Implementation of Balanced Mixture Design in Missouri Test Sections with Modifiers

The overarching goal of this study was to advance the deployment of innovative pavement technologies prevalent in the state of Missouri. In this study, the focus was on evaluating recycled polymers for use in asphalt mixtures and Balanced Mixture Design (BMD) implementation. Nine test sections were constructed on I-155 near Hayti, MO. Six sections were constructed with Superpave dense graded mixtures and the other three with Stone Matrix Asphalt (SMA) mixtures. These sections were modified with recycled polymers such as ground tire rubber and different kinds of waste plastics, and with virgin polymers such as Styrene-Butadiene-Styrene (SBS) and Polyphosphoric Acid (PPA). A Joint Special Provision (JSP) was utilized for this project, which recommended the BMD thresholds for CT-Index to be 45.0 for dense-graded mixtures and 160.0 for SMA mixtures. The Hamburg rutting criteria was 12.5 mm at 15,000 passes. Additionally, an elevated BMD criteria of CT-Index = 80.0 was imposed for two of the six dense graded mixtures. The team conducted cracking, rutting, as well as moisture damage tests on the specimens produced in the lab and in the plant. All the results indicate that the mixtures incorporating recycled polymers perform equivalently or better than the virgin polymer mixtures. In the future, the research team will continue to evaluate the long-term performance of these sections with periodic field visits, with an aim of correlating field observations to laboratory results. This will help finetune the BMD thresholds, leading to more optimized mixture designs. Furthermore, the long-term performance of the recycled polymer sections will inform the development of specifications to facilitate the adoption of recycled polymers in lieu of virgin polymers. 

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Report number: cmr 25-001
Published: January 2025

Project number: TR202418

Authors: William Buttlar, Punyaslok Rath, Jim Meister, Ahmed I.H. Mohamed, Helmut Leodarta, and Katie Distelrath

Performing organization: University of Missouri-Columbia