An entropy weight-TOPSIS decision support method for viscosity reduction of rubberized bitumen

Crumb rubber modified bitumen (CRMB) offers sustainable pavement solutions by recycling waste tires, but its high viscosity significantly limits its application. Two prevailing viscosity-reduction approaches, namely warm mix asphalt (WMA) and rubber devulcanization, differ in production equipment, cost, and performance, complicating the selection of viscosity-reduction strategy for different climate and traffic conditions. Therefore, this study proposes a novel decision-making framework to support the determination of viscosity-reduction strategy by integrating the entropy weight method with a Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) model considering workability, mechanical performance, cost, and energy consumption. The comprehensive ranking for different viscosity-reduction solutions was calculated for seven climate zones in China. Results show the warm-mix CRMB yields better high- and intermediate-temperature performance but higher costs and energy consumption. Conversely, devulcanization technology presents superior energy- and cost-effectiveness, which is suitable for both tropical and cold regions.