Effect of Various Metal Hydroxide Flame Retardants on the Rheological Properties of Asphalt Binder

摘要

Metal hydroxide has been widely used as flame retardant to reduce the hazards of tunnel fire, however, few researches investigate its effect on the rheological properties of asphalt binder systemically. This study explores and compares the effect and mechanisms of magnesium hydroxide (MH), aluminium hydroxide (ATH), hydrated lime (HL), and layer double hydroxides (LDHs) on the rutting resistance, anti-aging resistance, as well as the thermal cracking resistance of asphalt binder. Rotational viscosity (RV) test, dynamic shear rheometer (DSR) test, and bending beam rheometer (BBR) test are involved in the project. Test results indicate: (1) the addition of metal hydroxide generally improves the rutting resistance of asphalt binder during high temperatures due to the typical filler effect, while weakens the resistance to thermal cracking of binder at low temperatures because of the stress concentration; (2) HL and LDHs enhance the anti-aging resistance of asphalt binder; (3) LDHs modified binder, which is proved with better rheological properties, including great rutting resistance, anti-aging resistance and passable resistance to thermal cracking, is recommended for further use. However, the high procurement price is still a big obstacle for its wider application.