Study On The Preparation And Pavement Performance Of Flame Retardant Asphalt Concrete

Asphalt pavement was constructed widely in domestic and international freeways, bridge and tunnel, with the good performance, such as no joints, surface formation of good, smooth ride, comfortable oriented, high degree of mechanization construction, progress rapidly, good quality, and simple maintaining. However, traffic tunnel fire was an international problem, and many countries of the world have been appearing very serious tunnel fire. Asphalt is the flammable material;so there have dangers of fire in the tunnel that asphalt concrete was used. Research flame retardant asphalt and apply in the tunnel is a historical advance.For the former part, this paper described the preparation of flame retardant asphalt and the effect of various flame retardants and contents. The limited oxygen index (LOI) and DSC-TG testing method was employed to study flame retardancy of flame retardants modified asphalt. After successful preparation of flame retardant modified asphalt that meet both pavement properties and flame retardancy, AR2000 dynamic shear rheometer and Brookfield viscometer were employed to investigate the rheological properties of aging and unaging flame retardant asphalt. The viscosity-temperature curves show the effect of type and concentration of flame retardants on rotational viscosity. By observing the G~*-T curve , the complex modulus of flame retardant asphalt was analyzed and by observing the δ-T curve , the changes of the elastic deformation and the viscous deformation was investigated. The properties of rutting was analyzed by the G~*/sinδ-T curve. The stone mastic asphalt design method was employed to design and prepare flame retardant asphalt mixture and the volumetric and pavement performance were tested. Both aggregates were substituted by mineral powder method and fuel burning simulation method was designed to investigate the flame retardancy of flame retardant asphalt mixture.The experiment results indicate that the incorporation of several kinds of flame retardants enhances asphalts flame retardancy and its engineering properties meet demands. Comparison neat asphalt and flame retardants modified asphalt, after flame retardants modified the viscosity and softening point increase and penetration and ductility decrease. The complex modulus (G*) and rutting factor (G*/sin8) increase but The phase angle (8) of flame retardant asphalt binder lower than origin asphalt's at low temperature, and at high temperature, the phase angle (5) of flame retardant asphalt binder higher than neat. The flame retardant asphalt mixtures have good flame retardancy and pavement performance.The further test results and analysis indicated that flame retardant asphalt mixture is feasible to apply in tunnel through mixed appropriate multiplex flame retardants. Engineering practice results of Yidou to Changyang tunnel highway proved that flame retardant asphalt and its mixtuers is exactly what control asphalt mixtuer is demanded. The flame retardant asphalt pavement act well.