Development Of Performance-Based Acceptable Laboratory-Molded Desnity Range For Mix Design And Quality Management

Laboratory-molded density significantly influences the design, production, and performance of asphalt mixtures. The standard density of 96.0%, commonly used for mix design and quality assurance (QA), has been associated with challenges such as drier mixes, lower asphalt binder content, increased cracking susceptibility, and limitations in adopting the Balanced Mix Design (BMD) approach. Field sections in Texas constructed with densities between 96.5% and 98.0% have performed well without rutting, suggesting the feasibility of expanding the acceptable laboratory-molded density range, but few studies have thoroughly investigated laboratory-molded density adjustments. This study examined the impact of laboratory-molded densities of 94.5%, 96.0%, 97.5%, and 99.0% on Superpave mixture performance. Tests on rutting, cracking, strength, and raveling indicated that higher densities, such as 97.5%, can achieve satisfactory performance. Key findings highlighted the benefits of optimizing asphalt content (OAC), incorporating up to 30% RAP, and using additives to enhance rutting and cracking resistance. A full-scale demonstration project was carried out to implement the findings of this study. This research provides guidelines for addressing distress at higher densities, offering strategies such as binder adjustments and additive use. These findings support the development of broader laboratory-molded density ranges, advancing durable and high-performing asphalt mixtures and facilitating the implementation of the Balanced Mix Design approach.