How we make the concrete segments lining Sydney Metro Northwest’s rail tunnels
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How we make the concrete segments lining Sydney Metro Northwest’s rail tunnels

October 12, 2019


We started on-site in October 2013 when literally all that was behind me was a cow paddock and a few houses. It only took seven months to turn a vacant site into a precast factory. One of the key things we needed to do was to get our high performance concrete mix just right. We had to follow a strict recipe that combines high tensile steel wires with polypropolene fibre, cement and fly ash as well as aggregates and sand. The critical factor in the whole batching process is moisture control. The concrete has to be wet enough that it goes through the flying bucket system and dry enough that we can finish the concrete. The concrete’s then poured into specially designed steel moulds. Probably one of the most important innovations we’ve made in terms of this project is the casting gasket which ultimately helps us achieve a better final product. It gives us a better chance of achieving a watertight tunnel. The mould will then go to the concreting station where they’ll finish the mould before it goes into the curing chamber. The moulds will travel through the oven for approximately 5 ½ to six hours at 60° Celsius. Once the segments come out of the curing chamber they’re removed from the moulds using a vacuum lifter attached to the crane. The segments are then stored inside the factory for the appropriate quality checks, identification via a bar code or documentation system for stockpiling outside. They’re ultimately stacked in threes. That’s the way the segments get delivered to the TBM and there’s a certain order in which the segments have to be built to build a ring. Once we’ve got 28 days strength we can then send the segments to the TBM sites. We began producing segments in May 2014 which was four months before the first TBM was launched And now, just ten months after production started we’ve reached the 50 percent mark. 50 thousand segments produced. It’s a great achievement by the entire team and we’re justifiably proud of this achievement.

2 Comments

  • Reply JD's Transport Films July 10, 2015 at 8:21 am

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  • Reply JD's Transport Films July 10, 2015 at 8:21 am

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