VISCOSITY OF NEAT AND POLYMER-MODIFIED BITUMINOUS BINDERS

Abstract

Polymer modification is widely used to improve the high-temperature performance and durability of asphalt binders; however, polymer type and dosage can substantially affect binder workability and production temperatures. This study evaluated the rotational viscosity (RV) behavior of three base bitumens (Caspi 70/100, Shymkent 70/100, and Pavlodar/PNXZ 100/130) and several polymer-modified binders prepared using Butonal (3.5% and 5.0%), SBS (3.5%), and Titan (3.5%). RV was measured using a Brookfield Thermosel viscometer in accordance with ASTM D4402 at 135 °C and 165 °C, and over a programmed temperature range from 120 °C to 190 °C with 7 °C increments to construct viscosity–temperature curves and determine mixing and compaction temperature ranges. Polymer modification increased viscosity at both 135 °C and 165 °C relative to the corresponding base binders, indicating increased stiffness. Among the modified binders, 5.0% Butonal produced the highest viscosity and the poorest workability, with mixing temperatures exceeding 190 °C and compaction temperatures near 185 °C. Reducing Butonal content to 3.5% decreased production temperatures (≈175 °C mixing and ≈163 °C compaction). The SBS-modified binder showed a smoother viscosity trend and intermediate production temperatures (≈178 °C mixing and ≈167 °C compaction). The most favorable workability was achieved with 3.5% Titan, which yielded the lowest viscosity curves and the lowest production temperatures (≈149 °C mixing and ≈144 °C compaction), while remaining below the 3000-cP handling threshold consistent with ASTM D6373. Overall, the results demonstrate that polymer type and dosage govern the balance between stiffness enhancement and manufacturability, and that multi-temperature RV profiling improves the precision of mixing and compaction temperature selection.