Performance investigation of Micronized Rubber Powder (MRP) modified Asphalt over polymer modified.

Abstract: Over the years, research has been ongoing to improve the quality of asphalt by adding different additives. In recent years, crumb rubber manufactured from waste vehicle tires has been utilized to enhance the mechanical and durability performance of asphalt binders. Many studies have been conducted on crumb rubber-modified asphalt binders and observed improved properties. However, it has not been implemented widely due to some issues associated with particle size and optimum amount of substitution. In this study, Micronized Rubber Powder (MRP) ( < 75 μm) was used to modify the PG 64-22 binder, and the properties of the modified binder were compared with that of a styrene-butadiene-styrene (SBS) modified PG 70-22 binder. The main aim of this study was to assess the feasibility of utilizing MRP in asphalt as an alternative to polymer (SBS). The experiment was performed by blending 5%, 10%, and 15% MRP, with virgin PG 64-22 binders. Some Superpave rheological and selected chemical tests (Fourier Transform Infrared [FTIR] and Nuclear Magnetic Resonance [NMR] spectroscopy analyses) were conducted to assess the properties of all binder samples. The investigation found that MRP increased the viscosity significantly, and 15% of MRP exceeded the Superpave viscosity limit. Further, the rutting factors, Superpave critical temperature, and percent of creep recovery were substantially higher in MRP modified than the unmodified and SBS-modified binder. In addition, the low-temperature stiffness of MRP-modified binders was less than the unmodified and SBS-modified counterparts, indicating less susceptibility to low-temperature cracking. The chemical analysis from FTIR and NMR test results reported some distinct chemical compounds in MRP- and SBS modified binders. Based on the overall performance, a 10% MRP content was recommended as the optimum dosage for asphalt mixes and field implementation.