Fire Behaviour and Heat Release Properties of Asphalt Mixtures

A comprehensive analysis of the fire properties of asphaltic materials has undoubtedly become a primary need to provide proper instruments for the fire safety engineering in highway tunnels. Here, a propaedeutic research is proposed to define and develop fire-safe road construction materials. Limiting Oxygen Index test was performed to investigate the influence of magnesium hydroxide (MH) and aluminium hydroxide (ATH) in asphalt mastics ignitability. The most remarkable improvement was achieved with the 100% by weight of ATH. Limestone filler mainly composed of calcium carbonate was also investigated and resulted poorly influent in enhancing asphalt binder fire reaction. Cone calorimeter tests were then performed to evaluate fire properties of wearing course asphalt mixtures. As the bitumen content increases, the heat release significantly rises and the same occurs for incomplete combustion products, such as smoke and carbon monoxide. At constant bitumen content, the use of aluminium hydroxide instead of traditional limestone filler leads to a significant reduction in the Peak of Heat Release, the Total Smoke Release and the CO Yield.