Flammability and thermal properties of bitumen with aluminium trihydroxide and expanded vermiculite

Effects of aluminium trihydroxide (ATH), expanded vermiculite (EVMT), organic expanded vermiculite (OEVMT) and their mixtures (ATH/EVMT and ATH/OEVMT) on flame retardancy of bitumen were investigated. The flammability and thermal properties of the bitumen with different flame retardants were evaluated by limiting oxygen index, thermogravimetry and differential scanning calorimetry tests. Results show that the mixed flame retardant of ATH and EVMT shows a much more significant influence on the flame retardancy of bitumen than the single one. This unusual flame retardancy arises from the positive synergetic effect between the ATH and EVMT components in this mixed flame retardant, which provide the water vapor and protective barrier during the burning test of bitumen. The thermal analysis reveals that the addition of mixed flame retardant (ATH and EVMT) improves the thermal degradation behavior of bitumen drastically, which also confirms the synergetic effect of ATH and EVMT on the flame retardancy of bitumen.