Products used: 8,500 tonnes of Tufflex HD, 3,000 tonnes of Tufflex and 1,800 tonnes of Tuffpave
Challenges: Difficult ground conditions, extremely heavy axle loads and tight time scales
Main contractor: VolkerFitzpatrick
Completed: Spring 2015
London Gateway, the deep-water container port and logistics park, has been constructed on the north bank of the River Thames at Thurrock, Essex. It provides 2,700 metres of quay designed to accommodate the next generation of 400 metre-long container ships as well Europe’s largest logistics park.
As well as being on the doorstep of the capital, London Gateway offers access to road and rail links to the whole of Britain, enabling shippers to reduce delivery times, haulage costs, fuel consumption and carbon emissions.
The first berth was opened at the end of 2013 with much fanfare, marking a major milestone in the development of the project which has been under way for more than a decade.
Planning considerations meant that the access routes into the port and distribution centre were left very late and needed to be completed quickly and carefully to meet operator DP World’s exacting standards.
The asphalt was required to last a minimum of 10 years without maintenance, despite extremely heavy use. The containerised cargo, which is transported from the port to the distribution centre, is also very heavy and carried on slow moving vehicles that are the most likely to cause wheel track deformation.
An added complication was the poor bearing capacity of the ground. The site is shale overlain with alluvial substrate so the sub-base was created and preloaded to allow as much as possible of the expected settlement to occur before construction began. It was also decided that the roads themselves should be able to accommodate a degree of movement.
This meant the base and binder layers had to display workability, early strength and fatigue resistance as well as provide a high softening point to produce a very heavy duty asphalt with a high resistance to deformation.
Working with main contractor VolkerFitzpatrick and asphalt sub-contractor Toppesfield Ltd we only had one week from award of contract to starting work on site – and only eight weeks to complete the access roads.
The asphalt chosen needed to have the ability to spread the load from the slow moving heavy traffic at higher temperatures to prevent wheel track deformation. We conducted a series of trials to confirm the performance characteristics required, which resulted in the selection of our Tufflex proprietary asphalt for the lower layers using Endura Z2 binder from specialist Nynas Bitumen UK – a highly polymer modified hot mix binder which gives strength and flexibility.
The base course was 190mm thick and used 8,500 tonnes of Tufflex HD (heavy duty) with 20mm aggregate; the binder course was 60mm thick and used 3,000 tonnes of Tufflex with 14mm aggregate; and surface course was 40mm thick and used 1,800 tonnes of Tuffpave with 10mm aggregate.
The project ran very smoothly and the resulting roads are defect free. Through working with our client, we were able to develop and supply a perfect asphalt solution for a unique set of site conditions.