Abstract: The modified asphalt was prepared by using aluminum hydroxide (ATH) with four particle sizes of 1 μm, 6.5 μm, 25 μm, and 45 μm.The influence of ATH particle size on the flame retardant effect and thermal oxidation decomposition temperature zone of asphalt is studied by limiting oxygen index and thermogravimetric analysis. The penetration and softening point tests are used to study the influence of ATH particle size on the basic performance indexes of asphalt. The results show that when the flame retardant content is 25%, in the range of 1~45 μm, the larger the particle size of ATH, the better the flame retardant effect of the asphalt. Among them, the 45 μmATH modified asphalt has the best flame retardant effect. The oxygen index value of asphalt can be increased to 28.5%; Thermogravimetric analysis results show that both 1 μmATH and 45 μmATH advance the thermal oxidation decomposition temperature zone of each stage of asphalt, and the first weight loss peak rate of 1 μmATH modified asphalt is obviously greater than 45 μmATH modified asphalt. At the same time, the penetration value of asphalt shows a downward trend with the increase of ATH particle size, and there is no obvious law of softening point.

Key words: aluminum hydroxide, particle size, asphalt, oxygen index, thermogravimetric analysis