Study On Preparation Of Synergist-Hydroxide Flame Retardant Asphalt And Properties Of Asphalt Mixture

Traditional flame retardants have certain flame retardant effect,but there are many problems,such as high smoke volume,high toxicity of flame retardants or high cost of use,etc.The poor economic and environmental benefits hinder the development of tunnel asphalt pavement in China to a certain extent,while pure inorganic materials have the advantages of non-toxic,harmless,low carbon environmental protection and good economic benefits.In this paper,several representative inorganic flame retardants were selected.The mix proportion was designed based on penetration test,ductility test,softening point test and limit oxygen index test.After surface modification by silane coupling agent,the compatibility between inorganic flame retardant materials and organic asphalt was improved,and finally the formula of flame retardant was formed.Through a lot of experimental studies on road performance and combustion performance of self-made flame retardant asphalt binder and its mixture,the following conclusions are drawn:(1)When the mixture ratio design was carried out,it was found that the penetration of the asphalt decreased and the softening point increased after the addition of the flame retardant,indicating that the high temperature performance was improved,but the low temperature ductility was reduced to some extent;the LOI value was improved.The flame retardant performance of the asphalt is improved.When the compounding ratio is ATH:MH:ZB=4:1:1,the total amount of the three is 30%,the LOI value is 29.3,and the synergistic flame retardant efficiency SE has a maximum value of 1.34.And only a small amount of smoke is produced.(2)According to the activation index and the viscosity test of flame retardant/liquid paraffin system,it can be seen that when the amount of KH-550 silane coupling agent is 1.2%,the reaction temperature is 70℃,and the reaction time is 45 minutes,the surface modification effect of flame retardant A-Si powder is better,which is verified by macro-hydrophilicity test and micro-SEM scanning test.(3)The results of temperature scanning and frequency scanning test show that the complex shear modulus and rutting factor of flame retardant modified asphalt increase,which indicates that flame retardant A-Si can enhance the ability of asphalt to resist rutting deformation at high temperature,and the phase angle decreases,which indicates that the elastic component of viscoelasticity of flame retardant modified asphalt increases.According to the rheological test of bending beam at low temperature,the flexural creep modulus of flame retardant modified asphalt increases with the increase of the content of flame retardant A-Si,while the creep rate decreases,indicating that the stress relaxation ability of flame retardant asphalt decreases.(4)The road and combustion performance tests of asphalt mixtures show that the self-made flame retardant A-Si can improve the flame retardancy of asphalt mixtures and reduce the loss of road performance after combustion.It is suitable for tunnel asphalt pavement construction.