Performance of crumb rubber bitumen and asphalt modified in the wet process alone and in combination with SBS polymer

Crumb rubber can be used as a bitumen or asphalt mixture modifier. Many investigations showed promising properties of crumb rubber-modified bitumen. However, the performance of crumb rubber-modified bitumen depends on crumb rubber properties, modification conditions and neat bitumen properties. The goal of this study is to determine the effect of the amount of crumb rubber and crumb rubber and SBS polymer combination on modified bitumen properties and also to evaluate the resistance to rutting of the asphalt mixture with crumb rubber-modified bitumen. The experimental research results showed that 2% crumb rubber can reduce the required amount of SBS polymer by half and ensure the main properties are equal to those of polymer-modified bitumen. It was also found that crumb rubber-modified bitumen (4% of the crumb rubber) and crumb rubber and SBS polymer-modified bitumen (2% of crumb rubber and 2% of SBS polymer) are equal in rutting resistance.