Synergistic effects of developed composite flame retardant on VOCs constituents of heated asphalt and carbonized layer compositions

Synergistic inhibitory effects of developed composite flame retardant (CFR) on the chemical constituents of toxic volatile organic compounds (VOCs) and their release amounts during asphalt thermal decomposition were studied by the pyrolysis-gas chromatography-mass spectrometry. The impacts of CFR on the chemical valence states of elemental compositions in carbonized layer were discussed using X-ray photoelectron spectroscopy. Test results indicate that CFR effectively reduces toxic VOCs constituents and their release amounts, as well as lowers the harmfulness of VOCs emitted from asphalt thermal decomposition. The CFR hinders and retards the thermal decomposition progress of asphalt, producing fewer hydrocarbon derivatives and cyclic substances. Additionally, the carbonized layer of asphalt is mainly composed of coke and hydrocarbons with ring, chain and C–O structures. The carbonized layer of FR asphalt primarily includes chain and ring structures with C–C bonds. CFR reduces the production of solid benzene-containing substances, ketones and aldehydes.