Research on the Electrical Capacitance and Electrical Conductivity of Char Resulting From Natural and Treated Wood

Abstract

Abstract. Wood is a material widely used for construction purposes and having quite a number of advantages. However, one of the major drawbacks of wood are its flammability. in case of fire in wooden buildings or constructions made of timber structures, the most noticeable feature of combustion is charring these structures. this property is important for identifying the cause of a fire. therefore, it is necessary to relate charring timber structures with certain significant effects of fire such as its duration or temperature. it is also particularly important to identify whether timber has been treated with fire retardant solutions before the fire break-out. the values of electrical capacitance and conductivity for the media obtained from char resulting from natural wood and that treated with fire retardant solutions and dispersed in distilled water depending on heating time have been determined. Moreover, it has been stated that the electric conductivity of char resulting from natural wood is 100 times lower, and the electrical capacitance of such char is 1000 lower than those resulting from treated wood. the regression analysis of the obtained data has been performed. the empirical equations have been derived. the results of the conducted research have been summarised. priority has been given to the application of the method evaluating electrical conductivity.

Prediction of temperature of standard fire exposure

“…Conversely, if timber has not been impregnated before a fire, the electrical conductivity will be < 0.1 mS/cm. The electrical conductivity of a medium made up of impregnated charcoal and distilled water varies insignificantly when heating the timber for 30 minutes or longer, and the lowest value was 0.1 mS/cm, regardless of the type, output and extinguishing method of the flame-retardant solution used in Lithuania (Mačiulaitis et al 2015).…”

“…The composition of the medium was 50 g of distilled water and 0.1 g of the dispersed testing material (Mačiulaitis et al 2015).…”

“…The electrical conductivity of samples was measured using a multi-meter Hanna HI4521 (Mačiulaitis et al 2015).…”

“…It has been assumed that in order to establish impregnation with flame retardant solutions, methods of electrical capacity or electrical conductivity can be used, because flame retardants used in Lithuania are saltbased. Data from previous studies has shown that flame retardants affect the values of the electrical conductivity and the electrical capacity, and so these methods can be used to determine the impregnation of wood (Mačiulaitis et al 2015).…”

Extraction of Soluble Salts and Iron Sulfides from the Wood of the “Huaguangjiao I” Shipwreck

“…Therefore, the electrical conductivity of the solution no longer significantly increased with time and stabilized around 80~100 µs/cm in the eighth cycle, indicating that the soluble salt ions in the wood were no longer migrating noticeably. Comparing this conductivity with that of the cold water extract of pine wood, which ranges from 60~180 µs/cm [27,28], it can be concluded that most of the soluble salts in the wood had been successfully removed, and the extraction of iron sulfides could be implemented. Therefore, the electrical conductivity of the solution no longer significantly increased with time and stabilized around 80~100 µs/cm in the eighth cycle, indicating that the soluble salt ions in the wood were no longer migrating noticeably.…”