page_title: Asphalt concrete
section_title: Recycling
hierarchical_section_title: Asphalt concrete / Recycling
caption_attribution_description: English: Falcon's asphalt recycler / hot box will recycle asphalt, haul hot mix asphalt and heat cold patch asphalt.
context_page_description: Asphalt concrete is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. Asphalt mixtures have been used in pavement construction since the beginning of the twentieth century. It consists of mineral aggregate bound together with asphalt, laid in layers, and compacted. The process was refined and enhanced by Belgian inventor and U.S. immigrant Edward De Smedt.
  The terms asphalt concrete, bituminous asphalt concrete, and bituminous mixture are typically used only in engineering and construction documents, which define concrete as any composite material composed of mineral aggregate adhered with a binder. The abbreviation, AC, is sometimes used for asphalt concrete but can also denote asphalt content or asphalt cement, referring to the liquid asphalt portion of the composite material.
context_section_description: Asphalt concrete is 100% recyclable and is the most widely reused construction material in the world. Very little asphalt concrete — less than 1 percent, according to a survey by the US Federal Highway Administration and the National Asphalt Pavement Association conducted annually since 2009 — is actually disposed of in landfills. When asphalt pavement material is reclaimed for reuse, it is able to replace both virgin aggregates and virgin asphalt binder. In 2018, new asphalt pavement mixtures produced in the United States contained, on average, more than 21% reclaimed asphalt pavement.
  There is asphalt recycling on a large scale (known as in-place asphalt recycling or asphalt recycling performed at a hot mix plant) and asphalt recycling on a smaller scale.  For small scale asphalt recycling, the user separates asphalt material into three different categories:
  Blacktop cookies
  Chunks of virgin uncompacted hot mix asphalt which can be used for pothole repair. The use of blacktop cookies has been investigated as a less expensive, less labor-intensive, more durable alternative to repairing potholes with cold patch. In a program in Pittsfield, Massachusetts, workers purchased new hot mix asphalt and spread it liberally on the ground to produce approximately 25 lb. wafers. Once cooled, the wafers could be stored until reheated in a hotbox to make minor road repairs. Blacktop cookies may also be produced from leftover material from paving jobs.
  Reclaimed asphalt pavement (RAP)
  Chunks of asphalt that have been removed from a road, parking lot or driveway are considered reclaimed asphalt pavement (RAP).  These chunks of asphalt typically are ripped up when making a routine asphalt repair, man hole repair, catch basin repair or sewer main repair.  Because the asphalt has been compacted, RAP is a denser asphalt material and typically takes longer to recycle than blacktop cookies.
  Asphalt millings
  Small pieces of asphalt produced by mechanically grinding asphalt surfaces are referred to as asphalt millings. Large millings that have a rich, black tint indicating a high asphalt cement content are best for asphalt recycling purposes. Surface millings are recommended over full depth millings when choosing asphalt millings to recycle. Full depth millings usually contain sub-base contaminants such as gravel, mud and sand.  These sub base contaminants will leach oil away from original asphalt and dry out the material in the recycling process. Asphalt milled from asphalt is better than asphalt milled from concrete.  When milling asphalt from concrete the dust that is created is not compatible with asphalt products because it is not asphalt.
  Small scale asphalt recycling will usually involve high speed on-site asphalt recycling equipment or overnight soft heat asphalt recycling.
  Small scale asphalt recycling is used when wanting to make smaller road repairs vs. large scale asphalt recycling which is done for making new asphalt or for tearing up old asphalt and simultaneously recycling or replacing existing asphalt.  Recycled asphalt is very effective for pothole and utility cut repairs.  The recycled asphalt will generally last as long or longer than the road around it as new asphalt cement has been added back to the material.
  For larger scale asphalt recycling, several in-place recycling techniques have been developed to rejuvenate oxidized binders and remove cracking, although the recycled material is generally not very water-tight or smooth and should be overlaid with a new layer of asphalt concrete. Cold in-place recycling mills off the top layers of asphalt concrete and mixes the resulting loose millings with asphalt emulsion. The mixture is then placed back down on the roadway and compacted. The water in the emulsion is allowed to evaporate for a week or so, and new hot-mix asphalt is laid on top.
  Asphalt concrete that is removed from a pavement is usually stockpiled for later use as aggregate for new hot mix asphalt at an asphalt plant. This reclaimed material, or RAP, is crushed to a consistent gradation and added to the HMA mixing 
caption: A small-scale asphalt recycler
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