Long term performance and benefits of combined balanced mix design and chemical WMA technology

This study evaluates the combined implementation of Balanced Mix Design (BMD) and chemical Warm Mix Asphalt (WMA) technologies to improve long term pavement performance. Asphalt binders and mixtures commonly used in Oklahoma were selected as case study materials to quantify the benefits of reduced temperature chemical WMA production within a BMD framework. A multi-scale experimental approach was adopted, consisting of binder characterization, mixture performance testing, and mechanistic-empirical pavement analysis. Four asphalt binders frequently used in Oklahoma Department of Transportation (ODOT) projects were conditioned at reduced Rolling Thin Film Oven (RTFO) temperatures to simulate plant-level WMA production. Rheological and chemical properties, evaluated with and without chemical WMA additives, demonstrated that reduced oxidative aging improved both load-related and non-load-related cracking resistance while preserving adequate rutting resistance. FTIR results further confirmed the benefits of reduced short-term aging. These trends were then examined at the mixture scale using two Superpave mix designs. Initial testing showed that both mixtures failed to meet the cracking thresholds, prompting redesign using the BMD approach. When the same mixtures were produced at lower mixing and compaction temperatures with chemical WMA additives, the optimum binder content decreased while still meeting performance requirements, indicating potential material and cost savings. Pavement performance prediction using TxME showed 30-50% increase in fatigue service life for WMA+BMD mixtures under both medium and high traffic. Finally, Life Cycle Cost Analysis (LCCA) using RealCost demonstrated that pavement sections constructed with WMA+BMD mixtures lead to more cost savings over pavement sections constructed with HMA+BMD mixture. Overall, this research establishes that integrating BMD with reduced-temperature chemical WMA technology provides benefits at binder, mixture, and pavement levels. This Ph.D. research lays the necessary foundation for state and local highway agencies to develop specifications supporting and governing the combined implementation of BMD and reduced temperature chemical WMA technologies.