Wirtgen Group machines slash the completion deadline

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.

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.

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.

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.

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