This standard specifies the properties of aggregates obtained by processing natural or recycled crushed unbound aggregates for use in construction of the ballast layers of railway track. For the purposes of this standard, the aggregate is referred to as railway ballast.
For new construction track, new natural ballast should be used. For maintenance, recycled ballast can be used together with new ballast.
Railway ballast should not release any dangerous substances in excess of the maximum permitted levels specified in a relevant national or international standard for the material.
New railway ballast used in construction should comply with all the requirements of this standard. The standard includes comprehensive and specific requirements for natural aggregates and recycled ballast, dealing with, for example, the stability of certain ballast.
For materials from some other secondary sources, however, work is ongoing and the requirements are incomplete. In the meantime such materials, when placed on the market as railway ballast, should conform fully to this standard but may also be required to conform to specific relevant additional requirements at the place of use. Additional characteristics and requirements may be specified on a case by case basis depending upon experience of use of the product, and defined in specific contractual documents.
This standard was developed with the following objectives: