Novel organic-inorganic hybrid towards enhancement of flame retardancy, suppression of volatile organic compounds and toxic smokes for asphalt

The enhancement of flame retardancy, the suppression of volatile organic compounds (VOCs) and carcinogenic smokes at elevated temperature are urgent for the widely application of asphalt. In present work, an organic-inorganic hybrid flame retardant (ATH@SA@Fe3+) was designed via simple two-step reactions, including in-situ growth of sodium alginate (SA) on the surface of alumina trihydrate (ATH) and a crosslinking of iron ion (Fe3+) on ATH@SA. The three-dimensional network crosslinking structure of ATH@SA@Fe3+ effectively hindered and retarded the thermal decomposition progress of asphalt, producing fewer hydrocarbon derivatives, reducing VOCs constituents and their release amounts. For the Asphalt/10ATH@SA@Fe3+ composites, the total heat release (THR), the total smoke production (TSP) and the peak smoke production rate (pSPR) was reduced by 28.2%, 35.2% and 28.0% respectively, indicating a high flame-retarding and smoke suppression efficiency via the formation of expanded, impact and continuous carbon layer. Meanwhile, the network crosslinking structure could arrest the molecular motion and lead to the thermal stability, elasticity rutting resistance enhancement of asphalt materials. In perspective, the research results provided a scientific basis for the management of flame-retardant materials for asphalt pavement and the formulation of emission reduction strategies.