Whenever the town of Brno is mentioned, motor racing fans get excited.
Races have been held here since 1930. After a few rather subdued years, the course is now back to its former glory. Both the infrastructure and the carriageway have been renovated. Riders are enthused about the special asphalt, made in a Benninghoven plant and paved by three Vögele pavers and material feeders.
International race tracks have particularly stringent requirements for evenness, grip and a homogeneous texture, amongst other factors. Maximum grip and consistent evenness are key — as is the safety of riders travelling at speeds of around 200 mph. All 3.35 mi. of the Masaryk Circuit were resurfaced: three Vögele pavers and material feeders paved a 1-in. thick level-regulating course and a 1.6-in. thick surface course across an average width of 49 ft. — on the Start/Finish straights, this width increased to as much as 56 ft.
Stringent Requirements, Little Time
Apart from the precise specifications for both asphalt material and paving process, the paving team managed by David Tejkal, construction manager of general contractor Strabag a.s., faced another challenge.
"We had a strict deadline," he said. "The track had to be handed over two months before the Grand Prix." This meant a very short preparation period of just four weeks. The team could only work during the day, So 50 workers and 5 engineers were on site each day. "The tight schedule demanded precise coordination between all those involved — as well as utterly reliable, high-performance machinery," said Tejkal.
Special Asphalt Material
The first task was to find the perfect asphalt material to deliver the ideal carriageway surface: better grip, faster, safer. Consulting engineers Hart Consult drafted a resurfacing concept for the track.
"Among other things, we drafted project-specific specifications for all raw materials, asphalt composition, processes and quality assurance which were also agreed with FIM, the Fédération Internationale de Motocyclisme (International Motorcycling Federation) and we monitored the implementation of those specifications on site," said Mario Peiker, managing director and technical director of Hart Consult International GmbH. Any deviation from these specifications would potentially impact performance and safety. The special asphalt was produced in a Benninghoven BA 4000 asphalt mixing plant from Brnenska Obalovna/Strabag.
Smart Weighing System for Consistent Asphalt Quality
The smart weighing system from Benninghoven proved ideal for this project. It has no sensors and teaches itself to dose at maximum efficiency and to minimum tolerances — even under varying conditions such as fluctuating temperatures or differing proportions of white mineral. The system reacts to the flow of material in real time, creating the conditions for managing the formula precisely — something which would be almost impossible using conventional methods. This renders the smart weighing system valuable wherever extremely low formula tolerances are required — such as in this project, where any deviation from the specifications would have an impact on performance and safety.
In order to be able to use the smart weighing system, however, the first step was to integrate the latest version of the mixing plant control system, BLS 4 from Benninghoven in the existing BA 4000 from Brnenska Obalovna. This control unit conversion also was completed in double-quick time as a result of close collaboration between Benninghoven, Hart Consult and Strabag.
"It was really impressive to see how the new control software benefitted production precision. As we reduced production tolerances by almost 50 percent compared to national standards, these specifications could only be maintained using a perfectly calibrated mixing plant," said Peiker.
Even Flow of Material, Seamless Paving
The special asphalt had to be paved without interruptions and without any loss of temperature in order to satisfy the stringent quality requirements. This was taken care of by precisely harmonised logistics: thermally-insulated trucks delivered the material straight to three Vögele MT 3000-2i standard type material feeders. They took on the load in the shortest possible time and continuously conveyed material to the Vögele pavers. In the process, the sensor-controlled conveyor belt heating of the material feeders ensured that the asphalt arrived at the pavers without any heat loss.
Paving itself was implemented by the hot-to-hot method to achieve a seamless surface, otherwise the high shear forces on the race track would very soon force open any joints. Three pavers of the Super 1800‑3i type worked on parallel carriageways with a slight offset — across the full carriageway width of 49 ft. to 56 ft. Hot-to-hot paving ensured optimum bonding and a water-impermeable, stable and durable carriageway surface.
System of Sensors Ensures Maximum Evenness
To ensure precision maintenance of longitudinal evenness, the team used the Niveltronic Plus system for automated grade and slope control in combination with the Big MultiPlex Ski. Three multi-cell sonic sensors were fitted to the brackets to scan the roadbase of the level-regulating course and the surface course at several points simultaneously. The system for automated grade and slope control used these measurements to calculate an average value over the entire measuring range, compensating even extended irregularities. The AB 500 TV extending screed (with tamper and vibrators as compacting systems) secured a high degree of precompaction, leading to a high-quality surface. The result was a homogeneous, even asphalt surface course with the optimum texture — ideal for a race track.
Paved, Tested, Approved On Time
Despite the challenging schedule, this project was completed on time. In just four weeks, a total of around 14,000 tons of asphalt material were paved at Brno Circuit. The whole track was inspected and approved by the authorities, So motor racing fans can once again look forward to lots of great racing in Brno.
For more information, visit wirtgen-group.com.
