Preparation and Evaluation of Composite Flame Retardant Asphalt in Tunnel

Asphalt pavement becomes more and more popular in tunnel engineering, while its flammability is a serious problem that limits its development. In order to obtain a flame retardant asphalt, orthogonal design was utilized to investigate the best flame retardant content of magnesium hydroxide (MH), phosphorus (P) and decabromodiphenyl ethane (DBDPE). Limiting oxygen index (LOI), penetration, softening point and ductility tests were employed to evaluate the flame retardancy and pavement performance of asphalt. The results show that three kinds of flame retardants have positive influence on the low temperature performance and flame retardancy of SBS modified asphalt but not good for its high temperature performance. The best flame retardant content is determined as: 4% MH, 6% P and 8% DBDPE.