In Road Construction

I am constructing a road and would like to use recycled industrial materials. What materials can I use and where?


Roadways are a central component of the nation's infrastructure and present a wide array of opportunities for using industrial materials. This diagram illustrates the most common roadway applications for industrial materials. Be sure to consult state and local environmental agencies to determine approved uses of industrial materials.

Recycling Industrial Materials in Concrete Pavements. This image portrays the use of industrial materials in hot-mix asphalt pavement (HMA); however, industrial materials have very similar applications in traditional portland cement concrete pavement (PCC). Both HMA and PCC pavements require aggregates, and the list of aggregates under the "Concrete Retaining Wall" and "Asphalt Base" applications can be used in both HMA and PCC roads. PCC roads can incorporate ground granulated blast furnace slag and reclaimed concrete aggregate (RCA) more easily and in larger volumes than HMA can. See the American Association of State Highway and Transportation Officials (AASHTO) provisional standard MP 16-07 for use of RCA in hydraulic cement concrete. Click on the number for more information.

Road Construction Materials

Source: U.S. EPA

Topsoil on roadside embankments can be amended with compost, pulp and paper byproducts, FGD material, or steel slag, if soil conditions merit. These industrial materials can improve the condition of the soil, increase plant growth, and reduce runoff. Foundry sand, steel slag, and coal ash are suitable for embankment fill.

Retaining walls hold back soil and rock and prevent the erosion of roadside slopes; they are often made of concrete or modular blocks.
•  Fly ash and ground granulated blast furnace slag can be used as partial replacements for portland cement in concrete, making the concrete stronger and durable.
•  Concrete aggregates can include bottom ash, foundry sands, reclaimed concrete, and blast furnace slag.
•  Portland cement can contain fly ash, FGD gypsum, foundry sands, drywall, blast furnace slag, and steel slag.

Blast furnace slag, steel slag, and boiler slag can replace virgin aggregate in the asphalt surface layer.

Fly ash, bottom ash, foundry sands, and reclaimed concrete and asphalt can be used as aggregate in the asphalt base layer.

Ground rubber tires and ground roofing shingles can be added to the hot asphalt surface and base mix, increasing the flexibility and durability of the pavement and reducing the need for costly virgin asphalt.

A variety of industrial materials can be used as granular base and sub-base, including:
•  Bottom ash
•  Foundry sand
•  Reclaimed concrete and asphalt
•  Glass
•  Roofing shingles
•  Blast furnace slag
•  Steel slag

Fly ash can also be used as mineral filler in asphalt base, granular base, and sub-base.

Fly ash can be used to improve the structure and stability of the subgrade upon which the road will be built.

Structural fill supports and relieves pressure from retaining walls.
•  Shredded scrap tires are particularly well suited for fill applications; they are lightweight, drain well, and resist frost penetration.
•  Fly ash, reclaimed asphalt pavement, concrete, crushed glass, and foundry sand can also be used as backfill for retaining walls.

One environmentally-friendly way to provide adequate drainage for roadways is through vegetated swales, which can help improve water quality.

Scrap tires, reclaimed concrete or asphalt, glass cullet, and blast furnace slag can be used in place of traditional drainage materials, such as virgin sand or gravel.

RESOURCES

All Industrial Materials

C&D Materials

  • Technical Advisory: Use of Recycled Concrete Pavement as Aggregate in Hydraulic-Cement Concrete Pavement
    This Technical Advisory issues information on state-of-the-practice and guidance for the use of recycled concrete pavement as aggregate in concrete used for pavements.
  • ShingleRecycling.org
    Developed by the Construction Materials Recycling Association and the University of Florida in partnership with U.S. EPA Region 5, this website provides information on asphalt shingle recycling, including state experience, markets, environmental regulations, worker health and safety, and links to additional resources.
  • ConcreteRecycling.org
    Created by the Construction Materials Recycling Association (CMRA) this site provides all of the available information about concrete recycling. Information contained here will assist recyclers in increasing their markets and will answer questions regulators and purchasing agents for end markets, such as state DOT officials, might have about the recycled concrete aggregate product.

Coal Combustion Products

  • Technical Advisory: Use of Coal Ash in Embankments and Bases.
    U.S. Department of Transportation, Federal Highway Administration, May 1988. To set forth guidance and recommendations relating to the use of coal ash in bases and embankments. This Technical Advisory covers the history of coal ash use in these applications along with discussions on environmental, design, and construction considerations.
  • Coal Combustion Products Partnership's (C2P2) Highway Applications
    Provides links to technical publications on the use of coal combustion products in highways.
  • Using Coal Ash in Highway Construction PDF
    Provides information on both the environmental benefits and potential impacts of using coal combustion products in various highway construction applications. Produced in 2005, This booklet is sponsored by the U.S. Environmental Protection Agency, in cooperation with the Department of Energy, Federal Highway Administration, the American Coal Ash Association, and the Utility Solid Waste Activities Group.
  • Fly Ash Facts for Highway Engineers PDF
    Provides basic technical information on the various uses of fly ash in highway construction. Produced in 2003, this booklet is sponsored by the U.S. Department of Transportation's Federal Highway Administration, in cooperation with the American Coal Ash Association and the U.S. Environmental Protection Agency.
  • Guidebook on Fly Ash
    Produced by the Federal Highway Administration, this guide provides information on specifications, mix design, and recommendations for the use of fly ash as a mineral admixture in the production of concrete.
  • Green Highways Partnership
    Provides information on using coal combustion products and slag cement in roadway construction.

Ground Granulated Blast Furnace Slag

  • Guidebook on Ground Granulated Blast Furnace Slag
    Produced by the Federal Highway Administration, this guide provides information on specifications, mix design, and recommendations for the use of ground granulated blast furnace slag as a mineral admixture in the production of concrete.
  • Green Highways Partnership
    Provides information on using coal combustion products and slag cement in roadway construction.

Silica Fume

  • Guidebook on Silica Fume
    Produced by the Federal Highway Administration, this guide provides information on specifications, mix design, and recommendations for the use of silica fume as a mineral admixture in the production of concrete.

Foundry Sand

  • Foundry Sand Facts for Civil Engineers PDF
    Produced in 2004, this document provides technical information on the potential uses of foundry sand in civil engineering applications. This booklet is sponsored by the U.S. Department of Transportation's Federal Highway Administration, in cooperation with the Foundry Industry Recycling Starts Today, and the U.S. Environmental Protection Agency.

Other Resources

  • Federal Highway Administration (FHWA) Recycled Materials Policy
    FHWA's policy statement is designed to advance the use of recycled materials in highway applications. The policy outlines the importance of re-using materials previously used in constructing the Nation's highway system, and calls upon the FHWA and State transportation departments to explicitly consider recycling as early as possible in the development of every project.
  • The Recycled Materials Resource Center (RMRC) is a national center that promotes the appropriate use of recycled materials in the highway environment. The RMRC web site provides access to research efforts and results as well as other technical resources related to the use of recycled materials in transportation applications. The RMRC is funded by the Federal Highway Administration and the U.S. Environmental Protection Agency.