Cold recycling saves time, cuts costs and is particularly environmentally friendly
The Eastern Chinese province of Anhui frequently has to contend with the consequences of extreme weather. In Bengbu, once famous for its pearl diving industry, the severely damaged Wuhe section of the Changwu Road had to be completely renewed. The lead contractor on the project decided to take advantage of the environmentally friendly and cost-efficient Wirtgen in-place cold recycling method.
A cold recycling train made up of two Wirtgen W 380 CR cold recyclers, two Vögele pavers and several Hamm compactors was deployed for the rehabilitation of the road.
Wirtgen CR series cold recyclers are powerful machines designed and built to deliver maximum performance. As a part of a recycling train, these machines can rehabilitate roads in a single pass. In the process, the damaged asphalt pavement is first milled off and granulated and then mixed on the spot with additives such as pre-spread cement and foamed bitumen, which is why we speak of in-place cold recycling. The machine’s discharge conveyor transfers the recycling mix directly into the material hopper of the Vögele paver, which then paves it true to grade and slope. The newly paved asphalt is then compacted by Hamm rollers. The entire construction process is not only an extremely efficient and cost effective way of delivering high-quality paving results, but, as a result of the reuse of the existing pavement material, also conserves valuable resources and reduces harmful carbon emissions.
The clear advantages of in-place cold recycling also convinced the lead contractor on the project in Bengbu. The project parameters – shorter construction time, minimisation of traffic disruption and higher construction quality – were fulfilled in every respect. On this particular project, two cold recyclers were used to ensure that the recycling of the existing pavement structure progressed as efficiently and effectively as possible. The new base layers offer the best prerequisites for a long service life of the road and good protection against future damage caused by extreme weather.
With a working width of 3.8 m, the W 380 CR enables seamless recycling of a complete lane. In Bengbu, two cold recycling trains worked one behind the other to optimise the construction process and enable fast rehabilitation of the damaged section of the road. The closed lanes were reopened to traffic again immediately after completion of the work. This ensured that traffic disruption was kept to a minimum.
China is committed to the use of environmentally friendly technology
In-place cold recycling offers numerous advantages in comparison to conventional rehabilitation methods: Apart from the complete recycling of the existing pavement material, what is particularly impressive is the high quality of the newly produced mix. The costs for material haulage and the carbon emissions it produces are almost completely eliminated. The overall reduction of carbon emissions in comparison to traditional rehabilitation methods can be up to 60%.
The robust cold recycling base layers provide an ideal substrate for subsequently paved asphalt surface layers. In addition to these contributions to sustainability, the cold recycling method also brings particular benefits in the form of lower construction costs and shorter project timeframes. The overall construction time is significantly shortened by the use of the two-layer method and the recycling of the old material, and the reduced need for material haulage to and from the site cuts the construction costs by around 30%.
In view of developments focused on the achievement of a low-carbon and low-energy economy, these environmental aspects are essential factors when it comes to satisfying China’s increasing demand for the construction of new roads and maintenance of its existing road networks.
The advantages of foamed bitumen cold recycling technology
