Near-record performance in race track rehabilitation: Cold recycler and asphalt pavers rehabilitate legendary racing circuit in the Czech city of Brno

Maximum surface evenness – that’s one of the most important properties a good racing circuit must have. An excellent example of this is the world-renowned motor racing circuit in the Czech city of Brno, where both David Coulthard and Valentino Rossi set record times. Because the pavement no longer fulfilled the high demands of the world’s best race drivers in terms of quality, a cold recycler and road pavers from the Wirtgen Group were at the starting grid in March and April 2008 to rehabilitate the difficult circuit in near-record time.

Racing the track with nearly 1,200 hp

Top speed was a must, because bad weather had prevented the operation from beginning until March. The first racing event had been scheduled for mid May – leaving just six weeks for rehabilitation of the 15 m wide and 5.4 km long track. Construction time was therefore an important aspect that influenced the decision in favour of using a WR 4200 cold recycler. “Cold recycling in-situ is often the fastest and most economically efficient method to produce a new base layer. What’s more, it offers flexibility in terms of designing the overlay which can then be fully adapted to the road’s traffic load,” says Thomas Krause, Site Manager at German contractor Kutter Spezialstraßenbau GmbH, explaining the reasons behind the decision to use cold recycling.

Prior to the cold recycling train commencing work, several large milling machines from Wirtgen had removed the top layer of the old pavement at a depth of 10 cm. In a second operation, the remaining asphalt package was granulated and levelled down to a depth of 15 cm. Powered by a total of 1,180 hp, the brand-new WR 4200 then gave an impressive demonstration of its performance capacity. Working at widths varying between 3.80 m and 4.10, the cold recycler needed four laps to mix bitumen emulsion, water and pre-spread cement into the previously milled asphalt package. Mix designs had been carried out prior to recycling to determine the weight percentages of the different binding agents. Site Manager Krause is happy to have “such a tremendously powerful machine” in the WR 4200, enabling him and his team to hand the new base layer – totalling 80,000 m², after all – over to the asphalt paving gang after just 15 days. For Martin Diekmann, product manager cold recycling at Wirtgen GmbH, was the job in Brünn one more demonstration for the efficiency of WR 4200: “On the Grand Prix circuit in the Czech Republic, the WR 4200 cold recycler gave impressive proof yet again that the machine itself, as well as the cold recycling technology are matchless in terms of quality, economic efficiency and economy of time. As in motor racing, success in road construction is, of course, always backed by a professional team of machine operators, applications specialists and engineers who take the WR 4200 to the starting grid and lead it to victory. A major aspect of the entire process is applications consulting, which we offer to support our customers around the globe. From the North Cape to Australia, we collaborate with the parties in charge to work out technically and economically suitable concepts for the rehabilitation of roads.”

Vögele pavers ensure perfect surface evenness

Unlike the cold recycler, the Vögele pavers – one Super 1800-2, one Super 2100 and one Super 1900 – were allowed just two laps around the racing circuit, which is situated in a breathtaking landscape. Equipped with AB 600-TP2 high-compaction screeds by contractor Kirchhoff from Leipzig, they placed a 4 cm surface course on top of a 6 cm binder course. High compaction was also used when paving the surface course, though the pressure bars were operated at reduced pressure. This left a maximum time frame for compaction in spite of the low ambient temperatures.

As with all racing circuits, surface evenness of the track pavement was of top priority also on the Brno race track. The requirements placed on compaction were typical for motor racing but extremely high compared to standard road construction: The maximum allowed tolerance was 5 mm over a length of 4 m for the binder course. The specified high degree of precision was achieved by the two pavers working on the left and right, which scanned reference wires and were fitted with grade sensors. The paver working in the middle used sonic sensors for scanning the newly paved layer. The tracked pavers successfully used the highly accurate Niveltronic system for paving the surface course, the specifications of which were even stricter. Also the head of applications technology at Joseph Vögele AG, André Felchner, knows the big challenge for the Vögele technologies: “Excellent surface evenness is always a crucial issue on race tracks. That’s when Vögele’s automatic levelling system and high-compaction screeds demonstrate their tremendous performance capacity. With our paving screeds, customers can control and adjust the compaction systems separately and independently. Maximum evenness and quality of the pavement are achieved by adjusting the tamper correctly and by setting the pressure at the pressure bars to match both the paving speed and layer thickness.”

The Super pavers produced the top-quality pavement in near-record time of just 7 days for the binder course and additional 4 days for the surface course, making sure that rehabilitation of the racing circuit was completed in time for the new racing season.