Tunnel flame-retardant asphalt was prepared by zinc borate(ZB)and self-made flame retardant(BFRSi),and its combustion performances were systematically investigated through cone calorimetry,thermal gravimetric analysis and smoke density analysis methods.The synergistic effect of BFR-Si and ZB was discussed.The results indicate that ZB and BFR-Si have synergistic effect which made the smoke density(Ds),the heat release rate(HRR),mass loss rate(MLR)and the effective heat of combustion(EHC)indicators of road as...