Application Sequence
- Clean roadway of objectionable materials and perform any necessary patching or pre-milling.
- Corrective Aggregate and/or active filler, if required, are spread on the road ahead of the recycler.
- The recycling train mills up 2-5 inches (50 – 125 mm) of the existing asphalt pavement.
- The millings are sized.
- The additives and recycling agent (emulsified asphalt or foamed asphalt) are added and mixed with the RAP.
- The recycled mix is either placed in a windrow on the pavement and placed into a paver using a windrow elevator or placed directly into the paver hopper.
- The mat is compacted by heavy pneumatic and double drum vibratory rollers.
- The road is opened to traffic soon after compaction is achieved (within hours).
- A fog seal and blotter sand are applied if raveling is a concern.
- The recycled mixture is allowed to cure for a minimum of three days.
- With emulsified asphalt recycling agent, consider rerolling when the pavement temperature exceeds 80 F (27 C) to reduce air voids.
- A surface course is applied after the recycled mixture has cured.
Application Guidelines
CONTROL STRIP:
- If required, a control strip should be placed in conditions similar to those that are expected to occur during the construction
RECYCLING ADDITIVES (IF REQUIRED):
- Spread ahead of the train in a controlled way
- Canvas Patch test or similar can verify application rate
MILLING DEPTH:
- Measure cutting depth along longitudinal joint
- Milling machine should cut to the desired depth (constant or variable by ski). Uncontrolled variations such as rising/dipping could mean a hydraulic problem
PAVEMENT THICKNESS:
- Variable thickness of existing asphalt can lead to breakthroughs and affect smoothness
MIXTURE:
- Particles should look evenly coated
- Particle size should meet specification requirements (especially top size)
- No blobs or stringers of undispersed recycling agent
- No segregation in windrow or in paver
FRESH MAT:
- Uniform look with no major segregation, streaks, fat spots
- Placed to consistent depth
- The mat will look coarser than a typical hot mix mat. This is normal, as the CIR mix has higher voids and larger aggregate max size than a dense graded asphalt. With rolling traffic, the surface of the CIR will knead together and look tighter
- At first, the mat may look brown. Some emulsified asphalts have a brownish color before the emulsion breaks and turns black. This happens soon after placing
- Check for slope/crossfall directly behind the paver
COMPACTION:
- Establish rolling pattern via control strip to achieve target density
- Ensure roller drums are clean and not covered with picked up material
- Roller skirts are not needed as the mix temperature is close to ambient
- Rollers should not be stopped on the fresh mat
- For foamed asphalt mixes, keep the water content at optimum moisture content to aid compaction
- Check compaction with nuclear gauge
- Check slope with straightedge/smart level after final rolling
RETURN TO TRAFFIC:
- Control traffic to keep stopped traffic off the fresh mat
- Traffic should be piloted slowly on the fresh mat to prevent ravelling
- If fog seal is used to prevent raveling, apply sand blotter and/or wait for the fog seal to cure before allowing traffic
- Watch for early signs of rutting, ravelling, or other distresses, and notify the Contractor immediately if a problem persists
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