Highly stable surfactant-crumb rubber-modified bitumen: NMR and rheological investigation

In this paper the properties of a new modified bitumen with crumb rubber (CR) additive andstabilising surfactants (a fatty acid – FA and an organosilane OS) are investigated. The characterisationof the surfactant-CR binder has been conducted by a set of laboratory tests, aspenetration, softening point and Fraass breaking point, and by comparison with a referenceneat bitumen and a CR modified bitumen. Dynamic shear rheometer (DSR) tests and nuclearmagnetic resonance relaxometry (T2-NMR) were used to investigate the rheological propertiesand the molecular interactions of both pristine and modified bitumen. The stability of thebitumen systems was determined by the Tuben test method. Experimental results suggest aclear improvement of the viscoelastic properties of the modified bitumen. All data show thatsurfactant-CR binder features comply with standard requirements. Surfactant modification, infact, is crucial because it allows using CR as a modifier with elimination of its separationduring transportation and storage at high temperature.