## 3 Results
### Air Drying of Sediment-Based Bricks  
#### 3.2.1 Sediment-Based Bricks with No Fibers  
The monitoring of the drying of sediment-based bricks allows us to determine the duration of air drying, an essential parameter for the manufacturing of bricks at an industrial scale. Measurements began after the bricks had been de-molded, i.e., 1.5 h or 0.0625 days after de-molding. This parameter can be deduced from the weight-time graphs on a decimal scale (horizontal asymptote, Figure 9a) or from the intersection of two lines on a logarithmic scale (Figure 9b). For unfired bricks with no fiber, three moisture contents of 19%, 22% and 25% were selected, with 22% being considered the optimum from the Proctor test. Three samples, A, B and C, are manufactured for each water content. Figure 9a shows that the drying time increases as the water content increases. But the initial phase is common whatever the water content; see the initial tangent in the same figure giving a normalized weight loss of 0.025/day. The different phases of drying can be better observed in Figure 9b on a semi-logarithmic scale, i.e., initiation of drying; drying and end of drying. The drying phase concerns the linear part where the negative slope increases as the water content increases but is coupled with a rotation. The minimum weight of the bricks is obtained after an average period of 15 days and 8 h plus or minus 1 day and 8 h for a theoretical average water content of 22% \(\pm\) 3%. Table 3 shows the water content determined at the end of the drying period. In fact, the experimental average moisture content is around 20.6% \(\pm\) 3.5%. This difference is linked to the relative humidity of the test room on the one hand and to the water remaining in the core of the specimen on the other. Moreover,  
\begin{table}
\begin{tabular}{l l l} \hline
**Parameters** & **Bricks with No Fibers** & **Bricks Reinforced with Short Flax Fibers** \\ \hline Water content W (\%) & 19,22,25 & 22 \\ \hline Fiber length LF (cm) & - & 2, 3, 4 \\ \hline Fiber content FC (\%) & 0 & 0.1, 0.2, 0.3, 0.4, 0.5 \\ \hline
3 samples per set & A, B, C & A, B, C \\ \hline  & W19A,W19B,W19C & L2-0.1A, L2-0.1B, L2-0.1C; L2-0.2A, L2-0.2B, L2-0.2C; \\ References & W22A,W22B,W22C & L2-0.3A, L2-0.3B, L2-0.3C; L2-0.4A, L2-0.4B, L2-0.4C; \\  & W25A,W25B,W25C & L2-0.5A, L2-0.5B, L2-0.5C; continued for L = 3 cm and 4 cm. \\ \hline \end{tabular}
\end{table}
Table 2: Investigated parameters and unfired brick references.  
beyond the minimum mass observed, oscillations in the normalized mass can be observed in Figure 9a or Figure 9b.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Targeted** & **Final Normalized** & **Water Weight 1 (g)** & **Averaged** \\
**Water Content (\%)** & **Weight 1 (-)** & **Water Weight 1 (\%)** & **Water Content 1 (\%)** \\ \hline
19 & 0.85 & 55.61 & 17.1 \\
22 & 0.83 & 69.08 & 20.7 \\
25 & 0.80 & 79.81 & 24.1 \\ \hline \hline \end{tabular}  
* Averaged values for samples A, B and C.  
\end{table}
Table 3: Targeted or desired moisture content.  
Figure 9: Normalized weight of sediment-based bricks with no fibers during air drying: (**a**) decimal time scale, (**b**) logarithmic time scale.