# Mechanical Properties and Flexural Behavior of Sustainable Bamboo Fiber-Reinforced Mortar
## 4 Conclusions  
This study focused on the development of a sustainable and affordable mortar mixture consisting of a high amount of fly ash (656 kg/m\({}^{3}\)) and varying contents of bamboo fibers (4/6/8 V%) from waste by-products of engineered bamboo-composite fabrication. The bamboo fibers, obtained from bamboo composite production waste, were categorized into two groups of 300 \(\upmu\)m and 500 \(\upmu\)m and were incorporated at three different volumes of 4/6/8 V% within each mix. The mechanical performance of the developed formulations was assessed via the measurement of the mechanical and fracture properties. From these results, the following conclusions can be drawn:  
The addition of 4/6/8 V% of bamboo fibers has a reasonably modest effect on the compressive strength of the mixtures. Compared to the control mixture without fibers, the reduction of the compressive strength of the mixtures with 300 \(\upmu\)m fibers is between 7.8% and 19.9%, with larger fiber volume fractions corresponding to a greater reduction of strength. * The mixtures with 500 \(\upmu\)m fibers were reduced in compressive strength between 9.1% and 27.0% by the same range of 4/6/8 V% of fiber content. The reduction of the compressive strength for both the 300 \(\upmu\)m and 500 \(\upmu\)m fibers could be related to the lower mechanical properties of the bamboo fibers as well as the influence of their aspect ratio. * The compressive strengths of the mixtures with 8 V% of fibers were shown to be 60.2 MPa and 54.6 MPa for the 300 \(\upmu\)m and 500 \(\upmu\)m mixtures, respectively, and is within a reasonable range for use in structural members. \begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mix**} & \multicolumn{2}{c}{**Limit of**} & \multirow{2}{*}{**SD**} & \multirow{2}{*}{**SD**} & \multirow{2}{*}{**MOR**} & \multirow{2}{*}{**SD**} & \multirow{2}{*}{**SD**} & \multirow{2}{*}{**SD**} & \multicolumn{2}{c}{**Tough-Ness**} & \multirow{2}{*}{**SD**} & \multirow{2}{*}{**SD**} & \multicolumn{2}{c}{**Tough-Ness**} \\  & & & & & & & & & & & & at 2 mm & \\ \hline  & [N] & [N] & [\%] & MPa & [MPa] & [\%] & [J] & [J] & [\%] & [J] & [J] & [\%] \\ \hline Contr. & 3321 & 231.7 & 7.0 & 4.0 & 0.26 & 6.6 & 0.0 & 0.00 & 0.0 & 0.0 & 0.0 & 0.0 \\
300-8P & 5295 & 860.9 & 16.3 * & 6.4 & 1.03 & 16.2 * & 2.6 & 0.95 & 35.9 * & 3.4 & 1.35 & 39.8 * \\
300-6P & 4678 & 914.2 & 19.5 * & 5.6 & 1.08 & 19.3 * & 2.1 & 0.70 & 33.2 * & 2.7 * & 0.86 & 32.0 * \\
300-4P & 4327 & 226.5 & 5.2 & 5.2 & 0.29 & 5.7 & 1.5 & 0.09 & 6.1 & 1.9 & 0.12 & 6.5 \\
500-8P & 5345 & 406.5 & 7.6 & 6.4 & 0.46 & 7.2 & 2.4 & 0.14 & 5.9 & 3.3 & 0.37 & 11.3 \\
500-6P & 4374 & 491.9 & 11.2 & 5.2 & 0.59 & 11.3 & 1.9 & 0.08 & 4.3 & 2.5 & 0.12 & 4.9 \\
500-4P & 3839 & 484.5 & 12.6 & 4.6 & 0.57 & 12.4 & 1.6 & 0.12 & 7.6 & 2.1 & 0.04 & 2.2 \\ \hline \hline \end{tabular}
* The high standard deviation is a result of a significantly lower bending performance of one specimen.  
\end{table} 
Table 4: Flexural strength and toughness parameters of the four-point bending test. Figure 10: Toughness of the mixtures at 1 mm deflection measured according to RILEM RC 162-TDF [53]. * The splitting tensile strength of the bamboo fiber-reinforced mixtures displays a reduction of between 6.9% and 31.9% compared to the control mixture depending on the fiber volume and aspect ratio. The mixtures containing the 500 \(\upmu\)m fibers (lower aspect ratio) show lower strength in comparison with the 300 \(\upmu\)m mixtures. * All bamboo fiber-reinforced mortar mixtures display a strain-softening behavior. The mixtures with 8 V% of fibers show better crack-bridging effects than those with lower volume fractions, resulting in higher residual strength. * The toughness of the mixtures was evaluated at a mid-span deflection of L/150. The 300 \(\upmu\)m fiber mixtures show values of 2.6, 2.1 and 1.5 Joule for 8, 6 and 4 V% of fibers respectively, whereas the 500 \(\upmu\)m mixtures show, in general, lower toughness of 2.40, 1.90 and 1.63 Joule.