Fabrication of fire-retarded epoxy asphalt composites with compatibilization and toughening for road tunnel pavements

Abstract

Although epoxy asphalt (EA) mixtures have been widely used for the pavement in tunnels, it was limited by its flammability, poor compatibility and low mechanical property. To solve the above problems, a compatibilized and toughening flame retardant (ESO-AA-DOPO) was prepared via the epoxidized soybean oil (ESO), arachidonic acid (AA) and 9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO). The presence of ESO-AA-DOPO significantly improved the flame retardancy, in which passing the UL-94 V-2 rating. The peak heat release rate (PHRR) reducing by 46.2 % for EA/40A-ESO-AA-DOPO composites comparing to that of pure EA. The analysis of char residue confirmed that the catalytic formation of dense and continuous char layer residue with good thermal oxidation stability originating from the ESO-AA-DOPO. The initial stage viscosity of ESO-AA-DOPO modified EA was lower than that of pure EA. Under the action of aliphatic epoxy resin and double bond, the molecular chain of epoxy resin presented a network structure, the base asphalt was divided into micelles, and the overall distribution of EA system was a 3D networks “sea-island”, which ensuring the increase in the glass transition temperature (Tg) of the EA system. The tensile strength and elongation at break of EA/40A-ESO-AA-DOPO composites were 123 % and 207 % higher than those of pure EA attributing to the improved compatibility and the formation of 3D networks “sea-island” structure.