Transporting the old road to the cold recycling mixing plant.

When cold recycling road pavements, contractors can choose between processing the milled material “in-situ”, meaning on the job site, or “in-plant”, meaning in a cold mixing plant. Their decision is influenced, however, not only by the damage patterns of the road to be repaired. What are the advantages offered by “in-plant” cold recycling? How does it work? What kinds of damage patterns can cold recycling “in-plant” be used for?

One speaks of cold recycling “in-plant” when the reclaimed asphalt material of roads in need of rehabilitation is recycled in a nearby mixing plant, transported back to the job site, and then placed again by road pavers. The method is often used with roads that are exposed to high loads by heavy traffic, and with damages extending all the way into the pavement subgrade, but where site conditions do not allow the operation of an “in-situ” cold recycling train.

Cold recycling mixing plant recycles 100%

When cold recycling “in-plant”, a mobile cold recycling mixing plant is usually set up in the vicinity of the job site. Trucks deliver the reclaimed asphalt material from the job site straight to the plant. Technically speaking, the cold recycling mixing plant and “in-situ” cold recycler perform one and the same job: The old asphalt material is recycled 100% by adding one or several binding agents. When recycling is complete, trucks transport the cold recycled mix back to the job site.

Road paver places the recycled mix

Road pavers use the cold recycled material to replace the old pavement of the road with two new layers. A new surface course meeting all the requirements placed on the surface of the recycled road is placed on top of the cold recycled base layer. The cold recycled base layer is ideally suited for compaction by heavy vibratory rollers. Final compaction of the surface course is similar to that of other construction methods, using oscillation rollers.

Recycling mix for stockpiling

Cold mix which has been recycled in the cold recycling mixing plant using foamed bitumen as a binding agent is suitable for stockpiling over extended periods of time. Cold mixes do therefore not have to originate from the same job site that they are used for later.

Re-mix aggregate fractions

“In-plant” cold recycling is mostly used for smaller contracts where setting up and supplying a recycling train with water and binding agents would be less economically efficient. There is, however, an additional argument speaking in favour of transporting the milled material from site: When access to the job site is difficult from a logistical point of view, it is much easier to recycle the milled material separately in a cold recycling mixing plant.