Development of fire protective blankets based on expandable graphite

Fire hazard in constructions represents a very common risk that can happen anytime or in any situation, it is not related to the geographical position or time of the year. The basic way to protect a structure during a fire event is to use a passive fire protection system, this represents the main reason why it is necessary to develop new and more efficient passive fire protection systems. Expandable graphite is a relatively new intumescent material, which exhibits good thermal insulation properties after the expansion. The main focus of this study is the development of a new passive protection system based on expandable graphite and a fibreglass textile material. The textile material is supposed to improve the poor mechanical properties of the expanded graphite. To develop an effective protection system it is crucial to understand basic concepts related to fire chemistry and the thermal properties of the construction materials which will be protected. Based on the different types of textile materials and the quantity of expandable graphite it is possible to obtain a large array of blankets with different thermal properties and behaviour at elevated temperatures. An iterative process was used in order to obtain the most effective protective blanket system. Sample testing at elevated temperatures was performed by using an equipment manufactured specifically for this task. Insulation materials are not equally effective for all the construction materials, therefore different materials were used during testing to observe if this may influence the outcome. A series of tests were performed on the burned samples in order to determine the thermal properties which can be used afterwards to compare the effectiveness of the system to commercial products that are available on the market. Using a finite element software, different models were built with the purpose of validating the experimental data. The thermal conductivity of the protective blanket determined during the experiments is representative for the burned sample when the graphite is expanded. By performing a sensitivity analysis which is meant to calibrate the numerical and the experimental results, to a certain extent, it was possible to obtain the initial values of conductivity, prior to the graphite expansion. The general conclusion is that the effectiveness of the fire protection system comes from the good balance between the thermal properties of the protective product and the thermal behaviour of the protected structure.