Wirtgen, a brand of the Wirtgen Group (John Deere), premiered the WR 250 X wheeled cold recycler and soil stabilizer at CONEXPO-CON/AGG 2026 in Las Vegas. As the most powerful machine in the WR series, the WR 250 X produces the highest productivity and power reserves in every situation, equipped with a 563 kW John Deere engine rated at 1,950 min-1 and a 2,400 mm milling/mixing rotor with a maximum working depth of 560 mm. Cold recycling granulates damaged asphalt pavement in place, then injects precise quantities of bituminous binding agents, cement, and water to produce a homogeneous base material that can be directly re-paved-eliminating the cost and logistics of hauling millings to a hot-mix plant.
The engineering breakthrough is the "MIX ASSIST" automation suite, integrated with the Wirtgen Group COPILOT digital platform. Cold-recycled base quality depends on the uniformity of the binding-agent dispersion through the milled material; under-dispersion leaves weak zones, while over-dispersion produces a brittle, cracked base. MIX ASSIST automatically modulates the rotor speed and binding-agent injection rate based on the milling rotor's instantaneous torque. When the rotor encounters harder, aged asphalt that resists granulation, the torque rises; the controller reduces the rotor speed by 15% to allow the cutting teeth to fully pulverize the material before the next dose of bitumen emulsion is injected. When the rotor enters a softer, previously-patched zone, the torque drops; the controller increases the rotor speed and proportionally increases the cement-water slurry flow to maintain the design binding-agent-to-aggregate ratio.
The system also features a "Separate CAN Bus" architecture for continuous function monitoring. The milling and mixing circuit, the binding-agent injection circuit, and the machine travel circuit operate on independent CAN networks, so a fault in one system does not cascade into the others. The self-explanatory diagnostic technology flags a blocked injection nozzle or a worn rotor tooth before the operator sees the effect in the finished base. Field validation on a German autobahn rehabilitation project demonstrated a 30% reduction in base-strength variability and an 18% reduction in binding-agent consumption compared with manually-controlled cold recycling.
