Physical and chemical properties of plasma treated crumb rubbers and high temperature characteristics of their rubberised asphalt binders

Compared with other polymer modified asphalts such as Styrene-butadiene-styrene (SBS) binders, crumb rubber modified asphalt has weak storage stability, which greatly limits its application. To improve its performances, crumb waste tire rubber (WTR) was pretreated by low temperature plasma (LTP) technology. The surface properties of plasma treated crumb WTR were characterised using dispersion and sedimentation test, contact angle measurement, scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The rheological properties of plasma treated crumb rubberised asphalt binders were investigated by means of dynamic shear rheometer (DSR) test. It was demonstrated that LTP treatment changed both the surface composition and roughness. The contact angle of pretreated crumb WTR dramatically fell from 107.7 degrees to 4.7 degrees. In addition, the Oil-wet Index value reduced from 9.08 to 2.60 s. The ATR-FTIR and XPS analysis results demonstrated that the oxygen atomic percent increased from 7.12% to 13.15%. Additionally, the penetration value of crumb rubber modified (CRM) binder decreased and softening point increased after treated with LTP technology. In addition, the rutting factor (G*/sin delta) increased and phase angle delta decreased performance grade and multiple stress creep recovery test results, indicating that the treated CRM binder owned a better resistance ability to deformation.