Stratford Bridge - Stratford, East London
The new H23 Stratford Bridge, which spans the main London rail line, provides access to an area of significant regeneration. The bridge construction utilised 13,000m3 of 10-20mm Leca® LWA to backfill against the high retaining wall abutments reducing the loading by 75% over traditional fill materials. Leca® LWA is a lightweight expanded clay formed by heating and firing natural glacial clay. It's high volume by weight reduced the expected number of truck deliveries onto this busy and difficult to access construction site. Leca® LWA is also very easy to handle on site, allowing the simultaneous spreading and compaction of the Leca® LWA with the same tracked machine. Leca® LWA 10-20mm is a free draining, lightweight fill material which has an average density of 300kg/m3 which is just a seventh of the weight of sand, gravel or crushed rock. It also offers good resistance to moisture retention allowing installation during wet weather. The Stratford Bridge project is a key element of the complete transport infrastructure development in East London. It was designed and specified by Arup and the build project awarded to Balfour Beatty. Project leader Pete Wilkinson had previous experience of using Leca® LWA fill. “It’s a great product, easy to handle and the delivery schedule worked well for us even though we had some weather problems." The low weight, high volume benefits of Leca® LWA decreased the abutments loading by 75% over traditional fill and the quick compaction, in comparison to traditional fill, enables a faster completion of the build project. Leca® LWA also gives a reduced loading on the ground structure, which is important at the Stratford location where much of the site is reclaimed or disturbed ground. Leca® LWA exerts much lower horizontal earth pressures compared with other backfill materials, which helps improve stability.