Deep Recycling

Deep Recycling is a specialist road recycling processes used as an alternative to conventional reconstruction. As the market leader in road recycling Colas offers expertise and professional advice to ensure this process is carried out to meet industry standards.

Deep Recycling is a fast, economical cold reconstruction process, which reconstructs the entire road surface or haunches to a depth of 150mm to 350mm, the materials are then mixed with new binders to form a uniform and strengthen structure.

Colas' Deep Recycling process offers in-situ and ex-situ alternatives depending on the site requirements and the materials specified and is the preferred solution for reducing waste to landfill together with reduction in energy and cost.

In-situ

This is the preferable solution to the deep road recycling process cutting out most of the material transport that is necessary when reconstruction a road conventionally.

Following a site investigation which includes carrying out trial holes a mix design is carried out. Together with information about road category and according to either TRL 611 or 386 the treatment depth and binders are established.

Once on site, the surface course material is planed off if necessary to allow for finish surface course at the end. Then the existing pavement is scarified to the established depth and the hydraulic binders are mixed into the material according to the chosen design mix. The material is compacted and graded to the required levels before being overlaid with new asphalt material.

During the recycling process material samples are taken and tested off site and nuclear density tests are carried out to control the compaction on site. This guarantees quality control on site and ensures that mixes are produced to the standard required to offer the same life expectancy than a conventional reconstruction.

This process is ideal when dealing with existing tarbound material as no contaminated material is leaving the site during the process and is encapsulated after completion which is in accordance to existing Health, Safety and Environment regulations. There is no need for extensive Waste Management Plans and the cost savings for the disposal of contaminated material are immense.

Ex-situ

Similar to the in-situ process the existing pavement material is inspected and trial holed. Information about the road category and CBR tests of the subgrade establishes the construction depth to which the road is to be recycled. Mix designs are carried out prior to commencemet of works to make sure the required road strength is achieved.

On site, the existing material is planed off and the material is transported to a recycling compound (preferably nearby the site). The material is then crushed and screeded before being mixed with the binders creating the design mix according to TRL 611 using a recycling mixing plant. The material is loaded and transported back to site where it is laid through a conventional paver to the required depth. The material is then compacted before being overlaid with conventional asphalt course material.

Quality control off site and level control on site are benefits of this process and through thorough pre-planning tarbound materials can also be treated following all environmental regulations.

Other recycling processes

Benefits

• Achieve total carriageway reconstruction without the removal of any materials
• Reduced carbon emissions
• Reduced energy consumption
• Avoid waste being sent to landfill
• Minimised disruption to the local road network
• An ideal solution for tar bound and hazardous materials
• Reduced time on site and road space occupation
• Reduced cost

Challenges of disposing tar bound and hazardous materials

Colas' Deep Recycling process provides an ideal solution for the reconstruction of carriageways containing hazardous tar bound materials.

The operational techniques of Colas' Deep Recycling process allows for the hazardous tar bound materials to be reused and sealed in-situ. The TRL report 611 "A guide to the use and specification of cold recycled materials for the maintenance of road pavements", recommends cold road recycling processes as the most capable and developed operational techniques for successfully managing and reusing hazardous tar bound materials.

More recently Colas' Deep Recycling process was specified for exactly this challenge. Road more  about the challenges faced and the benefits Colas' Deep Recycling process brought to the client in our project report.