The project was to renew the agricultural road near the Dutch village of Ferwert quickly and economically using low-emission machinery. The contractors consequently decided to use the in-place cold recycling method, as this prepares the reclaimed material on site immediately and then reuses it for the paving process. They used a tried and tested combination of Wirtgen Group machines: the W 240 CRi cold recycler from Wirtgen and the new SUPER 2100-5i Highway Class paver from Vögele.
Save CO₂ and money
The environmental performance of road construction projects is becoming more and more of a focus. In-place cold recycling has become established as a resource-saving technique which also delivers economic benefits as a result of the time and expense saved. Dutch companies KWS and Freesmij opted for this rehabilitation method for an asphalt road 1.3 km long and 3.1 m wide 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. “In-place cold recycling is the response to the ecological and economic demands of modern road construction,” says Raymond van de Stadt, Managing Director for 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 first used a W 100 Fi compact milling machine from Wirtgen to pre-mill at a width of 1 m and to 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 new 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 an hour at a maximum pave width of 2.35 m, whilst the SUPER 2100-5i can take up to 20 tonnes of material with an extra material hopper and pave up to 1,100 tonnes an hour.
On the jobsite In Ferwert, the cold recycler milled out the old road material to a depth of 15 cm in one pass and in the mixing chamber, prepared the material to form homogeneous BSM by adding foamed bitumen using an integrated Vario spray bar. The W 240 CRi then transferred the material to the following Vögele paver, which paved the 15 cm-thick base course at a speed of around 4 m per minute. Once recycling work was complete, the SUPER 2100-5i paved the base course with a 4 cm-thick asphalt surface course.
Sustainable machine technology
The contractors relied on environmentally-friendly technologies, both for the machines used and for the rehabilitation process itself. The Vögele large paver of the new “Dash 5” generation features a particularly sustainable drive concept, for example: with a 6-cylinder John Deere engine, the SUPER 2100-5i meets European exhaust emissions standard stage 5 and still achieves 178 kW at 1700 rpm, even in ECO mode. The intelligent engine management system and Vögele EcoPlus optimized low-emissions package also reduce fuel consumption and 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 handling 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 other, ensuring that material feed is even more consistent and precisely coordinated. This avoids load peaks, saves fuel and enables an optimum head of material in front of the screed and thus uninterrupted paving. On the jobsite, 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 coursewithin 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.
Rehabilitation process with a future
The entire 1.3 km stretch of road was completely rehabilitated after just two days, this successful test run convincing the contractors of the economic and environmental benefits of the method. The resource-saving use of material, the high quality of the prepared material, the reduced transportation required and the drop in CO₂ emissions - as well as rehabilitation in one pass - make a significant contribution to greater climate protection and efficiency in road construction. “Cold recycling technology is a model for road rehabilitation which will continue proving its efficiency in the future,” says Henk Vreeswijk, Managing Director of Freesmij.
Content produced in association with Wirtgen Group