Novel fire testing frameworks for Phase Change Materials and hemp-lime insulation
McLaggan, Martyn Scott
Modern buildings increasingly include the usage of innovative materials aimed at improving sustainability and reducing the carbon footprint of the built environment. Phase Change Materials (PCMs) are one such group of novel materials which reduce building energy consumption. These materials are typically flammable and contained within wall linings yet there has been no detailed assessment of their fire performance. Current standard fire test methods provide means to compare similar materials but do not deliver knowledge on how they would behave in the event of a real fire. Thus, the aim of this thesis is to develop a novel testing framework to assess the behaviour of these materials in realistic fire scenarios. For PCMs, a flammability study is conducted in the bench-scale cone calorimeter to evaluate the fire risk associated with these materials. Then, micro-scale Thermogravimetric Analysis (TGA) is used to identify the fundamental chemical reactions to be able to confidently interpret the flammability results. Finally, intermediate-scale standard fire tests are conducted to evaluate the applicability of the bench-scale results to realistic fire scenarios. These take the form of modified Lateral Ignition and Flame spread Test (LIFT) and Single Burning Item (SBI) tests to understand flame spread and compartment fires respectively. Finally, a simplified method to combine this knowledge for use in building design is proposed. This method allows the balancing of potential energy benefits with quantified fire performance to achieve the specified goals of the designer. Hemp-lime insulation is a material which has also becoming increasingly popular in the drive towards sustainability. The porous nature of the material means that smouldering combustions are the dominant reaction mode but there is currently no standardised test method for this type of behaviour. Thus, hemp-lime materials also represent an unquantified risk. The work in this thesis defines a simple, accessible and economically viable bench-scale method for quantifying the fire risk associated with rigid porous materials. This is applicable for both downward opposed flow and upward forward flow smoulder propagation conditions. The behaviour is then interpreted using micro-scale thermogravimetric analysis to understand the underlying pyrolysis and oxidation reactions. Designers can utilise this framework to quantify the smouldering risk associated with hemp-lime materials to enable their usage in the built environment. The holistic fire risk assessment performed in this thesis has quantified the behaviour of PCMs and hemp-lime insulation applicable to realistic fire scenarios. The simplified design method empowers designers to be able to realise innovative buildings through fundamental understanding of the fire behaviour of these materials. The outcomes of this thesis allow designers to mitigate the fire risk associated with these materials and achieve optimised engineering solutions. Furthermore, the novel fire testing frameworks provide the economically viable means to assess the fire performance of future PCMs and hemp-lime products which ensures lasting relevance of this research in the future.
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