Improving mechanism and effect analysis of sulfurated and grafted Eucommia Ulmoides Gum modified rubber asphalt

- EUG is originally applied in asphalt pavement to substitute TOR.
- Crosslinking sulfuration occurs between crumb rubber and EUG.
- Maleic Anhydride grafting EUG reacts with the amino groups in the asphaltene of asphalt.
- Grafted EUG increases the elasticity, viscosity, modulus and softening point of rubber asphalt.
- The compatibility of crumb rubber particles and asphalt is improved by EUG.

As a kind of Chinese specialty natural rubber, Eucommia Ulmoides Gum (EUG) is used to cross link crumb rubber and asphalt (rubber asphalt) in the proper method, and thus improve the properties of the blends of rubber asphalt and also alleviate the reliance of trans-polyoctenamer rubber (TOR), an expensive patented chemical product. The research is composed of the following steps. First, through the microscopic analysis of the dry-blend of crumb rubber and EUG, it is found that the cross-bonding sulfuration could occur between the crumb rubber and EUG. Second, following the graft method of the polybutadiene, a similar approach is used to graft EUG with Maleic Anhydride (MA), which establishes the crosslinking chemical bond between EUG and asphalt. Then, a series of rheological, pavement-performance and microscopic tests are conducted. It is found that grafted EUG increases the elasticity, viscosity, modulus, softening point, rutting resistance, and storage stability of rubber asphalt. Furthermore, by the modification of grafted EUG, an effective three-dimensional network is established in the blends, which not only improves the binder properties but also promotes the compatibility of the rubber asphalt. With the further research and wide application, it is believed that it will significantly contribute to the sustainable development of a natural compatibilizer in pavement material area with engineering, economic and environmental benefits.