In recognition of National Collect Rocks Day on September 16, Bituminous Roadways, Inc. (BR) is sharing some information on what types of rocks are used to produce asphalt. BR uses a wide variety of aggregates, a.k.a. “Rocks,” to produce asphalt mixtures. Since every job site is different, we need to take a few things into consideration before mixing the asphalt. Depending on the amount and type of traffic, and how deep in the pavement structure the asphalt is being placed, there are different requirements for the type of aggregates used.

Granite Rocks

High-volume roadways, such as interstates, demand hard, durable rock. Granite originating from St. Cloud or trap rock from Wisconsin, are good examples of igneous rocks that are quite durable. These stones have low absorption, rough texture and don’t polish when subjected to stop and go traffic, maintaining great skid resistance for enhanced traffic safety.

Medium and low-volume roadways, such as county roads and city streets, typically are made of crushed gravel from open-pit mines or limestone, a sedimentary rock. Gravel and limestone aggregates typically cost less than granite and trap rock because they are less durable, locally available and hauled shorter distances.

Crushed Limestone Gravel

As a leader in asphalt paving throughout the Twin Cities metro area, BR is dedicated to producing high quality asphalt. Understanding each job and the needs of our customers is critical to “collecting rocks” to be used in the best asphalt mix. This in turn produces a quality paving project lasting for years to come.

For more information or to receive a free quote, call BR at 651-686-7001.