Efficient highway rehabilitation

Wirtgen Group machines slash the completion deadline

The lead contractor removed and replaced the binder course and surface layer of a section of the L 98 close to the French-German border. It took Knäble GmbH Strassenbau only twelve days to complete the rehabilitation of the around 3.2 km section of road.

Germany | Kehl

The highway rehabilitation project near Kehl was the first contract for the contractor’s brand-new Vögele SUPER 2100-3i paver. Its premiere, working together with a Vögele MT 3000-2i Offset PowerFeeder, a second SUPER 1800-3i paver and four Hamm HD 150 TT, HD 12 VV and HD 12 VT rollers, was a resounding success: The construction work was finished three days earlier than originally planned.

The lead contractor, Knäble GmbH Strassenbau, sourced the asphalt mix for the project from an equally brand-new Benninghoven BA RPP 4000 Asphalt mixing plant.

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Vögele MT 3000-2i Offset PowerFeeder
Vögele SUPER 2100-3i paver
Vögele SUPER 1800-3i paver

Wirtgen Group machines assure high quality

Confident control of the entire process is essential for anyone wishing to produce sustainably durable, high quality asphalt roads. This means that everything must be perfectly coordinated – from the production of the ideal mix with precisely classified base materials and smooth and seamless site logistics, to high-quality paving and compaction. With this constantly in mind, Knäble GmbH Strassenbau from Biberach (Baden) delivers a wide range of traffic infrastructure projects in the Central Black Forest region of Germany. ‘Our team is highly experienced and proud of its daily performance. And you can see it in the results we deliver’, says Managing Director Nicolas Knäble.

To ensure that Knäble GmbH fulfils its targets, the long-established company relies on machines and plants from the Wirtgen Group. For instance, Knäble’s equipment line-up includes Wirtgen milling machines, Vögele paversand mobile feeders, Hamm rollers, a Kleemann screening plant and a Benninghoven asphalt mixing plant. ‘We have been working with the Wirtgen Group for many years. Thanks to the outstanding machine technologies and service they provide, we always feel that we are in the best of hands’, says Nicolas Knäble.

‘Our team is highly experienced and proud of its daily performance. And you can see it in the results we deliver.’

Nicolas Knäble (left) with Andreas Knäble, the Managing Directors of Knäble GmbH Strassenbau

A picture-book example of a paving project: the rear tipper offloads the hot asphalt mix to a Vögele MT 3000-2i Offset PowerFeeder that then transfers it first to the material hopper of one and then the other of the two Vögele pavers to ensure uninterrupted paving.

A new SUPER 2100-3i boosts the performance of the paving fleet

Knäble’s paving train took on the contract close to the border to France near the south-western German town of Kehl with a brand-new Highway Class paver from Vögele. The concept of the SUPER 2100-3i is designed to enable extremely economical paving on even the largest projects. The machine itself is characterised by high levels of comfort and performance paired with minimal fuel consumption.

The new SUPER 2100-3i deployed by Knäble GmbH is equipped with an AB 600 extending screed with a tamper and a pressure bar (TP1). Thanks to its high pre-compaction performance, this enables precise, true to line and level paving with a maximum paving width of 9.5 m.

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‘This new large paver puts us in an ideal position when it comes to highway construction projects.’

Nicolas Knäble, Managing Director Knäble GmbH Strassenbau

Rehabilitation starts with Wirtgen milling machines

The project remit was the removal and replacement of the binder course and surface layer on a 3.2 km section of the L 98 highway. A maximum of 15 working days was set for the removal and replacement of 28,000 m² of asphalt pavement.

First of all, two Wirtgen W 250 Fi large milling machines successively removed the 4 cm surface layer and the 8 cm binder course.

‘This means that the old asphalt is already presorted. This brings us significant advantages during the recycling process in our Benninghoven BA RPP 4000 asphalt mixing plant. It lets us realise such high recycling rates that we concentrate our search for invitations to tender on those where we can extract usable milled materials, as in the case of this project’, explains Nicolas Knäble.

Paving with three Vögele machines

The Wirtgen milling machines were followed by the asphalt paving train. With the support of a Vögele MT 3000-2i Offset PowerFeeder, a team comprising a SUPER 2100-3i and a SUPER 1800-3i paver first laid the binder course and then followed up with the surface layer. The two pavers each laid a width of 4 m using the ‘Hot on Hot’ method.

The mix offloaded from tippers was transferred to the two pavers by the mobile feeder. Thanks to its slewing conveyor, the MT 3000-2i Offset PowerFeeder can supply the mix to two separate pavers without having to move from one side of the road to the other.

The ErgoPlus 3 standardized operating concept

Another advantage was the intuitive operating concept. The ErgoPlus 3 operating concept from Vögele is identically configured across all machine models. This meant that the paving team could begin working as usual with the new machine without a longer familiarisation process – a real advantage.

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Knäble deployed a team of four Hamm tandem rollers for compaction – two HD 150 TT models (shown here), one HD 12 VV and an HD 12 VT.

Mix with high RAP material rates

The mix for the construction project on the L 98 was produced by a Benninghoven BA RPP 4000 asphalt mixing plant, in which Knäble had recently invested. Thanks to industry-leading recycling technology – the Benninghoven hot gas generator – the plant fulfilled both the contractor’s stringent demands and all official requirements. Due to this, Benninghoven was the only manufacturer able to fulfil the requirements of the new technical instructions on air quality control (Technischen Anleitung zur Reinhaltung der Luft - TA-Luft), which came into force in Germany in 2021. What’s more, the hot gas generator heats the old asphalt indirectly and thus more gently, which enables the plant to achieve RAP material rates of 90 + X%. Regarding the process as a whole, this simultaneously reduces CO₂ emissions.

‘In the production of base layer mix we already have an RAP material rate of 96% with our BA RPP 4000 plant’, reports Nicolas Knäble. That his company can achieve such high RAP material rates is also important for the following reason: Baden-Württemberg, the German Federal State in which Knäble operates, strongly promotes maximum recycling. This means that the legally permissible quantities of old asphalt added in the production of new mixes must be fully exploited. With this investment, Knäble is now ideally set up for the future in this respect – and has no difficulty whatsoever in the conversion of its milled material into fresh mix.

‘We can realise such high RAP material rates with our Benninghoven BA RPP 4000 asphalt mixing plant that we can concentrate on the search for contracts that involve the production of milled material.’

Nicolas Knäble, Managing Director, Knäble GmbH Strassenbau

Rehabilitation completed three days earlier than planned.

Thanks state-of-the-art, high-performance Wirtgen Group technology and the enormous commitment of the team on-site, Knäble GmbH Strassenbau was able to complete the rehabilitation job on the L 98 in only 12 days, instead of the originally planned fifteen – despite a period of bad weather with low temperatures.

‘If the quality is faultless and we were able to keep the impact on traffic lower than expected, then we know we have done a good job’, says a visibly delighted Nicolas Knäble.

About Knäble

  • Founded in 1922 as a paving contractor
  • Today, one of the oldest and highly respected road construction companies in the Ortenau District of the Central Black Forest region of southern Germany
  • Operates its own asphalt mixing plant since 1965 – with recycling technology since 1992
  • Managing Director is Nicolas Knäble, the fourth generation of the family at the helm of the company
  • Today, the company’s ultra-modern fleet includes Wirtgen milling machines, Vögele pavers and rollers from Hamm
  • A milestone for Knäble was the investment in an innovative Benninghoven BA RPP 4000 asphalt mixing plant that enables the contractor to achieve an RAP material rate of up to 90 + X%.