Economical efficient and environmentally friendly use of Wirtgen Green Mix cold recycling technology with foamed bitumen cuts costs, reduces emissions and saves on material.
Beijing, China (August 03, 2010) /ChinaNewswire.com/ — On June 28th, 2010, after being closed for 53 days, the southern half of the Tongguan to Xian section of the Lianhuo Expressway improvement and widening project was reopened with four lanes in two directions. This is the first expressway in China which has been improved and widened on large scale using Green Mix foamed bitumen cold recycling technology from Wirtgen. As the existing pavement material was reused as efficiently as possible, the cost saving was around CNY 28,000,000. This provides a reference example for highway overhaul, improvement and widening in Shanxi province with clear economic efficiency and environment benefits from this project.
A traditional pavement overhaul focuses mainly on substitution and strengthening. Substitution results in higher costs, longer time duration, and a more complex project. A large quantity of milled material would not be reused properly, resulting in waste and pollution. Strengthening has the drawbacks that pavement bearing capacity can not be meaningfully increased and pavement defects can not be effectively eliminated. With the advent of the 21st century, many high-class roads need to be maintained and repaired or improved — around 12% of pavement needs to be overhauled every year – and this requires a total quantity of around 2,200,000 tons of existing pavement material. Recycling of this material and reusing it in new construction and repair of pavement, will be not only be environmentally friendly, but will also result in major cost savings. Especially in western area of the country, reusing large quantity of existing pavement material, will reduce pollution, conserve water and soil, and allow the building of more roads with less investment. So, it has very important effect.
Recently Wirtgen's Green Mix foamed bitumen technology has become more and more popular, both in China and abroad. It provides a new method for modernized cost effective repair and maintenance of roads. "Individual study of foamed bitumen cold recycling" was supported by technology finance from Ministry of Finance, and was declared to be a technology development project for Shaanxi province. When this study is finished, the annual cost saving on material through recycling will be CNY1.500 billion.
In foamed bitumen technology water is injected into hot bitumen, making it expand and become bitumen foam. The foam will settle down after a short time. The foam bitumen becomes millions of tiny particles spread over fine material and forms a slurry. After mixing and compaction, it will bind the coarse particles and make the pavement course stable. Compared to traditional methods, the advantages of foamed bitumen technology include: long time storage of mix, higher shear strength, and less sensitivity of the mix to water.
With regard to energy saving, Green Mix foamed bitumen has a number of very strong points. According to Mr. Li Jingde, in traditional design, bitumen content of the asphalt base course is 3.4%, and for the binder course it is 4.4%. When using foamed bitumen, existing material will be reused extensively, saving crushed stone. When paving on hard shoulders, it replaces binder and base courses with a bitumen content of only 2.1%. This equates to saving half of the bitumen. He says the detailed calculations are as follows: "The cost of 12 cm base course is CNY 98/m², the cost of 6 cm binder course is CNY 61/m², resulting in a total cost of both courses together of CNY159/m². The cost of 18 cm foamed bitumen course is only CNY76/m². So, replacing the base and binder courses with foamed bitumen mix gives a cost saving of CNY 83/m². That is CNY 259,790 cost saving per kilometer. The total foamed bitumen recycled material in Xsitong expressway project is about 61,800 m³, and gives a total cost saving of around CNY28,000,000. It really makes waste profitable." Further more, foamed bitumen recycling requires less labor and investment in machines. It cures naturally and this can be finished within two days in thesummer time. In comparison the traditional water spreading curing method needs seven days.
As a new road technology, foamed bitumen recycling has been tested and applied throughout the country. But, for expressway improvement and widening like Xitong expressway project, there is no experience or reference data. Xitong expressway improvement and widening is the first project in China to use this design and construction and to benefit from major savings in cost material and emissions.
About the Wirtgen Group
The Wirtgen Group is an internationally operating group of companies in the construction machinery sector incorporating four traditional brands: Wirtgen, Vogele, Hamm, and Kleemann. As a technological leader, they offer their customers mobile machine solutions for road construction and road rehabilitation, as well as for mining and processing minerals.
The Wirtgen Group has been present in China for more than 20 years and, since 2004, has operated an assembly factory in Langfang, Hebei Province. With more than nine branches and 250 employees, Wirtgen China are always close to their customers.
For more information: www.wirtgen-china.com.cn