Sustainable and economical rehabilitation

The project was to renew the agricultural road on the coast behind the dike of the Dutch village of Ferwert quickly, economically and with low emissions, So the contractors KWS and Freesmij opted for the cold in-place recycling process, in which the reclaimed material is processed on the spot and reused immediately. A well-established combination of Wirtgen Group machines was used: the W 240 CRi cold recycler from Wirtgen and the new SUPER 2100-5i Highway Class paver from Vögele.

Ferwert | Netherlands: The environmental sustainability of road construction projects is becoming an increasingly important issue. Cold in-place recycling has established itself as a resource-saving, low-emission technology that is also cost-efficient thanks to significant time and cost savings. The Dutch companies KWS and Freesmij opted for this rehabilitation method on the 1.3 km (0.8 mile) long and 3.10 meter (10.2 ft.) wide asphalt road near the village of Ferwert. Deploying the Wirtgen Group‘s cold recycling train, the paving team scarified the existing asphalt layer and prepared the material on-site, also referred to as ‘in-place’ or ‘in situ’, by mixing in binders and other aggregates to form a new BSM (bitumen-stabilized material) base course. This was all achieved in a single pass, without truck transport and without disposing of material. “Cold in-place recycling is the response to the ecological and economic demands of modern roadbuilding,” says Raymond van de Stadt, Managing Director Asphalt at primary contractor KWS. “In just two days, we renewed the entire stretch of road using 100% recycled material; compared to using conventional methods, this reduced CO₂ emissions significantly and also saved time and costs, of course.”

Powerful cold recycling train

For application on the narrow agricultural road, another advantage of cold recycling was decisive: the entire recycling train requires only the width of one lane. To rehabilitate the 3.10 meter (10.2 ft.) wide road in one pass, the team from milling specialist Freesmij first used a W 100 Fi compact milling machine from Wirtgen to pre-mill at a width of 1 meters (3 ft.) and a depth of 15 cm (5.9 in.). This was followed by the cold recycling train, consisting of water and bitumen tank wagons, the Wirtgen W 240 CRi cold recycler and the SUPER 2100-5i large paver from Vögele. As this process prepares the reclaimed material in situ and uses it for the paving process immediately, both the recycler and the paver had to achieve a high output. The W 240 CRi can produce up to 800 metric tonnes (882 tons) of material per hour, the SUPER 2100-5i with extra material hopper can hold 20 metric tonnes (22 tons) of material and pave up to 1,100 metric tonnes (1,213 tons) per hour.

Sustainable machine technology

When selecting the machines, the contractors were not only concerned with performance and efficiency, but also with environmentally friendly technologies. After all, the aim was to carry out the entire construction project as sustainably as possible. The sustainable drive concept of this large paver of the new Vögele “Dash 5” generation is ideal for the purpose. With a John Deere 6-cylinder engine, the SUPER 2100-5i complies with European exhaust emissions standard stage 5, and still delivers 178 kW at 1700 rpm even in ECO mode. In addition, the intelligent engine management system and the Vögele EcoPlus optimized low-emissions package reduce fuel consumption by up to 25%, and as a result also lower CO₂ emissions. The splitter gearbox, the controlled hydraulic oil temperature circuit, the energy-optimized tamper stroke and the speed-controlled fan all contribute to the reduction.

Optimized material management and high pre-compaction

Another new feature of the Dash 5 pavers was also of benefit in terms of the construction project’s environmental sustainability and quality: the updated material transport control system. The auger and conveyors now communicate with each other, ensuring that the material feed is even more consistent and precisely coordinated. This avoids load peaks, saves fuel, enables an optimum head of mix, and so uninterrupted paving. The new hydraulically extendable limiting plate for the auger tunnel, called the Power Tunnel, additionally ensured an optimum material height in front of the AB 500 TV extending screed used on the jobsite. Equipped with tamper bar and vibrator compacting systems, the screed also achieves a high degree of pre-compaction. With the hydraulic tamper stroke adjustment, the paving team was able to adjust the tamper stroke at the touch of a button from 4 mm (0.16 in.) to 8 mm (0.32 in.), optimally setting it within seconds for paving the base course and then the surface course. This significantly shortens set-up times compared to mechanical adjustment. The simple and accurate adjustment method also ensured optimum pre-compaction, good screed floating behavior, and consequently an ideal paving result. “This allowed us to completely avoid displacement caused by the rollers and to meet the high quality demands in cold paving,” says van de Stadt.

Machines and expertise from a single source

After only two days, the entire 1.3 km (0.8 mile) stretch of road was completely rehabilitated. This speedy implementation was not only due to the time-saving repaving of the existing material, but also to the smooth processes on the jobsite. Since the machines and expertise come from a single source, the technology is precisely coordinated in terms of output, capacity and handling. “The Wirtgen Group team advised us on the choice of machines and the procedures on-site,” says Henk Vreeswijk, CEO of Freesmij. “Efficient processes are particularly important in cold recycling, be it in terms of machine availability, operational readiness, set-up times, or the removal, transfer and paving processes. So the combination of the latest-generation machines and the support during rehabilitation was very helpful.”

Rehabilitation process with a promising future

After the test run, the company intends to continue using cold in-place recycling in future. The team was particularly impressed by the economic and ecological advantages of the process, in particular by the resource-saving use of materials, the high quality of the processed material, the avoidance of transport routes, and the associated reduction in CO₂ emissions, as well as by the rapid removal of the old road profile and the repaving process, all carried out in a single working pass. “Cold recycling technology is a model for road rehabilitation that will continue to prove its efficiency in the future,” says Vreeswijk.