# Thermal Conductivity and Thermal Behavior of Mortar Containing Wood Shavings and Sawdust
Overall, the use of wood sawdust and shavings in concrete or mortar offers a solution to wood waste byproduct management while also improving the thermal behavior of the composite by reducing the heat transfer through it. Nevertheless, since the way that concrete and wood behave at high temperatures varies greatly, it is crucial to conduct a thorough investigation of these two materials' behaviors, as this research does. In the present study, mortar mixes with 0, 30, 50 and 70% by volume replacement of conventional fine limestone aggregates with wood shavings were made. Also, mixes with 0, 10 and 20% by volume replacement of aggregates with wood sawdust were made. Thermal conductivity of hardened mortar was determined with the guarded hot plate method according to standard EN 12667:2001 [23]. One way to classify thermal conductivity methods is based on whether they are in a steady state or transient. Steady-state methods apply a constant heat flux to a sample and measure the resulting temperature difference across the sample. Transient methods apply a heat pulse or a periodic heat source to a sample and measure the temperature response over time. A steady-state method is the guarded hot plate method and it is considered a very commonly used method for building materials [24]. Specimens were also submitted to 100, 200, 300, 400, 500 and 600 \({}^{\circ}\)C to study their thermal behavior at those temperatures. Physical and mechanical properties such as density, ultrasonic pulse velocity and compressive strength were also measured prior to heating. These results, together with relevant data from existing literature, are intended to support future meta-analyses comparing the effects of different wood types, mix designs and materials. This study contributes to the relatively limited body of literature concerning the use of wood shavings and sawdust as a lightweight aggregate in cementitious mortars, particularly with respect to their thermal behavior under elevated temperature exposure. While previous studies have explored the mechanical and insulating properties of bio-based aggregates, few have specifically examined the thermal coefficient and post-exposure behavior of wood shavings at elevated temperatures up to 700 \({}^{\circ}\)C. Most studies focus on ambient or moderately elevated temperatures, with limited attention to fire-related thermal performance. This paper addresses that gap by providing novel data on the response of wood-based mortars to high-temperature exposure, offering insight into their potential use in thermally demanding environments. Further research is needed to explore long-term durability under cyclic thermal loads, the influence of different wood species and particle sizes, and the optimization of binder-to-aggregate ratios for enhanced thermal and mechanical performance. These directions remain largely unexplored and represent key opportunities for expanding the applicability of wood-based mortars in sustainable construction. Wood shavings and sawdust were chosen in this stage to be used as they are, without any pretreatment. Pretreatment as premixing with resins could be used to enhance the durability, but it would also increase the cost. Further study of those pretreatments and a technoeconomic study, along with the durability of concrete, is needed.