| Recently,warm-mix and flame-retarded technique has been widely used in the pavement of tunnels.As one of paving materials,studies on the flame retardancy of epoxy asphalts(EA)become more and more important since both epoxy resin and asphalt are flammable.Taking account of the demand of environmental protection,the flame retardancy of halogen-free synergistic flame retardants of aluminium hydroxide(ATH)/zinc borate(ZB)and environmental friendly flame retardants of brominated epoxy resin(BER)/antimony trioxide(AO)modified cold-mix epoxy asphalt binder(CEAB)and warm-mix epoxy asphalt binder(WEAB)were investigated,respectively.First,both ATH and ATH/ZB were filled in CEAB as flame retardants.Limiting oxygen index(LOI)meter,Brookfield rotational viscometer,thermogravimetric analyzer(TGA),differential scanning calorimetry(DSC),universal test machine and scanning electron microscopy(SEM)were used to evaluate the flame retardancy,rotational viscosity(RV),thermal stability,glass transition temperature(Tg),mechanical properties and morphology of flame-retarded CEAB.Results showed that the LOI values of ATH flame retarded CEAB did not reach the technical requirements of LOI value for flame retarded asphalt used in tunnels,even if the ATH content was as high as 30 wt%.However,the addition of ZB greatly increased the flame retardancy of ATH.In addition,the addition of ATH/ZB also promoted the viscosity,Tg and thermal stability of CEAB.Besides,the presence of ATH/ZB increased the tensile strength of CEAB,while the elongation at break,toughness and Young’s modulus decreased with the addition of flame retardants.Morphological observation indicated that uniform dispersion of flame retardants was found in the CEAB matrix.In a word,with addition of 20 wt%ATH/ZB,CEAB performs the most excellent flame-retarded and mechanical properties,which satisfies the technical requirement of epoxy asphalt for flame retarded pavement of tunnels.Second,BER/AO was added into WEAB as flame retardants.The influence of flame retardants on the flame retardancy,RV,thermal stability,Tg,cure behavior,mechanical properties and morphology of WEAB were characterized by Brookfield rotational viscometer,TGA,DSC,FTIR,universal test machine and laser scanning confocal microscope(LSCM).The addition of BER/AO significantly improved the flame retardancy and thermal stability of WEAB.Furthermore,the existence of BER/AO slightly decreased the viscosity of EA,which extended the construction time.The incorporation of flame retardants slightly increased Tg of WEAB.However,the addition of BER/AO had little effect on the mechanical properties of EA.The presence of synergistic flame retardants did not change the phase separation structure of EA.Nevertheless,the diameters of asphalt particles in the disperse phase became smaller and the distribution of asphalt particles became more disordered.Generally speaking,with addition of 8 wt%BER/AO,WEAB can have enough operable time and mechanical properties to reach the technical requirements for flame retarded pavement in tunnels. |
