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Materials

334: Recycled asphalt (RA or RAP)

Problem:

Under normal circumstances, a road building or renovation project consisting of two or three asphalt layers which are installed successively, would require 25,000 truck journeys of 70km, to bring the material to the site.

Solution:

Recycled asphalt (RA or RAP)


Ammann Group Holding AG is a Swiss mechanical engineering company specialised on machines for the building industry and road construction.

In Ariolo, a municipality in the Swiss Alps, Ammann is working on a €240 million project to completely renovate a 10km stretch of the N2 motorway. The work is due to be completed in 2022, but challenges include the fact that the current road base consists of material created during the excavation of the nearby Gotthard Base tunnel – the aggregate has a fine-grain content of more than 8%, meaning it is not frost-resistant.

The project is proceeding under the auspices of the Federal Roads Office (Astra), which has stipulated that the materials that form the current road base be processed on site and reused in the new asphalt mix.

In addition to this, however, the project planners calculated that transport of 55,000 tonnes of gravel would be required, as well as almost 400,000 tonnes of asphalt, of which 140,000 tonnes would be reclaimed.

For this reason, an area beside the motorway was provided for asphalt preparation and production. On the site – a former military airfield – an asphalt crushing plant, an ABP 240 HRT asphalt mixing plant and a gravel washing plant were all installed adjacent to the N2 motorway in the Swiss Alps

In the RAH100 system, the recycled asphalt is heated by a counter-current process. Rocks and bitumen are indirectly and evenly heated and protected from overheating. The plant can produce between 240 and 310 tonnes per hour of asphalt depending on moisture levels.

Ammann’s solution has crossed the Atlantic where Ryan Smith has set up RAP Management on a site near John Glenn Columbus International Airport Columbus, Ohio. From here a fleet of almost 200 trucks drop off loads of old road material, while others haul away new hot mix for parking lots and streets.

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