Local Agency Balanced Mix Design with Superpave Volumetric Foundation
Civil and Environmental Engineering
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Asphalt Concrete (AC) mix design has been a common challenge to provide sustainable roadways with high performance over their pavement service life. Several mix design methods have evolved with the same target of generating durable and stable pavements under various traffic and climatic conditions while considering the visco-elastic behavior of asphalt binders, which may alter pavement responses at a certain temperature and aging level . Current asphalt mixture design methods are structured around meeting a range of volumetric requirements. Although this allows for volumetric parameters to be monitored and controlled during production, it does not give much engineering insight as to how the mixture will perform in the field.The aim of this research study is to present for the Regional Transportation Commission of Washoe County (RTC) an implementation strategy to switch from Marshall mix design method to an optimized mixture design for flexible pavement following the Balanced Mix Design (BMD), using the Superpave gyratory compactor. Shifting toward to a BMD approach based just on performance testing, could be a precarious move for any agency considering new concepts in designing asphalt mixtures. Therefore, the design analysis adopted in this study was based on the balanced mix design approach, while considering both requirements for the volumetric properties and performance thresholds known as “Volumetric Design with Performance Verification”. Eight new mixtures generated in this study were designed to meet the Superpave volumetric criteria, and subsequently verified with performance testing intended to be related to the most prevalent distresses in Northern Nevada including long-term durability (cracking and stripping resistance) while maintaining a rutting resistance test that also provides additional moisture resistance data.