Predicting the rheological response of Uzbekistan’s polymer-modified binders: a comparative analysis of conventional empirical tests and the complex shear modulus

Abstract

The transition towards performance-based pavement specifications in Central Asia is often hindered by the limited availability of advanced rheological instrumentation. This study bridges this gap by characterizing the viscoelastic performance of asphalt binders currently utilized in Uzbekistan through theoretical modeling based on routine quality control data. A comprehensive laboratory program was conducted on conventional unmodified bitumen (BND 50/70) and three complex modified binders: locally produced polymer-modified bitumen (PMB), crumb rubber modified ('Rezina') bitumen, and sulfur-extended ('Sero') bitumen. Using experimental results from Penetration, Softening Point, and Elastic Recovery tests, the Complex Shear Modulus (G*) and Phase Angle were estimated using the Ullidtz and Van der Poel predictive models, calibrated for the non-Newtonian behavior of modified binders. The study provides a cost-effective framework for predicting high-temperature rutting resistance, demonstrating how traditional empirical data can be transformed into fundamental rheological parameters for mechanistic-empirical pavement design in Uzbekistan's specific climatic conditions.