SUPER 1900 - Test Circuit with Parabolic Profile in Michoacan, Mexico
Taking the Bend at Full Throttle
Construction of a test circuit in Mexico was a great challenge to everyone in the paving team, not only because of the blazing heat. The circular track featuring a parabolic profile was built by a SUPER 1900 paver that came with a screed specially conceived for parabolic projects. The trick behind the track is: though steering straight ahead, the car follows the bend. As everyone knows, compacting a concave banking is not an easy job. It was another scene for VÖGELE High Compaction Technology to furnish proof of its capabilities.
General Motors’ circular test track has a length of 5.6km.
The test track is located in the state of Michoacan, one of the hottest places in Mexico.
Paved in 5 strips
SUPER 1900 with special screed for parabolic profiles paves on the steep banking.
Supra Construcciones S.A., who won the track building contract, paved the first asphalt layer in 5 horizontal strips from bottom to top. This way of proceeding offered the advantage that, on the banking, each strip of freshly paved mix was “supported”, as it were, by the previously laid one. For paving the lowest, uncomplicated strip, the paving team installed tensioned wires on either side of the paver for referencing. For the next strips, a tensioned wire was set up on the outside only and a 9m averaging beam installed on the inside using the already placed layer as a reference. These strips on the steep banking were paved 3.4m to 3.8m wide, which required reduction of the screed in width. For optimal floating of the screed, a Screed Assist pressure of up to 20 bar was applied.
Car manufacturer General Motors awarded a contract for building a high-speed test circuit in Cupuan del Rio in the Mexican state of Michoacan. As a result of the circular track’s parabolic profile featuring a maximum transverse slope of 32%, cars can always be steered straight ahead. Due to the different radii on the concave banking, they are pulled through the long bend so you would think they are travelling on rails.
Test track with transverse slope of 32%
Test track with a maximum transverse slope of 32%.
In the area of the banking which was steepest, a second machine was on the scene for reasons of safety, supporting the paver from below. When paving the test circuit’s wearing course in a thickness of 10cm, placed in 2 layers, the second paver served as a counterweight. While paving, the two machines were connected by steel cables.
Test Circuit “General Motors Proving Ground Cupuan del Rio, Mexico”
General Motors awarded a contract for building the 5.6km test circuit. It will be a location for car testing at high speeds. The circular circuit is designed for speeds up to 170km/h. Thanks to the parabolic profile and a maximum slope of 32%, cars can always be steered straight ahead.
Project
Happy about successful completion
of the job: the paving team
of Supra Construcciones S.A.
Construction of test circuit “General Motors Proving Ground Cupuan del Rio, Mexico“
Length
5.6km
Width
17.5m
Maximum Transverse Slope
32%
Equipment
SUPER 1900 with Screed for Parabolic Profiles
in TP2 Version for High Compaction
Asphalt Wearing Course
Tamper stroke: 4mm
Tamper speed: 1,600 rpm
Pressure bars: 80 bar
Pave speed: 4–7m/min.
Pave Width
5 strips between 3.4m and 3.8m
Thickness of Surfacing
10cm, placed in 2 layers
High compaction on the steep banking
VÖGELE High Compaction Technology in TP2 version, though paving with a Screed Assist pressure of 20 bar, produced a density of 88 – 91% behind the paver. Achieving the final density called for no more than 2 passes by rubber-tyred rollers. The parabolic profile built for the Mexican test circuit was accurate within +/-3mm, so that the tight tolerance requirements of the specifications were met without fault.
Paving at 50° Centigrade
The hostile job site environment under the blistering sun of Mexico posed a challenge primarily on logistics. In the lower and still rather flat area of the parabolic banking, supply of the paver with mix could be managed by feed lorries alone as usual. In the upper and steeper area of the banking, however, a mobile feeder had to be positioned in between. A conveyor belt supplied hot mix into the SUPER 1900’s material hopper.
In the area of the banking which was steepest, supply of the paver with mix was by a mobile feeder.
Paver Gets The Curved Job Done
The transverse profile of a pavement is not always flat. Besides sloped shapes, VÖGELE screeds are capable of handling positive or negative crown and positive or negative gullwing profiles. A true VÖGELE “speciality”, however, is paving parabolic profiles. VÖGELE High Compaction Technology is particularly valuable when it comes to parabolic projects. On a steep banking, manoeuvring rollers is difficult and rollers are always at risk of spoiling the pavement profile. This is why it is the screed’s part to produce a density as high as possible. Not only can the specified profile be accurately shaped by the 8 segments of the special VÖGELE screed, they also exert a high pressure on the pavement layers. Thanks to VÖGELE HPC Technology, the screed achieves excellent results: the asphalt compacted to high density is perfectly prepared for subsequent roller passes.
Screed split into 8 segments
VÖGELE have modified one of their HPC screeds for paving parabolic profiles. The crucial difference between this special HPC screed and a conventional one is its splitting into segments. The screed comes with 8 segments of 0.5m each. The segments’ positions in relation to each other can be adjusted within the range of 25mm by electro-hydraulic stepper motors and mechanical crown control. The special screed for parabolic profiles is capable of paving in a maximum width of 4m. For fully automatic control of tractor unit and screed, programmable MCS software (Motor Control System) is installed.
VÖGELE Screed for Parabolic Profiles
The segments’ positions in relation to each other can be adjusted by 25mm. The 8 adjustable segments, each 0.5m wide, shape the parabolic profile.
- Pave width 4m.
- For paving parabolic profiles, this special screed is split into 8 segments of 0.5m each.
- The segments’ positions in relation to each other can be adjusted by 25mm.
- Adjustment is by electric stepper motors and mechanical crown control.
- Equipped with VÖGELE High Compaction Technology in TP2 version.
- Fully automatic control of tractor unit and screed by programmable MCS software (Motor Control System).
