Use of crushed brick in reinforced earth railway structures

The Bermondsey Dive-Under Scheme is a key part of the Thameslink Programme which will remove the existing bottleneck that severely limits the number of trains that can pass through London Bridge Station. The scheme involves extensive demolition of 900m of masonry viaduct followed by the construction of 900m of new structures, 200m of reinforced earth structures, and 200m of embankment widening and raising. This paper describes a study undertaken in 2012 that examined the viability of recycling the demolished brickwork material into a crushed engineered fill material for use in the permanent works. The overarching objective of the study was to seek to reduce the significant volumes of both imported fill and exported demolition material that would be required for the BDU scheme. In addition to the associated sustainability benefits, the significant reduction in lorry movements from London’s congested streets would result in significant environmental and safety benefits. The paper details the sampling and testing of brickwork that was undertaken as part of the study and presents the findings from the study. A synopsis of the properties of the crushed brick and the material requirements for engineered fill is included. The paper also discusses some of the issues associated with introducing innovation within major works programmes. The Bermondsey Dive Under Scheme is currently under construction and is scheduled for completion in 2017.