## 3 Results and Discussions
### Mechanical Properties in Hardened State
Adding WFT and WFR fibers at a volume fraction of 0.5% significantly boosted flexural strength when compared to 0.3% and 1% fiber volumes. A loss in strength above 0.5% fiber volume could be due to a balling problem and uneven fiber distribution [5]. Figure 17: Flexural strength test results after 7 days of curing in water for controlled mortar, and mortar with WFT fibers and WFR fibers. Figure 18: Flexural strength test results after 28 days of curing in water for controlled mortar, and mortar with WFT fibers and WFR fibers. After 28 days of curing in water, the MWFR20 samples containing fibers collected via a 20 mm sieve (with an average length of 15.81 mm) exhibited the most favorable result, with an 81.79% enhancement in flexural strength. Therefore, it can be inferred that fibers produced by cutting WFT (polyethylene) using a 20 mm sieve yield optimal outcomes when incorporated into the mortar at a volume of 0.5%. Fiber derived by cutting WFR (polypropylene) demonstrates favorable outcomes as well. However, their performances are slightly inferior when compared to WFT fibers. The significant rise in flexural strength is apparent based on previous studies. [PERSON] et al. [5] observed a significant 41.66% enhancement in the mortar when a 20 mm fiber with a volume fraction of 1.5% was included. Furthermore, Ref. [22] documented a 35% rise, Ref. [6] documented a 41% rise, and Ref. [24] showed a 41.56% rise in flexural strength as a result of incorporating fibers. Past research has provided little information about the valorization of waste fishing rope (WFR). Waste fishing trawl (WFT) valorization has been the subject of the majority of prior research. Hence, comparing the results of WFT and WFR is challenging, and we suggest conducting more research to have a comprehensive understanding of the contrasting mechanical performances of WFT fibers and WFR fibers. The superior mechanical performance of WFT over WFR in our situation may be attributed to the higher density, greater tensile strength, and lower water absorption of WFT in comparison to WFR. The results are consistent with [PERSON] and [PERSON]'s [23] findings, indicating that adding fibers to the cement matrix can create more voids, leading to a decrease in the compressive strength of the material. This decrease in compressive strength aligns with observed patterns in other research investigations. The increase in flexural strength observed is also consistent with prior findings mentioned in the introduction. The results highlight the significance of taking into account fiber length and volume proportion in CM formulations and offer significant insights for enhancing mechanical performance. The MWFT-20 and MWFR-20 with 0.5% fiber volume have yielded the most optimal mechanical outcomes. In order to enhance the comprehension of these two categories of fiber-reinforced cementitious material, mid-span deflection curves and toughness indices were formulated. The experiment involved conducting three-point flexural tests on three samples, with each having dimensions of 4 cm \(\times\) 4 cm \(\times\) 16 cm. It was visually observed that MC broke into two pieces after the application of maximum force, while MWFT-20 and MWFR-20 sustained the load and did not split entirely into two (Figure 19). Figure 19: Samples after the application of maximum flexural load. Mid-span deflection curves and toughness indices are developed specifically for the MWFT-20 and MWFR-20 (0.5% fiber volume) to be compared with controlled mortar (MC). Since these formulations have yielded the best results, mid-span deflection curves and toughness indices are produced to gain a deeper understanding of their flexural behavior. Figure 20 illustrates the load-mid-span deflection curves for each of the three formulations. When making a comparison between MC, MWFT-20, and MWFR-20, it becomes apparent that the latter two demonstrate a higher peak load. The MC exhibits a brittle failure mode characterized by a sudden fall in applied load to zero following the peak load.