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 contractors KWS and Freesmi consequently decided to use the cold in-place recycling method, as this prepares the reclaimed material on site immediately and then reuses it for paving. 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 | The Netherlands: the environmental performance of road construction projects is becoming an increasingly important issue. Cold in-place recycling has established itself as a resource-saving, low-emission technology which is also cost-efficient thanks to significant time and cost savings. Dutch companies KWS and Freesmij opted for this rehabilitation method on the 1.3 km long and 3.1 m wide asphalt road near the village of Ferwert. The paving crew used the Wirtgen Group cold recycling train to mill off the existing asphalt layer and also to prepare the material on site (also called “in situ” or “in-place”) and make a new base course of bitumen-stabilised material (BSM) by mixing in binders and other aggregates. 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

Another benefit of cold recycling was key in this application on a narrow agricultural road: the entire recycling train requires only the width of one lane. To rehabilitate the 3.1 m 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 a width of 1 m and a depth of 15 cm. 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 tonnes of material per hour, the SUPER 2100-5i with extra material hopper can hold 20 tonnes of material and pave up to 1,100 tonnes per hour.

Sustainable machine technology

When selecting the machines, the contractors prioritised environmentally-friendly technology as well as performance and efficiency. After all, the aim was to carry out the entire 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 meets European exhaust emissions standard stage 5 and still achieves 178 kW at 1700 rpm, even in ECO mode. In addition, the intelligent engine management system and the Vögele EcoPlus optimised low-emissions package reduce fuel consumption and thus also CO₂ emissions by up to 25%. The transfer gearbox, the controlled hydraulic oil temperature circuit, the energy-optimised tamper stroke and the speed-controlled fan all make a contribution.

Optimised material management and high pre-compaction values

Another new feature of the “Dash 5” pavers - the updated material handling control system - was also beneficial in terms of the environmental performance and quality of the construction project. The auger and conveyors now communicate with one another, ensuring that material feed is even more consistent and precisely coordinated. This avoids load peaks, saves fuel, enables an optimum head of material in front of the screed and thus uninterrupted paving. On the job site, the new hydraulically extending limiting plate for the auger tunnel, referred to as the Power Tunnel, additionally ensured an optimum level of material in front of the AB 500 TV extending screed used. Equipped with the compacting systems of tamper and vibrators, the screed also achieved high pre-compaction values. Hydraulic tamper stroke adjustment enabled the paving crew to adjust tamper stroke from 4 mm to 8 mm at the touch of a button, making the perfect settings for paving the base course and then the surface course within seconds. Compared to mechanical adjustment, this reduced set-up times significantly. This simple and accurate adjustment method furthermore ensured optimum pre-compaction values, good floating behaviour of the screed and thus an optimum paving result. “This allowed us to completely avoid displacements caused by the rollers and to meet the high quality requirements for cold paving,” says van de Stadt.

Machines and expertise from a single source

The entire 1.3 km stretch of road was completely rehabilitated after just two days. This speedy implementation was due not just 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 respective technology is precisely coordinated in terms of output, capacities and handling. “The Wirtgen Group team advised us on the choice of machines and the measures on site,” says Henk Vreeswijk, Managing Director of Freesmij. “Efficient processes are particularly important in cold in-place recycling, be it in terms of machine availability, operational readiness, set-up times or the removal, transfer and paving processes. That’s where the combination of the latest-generation machines and the support during the rehabilitation measure was very helpful.”

Rehabilitation procedure with a promising future

AFollowing this test run, the company intends continuing to use cold in-place recycling in the future. The team was particularly impressed by the economic and ecological benefits 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 pass. “Cold in-place recycling technology is a model for road rehabilitation which will continue proving its efficiency in the future,” says Vreeswijk.