Building bridges in Bratislava

One of Central Europe’s biggest infrastructure projects, that of the D4R7 arterial, is now nearing completion in Slovakia. The construction project has been implemented to increase transport capacity into the Slovak capital Bratislava and the surrounding region and thus to improve not just the local but also the international links to and from the conurbation. And MC’s expertise was in high demand for the bridge-building work.
The D4R7 construction project comprises the 27 km long D4 motorway, a bypass to the south of Bratislava, and the 32 km long R7 freeway, part of the southern motorway network connecting the western and eastern parts of Slovakia. The investment outlay for the project amounts to € 860 million, and the work began in October 2016. This major infrastructure undertaking also involves constructing a number of bridges, for which Doprastav a.s. and STRABAG s.r.o. have been supplying the precast concrete components. MC Slovakia has worked successfully with both companies for many years and developed the requisite concrete formulation in close cooperation with them.

 

Road traffic bridges

The prestressed concrete bridge parts were manufactured by Doprastav a.s., using the high-performance superplasticiser MC-PowerFlow 1130 and the concrete release agent Ortolan Premium 702, specially formulated for high-quality fair-faced concrete. MC-PowerFlow 1130 is a synthetic superplasticiser of the latest generation and is based on MC’s PCE technology. Its special action mechanism ensures that, especially in precast construction, high-performance concretes with excellent processing properties and a high-quality appearance can be produced at economical dosage rates and with above-average water savings.

 

And Ortolan Premium 702 is the perfect adjunct. It is suitable for smooth formwork and facilitates the production of high-quality exposed concrete surfaces of classes SB 3 and SB 4. It provides for excellent release, has a corrosion-inhibiting effect with a continuous, closed film, and protects and preserves the steel formwork.

 

Green bridges

In addition to the traffic-bearing bridges, it was also necessary to provide a number of new green bridges in order to mitigate the consequences of the fragmentation of the countryside, caused by the road. Built with precast concrete elements from STRABAG, these bridges were designed with widths of 50 to 80 metres so as to meet their primary purpose of enabling wildlife to safely cross heavily trafficked routes. Again, they were constructed with the aid of Ortolan Premium 702 together with, MC-PowerFlow 3130 and Centrament Air 202.

 

Enabling the production of concretes with low tack and accelerating early strength development, MC-PowerFlow 3130 is a synthetic superplasticiser which is again based on MC’s PCE technology. Hence it is particularly suited to precast concrete production applications. The air-entraining agent Centrament Air 202 makes the concrete more pliable, easier to work and more readily compactable, while also increasing a component’s resistance to freeze-thaw cycling and de-icing salts.

 

Through a perfectly coordinated combination of additives and release agents, MC and its two cooperation partners have been able to contribute to technically and visually impressive results in the production of the prefabricated parts for the numerous bridge constructions used in this major infrastructure project. Final completion of the D4R7 arterial is due towards the end of 2020.