Rheology and volatile organic compounds characteristics of warm-mix flame retardant asphalt

Warm-mix flame retardant asphalt (WF-A) is widely used in tunnel pavement owing to its positive con-struction and workability, as well as excellent flame retardant performance. When flame retardant (FR) improves the flame retardancy of asphalt binders and warm mix agent reduces the construction temper-atures, the combined effects of the two additives on asphalt binders' performances need to be studied. In this study, through orthogonal experimental design, limiting oxygen index (LOI) test and viscosity test, the optimum WF-A was selected. Afterward, the service performances of WF-A were comparative ana-lyzed with warm mixing asphalt, SBS modified asphalt and flame retardant asphalt, including construc-tion temperatures, high-temperature rheological property and aging resistance. Additionally, the characteristics of volatile organic compounds (VOC) emission are assessed by gas chromatography mass spectrometry (GC-MS). The results show that the optimum WF-A is that with the content ratio of 3.5% EC-120 and 8% FRMAX under the mixing temperature of 150 degrees C, and warm mix agent (EC-120) can obvi-ously reduce the high-temperature viscosity of SBS modified asphalt binder, and increase the high-temperature fluidity; flame retardant (FRMAX) adversely affects the viscosity reducing effect of EC-120. The additions of the two additives are not conductive to the aging resistance of asphalt. Besides, both EC-120 and FRMAX have the effect of reducing asphalt fumes, and the optimum WF-A can reduce VOC emissions by 45.5% compared with SBS modified asphalt binder. The study provides significant references for further applying WF-A in the sustainable and safe construction of road networks. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the optimal warm-mix flame retardant asphalt (WF-A) through experimental design and testing, comparing its performance with other types of asphalt. It was found that the warm mix agent and flame retardant had different effects on asphalt performance, but were not conducive to aging resistance, while also reducing volatile organic compound emissions.