Cold recycling technology – Pioneering solutions from Wirtgen

The demand for technologies that conserve resources has spiraled in recent times. In this domain, the cold recycling process has built up an excellent track record in road construction projects worldwide. With ten plants and machines, market leader Wirtgen has just the right equipment – ranging from wheeled and tracked cold recyclers and the cold recycling mixing plant KMA 220 to ancillary equipment such as the laboratory compactor WLV 1, which is making its world premiere. In Shanghai, Wirtgen is exhibiting no less than six machines from its cold recycling line.

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Roads that are subject to heavy and continual loads frequently show signs of damage in the subgrade. If this is to be rectified, the entire structure of the road must be repaired. In the cold recycling process, 100% of the reclaimed material is reused and cost-effectively treated, making it both an economical and an environmentally friendly option. As a pioneer of cold recycling technology, Wirtgen has played a key role in shaping the process over the last 30 years and has systematically advanced the range of cold recycling products.

Cold recycling in-situ

Wheeled cold recyclers of the WR series

Wirtgen offers three wheeled recyclers: the WR 200, WR 240 and WR 250 models. Equipped with a powerful milling and mixing rotor as well as cutting-edge injection systems, they mill and granulate asphalt pavements, inject binding agents and water in precisely metered quantities and mix everything together – all in a single operation.

Tracked cold recyclers and a new process

Wirtgen also offers two tracked machines: the 2200 CR and 3800 CR cold recyclers with working widths of 2.2 and 3.8 m respectively. Like the models of the WR series, they process asphalt roads on the spot (in-situ). Both of them, however, can also be fitted with an integrated, infinitely adjustable Vögele paving screed with tamper and spreader auger in order to precompact the freshly recycled asphalt true to line and level.

In addition to recycling with the conventional up-cut method, the two models can also perform what is known as down-cut milling, a recent development by Wirtgen in its drive to optimize the cold recycling process. In this case, the recycled material is rear-loaded directly onto a paver, which immediately paves and compacts it. Rollers subsequently carry out final compaction. The down-cut process allows the particle size to be precisely controlled during material processing, especially when milling very old and brittle asphalt roads.

Wirtgen ancillary equipment enhances quality in construction projects

An extensive analysis of the entire road pavement as well as comprehensive mix suitability testing are essential beforehand if the quality of the paving is to be determined in advance. At bauma China, Wirtgen is presenting three exhibits from its range of ancillary equipment, developed specifically for this purpose. They allow 1:1 simulation of the cold recycling process in the road construction laboratory.

World premiere of the laboratory compactor WLV 1

Wirtgen will be unveiling its laboratory compactor WLV 1, a plant designed for the laboratory production of cold recycling mix test specimens, on the world stage in Shanghai. Specially developed for cold recycling applications, the compaction process allows test specimens with a diameter of 150 mm x 95 mm to be produced. These are used to measure the indirect tensile strength of the cold recycling mixture. Large test specimens with a diameter of 150 mm x 300 mm can also be produced for the purposes of a triaxial test. In combination with a test system specific to the WLV 1, information is obtained from the specimens that can then be used to determine the required material properties for dimensioning the road pavement.

Laboratory foamed bitumen plant WLB 10 S

Foamed bitumen is increasingly being used as a binding agent in economical cold recycling. Preliminary testing with the WLB 10 S mobile laboratory unit allows the quality of the foamed bitumen to be defined precisely in the lab even before construction work begins. The system is very easy to use, allowing parameters such as water quantity, pressure and temperature to be varied quickly.

Twin-shaft compulsory mixer WLM 30

The optimum mix composition can be defined in combination with the twin-shaft compulsory mixer WLM 30. In large batches of 25 kg, the powerful mixer generates the reliably homogeneous specimen mixtures with lime, cement, bitumen emulsion and foamed bitumen. When combined with the laboratory foamed bitumen plant WLB 10 S, the foamed bitumen is added directly into the continuous mixing process.

Cold recycling in-plant

Wirtgen cold recycling mixing plant KMA 220

The mobile concept of the Wirtgen KMA 220 offers easy setup and efficient mix production close to the construction site. All of the reclaimed asphalt is reused and processed. The mixing plant is environmentally friendly in every respect: The source materials for mix production do not need to be dried or heated, saving a great deal of energy and costs. Time-consuming trucking between the mix production site and the job site is reduced to a minimum. This has a huge positive impact on fuel costs while at the same time drastically cutting CO2 emissions.