Study of tunnel pavements behaviour in fire by using coupled cone calorimeter – FTIR analysis

In recent years there has been a growing interest in analyzing the contribution of pavements to fire growth for improving safety in tunnels. However, only few analyses take into account or quantifying toxic gases emitted during the pavement burn out. In this study, simultaneous cone calorimeter and FTIR analyses were conducted to evaluate the contribution to fire growth of two different types of fireproof pavements (concrete and asphalt) obtaining averaged values of heat release rate per unit area of 0 and 50 kW/m2 respectively. The CO released was monitored as a valuation of how complete is the combustion taking place and also to compare the toxic potential of such materials. Further approximated ignition temperatures of asphalt in the range of 420–450 °C were also obtained. The results indicate that concrete pavement do not contribute to fire growth since no ignition was observed while asphalt pavement contributes similarly to other components generally found in vehicles. Very opaque fumes with significant concentrations of CO were detected during asphalt pavement combustion. Severe thermal degradation was observed in the asphalt pavement samples, including calcination and the detachment of aggregates while on the surface of concrete pavement samples just some minor cracks were reported.