Optimum content of styrene-butadiene rubber/styrene-butadiene-styrene block copolymer/rubber powder in high viscosity composite modified asphalt based on Box-Behnken method

Abstract

Response surface (Box-Behnken) method was used to establish respective response surface models with the contents of styrene-buta-diene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS) and rubber powder as the influen-cing factors, and the three technical indexes of asphalt, dynamic viscosity 60 ℃ and Brinell viscosity at 170 ℃ as evaluation indexes. The effects of contents of three additives on technical indexes of the asphalt were discussed, and the optimum contents of SBR, SBS and rubber powder in high viscosity composite modified asphalt were selected. The results showed that the high viscosity composite modified asphalt with mass fraction of SBS of 5%, SBR of 5% and rubber powder of 15% respectively had the best performance, its penetration was 4.63 mm, ductility was 364 mm, softening point was 86.5 ℃, dynamic viscosity at 60 ℃ was 78 158 Pa·s, and Brinell viscosity at 170 ℃ was 2.72 Pa·s. All the indexes were higher than the standard requirements.