# Effect of Wood Densification and GFRP Reinforcement on the Embedment Strength of Poplar CLT
## 3 Results and Discussion  
### Effect of Densification Ratio and Loading Direction on Embedment Strength  
With a confidence level of 95% (\(p\)-value \(>\) 0.05), the results of the analysis of variance (ANOVA) shown in Table 3 suggest that both the densification ratio and the loading direction had significant main impacts on embedment strength. As can be seen in Table 4, when compared to the control specimens, the embedment strength of CLT samples improved by 46% and 66.8%, respectively, with a 25% and 50% increase in densification ratio. Furthermore, it was discovered that the embedment strength of the CLT samples was 8% greater in the longitudinal (L) direction compared to the transverse (T) direction when the main effect of the loading direction of the CLT samples on embedment strength was considered. This was due to the fact that both of these factors were changed simultaneously. In addition, the findings showed that the embedment strength of CLT samples with a densification ratio of 0 (control samples), 25%, and 50% in the longitudinal loading direction of CLT samples was 10.9%, 5.4%, and 8.8% greater, respectively, compared to the transverse loading direction. \begin{table}
\begin{tabular}{l l c c c} \hline \hline
**Property** & **Source** & **df** & \
\begin{tabular}{c} **Mean** \\ **Square** \\ \end{tabular} & **F** & **Sig.** \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Embedment \\ strength \\ \end{tabular} } & Densification ratio & 2 & 2079.221 & 124.640 & 0.000 ** \\  & Loading direction & 1 & 151.877 & 9.104 & 0.004 ** \\  & Densification ratio \(\times\) loading direction & 2 & 4.520 & 0.271 & 0.764 \\ \hline \hline \end{tabular}  
* significant at 99% confidence level, ** non-significant.  
\end{table} 
Table 3: ANOVA table for main and interaction effects of densification ratio and loading direction on embedment strength of CLT samples. Comparing the embedment strength of CLT samples manufactured from densified wood and those reinforced with GFRP was one of the goals of this investigation. The embedment strength of the GFRP-reinforced CLT samples was compared with that of CLT samples constructed out of densified wood, and the average embedment strength of the CLT specimens is illustrated in Figure 4. The highest embedment strength belonged to the 50L samples (51.75 MPa), while the lowest embedment strength belonged to the 0T samples (28.24 MPa). The embedment strength of the CLT samples in the L direction was greater than in the T direction. More specifically, the embedment strength of 0L, 25L, 50L, and GFRP samples was 10.9%, 5.4%, 8.8%, and 6.8% more, respectively, than that of their counterpart samples tested in transverse direction. Reinforcement with 25% densification, 50% densification, and GFRP improved the embedment strength by 43%, 65.2%, and 43.4%, respectively, compared to the unreinforced samples in the L direction (0L). On the other hand, reinforcement with 25% densification, 50% densification, and GFRP improved the embedment strength by 50.6%, 68.5%, and 49%, respectively, compared to the unreinforced samples in the T direction (0T). In addition, no significant difference was observed in the embedment strength of reinforced CLT samples with 25% densification and GFRP in both directions (L and T). Therefore, it can be concluded that CLT with the same embedment strength can be produced using wood with a densification ratio of 25% rather than reinforcing it with GFRP. This alternate method demonstrates more efficiency in terms of both its cost and implementation. Previously, it was reported that embedment strength perpendicular to the grain was lower than that parallel to the grain [1,2,48,49]. Reinforcement with densification enhanced the wood density resulting in higher embedment strength of CLT samples. From a designer's point of view, wood density and dowel diameter are the main properties of design. There are also some approaches where density is the only parameter [22,50].