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Concrete In Australia : June 2012
6 Concrete in Australia Vol 38 No 2 NEWS Perth City Link major works on track As part of the $360 million Perth City Link rail project, the alignment of the new Fremantle Line tunnel has been completely cleared, allowing rigs to begin digging the tunnel walls of the new 600m covered section west of Perth Station. Parts of the tunnel will have multistorey buildings above them and so to provide a stable and strong foundation for these buildings, some of the foundations must go as deep as 40m below the surface, into the bedrock below. Perth City Link is led by the East Perth Redevelopment Authority and the Public Transport Authority (PTA). It is the first step in reconnecting the CBD and Northbridge by sinking the Fremantle Line between William Street and Lake/King Street to allow for street level connections between Roe Street and Wellington Street. Delivering the staged rail project is the Perth City Link Rail Alliance consisting of the PTA, John Holland and GHD. e alliance said the concrete used in the diaphragm walls (D-walls) for this section has been designed to meet certain criteria including the standard strength, slump and shrinkage. For example, the concrete mix being used for the D-walls had to exhibit a workable life of 3.5h and so to retain this level of workability Adva 142 superplasticiser and Daratard PR200 were used. e chloride and sulphate contents also had set limits that had to be met by the mix. ree laboratory trials and two field trials were undertaken to ensure concrete requirements were met. As excessive bleed (water loss during setting of concrete) is often a problem in D-walls, the alliance said it put a lot of effort into minimising the bleed. Work continues apace in other parts of the project and the first major concrete placement for the track invert slab at Perth Station was undertaken in March. Over the life of the project around 53,000m3 of concrete will be placed. Sinking the Fremantle Line is scheduled for completion in 2014. Reinforcement cage for the diaphragm-walls is lowered into place along the Freemantle Line in Perth. Gold Members