Determining patterns in the formation of an insulation layer of foam coke when protecting concrete against fire by reactive coating

Abstract

An issue related to using concrete for building structures is to ensure their stability and durability during operation within wide limits. Therefore, the object of research was the change in the properties of concrete in case of fire and its protection when applied with a reactive coating capable of forming a foam coke layer under the influence of high temperature on the coating. It has been proven that in the process of thermal action on the fire-resistant coating, the process of heat insulation of concrete involves the formation of soot-like products on the surface of the material. Thus, under the influence of the flame of the burner, a temperature arose on the surface of the sample, which led to the swelling of the coating by more than 18 mm. The measured temperature on the surface of the concrete sample under the layer of foam coke was no more than 140 °C, which indicates the formation of a fire barrier. In this regard, modeling of the process of heat transfer through the formed layer of foam coke in the process of its protection with a reactive coating was carried out and dependence was established, which makes it possible to estimate the coefficients of temperature conductivity and thermal conductivity during high-temperature action. According to the experimental data and the established dependences, the coefficient of temperature conductivity and heat conductivity of foam coke was calculated, which is 9.17·10–7 m2/s and 0.17 W/(m∙K). The assessment of the maximum possible penetration of fire through the layer of foam coke was carried out. A temperature was formed on the surface of the sample, which significantly exceeded the temperature of the destruction of concrete, and on the surface of concrete under the coating it did not reach 250 °C. So, there are reasons to assert the possibility of targeted regulation of concrete fire protection processes by using reactive coatings capable of forming a protective layer on the surface of the material that inhibits the rate of heat transfer