With the aim of contributing to sustainable development through the use of environmentally friendly techniques, ACCIONA Infrastructure used recycled concrete during landfill work at the Lai Chi Kok Viaduct (LCKV) in Hong Kong.

The Lai Chi Kok Viaduct (LCKV), with an initial budget of approximately 110 million euros, is part of the new Route 8 which will link Chep Lap Kok international airport with the Shatin area. The viaduct is a raised structure measuring 1.4 kilometres long, with four access and exit points, between the Ngong Shuen Chau viaduct and Eagle’s Nest tunnel. The majority of the viaduct has been constructed using a system of prefabricated concrete cantilevers, with spans ranging between 45 and 85 metres.

Recycled concrete as landfill material in trenches, embankments and backfill in retaining walls

In November 2006, ACCIONA Infrastructures suggested that the Hong Kong Government-Highways Department use recycled concrete as landfill material in trenches, embankments and as backfill in retainer walls. Prior to use on site, the material was tested to check that the granulometry met the project specifications. The results of the tests were positive and it was established that the concrete could be used as landfill material.

Concrete waste destined to be recycled by crushing on site came from the waste material resulting from the demolition of pavements and other concrete structures included in the project. The recycling process was carried out using a mobile plant located on site, OKADA BT-80, and connected to a conventional excavator. The equipment was able to reach production levels of 5-6 cubic metres per hour of recycled concrete. Almost 15,000 tonnes of concrete were recycled this way, and then used in different areas of landfill.

Huge environmental benefits

The environmental benefits of using recycled concrete are multiple:

• Acoustic: The use of this equipment reduced the noise levels produced during its operation.
• Environment: The environmental impact has been minimal, as the dust generated during the crushing process was hugely reduced through the use of spray irrigation.
• Waste: The dumping of a large volume of waste has been avoided.
• Natural resources: It was not necessary to use new natural resources for the landfill work.