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
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: firstname.lastname@example.org (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...