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In fire protection engineering an important field is to reduce the heat transfer to steel structures at elevated temperatures. There are a wide range of possible solutions to achieve this. One of these is by using insulation to decrease the heat flux to the steel. Boards made of calcium silicate are one type of insulation. Calcium silicate is an isotropic material and does not conduct heat well, which makes it suitable for insulation.To be able to decide the amount of insulation needed for protection the material properties have to be known, e.g. the thermal conductivity. Depending on the conductivity of a material it conducts heat differently. A low conductivity reduces the thermal impact from a heat source by decreasing the heat transfer within the material.There are several existing methods with the purpose of determining the conductivity of materials. Many of these methods are applicable for calcium silicate boards. There are however drawbacks with some of the methods and improvements can be made. For instance, some methods require expensive equipment or the equipment available are only self-made. There are also methods only valid for certain temperature spans, which reduces the area of application.The aim of this thesis was to evaluate a new method to determine the conductivity of insulation boards made of calcium silicate. The results are to be used in the area of fire protection engineering. Meaning, the results can be used to determine how much insulation is needed for protection at increased temperatures. The objective was to test calcium silicate boards in a cone calorimeter and measure the temperatures at the boundaries. The measurements were then used as input in computer models to determine the conductivity.A total of six insulation board samples were tested in a cone calorimeter. Two different set-ups were used in the laboratory tests to evaluate the influence of different boundary conditions. In four of the tests the insulation boards were exposed directly by the heating of the cone. In the other two a thin steel plate was attached to the top of the boards. This was done to accurately measure the temperature of the surface.The results showed a decreasing conductivity at elevated temperatures in all tests. Comparing the conductivity at 20 °C and 650 °C a reduction in conductivity of two-thirds was seen. At 440 °C the conductivity of the boards was calculated to approximately 0.16 W/(m×K). Since the methods have not been tested before further research and evaluations should be made to ensure its credibility and accuracy. An important part is to evaluate the methods at higher temperatures. Validerat; 20160312 (global_studentproject_submitter) |
