A Wirtgen recycler mills off the top pavement layer.

Cold recycling – from dusk to dawn

A cold recycling train from the Wirtgen Group completes the rehabilitation of two sections of an important motorway in Greece in the shortest possible time

Greek motorway operator Nea Odos SA, chose the in-situ cold recycling method with a cold recycling train from the Wirtgen Group for the rehabilitation of two sections of an important motorway, close to the city of Lamia and the town of Kamena Vourla. The sustainable, fast and cost-efficient method is ideal for the rehabilitation of busy motorways. On the E 75 motorway, the Wirtgen cold recycler W 380 CRi at the heart of the chain was accompanied by a latest generation SUPER 2100-5i Highway Class road paver, a SUPER 1800-3 Universal Class paver from Vögele and a team of Hamm rollers comprising of two HD+ 140i tandem rollers and a HP 280i pneumatic-tyre roller. Due to high daytime temperatures, the contractor scheduled all construction activities after midnight and finished before the early morning.

Lamia and Kamena Vourla

The sections of the motorway to be reconstructed, were located close to the city of Lamia and the town of Kamena Vourla are extremely busy and important traffic intersections. In all, the project involved the rehabilitation of an area of more than 50,000 m² / 540,000 sq ft of asphalt roadway in locations where complete closure would have led to absolute traffic chaos. The most efficient solution here was the use of a cold recycling train from the Wirtgen Group. Thanks to in-situ cold recycling, it was possible to reduce the construction time otherwise expected when using conventional methods by around 50% and direct the traffic flow around the rolling construction site without any problems.

In-situ cold recycling: the sustainable choice

In-situ cold recycling enables significant savings when it comes to costs for materials and transportation. The cold recycler from Wirtgen is the backbone of the rehabilitation project The W 380 CRi deployed on this project is capable of recycling the damaged road pavement in a single pass. In the course of this, cement, water and foamed bitumen are added to the existing material in-place (in-situ) to produce a bitumen stabilised material (BSM). This freshly produced, high-quality construction material can then be laid down on the spot. In Lamia, this eliminated the need for around 24,000 tons of virgin material – which not only conserved valuable resources, but also reduced CO₂ emissions on and around the construction site.

Facts & figures

Project: Rehabilitation of two sections of a motorway

Locations:E 75 – km 212 to 214 near Lamia and km 179 to 185 near Kamena Vourla
Overall length: ~8 kilometres / ~5 miles
Total area: 50,000 m² / 540,000 sq ft
Construction method: In-situ cold recycling with a Wirtgen Group Production System
Working width: 3.80 m / 10.2 ft
Project completion time: 15 days
Up to 90% reduction of resources required:Elimination of the need for 24,000 t of fresh asphalt mix
Up to 90% fewer transport movements:2,400 truck tours saved
Up to 100% reduction of waste for disposal
Up to 60% reduction of CO₂ emissions
Up to 60% reduction of overall costs

Graphic representation of a cold recycling train

Turning night into day

The LED floodlights of the W 380 CRi and the new Light Package Plus on the SUPER 2100-5i provided excellent lighting during the rehabilitation project. The integrated lighting systems provide even illumination of the entire working area. This not only ensured the safety of traffic driving past the site, but also of the crew on and around the cold recycling train.

Step-by-step to a new road surface

In the first step, cement was evenly spread across a working width of 3.80 m / 12.5 ft. The binding agent spreader was followed by the two tankers for the supply of water and hot bitumen to the W 380 CRi for the production of foamed bitumen. Precise doses of foamed bitumen and water are sprayed into the mixing chamber of the cold recycler via the Vario injection bars.

The W 380 CRi granulated the damaged asphalt package together with 50 mm / 2 in of the underlying crushed stone layer. The overall working depth was 250 mm / 10 in. The cold recycler mixed this milled material with foamed bitumen and water to produce a new homogeneous pavement material (BSM).

The mix produced in this way was transferred directly to a Vögele SUPER 2100-5i paver following behind the recycler. With an extra material hopper, the latest-generation Highway Class paver can take up to 20 tons of mix on-board and pave it at a laydown rate of up to 1,100 tons per hour.

The material was milled off, processed and transferred to the paver in a continuous process and paved true to grade and slope in-place (in-situ).

The AB 500 TV extending screed was equipped with a so-called ‘Plus Tamper Bar’ This tamper bar features a special geometry that, together with the 8 mm / 0.3 in stroke, ensures high pre-compaction and optimal floating behaviour of the screed.

The new option, Dual Power Shift, enables the stroke of the tamper bar to be conveniently set to either 4 mm / 0.15 in or 8 mm / 0.3 in at the press of a button.

To achieve a permanently stable road surface, two HD 140i tandem rollers compacted the paved material in a total of 7 passes. Continuous monitoring of the compaction performance was guaranteed by Smart Doc.

A SUPER 1800-3 paver laid down the new surface layer (HMA) after completion of the recycling process. A Hamm pneumatic-tyre roller (GRW) followed on immediately after the compaction by the two Hamm tandem rollers to perform the final compaction and thin cape seal surfacing.

The Vögele paver lays down the asphalt surface layer

Cold recycling train:

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