Renovation of Highway Slabs on the A13

Situation

The Swiss A13 highway is a two-lane road, with some sections expanding to four lanes. It is the second most important north-south connection in the country after the A2 highway. Certain sections experience very high traffic volumes, which leads to significant annual wear of the concrete slabs, cracking, and edge breakage. Additionally, blow-ups may occur in the summer on certain sections. The resulting damage must be repaired to prevent further issues and ensure safety on the highway. The closure times must be kept to a minimum to reduce traffic disruptions. This requires the use of concrete with an extremely fast strength development. Ideally, the work should take place during off-peak traffic times. Furthermore, the outdoor temperatures can be very low, requiring a precisely adjustable workability time for the fast-setting concrete.

Solution

For the slab replacement, only rapid-hardening concrete is suitable, as only a few hours are available after the damaged slab is removed. For the repair of the sections, an easy-to-process, rapid-hardening concrete that can be produced on-site was used. Concretum^® Q-CON is a fast-drying, rapid-hardening dry concrete with a maximum grain size of 16 mm. Both properties significantly speed up the construction process. For local repairs in smaller areas and at very low temperatures, Concretum^® Q-REP G, a rapid-hardening dry mix, was used. This mix is also prepared and applied on-site. With this rapid-hardening mortar, an open time of only 20 minutes was achieved, even at low temperatures. Just one hour after setting began, the concrete reached a strength of over 20 N/mm², allowing the highway to be reopened before peak traffic times at 4:30 PM.

Rapid response is essential to changes in temperature, weather conditions, or machinery failure. In addition to reliable rapid-hardening concrete, a well-coordinated team, experienced and decisive construction managers, and intensive support from Concretum specialists are crucial. The special conditions, tight construction schedule, and high concrete requirements present the highest demands on both materials and personnel.