According to the orthogonal test results in the reference information, the content of furfural extraction oil, waste rubber powder, stirring temperature and stirring time have effects on the properties of modified bitumen.

In the optimal scheme, the content of furfural extraction oil is 8% (mass fraction), the content of waste rubber powder is 25% (mass fraction), the stirring temperature is 210℃, and the stirring time is 2.5 hours. The SBS/CRMA modified bitumen prepared under the optimal scheme has the following properties: the ductility is 327mm at 5℃, the softening point is 78.0℃, and the elastic recovery is 91.6%. Compared with SBS modified bitumen and rubber powder modified bitumen, SBS/CRMA is more flexible at low temperatures and harder at high temperatures, with reduced temperature sensitivity and enhanced rutting resistance.

Therefore, the content of the best furfural extraction oil and waste rubber powder should be 8% and 25% (mass fraction), the best stirring temperature is 210℃, and the best stirring time is 2.5 hours. In this way, SBS/CRMA composite modified bitumen with excellent properties can be obtained.