The Airport Link stretches across approximately 6.7 kilometers (mainly underground) and is Australia’s longest road tunnel. The contract for this enormous undertaking, which cost AUD 5.6 billion (USD 5.1 billion), was awarded to LafargeHolcim Australia’s SEQ concrete team.
Subject to an extremely tight timetable, the project required the ability to meet three demanding targets:
- Cut-and-cover: providing and placing over 2,800 cubic meters of concrete in a marathon engineering effort over just one night. The contract called for a single pour to create the roof for a section of the tunnel.
- Continuous supply for the tunnel excavation: supplying 115,000 cubic meters of arch-lining concrete and 40,000 cubic meters of concrete pavement. The arch-lining concrete was used inside the excavated tunnels, which required high early strength. The concrete pavement became the structural roadway on which an asphalt overlay was applied.
- Tunnel boring machines (TBM): providing 200-meter-long machines that perform a number of functions, including boring the tunnel, removing the spoil via conveyor, and placing the tunnel lining segments as they go.
LafargeHolcim teams also submitted over 100 individual mix designs for project approval.
To accomplish the cut-and-cover method, a team of 50 concrete specialists, engineers, and laborers spent nine hours pouring the concrete. Forty-eight trucks were used to deliver 380 loads of concrete, which were scheduled to arrive every two minutes. Four concrete pumps were needed to ensure that concrete could be poured at a rate of 300 cubic meters an hour.