Concrete Recycling at Mt Eden

In a win-win for construction and sustainability alike, more than two Olympic-sized swimming pools-worth of demolished concrete has been crushed, cleaned and pulverised at the City Rail Link’s Mt Eden Station for reuse on site.

The crushed concrete is being used to make roads to support piling around the station’s tunnel boring machine portal – and if all goes well, the fill will be used to backfill the cut and cover tunnels.

The benefits are obvious; reusing the material that would have been discarded as waste after demolition is better for sustainability, the environment, the budget and for the timeline.

Not having to pay for disposal of the demolished concrete off-site and for new aggregate material to be delivered all adds up and environmentally it means less emissions and less heavy traffic on the surrounding roads.

So far, over 5000 cubic metres have been crushed with a stockpile of 500 cubic metres still to be used on site.

How concrete recycling works:

• During demolition works, concrete buildings and structures are pulled down with a large excavator with a claw-like attachment.

• The concrete chunks are then broken up into smaller pieces using a digger with a muncher/cracker jaw attachment and the big chunks of steel taken out and recycled.

• Then it is put through a concrete crusher which smashes it to 100mm bits.

• During this process the remaining steel is taken out by built in magnets in the crusher.

• The crusher also has a hose attachment which wets the concrete on the conveyor belt to decrease dust/air pollution.

• What’s left is a product similar to the import fill commonly used on construction sites.

• The crushed concrete is then used in lieu of imported fill to make temporary roads to support the piling rig and crane - and if all goes well it will be used to backfill on top of the cut and cover tunnels around the Mt Eden Station.

The Mt Eden team are still working at home so please don’t hesitate to get in contact. People can get in touch by emailing mteden@linkalliance.co.nz or calling 0800 CRL TALK (0800 275 8255).