Rheological Properties of Polypropylene Reinforced Asphalt Binder

Abstract

Polypropylene fibers (PP fibers) were used as additives to prepare fiber-reinforced asphalt binders in this work, with concentrations varying from 0 to 2.5 % in increments of 0.5 % by weight of asphalt. The microstructure of fibers and dispersion of fibers in the asphalt were analyzed via scanning electron microscopy (SEM) using a ZEISS microscope at different magnification rates. Penetration, softening point, dynamic shear rheometer (DSR), and Multiple Stress Creep Recovery (MSCR) tests were conducted to study the rheological properties and the results are compared. With the increase in the dosage of PP fibers, the penetration values were decreased while the softening points increased. Complex shear modulus was increased and phase angles were decreased. The Strategic Highway Research Program (SHRP) rutting parameter G*/Sinδ and the Shenoy’s rutting parameter, G*/(1 − (1/sinδ.tanδ)), were improved with fibers. MSCR results indicate that the non-recoverable creep compliance (Jnr) and percent of recovery (R%) are decreased and increased, respectively, with the addition of fibers. The results indicate that the asphalt with PP fiber reduces thermal sensitivity and increased resistance to permanent deformation at high temperatures. The Shenoy’s rutting parameter has better correlation with non-recoverable creep compliance (Jnr) and it can be considered as a better rutting predictor than G*/Sinδ for fiber modified asphalt binders.