Development and performance evaluation of composite flame retardant based on the thermodynamic properties of asphalt components

The demand for enhanced flame retardancy in asphalt pavement has increased due to its extensive use in enclosed spaces like tunnels. Based on four components of asphalt, the thermodynamic tests, basic performance tests, limit oxygen index tests, storage stability tests, and microscopic experiments were used to prepare and evaluate a new type of composite flame retardant asphalt. The results indicated that the thermal stability of the saturate and aromatic fractions was poor, while the resin and asphaltene components exhibited better thermal stability during combustion. The thermodynamic properties of the selected flame retardant materials were matched with different asphalt components. Three flame retardant systems were designed, and the final composition ratio was determined using orthogonal experiments and the entropy method. Compared to single and binary flame retardant systems, the asphalt with the three-component flame retardant system showed significantly better flame retardant performance. The softening point difference of asphalt increased continuously with higher flame retardant dosages. To maintain storage stability, the flame retardant content should be controlled below 12 %. Despite some agglomeration, most flame retardants were present as individual particles, indicating good dispersion in the asphalt. This study delves into the multi-stage combustion dynamics of asphalt from the perspective of its components and proposes a composite flame retardant formulation scheme. The findings are significant for the development of tunnel asphalt pavement and environmental protection.