Gravel bases are a critical component of roads, providing drainage, structural support, and load distribution within the pavement structure. Montana specifications currently exist for a 2-inch minus (Grade 5A) and 1½-inch minus (Grade 6A) crushed base course; however, gravel sources in parts of Montana are becoming limited, making the option to use a ¾-inch gravel base desirable. The objective of this project was to develop a standard specification for a new gravel base course with nominal maximum aggregate size of ¾ in.

Final Report
Project Summary
Implementation Report
Performance Measures Report