavior and resistance of reinforced self‐compacting concrete (SCC). The study aimed to improve the possibility of developing reinforced SCC slabs by using waste polyethylene terephthalate (PET) fibers, which were obtained from waste soda bottles, and strengthening them with carbon fiber‐reinforced polymer strips (CFRP strips). Various volumetric fiber ratios (0%, 0.5%, 1%, 1.5%, and 2%) were used to create SCC specimens, where fresh and mechanical properties (compressive, flexural, and splitting tensile strength and modulus of elasticity) were assessed. In addition, an impact resistance test was implemented on slabs containing various ratios of PET fibers. Mechanical strength increased with fiber content up to 1% at 28 days, while workability declined with higher fiber content. The slump flow decreased by 11.53%, while T50 increased by 50% compared to the control sample. The compressive strength improved by 12.06%, whereas the ultrasonic velocity of SCC incorporating 2% PET fibers decreased by 6.45% compared to the control sample. PET fibers improved impact resistance and energy absorption by 200% compared to the reference mixture. The maximum deflection times increased by 20%, 35%, 31.5%, and 18.2% for different fiber ratios. In the second phase, SCC slabs, with and without PET fibers, were wrapped with CFRP strips using the external binding method. A detailed analysis of binding methods and load failure performance was conducted. The results showed that SCC slabs with or without PET fibers, when strengthened with CFRP, required more energy to fracture and collapse. This combination of PET fibers and CFRP strips significantly enhanced impact resistance and energy absorption. The findings suggest that incorporating PET fibers and CFRP strengthening improves the mechanical and impact performance of SCC, offering a sustainable solution for concrete applications.