Cold recycling with foamed bitumen: most recent developments KMA 220 and WLB 10 S are launched

The interest in resource-saving cold recycling technologies has grown tremendously in recent years. The reasons are quite obvious: Continuously rising prices for energy and raw materials have led road construction authorities and construction companies to increasingly focus on the cost-efficient process for structural road rehabilitation. Wirtgen has taken the lead in the industry since the 1980s in researching this environmentally friendly construction method. With a range of nine machines and plants for in-situ or in-plant cold recycling, the construction equipment manufacturer is today offering its customers mature solutions for applications in all markets. The offer includes wheel-mounted and track-mounted recyclers, as well as a slurry mixing plant. Further enhancements include the KMA 220 mobile mixing plant and WLB 10 S laboratory plant.

Mobile plant design on the road of success

The KMA 220 cold recycling mixing plant focuses on the complete reuse and cost-effective processing of reclaimed road construction materials. With its mature functionality, the KMA 220 offers construction companies an attractive opportunity to successfully open up the potentials inherent in this line of business. The KMA 220 impresses with an outstanding mixing capacity of up to 220 t/h for the production of high-quality cold mixes from recycling construction materials. The mixing performance surpasses even that of many large stationary plants. The compact plant carries a powerful 6-cylinder diesel engine with an output of 131 kW, ensuring an appropriate performance capacity.

The KMA 220 achieves high daily production rates at a consistently high mix quality: Homogeneous mixing of the construction materials is guaranteed by a twin-shaft continuous mixer. The KMA 220 is capable of producing cold mix either in batch mode or in continuous mode. The mix is then directly loaded into trucks or stockpiled via the plant’s slewing discharge conveyor. The mobile plant design offers easy setup and economical mix production close to the construction site. Time-consuming truck transports between mix production and construction site are reduced to a minimum, which has a very positive effect on fuel costs. In addition, the source materials for mix production need neither be dried nor heated, which reduces CO2 emission even further.

Full range of mixing options

A clear advantage of the KMA 220 is its versatility in processing various unbound construction materials. With the addition of binding agents, cold mixes of superior quality are produced from a large variety of virgin aggregate mixtures and/or reclaimed recycling materials. Recycling materials suitable for processing include milled material and any construction materials from the upper road pavement. The KMA 220 offers a full range of options also with regard to binding agents. Using cement and/or bitumen emulsion and/or foamed bitumen, and adding water in addition to any of these, the mobile plant is capable of processing the source material into a cold mix suitable for use as a bound base layer. The formula for binding agents and aggregate is determined by preliminary laboratory testing. Using the innovative foamed bitumen is particularly efficient as the quantities to be added are typically very small. Precise weighing and metering of the binding agents is effected via a load cell and microprocessor control.

The new WLB 10 S and WLM 30 laboratory plants: Carrying out foamed bitumen mix designs quickly and reliably

Many construction companies are today offering the cold recycling process together with an in-depth analysis of the condition of the existing road pavement, and a design of the future pavement structure. In cold recycling, the suitability of the construction materials and construction material mixes used needs to be confirmed in detail for each project. The quality of the mixes to be produced for the construction project can be precisely defined by preliminary investigations carried out with a mobile foamed bitumen laboratory plant, such as the WLB 10 S. The results allow conclusions to be drawn on the material properties that can be achieved, such as the bearing capacity.

The WLB 10 S produces foamed bitumen in the laboratory by varying different parameters, such as bitumen temperature, bitumen pressure and the quantity of water during injection of the binding agent. The plant enables test series to be carried out for the purpose of determining the ideal foamed bitumen properties. The WLM 30 twin-shaft compulsory mixer is offered as an optional accessory to the new laboratory plant. The mixer is a Wirtgen in-house development as well and is ideally tailored to the new laboratory plant. The WLM 30 can be used for mix designs of both hydraulically bound and bituminous layers as the high mixing intensity fully reflects field application.

Feedback from the field: More setting options for greater accuracy

The WLB 10 S is widely used by university research institutes and specialist laboratories around the globe. Professor Kim Jenkins, cold recycling expert at Stellenbosch University in South Africa, has examined the new laboratory plant very thoroughly: “Our institute makes extensive use of the new WLB 10 S for foamed bitumen mix designs. Enhancements made to the new model include an improved control panel with temperature monitoring, and continuous setting options for the entire binder circulation. Temperature has a considerable influence on bitumen properties, so it is important to control the settings accurately. The control panel is also more user-friendly as it permits both the targeted and the actual settings to be displayed. Variable settings for the bitumen pump delivery rate have also been added, which also allows for greater accuracy in the application of the binding agent.”

For further information, please contact:

Wirtgen GmbH
Michaela Adams, Mario Linnemann
Corporate Communications
Reinhard-Wirtgen-Strasse 2
53578 Windhagen

Phone: +49 2645 / 131-0
Fax: +49 2645 / 131-499

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Favourable transport dimensions of 13.40 m in length (14.71 m including cabin), 2.50 m in width and 4 m in height, and a low overall weight of around 30,500 kg enable the KMA 220 to be relocated quickly from one construction site to the next.

Delighted with the new WLB 10 S: Professor Jenkins is an internationally acclaimed expert in cold recycling applications.

SBT, the laboratory for road and concrete construction based in the German city of Trier, also relies on the new WLB 10 S laboratory plant and WLM 30: Laboratory Manager Thelen (second from the right) and his team offer consulting services relating to cold recycling in Germany, Luxembourg and France. Martin Diekmann from Wirtgen GmbH (third from the left) trained the team in the use of the new plant.