| In general, asphalt pavement in tunnel is paved with the common HMA(Hot Mix Asphalt), but HMA would emission huge quantities of exhaust, if there is a bad ventilation, which have a serious impact on the quality of the environment around and physical health of constructers. At the same time, the flammability of asphalt causes much more fire hidden troubles. To remedy the above-mentioned disadvantages, double modification for asphalt should be researched to develop a type of viscosity reducing flame retardant asphalt, at the same time of reducing asphalt viscosity, improving asphalt flame retardant.Make use of orthogonal design method, could develop the optimum formula of viscosity reducing flame retardant asphalt, that is 4%EC 120+7%FRMAX, joined temperature of 150℃, stirring of 25 minutes when joining modifier. Through DSR,BBR tests, measurement the high-and-low temperature performance of viscosity reducing flame retardant asphalt. Through the change analysis of penetration and softening point of before and after asphalt ageing researching the anti-aging capability of asphalt, synchronously using microscope and isolation experiment to research the storage stability of viscosity reducing flame retardant asphalt, using poach test to research the adhesion of viscosity reducing flame retardant asphalt and aggregate. In addition, do rut test and low-temperature tensile test on the mix which added viscosity reducing flame retardant asphalt, research the high-low temperature capability of mixture, research water stability of mixture using Marshall test and seepage test. Initiative, apply oxygen index, smoke density and smoke toxicity to comprehensive appraisal the combustion property of mixture.Result of tests show that, oxygen index of viscosity reducing flame retardant asphalt has been rised, viscosity reduced, which is successful in flame retardancy and viscosity reduction; rut factor G*/sinδhas been increased, high-temperature performance has been improved; Warm-mixed and flame retardant disperse uniformity in asphalt, the storage stability is great; adhesion of asphalt and aggregate are reinforcement; but module of creep stiffness S and creep rate m are weaken than base asphalt, declining in low-temperature performance of viscosity reducing flame retardant asphalt; when asphalt aging, residual penetration is decreasing, softening point is rising, the aging ability is decline.The mix adding viscosity reducing flame retardant asphalt could be constructed in the temperature lower which is 15℃lower than normal asphalt mixtures, and the bulk performance doesn't impact, the result of rut test is 75% more than normal asphalt mixtures, soaking Marshall residual stability rising about 3.5%, tensile strength ratio after freeze-thaw splitting test rising about 2.5%, infiltration coefficient decline about 20%. The high-temperature of mixture, water stability and anti-leaking ability have improvement. In addition, the flame retardancy of mix added viscosity reducing flame retardant asphalt has great reinforcement, however, the component of flame retardant don't increase the toxicity of smoke. At the end of this article, as the control target, three combustion properties of viscosity reducing flame retardant asphalt have been suggested, which are oxygen index is no less than 27, SDR is no more than 25, smoke toxicity is no less than ZA2. |
