Non-halogenated fire protective coatings for structural applications

• Main Author: Ng, Yan Hao
• Other Authors: Tan Kang Hai
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Civil engineering; Engineering::Materials
• Online Access: https://hdl.handle.net/10356/144334
• Institution: Nanyang Technological University

Modern high-rise buildings are typically constructed with reinforced concrete-, or steel-framed structures. As fire incidents in a building threaten the lives of the people and inflict severe damages to the infrastructure, it is a regulatory requirement to protect steel structures with fire protective coatings. It is also practical to apply fire protective coatings on existing concrete structures if there are changes to fire-resistance rating. Therefore, the thesis focuses on the development of fire protective coatings, with particular emphasis on steel as the substrate due to their prevalence in the industry. The fire-retardant mechanism of the developed coating formulations is discussed in detail, and it was found that the expansion of expandable graphite formed an insulating barrier that is capable of reducing heat transfer to the substrate. Expandable graphite depends heavily on the physical flame-retardant mechanism as it does not react with the additives or the resin. Although studies on mechanism explain the reason behind the improved flame-retardant performance at the materials-scale, it is difficult to correlate the findings with the performance of the coatings at structural-scale. In the literature, this aspect is not well-studied, and the work performed in this thesis will bridge the gap between materials- and structural-scale experiments. It was found that the flammability characteristics obtained through materials-scale tests correlate to the initial 10 to 15 min of a structural-scale fire test. After the initial stage, materials-scale tests do not provide much insights on the performance of a coating and will require the use of bulk-scale fire tests. Thermal conductivity of the residue was also identified to be one of the key parameters that govern the rise in temperature at the later stage of a structural-scale fire test. The effective thermal conductivity of the coatings based on the structural-scale fire test was calculated and validated with numerical simulations. This provides a reference for the measured conductivity values and calculated effective thermal conductivity values from a bulk-scale cone calorimeter test. The effective thermal conductivity values obtained from the bulk-scale cone calorimeter were in agreement with the effective thermal conductivity values from the structural-scale fire test. It highlights the potential of using effective conductivity values to predict the performance of other coatings before conducting a structural-scale fire test. Based on the work performed on steel substrates, a generic flowchart to design fire protective coatings was proposed. The developed fire protective coatings were also extended to concrete structures and the results on performance were highlighted towards the end in this thesis. In conclusion, the work in this thesis provides a critical understanding of different parameters that contribute to performance at structural-scale. Correlating the materials-scale behaviour of the coatings to bulk- and structural-scale is a critical contribution of this work to the field. This is made possible through the knowledge gleaned from two engineering disciplines, which is currently lacking in the literature on fire-protective coating systems.