Asphalt Millings: The Alternative to Gravel
After a roadway has reached a level of disrepair that can not be fixed, the surface must be ripped up and replaced. Because asphalt surfaces are made of simple input materials, an old asphalt surface can be recycled to be used in new paving projects and other construction materials.
Asphalt Bitumen
Asphalt bitumen is a tar like substance that is viscous when heated and hard when cooled. Bitumen is used in asphalt paving for its ability to bind together aggregate,and because it can be reused. When asphalt is heated to around 300 degrees the bitumen will melt allowing it to be reused to pave a surface. Because of the qualities bitumen has, it makes it a great sustainable option for paving surfaces.
How is Asphalt Recycled?
Asphalt is first removed from a paved surface by either tearing it up or grinding the surface down. The debris that is left can be crushed up to ensure that the mix will be even when heated. Heating the asphalt debris up will melt the bitumen allowing the mixture to be repaved. When the recycled asphalt is heated it may be added to new asphalt paving materials that will ensure the quality is just as high as non-recycled asphalt.
Asphalt Inspection
The asphalt recycling process begins with an assessment of the surface. Certain factors like thickness of the asphalt and the kind of mix will determine if and how the asphalt should be recycled. Because not all asphalt surfaces have the same composition it is important to take note of the specific asphalt mix so it can be integrated and reused to match all paving regulations.
Asphalt Milling
Once the inspection is finished the asphalt can be milled or torn up. The asphalt is usually milled rather than torn away because the lower layers of an asphalt surface are usually still usable and strong. An asphalt surface is paved on top of loose aggregate and various layers that help with drainage and leveling. Only the top layers of the asphalt paving can be used for recycled asphalt designs because the top layers contain the asphalt bitumen.
Recycled Asphalt Storage
Recycled asphalt is moved to an asphalt plant for long term storage and processing. The recycled material is normally expensive to send to a landfill, but because it still has value it can be sold to asphalt plants. The recycled asphalt will sit at an asphalt plant until it is needed for a project or mix design. Asphalt plants will begin processing the material by grinding it into smaller pieces allowing it to be ready to heat and use.
Asphalt Heating
When there is a project that needs recycled asphalt, the plant will send the recycled material through an asphalt recycler. The recycler will heat up the asphalt and mix it to ensure that the bitumen is viscous and uniform. Extra aggregate and bitumen can be added into the recycled asphalt mix during its heating and mixing stage.
Recycled Asphalt Regulation
Depending on the local zoning and paving regulations recycled asphalt may have limited uses. For the balanced RAP/RAS Mix design in Austin, Texas the maximum amount of recycled asphalt used for city paving projects must be 20% at the surface, 30% at the intermediate level, and 40% at the base.
Local laws and paving regulation may require for the recycled asphalt be added to a mixture of virgin or new asphalt materials. Paving projects for private land and business has fewer requirements, and can use mix designs that have higher recycled asphalt in them.
Recycled Asphalt Shingles
For asphalt that does not make it into new paving projects, there are still many other uses for it. One of the many industries using old asphalt materials is roofing manufacturers. Roof shingles are made out of the asphalt bitumen, tar, and aggregate that is collected from old paving projects.
Sustainable Paving
Recycling asphalt paving projects allow paving plants to use less new input materials. The paving industry is highly reliant on recycled asphalt because they are able to keep costs low and conserve the environment. When an asphalt roadway is replaced the old roadway also does not need to be sent to a landfill.
Recycled Asphalt Paving Company
Lone Star Paving has it’s own asphalt plant located in Austin, Texas that processes recycled asphalt. We are able to take in recycled asphalt from projects around the Austin area and reuse the materials for you. For more information about recycled asphalt paving contact Lone Star Paving today.
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