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https://www.nationalacademies.org/trb/events

Developing a Balanced Mix Design (BMD) Framework for Low-Volume Surface Mixtures

Full implementation of balanced mix design (BMD) for dense-graded non-polymer-modified maintenance surface mixtures was achieved by the Virginia Department of Transportation (VDOT) in 2024. Most of the mixtures used to develop the BMD criteria incorporated 30% RAP and PG 64S-22 binder, a common combination in Virginia. The criteria developed from these mixtures were based on desired performance characteristics for primary or high-volume secondary routes, which have greater traffic levels and typically thicker pavement structures than low-volume routes. However, as low-volume routes comprise over 90,000 lane-mi of VDOT-maintained roads, there is a need to develop performance criteria to address their specific needs. OBJECTIVE: The primary purpose of this study is to develop a BMD framework specifically designed for dense-graded non-polymer-modified asphalt surface mixtures applied to low-volume roads. The performance needs of low volume roads along with mixture properties and performance will be evaluated to determine initial BMD threshold values to ensure adequate mixture performance. Historical information for a variety of routes and mixtures will be assessed to determine common properties indicative of their performance. Benchmark testing will be performed for current mixtures used on low volume routes. Modelling of low-volume routes will be performed to evaluate mixture properties necessary for acceptable performance. A strategy for the adoption of BMD criteria for these mixtures will be developed.