Unbonded Aggregate Surface Roads

Abstract : Engineers at the Vicksburg District (MVK) of the U.S. Army Engineer Division, Mississippi Valley (MVD), are responsible for the design and construction of levees all along the Mississippi River and its tributaries within the District's boundaries. The local Levee Boards are responsible for maintaining approximately 990 miles (1.6 million meters) of unpaved roads, and the District is responsible for maintaining approximately 390 miles (627,000 m) of unpaved roads that reside on top of the levees. Over the years, the MVK has developed its own specifications to meet these needs. Historically, MVK has relied upon sources of sand clay-gravel that could provide consistent products. However, these sources are becoming depleted, so the products have recently become inconsistent. As a result, the MVK has expanded its specifications to facilitate bid submittal by producers of crushed aggregates. The purpose of the investigation reported herein was to improve the MVK, MVD, specifications by characterizing various aggregate types in the laboratory, along with collecting performance data under traffic. Because of MVK's recent struggles in finding consistent aggregate sources, both natural and crushed sources of aggregate were included in this study. Trafficking and performance monitoring were accomplished under controlled test track conditions. A review of specifications used by other agencies was also conducted in order to take advantage of their knowledge.