Tecnologia

Fuel 85 (2006) 1298–1304 www.fuelfirst.com

Experimental investigation of related properties of asphalt binders containing various flame retardants
Shaopeng Wu a,*, Peiliang Cong a, Jianying Yu a, Xiaofeng Luo a, Liantong Mo a,b
a

Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Wuhan 430070, China b Road and RailwayEngineering, Civil Engineering and Goesciences, Delft University of Technology, Delft 2600GA, The Netherlands Received 27 January 2005; received in revised form 10 May 2005; accepted 24 October 2005 Available online 16 November 2005

Abstract The improved flame retardancy of asphalt binders containing various kinds of flame retardants including antimony trioxide, decabromodiphenyl ether (EBPED),aluminium trihydroxide (ATH) and zinc borate (ZB) under different additive concentrations was investigated by limited oxygen index (LOI) and differential scanning calorimetry (DSC) test. To assess the effects of the type and concentration of the flame retardants on rheological properties of asphalt binders, the softening point, penetration, ductility, storage stability and viscosity were tested. The thinfilm oven test (TFOT) was used to investigate the effect of short-term oxidation on flame-resistant asphalt binders. Experimental results indicated that all of selected flame retardants had a relatively small effect of rheological properties of the asphalt binders, but a great effect on flame retardancy. Asphalt binder with LOI of 25.9 was obtained by adding 6 wt% mixed flame retardants of EBPED: antimonytrioxide: ZBZ3:1:1 by mass. Asphalt binder was transformed from inflammable materials into flame retardant materials. Therefore, the asphalt binder with both good flame retardancy and rheological properties is a novel road functional material to meet two respects’ demands as flame retardant materials and road materials at the same time. q 2005 Published by Elsevier Ltd.
Keywords: Asphalt;Flame-resistant; Rheological properties

1. Introduction Asphalt is a complex mixture of organic molecules that vary in chemical compositions and molecular weights. As asphalt is extracted from crude oil, which has many different compositions according to its origin, the precise breakdown of the hydrocarbon groups in asphalt is difficult to determine. Therefore, four main chemical types are used toclassify the compositions of the bitumen: asphaltenes, resins, aromatics and saturates. It is mainly composed of saturates, naphthene aromatics, polar aromatics and asphaltenes. So, the asphalt materials are easy to burn at approximately 300 8C [1–3]. Asphalt can be applied as construction material in the field of domestic and pavement buildings. An expanded growth of asphalt application concurrent withthe proliferation of safety standards being set by government and private agencies has indicated that it is of primary importance to reduce the
* Corresponding author. Tel./fax.: C86 27 87162595. E-mail address: wusp@whut.mail.edu.cn (S. Wu).

0016-2361/$ - see front matter q 2005 Published by Elsevier Ltd. doi:10.1016/j.fuel.2005.10.014

flammability of asphalt materials. But theflame-resistant asphalt binders have been relatively little studied in the field of asphalt pavement. The mechanism and compositions of flame-resistant asphalt binders need to be investigated deeply. Generally, five burning processes are considered to be involved in asphalt flammability: heating, decomposition, ignition, combustion and propagation. Flame retardancy can be acquired by the disruption of the burningprocess at one or more stages so that the process is terminated within an acceptable period of time, preferably before ignition actually occurs [4,5]. In this study, various kinds and concentrations of flame retardants were added into the asphalt to cut out the burning process of asphalt binders, acting as a role of flame retardancy. It is well-know that all kinds of flame retardants have...