Determination of the Laws of Thermal Resistance of Wood in Application of Fire-Retardant Fabric Coatings

Abstract

The creation of environmentally safe fire-retardant materials for wooden building structures will allow influencing the processes of heat resistance and physicochemical properties of the protective coating during its service life. Therefore, there is a need to study the conditions for forming a barrier to thermal conductivity and determine a mechanism of inhibiting heat transfer to the material. In this regard, a mathematical model of the thermal conductivity process when using fire-retardant fabric as a coating is developed, the solution of which allows obtaining changes in the thermal conductivity of the material. According to experimental data, it is calculated that the thermal conductivity coefficient during fire protection in the temperature range from 0 to 110 °C increases due to water evaporation and then gradually decreases to 0.25 W/(m∙°С), which corresponds to the value of coked foam. It is proved that the process of temperature inhibition consists in the formation of soot-like products that insulate the wooden structure. This made it possible to determine the conditions of fire protection of wood, formation of a barrier to thermal conductivity using fire-retardant fabric. Experimental studies confirmed that the wood sample with fire-retardant fabric withstood the temperature effect, namely, under the influence of the heat flux, the coating swelled, heat insulation continued for 900 s. Estimation of the maximum possible temperature penetration through the coating is carried out. It is found that when creating the sample surface temperature, which significantly exceeded the ignition temperature of wood, the temperature under the fabric did not reach the ignition temperature, and on the unheated surface it did not exceed 100 °C. Thus, there are reasons to argue about the possibility of directed control of the processes of wood fire protection using fire-retardant coatings capable of forming a protective layer on the material surface, which reduces the burnout rate of wood