First Dynapac CompactasphaltTM Paver in China Starts Work on Hebei Expressway
As China's first CompactasphaltTM paver starts work on Hebei Expressway, Chinese Highway authorities study the use of the Dynapac machine in terms of quality and speed of construction for new trend towards asphalt wearing course construction.
The first Dynapac Compactasphalt paver to be delivered to China is being used on the construction of a new highway project in Hebei Province. The performance of the machine is being closely monitored by highway engineers and Provincial Authorities to see if this technology can be successfully employed elsewhere on China's huge program of highway construction.
The Compactasphalt method is a combination of a compact asphalt paver and a module carrying the wearing course mix. It simultaneously lays both upper asphalt layers (wearing and binder course) in a single pass, with both layers being laid Hot-on-Hot. This gives more deformation resistance, better interlocking of the courses, a saving on the thickness of the wearing course, and a reduction of the paving time.
This method also reduces the sensitivity to weather conditions. Paving can be done to 0°C, in part also due to the higher amount of asphalt laid (generally 4000 to 5000 t/day, maximum 10 000 t/day).
The possibility to use a thinner wearing course thickness ensures a more economical use of high-value minerals.
Officials of the highway division of the state-owned Bei Fang Construction Group had shown great interest in Dynapac's double-paving concept in the second half of last year, says Qun Luo, vice president of Dynapac in Beijing, and a group of engineers and executives had gone to Germany to see the concept demonstrated.
Dynapac had presented the Compactasphalt method at Bauma China in Shanghai last November, where it had attracted a good deal of attention. Bei Fang took delivery of a combined F300 CS compact asphalt paver with an AM 300 wearing course module for use on construction of the Zhang Shi Expressway, a 43 km highway that is being built between the Hebei provincial capital of Shijiazhuang and the city of Zhangjiakou.
The highway is being built as a continuously reinforced concrete pavement (CRCP) structure with an asphalt concrete (AC) wearing course. This is a road building concept that is currently gaining favors in China, which had previously preferred Portland cement concrete. A large volume of the highway's traffic will consist of heavy trucks, and the CRCP+AC structure is of particular interest to China's Highway Authorities.
A substantial part of the highway had already been constructed with a conventional asphalt paver. With the Compactasphalt method, equal or better mechanical properties are achieved than of the CRCP+AC method. The performance of the Dynapac Compactasphalt is therefore attracting great attention.
Mr. Luo says that the Dynapac machines arrived on site in May. Three Dynapac engineers from Germany spent two weeks on site with Bei Fang engineers to ensure that the equipment is used with optimum effect. The machine has subsequently been supervised and maintained from the Dynapac Beijing office, some 300 km away.
"The decision to purchase was made very quickly," he says. "Bei Fang told us they were interested in technology that would help them meet China's ambitious highway development projects.
"We understand now that other provincial authorities in China are studying progress with the machine, to see if this technology can be deployed on their own projects."
The F300 CS high-performance finisher, with a standard paving width of 3 m, is the biggest machine in the Dynapac tracked paver range. Equipped with a track length of more than 3,5 m, a hopper capacity of 15 t and an auger diameter of 500 mm, this model is developed to cope with maximum working widths of up to 16,0 m.
Configured as a Compactasphalt paver, it is equipped with a bigger hopper for the binder course material carrying 45 t and an AM 300 module that carries 25 t of wearing course material lifted into place by an MF 300 C tracked feeder.
The Zhang Shi Expressway is a two-lane highway with a hard shoulder that can be used as a third carriageway. Bei Fang's project manager Wan Zhi Yong said, "the double paver is able to lay the 7 cm wearing course and the 3 cm binder layer simultaneously across the entire 11,5 m width in a single pass".
He elaborated that without this form of compacted asphalt construction, the wearing course and binder layer would have been, in total, approximately 2 cm thicker. "Although no significant figures can be produced until the project is completed at the end of September", confirmed Mr. Wan, "the indications so far are that substantial savings are being made on materials that are also being more effectively utilised."
China plans to expand its national expressway network by using both concrete and asphalt pavements. One goal of the Chinese government is for the network to reach all 31 provinces of the country, and achieving this will require the addition of thousands of kilometres of highway.
Projections are that by 2020, the total length of China's expressways will exceed the total length of America's interstate highways.
© InfraStructures - Tous droits réservés - All rights reserved