# Development of Alfa Fiber-Based Mortar with Improved Thermo-Mechanical Properties
## 3 Results and Discussions
### Mechanical Performance Analysis  
Figures 13 and 14 display the flexural and compressive strengths variation of composite with AF mass content. Concerning flexural strength (Figure 13), it is worth highlighting that it increases with the growth of the AF mass ratio from 0% to 1% where a maximum value of about 5.65 MPa is achieved. This improvement in flexural strength of about 10.45% is attributed to the good AF-mortar matrix adhesion as explained in Section 3.2, to the enhancement of mechanical bonds between solid matrix \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Material (e = 20 cm)** & \(\rho\) **(kg:m\({}^{-3}\))** & **R (W\({}^{-1}\)-m\({}^{2}\)-K)** & \(\alpha\) **(m\({}^{2}\)-s\({}^{-1}\))** & **Time-Lag (h)** \\ \hline AFRM & 1492 & 0.58 & \(1.97\times 10^{7}\) & 10.37 \\ Hemp concrete & 440 & 1.81 & \(2.27\times 10^{7}\) & 9.6 \\ Cellular concrete & 600 & 1.43 & \(2.74\times 10^{7}\) & 8.6 \\ Earth block & 1850 & 0.20 & \(5.24\times 10^{7}\) & 6.2 \\ Solid brick & 1950 & 0.23 & \(5.41\times 10^{7}\) & 6.3 \\ Concrete & 2300 & 0.11 & \(7.93\times 10^{7}\) & 5.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison between the time-lag of AFRM 5% material and those of other materials presented in the literature. Figure 14: Variation of compressive strength with AF mass content at day 28. Measurements uncertainty is below 12%. Figure 13: Flexural strength variation as function of AF mass content at day 28. Measurements uncertainty is below 8.5%. (mortar) and reinforced AF, and to the high mechanical characteristics of AF, including high tensile strength and stiffness. However, for an AF ratio higher than 1%, it decreases to reach 3.87 MPa value for an AF mass ratio of 3.5%. This is due to the composite's porosity increase due to the excessive content of fibers in the mixture, resulting in a reduction of compactness and cohesion within the AF composite. This result is in agreement with previous research that dealt with mortar reinforcement with AF [48; 49]. Compressive strength as a function of AF mass content is shown in Figure 14 with a measurement error of less than 12% for all specimens. It can be noticed that the compressive strength behavior is compatible with the flexural strength behavior as the AF mass content is increased. The maximum is obtained at a weight percentage of 1%. This maximum represents an increase of 9% in the compressive strength. Beyond this percentage, it decreases by around 82.5% at a weight fraction of 5%. This diminution is due to the growth in porosity which affects negatively the compressive strength. Material Classification of the Developed Composite Based on Compressive Strength and Thermal Conductivity  
The lightweight material classification can be made based on the compressive strength (Rc) and thermal conductivity (k). These two quantities are considered as crucial parameters in choosing suitable material types to be used in thermal insulation buildings. The diagram reported in Figure 15 represents a relationship between these two variables for each AF mass percentage. It can be noted that as AF mass content increases, the thermal conductivity of AFRM composite decreases considerably along with compressive strength, except AFRM1% for which Rc reaches a maximum value of about 14.07 MPa. Thereafter, based on the functional classification of lightweight concrete of RILEM [50] (International Union of Laboratories and Experts in Construction Materials, Systems and Structures) and the results of Figure 15, this developed composite can be classified in two main classes as a function of AF mass content. Composites with Rc greater than 3.5 MPa and \(k\) less than 0.75 W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\) belong to Class II, while those with Rc greater than 0.5 MPa and k less than 0.3 W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\) are in Class III.