Abstract
With the rapid development of tunnel construction, tunnel safety and the shortage of high-quality aggregates have concerned researchers so that this issue has become a research hot spot in the past few years. In the present study, we intended to prepare warm-mixed flame-retardant asphalt concrete using steel slag aggregate and evaluate its pavement and flame retardant performance. In this regard, the chemical composition and microstructure of the steel slag were studied using X-ray fluorescence analysis (XRF) and scanning electron microscopy (SEM). Then diverse pavement performances, including the dynamic stability, immersion Marshall, freeze–thaw splitting strength and low-temperature bending, were investigated for the warm-mixed flame-retardant asphalt concrete with steel slag aggregate. Moreover, a creative method of the flame spray gun combustion test was proposed to characterize the combustion degree and evaluate the flame-retardant performance of the asphalt concrete with steel slag. The experimental results show that the high-temperature and moisture stability performance are improved due to the addition of steel slag, however, the low-temperature performance is reduced for the warm-mixed flame-retardant asphalt concrete while it is still higher than the requirement value of the Chinese specification (GB/T 30596-2014). Meanwhile, the ignition temperature is increased and the ignition time is delayed for warm-mixed flame-retardant asphalt concrete because of the addition of steel slag. It is concluded that asphalt concrete with steel slag has excellent flame-retardant performance so that it is an appropriate choice for tunnel pavement.
Highlights
Asphalt pavements are the mainstream pavements in the world due to their short construction period, convenient maintenance, and comfortable driving [1,2,3], and they have been widely used in tunnel engineering
Asphalt is a kind of inflammable material and will lead to the burning of asphalt pavement when there is a fire accident in the tunnel, which increases the difficulty of rescue and produces a large amount of volatile organic compounds (VOCs), causing more serious pollution and endangering people’s lives [4,5]
The asphalt concrete prepared by the steel slag aggregate has high specific heat capacity and low thermal conductivity [36]
Summary
Asphalt pavements are the mainstream pavements in the world due to their short construction period, convenient maintenance, and comfortable driving [1,2,3], and they have been widely used in tunnel engineering. Volatile organic compounds (VOCs) emission of traditional hot-mixed asphalt concrete is large during construction, while the semi-closed environment and poor ventilation of tunnels make VOCs pollution more prominent. In order to resolve this shortcoming, warm-mixed flame-retardant technology has been widely studied in the past few years [6]. Studies show that this technology can reduce the construction temperature of asphalt concrete and increase the safety performance of a pavement [7,8]. Many scholars have studied warm-mixed asphalt pavement and flameretardant asphalt pavement technologies [9,10]. Zhao Jiang et al [11]
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