Concrete and asphalt from a single source

Wirtgen Group machines rehabilitate the A5

Paver operator Pascal Reichmann is impressed with more than just the high user-friendliness of the Vögele SUPER 1900-2. The tips and tricks he learned in a one-week training class at the Vögele plant in Ludwigshafen also help him on the job every day.

These days, highways surfaced exclusively with concrete or asphalt are something of a rarity in Germany, particularly in its more densely populated regions. Hybrid roads are built instead, depending on the structural requirements and the predicted traffic volume –as was the case with the A5 near Karlsruhe. Bickhardt Bau AG, general contractors, are rehabilitating a 2.3-km stretch of this roadway using a variety of Wirtgen Group machines from its concrete and asphalt segments.

The A5 around Karlsruhe is one of the most heavily travelled highways in Germany: It handles up to 140,000 vehicles a day, 15 per cent of them being heavy-duty trucks. The roadway along this stretch of highway was over 30 years old in places, and forced to bear steadily rising volumes of traffic. It came as no surprise that this section needed resurfacing.

Wirtgen Group machines were deployed at all critical phases of the project: A tractor-towed stabiliser from Wirtgen paired with a compactor from Hamm provided for optimal compaction of the subbase. Most of this section of road was then paved in concrete with slipform pavers from Wirtgen. Immediately thereafter, asphalt pavers from Vögele and tandem rollers from Hamm built the adjacent asphalt approach and exit roads, as well
as a 100-m stretch near a bridge. Thanks not least to the Wirtgen Group’s reliable and efficient technologies, the crews succeeded in completing their work sections on schedule.

Wirtgen WS 250 and Hamm H 20i build the foundation
The old concrete roadway was removed over the entire stretch. The subbase then had to be stabilised in spots and completely repaved to meet water protection requirements. A Wirtgen WS 250 tractor-towed stabiliser together with a Hamm 20-tonne compactor built the 30 cm-thick stabilised subbase.

With its powerful milling and mixing rotor, and high material throughput – resulting from an optimised material flow in the mixing chamber – the tractor-towed stabiliser was capable of thoroughly and efficiently blending the soil. The H 20i compactor followed behind and quickly compacted the layer, giving
the subbase the required level of compaction and degree of penetration. An easy job for the Hamm compactor, thanks to its high compaction and static linear load of over 60 kg/cm.

Two Wirtgen SP 1500: Paving train for dual-layer concrete paving and maximum load requirements
A non-woven fabric was laid out on top of the base course to bridge cracks and for water drainage. The SP 1500 slipform paver, often referred to as a “rolling road factory,” went to work on top of it, placing a 27 cm-thick layer of noise-reducing, durable and skid-resistant exposed aggregate concrete of strength class C30/37 across a width of 12.50 m and 15.00 m. The special feature of the concrete surface is the fact that it comprises two layers of different compositions, which however are placed wet-in-wet in a single paving process. Finally, the TCM 1800 texture curing machine from Wirtgen provides the surface finish.

High compaction meets the highest demands
The SUPER 1900-2 was equipped with an AB 600 TP2 extending screed for its work on the job site near Karlsruhe. Michael Fuchs, foreman of the blacktop crew, likes the screed because “extending screeds from Vögele are more stable and display greater torsional resistance than other solutions.

For levelling, NIVELTRONIC Plus System was used for automated grade and slope control, combined with the associated sensors from Vögele’s extensive line. As a result, there was no stringline along the short stretch between the concrete roadways. The adjacent slot channel on the first lane was used instead as a reference, being scanned by sonic sensors. NIVELTRONIC Plus together with a slope sensor took care of the rest.

Hamm DV 85 VO: A roller with a view
Two DV 85 VO machines from Hamm were used on this project for final compaction. The pivot-steered tandem rollers are the ideal candidates for the job, because numerous corners and tie-ins had to be compacted on a relatively small surface area. From his positionable seat, roller operator always had an excellent view of the drum edge from the cabin.

For further information, visit www.wirtgen.com

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