## 3 Results and Discussions
### Mechanical Properties in Hardened State  
The determination of water-accessible porosity is conducted in accordance with the French standard NF P18-4592, 2022. The controlled mortar samples and the samples fabricated using WFT and WFR fibers were inserted into a container linked to vacuum equipment. The air was removed from the container until the pressure within reached 25 mbar or below. The pressure was sustained for a duration of four hours prior to being filled with water. The three types of samples were immersed in this water for a duration of 44 h. The mass of each sample was determined in water (Mwater) using a hydrostatic balance, in air (Mair) using a normal balance, and after drying in an oven to obtain the dry mass (Mdry). The measurement of water-accessible porosity was conducted using Equation (3). \[Porosity=\frac{M_{air}-M_{dry}}{M_{air}-M_{water}} \tag{3}\]  
The fiber proportion was maintained at 0.5% by volume, and the impact of length increase on water-accessible porosity of mortar incorporating WFR fiber (MWFT) and WFR fiber (MWFR) is shown in Figure 13.  
Figure 11: Workability of mortar, measured using a flow table for each size (the proportion for each fiber length included is 0.5% by volume). Figure 12: Workability of mortar, measured using a flow table for each size (the proportion for each fiber length included is 1% by volume). The study initially focused on how the length of fibers impacts the porosity of the mortar. The results clearly show a small increase in porosity as the fiber length increases. MWFR exhibits greater porosity values at the specified lengths at both 28-day and 90-day curing periods compared to MWFT. Porosity has been observed to decrease at 90 days when compared to porosity at 28 days. The subsequent objective is to determine how the volume of fibers influences the porosity of mortar while keeping the length of fibers constant (WFT-20). The porosity of mortar is significantly affected by the fiber proportion, as a noticeable rise in porosity is observed with an increase in fiber proportion. The porosity of mortar is 14% at 0% fiber volume and increases to 17.23% at 1% fiber volume for MWFT-20 and 17.80% for MWFR-20 after a 28-day curing period (Figure 14). Several studies have already documented an increase in the porosity of cementitious materials with the inclusion of fibers [36; 37; 38; 39]. Figure 14: Effect of fiber proportion on the water-accessible porosity of mortar. Figure 13: Effect of fiber length on the water-accessible porosity of mortar. Now, to measure three-point R\({}_{\text{f}}\) and R\({}_{\text{C}}\), prismatic specimens with dimensions of 4 cm \(\times\) 4 cm \(\times\) 16 cm were prepared as per NF EN 196-1, 2016. A total of eighteen samples were prepared, consisting of six samples using WFT fibers, six samples incorporating WFR fibers, and six samples without any fiber inclusion for each proportion and each length of the fiber. These samples were tested following 7-day and 28-day curing periods in water at room temperature. Figures 15 and 16 give the evolution of RC at 7 and 28 days for MC, MWFT, and MWFR. length does not significantly impact the compressive strength of CM. However, a slight drop is observed as the fiber length increases. Similarly, a rise in the proportion of fibers led to a modest drop in the compressive strength of CM. After 7 days of curing in water, MWFT4 experienced the greatest decrease in compressive strength, at 20.44%, with a 1% fiber volume, while MWFT20 had the smallest reduction, at 1.01%, with a 0.5% fiber volume. After 28 days of curing in water, the MWFR-WO sample with 1% fiber volume exhibited the highest drop in compressive strength, at 31.90%, whereas the MWFT-20 sample with 0.5% fiber volume showed the lowest reduction, at 2.26%. Figures 17 and 18 give the evolution of flexural strength at 7 and 28 days for MC, MWFT, and MWFR. The study showed a notable increase in flexural strength at 7 days and 28 days of curing, as seen in Figures 17 and 18.