# Thermal Conductivity and Thermal Behavior of Mortar Containing Wood Shavings and Sawdust
## 3 Results
### Thermal Behavior  
Ultrasonic pulse velocity decreases as fine aggregates are by volume replaced with wood shavings (Figure 5) or wood sawdust (Figure 6). This is attributed to the different properties of wood compared to the properties of conventional fine aggregates. The importance of ultrasonic pulse velocity is that it is significantly correlated with mortar elastic properties [21; 28; 29]. It is also an indirect method for quantifying homogeneity \begin{table}
\begin{tabular}{c c c c c c c} \hline  & **Ref-Sh** & **B30 Sh** & **B50 Sh** & **B70 Sh** & **Ref-Sd** & **B10 Sd** & **B20 Sd** \\ \hline Average & kg/m3 & 2252 & 2104 & 1935 & 1714 & 2204 & 2033 & 1996 \\ Standard deviation & kg/m3 & 16 & 8 & 55 & 103 & 14 & 30 & 34 \\ \hline \end{tabular}
\end{table} 
Table 2: Density of fresh mortar. Figure 4: Thermal conductivity of mortar containing (**a**) wood shavings and (**b**) wood sawdust. in mortar. Ultrasonic pulse velocity exponentially decreases as exposure temperature increases. R-squared at all fittings was greater than 0.86. Figure 5: Ultrasonic pulse velocity of mortars containing wood shavings after (**a**) 15 min, (**b**) 30 min and (**c**) 60 min at 25 (no exposure, reference), 100, 200, 300, 400, 500 and 600 \({}^{\circ}\)C.  
Figure 6: Ultrasonic pulse velocity of mortars containing wood sawdust after (**a**) 15 min, (**b**) 30 min and (**c**) 60 min at 25 (no exposure, reference), 100, 200, 300, 400, 500 and 600 \({}^{\circ}\)C.  
Flexural and compressive strength of mortars containing wood shavings are shown in Figures 7 and 8, respectively. For flexural strength, the prevailing parameter is the exposure temperature. It seems that any contribution to flexural strength from the percentage of replacing conventional aggregates with wood shavings is not significant enough to be detected due to measurement uncertainty itself. In other words, while a trend may be theoretically expected, the magnitude of is not sufficiently large to be distinguished from the potential error inherent in the measurement process. It is shown by Figure 7 that the variability of flexural strength results is greater than the maximum difference between the trendlines of any of the replacement percentages. For example, at 200 \({}^{\circ}\)C, the reference mix has higher flexural strength than the 30% mix, but at 300 and 400 \({}^{\circ}\)C has a lower flexural strength, but again at 500 and 600 \({}^{\circ}\)C has a higher flexural strength than the 30% mix. Wood shavings resulted in a decrease in compressive strength. This is an expected result [9; 10; 30] as wood shavings do not provide enough strength as fine aggregate in the mortar phase, and shavings may act like voids for compression. The organic nature of wood materials leads to weaker interfacial bonding with the cement paste compared to mineral aggregates. This results in a more porous and discontinuous matrix, as supported by the lower ultrasonic pulse velocity values observed in this study. Furthermore, wood particles tend to absorb water during mixing, which can alter the local water-cement ratio, potentially leading to incomplete hydration or increased microcracking upon drying [30]. Figure 7: Flexural strength of mortars containing wood shavings after (**a**) 15 min, (**b**) 30 min and (**c**) 60 min at 25 (no exposure, reference), 100, 200, 300, 400, 500 and 600 \({}^{\circ}\)C.  
Flexural and compressive strength of mortars containing wood sawdust are shown in Figures 9 and 10, respectively. For flexural strength, the prevailing parameter is the exposure temperature. It seems that any contribution from the percentage of replacing conventional aggregates is not significant enough to be detected due to measurement uncertainty itself. Wood sawdust resulted in a decrease in compressive strength. These results agreed fairly well with those obtained by other researchers [9; 12].