Research On The Performance Of DBDPE Composite Flame Retardant Asphalt

Along with the extensive use of asphalt pavement in tunnel construction,the flame retardant technology of asphalt pavement materials has increasingly attracted the attention of relevant scholars.Current application of flame retardant has the characteristics of toxic,large smoke and low comprehensive performance-price ratio.To conform to the development trend of non toxic,less smoke,high efficiency and compounding,it is of great significance and value to develop a bromine-based flame retardant that is compatible with smoke suppression and high cost performance.At the same time,the research on flame retardants is mostly the comparison of macroscopic performances,which is lack of characteristics and mechanism changes in real combustion process.In this paper,the combustion characteristics and mechanism of DBDPE composite flame retardant were studied based on the comprehensive properties of flame retardant,smoke suppression and using performance.Based on the DBDPE composite flame retardant(DBDPE:Sb2O3:ATH=4:1:1)developed by the research group in the early stage,tests of asphalt three main index,DSR,BBR,smoke density,limiting oxygen index and cone calorimeter were carried out to analyze the effect of DBDPE composite flame retardant dosage on high and low temperature performance,smoke suppression performance and flame retardant performanceunder condition of 6%、8%、10%、12%、14%dosing,which determined the best mixing amount.at the same time,correlation between evaluation methods was researched.The results showed that:DBDPE composite flame retardant can improve the high temperature performance of asphalt,but the improvement effect is limited when the dosage is more than 10%;the low temperature performance of asphalt is sensitive to DBDPE composite flame retardant,and the low temperature performance increases greatly with the increase of dosage.especially when the dosage is more than 12%,the low temperature performance drops rapidly;DBDPE composite flame retardant can improve the smoke suppression performance of asphalt,when the dosage is 14-16%,the smoke yield tends to be stable;DBDPE composite flame retardant dosage When dosage is more than 10%,the CO concentration of asphalt burning will be improved;DBDPE composite flame retardant has good flame retardant performance,but when the dosage is more than 12%,the flame retardant performance of asphalt is improved.Comprehensive smoke suppression,flame retardant and high and low temperature performance,the recommended optimum amount of DBDPE composite flame retardant is 10%.At the same time,the cone ignition calorimeter ignition time TTI,the total smoke production TSR and the limiting oxygen index LOI and the smoke density grade SDR are linearly correlated.The cone calorimeter TTI and TSR can be used instead of the limiting oxygen index and smoke density as the evaluation indicators,and the TTI value of the flame retardant asphalt cone calorimeter should be greater than 43.1s.Based on the combustion simulation test of cone calorimeter,the combustion characteristics of single component,two-component and three-component flame-retardant asphalt,such as heat release,smoke release,flammability,toxicity and mass loss,were studied.The flame-retardant effect of single flame-retardant in DBDPE composite flame-retardant asphalt,as well as the synergistic effect and mechanism among them,were analyzed.The results showed that:DBDPE composite flame retardant has good flame retardant effect and good smoke suppression effect.Compared with matrix asphalt,total heat release THR is reduced by 27.3%,total smoke production TSR is reduced by 8.52%,and ignition time is extended to 52s.The flame retardant performance is better than various single-component and two-component flame retardants.In DBDPE composite flame retardant,halogen-antimony mainly acts as a flame retardant,ATH acts as a smoke suppressor,and the flame retardant mechanism is halogen-antimony.And ATH flame retardant on the basis of their respective flame retardant mechanism,simple physical superposition,no chemical reaction between them,and did not change the respective flame retardant mechanism,and the halogen-fluorene flame retardant is mainly based on the gas phase flame retardant mechanism,The condensed phase flame retardant is supplemented,and ATH delays the combustion of the asphalt.The thermogravimetric-infrared analysis and thermal analysis kinetics of DBDPE-Sb2O3 flame retardant showed that the thermal decomposition of DBDPE-Sb2O3 flame retardant asphalt is mainly divided into four stages:physical volatilization and oxidation of low molecular matter,combustion of active volatiles,carbonization of asphalt,combustion of a small amount of volatiles and combustion of carbon residue,the first and second stages can be explained by the three-dimensional diffusion model of the Jander equation,and the third and fourth stages can be solved by the one-dimensional phase boundary reaction of the Mampel Power rule model to explain.At the same time,the most difficult phase of the matrix asphalt is the second stage,while the DBDPE-Sb2O3 flame retardant asphalt is the most difficult to burn into the fourth stage.The activation energy required for the first two stages of DBDPE-Sb2O3 flame retardant asphalt is slightly lower than that of the matrix asphalt,but The three or four stages with high weight loss rate are much larger than that of matrix asphalt.