To provide the best quality aggregates at the lowest costs, engineers have identified the most important physical properties, and they have developed standard lab and sampling procedures to make sure the aggregates will give the expected performance.  These engineers have set upper and/or lower limits for those test results, and these limits are the specifications.

There are several national organizations that develop specifications.  States, counties and cities usually adopt these specifications, but may adapt them with some changes based on the particular local conditions.  The two most common groups who write standard specifications for aggregates are:

  • ASTM (American Society for Testing and Materials), made up of users (government engineers) and producers (suppliers)
  • AASHTO (American Association of State Highway and Transportation Officials), made up of representatives from 50 states as well as the Federal Highway Administration

State Department of Transportation

Many states will set specification criteria unique to their state conditions.  Below are states with links to their individual state specifications.


Corp of Engineers

This gradation table covers a general requirement for riprap erosion aggregate.  This gradation or size standard is stated in particle mass as measured by weight. Please contact us for available locations and sizes.


Standard Sizes for RipRap


Railroad Commission

Quality track ballast is made of crushed natural rock – normally granite – traprock or quartzite material.  Sizes of the material generally are between 1” and 2½” top size.  Crushed aggregates are specified as they are angular rocks which interlock with each other reducing track bed movement.   Soft materials such as limestone are typically not utilized as they tend to break down and degrade under the heavy loads of today’s rail movements.

Gradations are typically referenced by size number. See below for standard or typical gradations table.

Milestone Materials is a major supplier of railroad ballast in the Upper Midwest, so contact us today for your ballast needs.

Typical Railroad Ballast Chart