At Zürich Airport, a number of slabs of the taxiways showed signs of fatigue as well as damage requiring repair. In order to minimise closure periods, the repair works were carried out during a nighttime slot. In this way the available window was severely restricted. In addition, the exceptionally hot summer in Zürich presented a further challenge to concrete production.
Solution and assessment
For this project, the rapid-hardening concrete, Concretum® Q-FLASH 2/20, was used. It reaches a compressive strength of approximately 20 N/mm2 just 2 hours after the start of mixing. Adapting the open time to the given conditions (temperature, transport and pouring time) facilitated an optimum construction process. The concrete produced at a nearby plant was transported to the construction site with dump trucks and placed with power shovels. The consistency was adjusted in such a way that the concrete was easy to compact and the surface could then be spread with a roller beam.
Finally, a broom finish was applied. This made it possible for the work to be completed in each case by 4:30 am, and the concrete reached the required strength in time – by 5:30 am (> 16 N/mm2). The newly renovated areas were then opened for normal operations.
Furthermore, Concretum® Q-FLASH 2/20 is also characterised by very low shrinkage which reduces the risk of cracks and allows for longevity.
Concretum® Q-FLASH 2/20
KIBAG AG, Bassersdorf