At Zurich airport, several concrete slabs in the runways were heavily damaged and had to be reconstructed. High traffic volume during the day, constrained this reconstruction work to a very short overnight time window.
Solution and assessment
The rapid-hardening concrete Concretum® Q-FLASH 2/20 reaches a compressive strength of approx. 20 N/mm2 just 2 hours after adding water and despite this speed, remains workable for approx. 60 minutes. In addition, Concretum® Q-FLASH 2/20 has low shrinkage. As a result, the slabs do not bow and the risk of cracking is considerably reduced. This guarantees a long lifespan for the new slabs. These specific properties of Concretum® Q-FLASH 2/20 allows the airport operator to carry out urgently required reconstruction work successively and without disrupting air traffic, even under the difficult initial conditions.
In order to remain free from time constraints, and optimise flexibility, the concrete was produced in mixer trucks. For this, the mixer trucks are first loaded in advance with the aggregates and the mixing water required for production. The mixer trucks are positioned around the slab. The binder is loaded from big bags and the desired concrete consistency is set with the water from the mixer truck. All mixer trucks unload together directly into the area being concreted. Because of the fluid consistency of the concrete, only limited compacting is necessary and the concrete surface can be spreaded with a vibrating beam finisher.
Typically, the area around a slab being replaced is closed at around 0:30 am and can be re-opened to aircraft traffic again at 5:30 am.
Concretum® Q-FLASH 2/20
Unique (Flughafen Zürich AG)
TIBAU AG, Zürich
Locher Ingenieure AG, Zürich