A 2 km long section of the motorway was to be rehabilitated by means of cold recycling “in-plant”, using foamed bitumen as a binding agent. The University of Changan determined the optimum water content and optimum weight percentage of hot bitumen for the production of foamed bitumen using a Wirtgen laboratory plant WLB 10.
In a first step of the recycling operation, a W 2000 cold milling machine from Wirtgen milled off the existing asphalt base layer. The milled material was immediately transported to the KMA 200 cold recycling mixing plant from Wirtgen, which had been set up in the vicinity of the job site. As a mobile plant, the KMA 200 offers the advantage that it can be transported from one job location to the next quickly and easily.
On the Xibao Expressway, the KMA 200 mixed the milled material with foamed bitumen and cement for a bituminous/hydraulically bound base layer, producing around 200 tons of cold mix per hour.
The cold recycled material was placed by a Super 2100 C paver from Vögele equipped with a paving screed type AB 575 TP2. The paver placed the mix at an average paving thickness of 26 cm, and up to 30 cm in some places. Two layers were paved to permit maximum evenness and density of the finished pavement. Compaction was effected by an HD 130 tandem roller and HD 150 TT pneumatic tyred roller from Hamm.