Recycling
Recycling asphalt pavement can save money for local governments and other owners, create additional business opportunities, save energy when recycling is done on site, conserve diminishing supplies of aggregates and oils, and help local governments reduce disposal and landfill quantities. Both cold and hot-in-place recycling are important elements of asphalt paving, and links are provided below to assist the user with those techniques.
Recyling is used to rehabilitate the surface and base courses of a structurally failed pavement. Existing pavement materials are uniformly pulverized and blended with a stabilizing agent to produce a new, stronger base course.
General information
about hot and cold in place asphalt recycling is available from the Integrated
Waste Management Board.
Standard
Specifications
Technical Memo
Cold in-place Recycling
Hot in-place Recycling
Mn/DOT
Standard Specifications are available online.
Technical
Memo 00-20-ENV-07, Reuse or Recycling of Waste Materials into Construction
Materials is available from Mn/DOT.
The Asphalt Recycling and Reclaiming Association defines cold in-place recycling (CIR) as a partial depth recycling process that rehabilitates the upper portion of an existing pavement. CIR is only used to stabilize asphalt and aggregate materials. It is not used to stabilize the supporting soil material below the pavement. If the supporting soil requires stabilization, full depth reclamation is typically used.
Cold in-place recycling involves removing the pavement with a specialized milling machine to a depth of three to five inches. The material is pulverized, sized, and mixed with an additive. Virgin aggregate may be added to modify the mix characteristics. An asphalt emulsion or a recycling agent is added, and the material is placed and compacted. An additional layer, such as a seal coat, is optional, or hot mix asphalt overlay may be placed.
A three piece paving train is used, and consists of the milling machine, a screening/crushing/ mixing unit, and conventional laydown and rolling equipment. The paving train occupies one lane of traffic.
More cold in-place recycling information:
Reclaimed
Asphalt Concrete User Guidelines
Review
of Cold in-Place Asphalt Recycling in Iowa
Hot in place recycling involves softening the pavement by heating, and scarifying or milling the pavement to a depth of ¾ to 1-1/2 inches. The material is mixed, and new hot mix material and/or a recycling agent is added in a single pass of the machine. A new wearing course may also be added with an additional pass after compaction.
More
information on hot in-place recycling
