Ground tire rubber thermo-mechanically devulcanized in the presence of waste engine oil as asphalt modifier

Abstract

Cross-linked elastomers network is main limitation for industrial usage of ground tire rubber (GTR) as asphalts’ and road pavements modifier. GTR was thermo-mechanically devulcanized via extrusion in the presence of waste engine oil (WEO) at temperature ranges from 150 to 280 °C. Combined impact of WEO content and extruder barrel temperature on the change of cross-linked structure of degraded GTR (DTGR) was investigated through sol fraction measurements and thermogravimetric analysis. Fourier-transform infrared spectroscopic analysis, storage stability, viscosity, temperature susceptibility and rheological properties of asphalt modified with DGTR were studied via infrared spectrometer, conventional tests, viscosity, dynamic shear rheology, dynamic mechanical analysis. Fluorescence microscopy was also applied to observe microstructure and the interfacial interaction between DGTR and asphalt. The results shown that the sol fraction of DGTR increases with the increase of WEO content, which results in low dynamic viscosity and storage modulus of the modified asphalts. Barrel temperature strongly affects the form of DGTR and final properties of modified asphalt. Modified asphalts with DGTR at barrel temperature in 180 °C and 210 °C show better rheological properties and broader operating temperature than that of at 280 °C, which is related to degradation of polymer main chain. In addition, 30 %wt. of DGTR content resulted in significant improvement rheological properties and storage stability of modified asphalt. Moreover, it was observed that higher content (above 40 %wt.) of DGTR causes the deterioration of performance properties of modified asphalts, due to the excessive quantities of undissolved rubber particles in asphalt.