« Back to Focus Areas

Development of a 3/4-inch Minus Base Course Type A Specification for Montana

Started: December, 2014 Ended: December, 2016 Project ID #4W5279 Status: Completed


The objective of the proposed project is to develop a standard specification for a new gravel base course with nominal maximum aggregate size of ¾".


Gravel bases are a critical component of roads, providing drainage, structural support, and load distribution to reduce pressures on subgrade soils. Montana specifications currently exist for a 2-inch-minus and 1½-inch-minus crushed base course. As gravel sources dwindle, particularly in the eastern regions of the state, a ¾ inch gravel base option is becoming more desirable. This project will develop a standard specification for a new gravel base course with a nominal maximum aggregate size of ¾ in. The results of this research will include a draft specification for a ¾-in. crushed base course that will be consistent with MDT’s current specifications. The results will also include all the information required for a Major Revision, as shown in MDT’s standard specifications revision process.


Sponsors & Partners

  • Montana Department of Transportation (MDT) Sponsor

Part of: Infrastructure Maintenance and Materials

Project Tagged In: base course aggregates, highway construction, gravel

« Back to Focus Areas