Clean Paving of Wearing Course with Low-Noise Stone Mastic Asphalt

In Munich’s Haidhausen district, a VÖGELE paver has provided the main arterial road with a new wearing course of low-noise stone mastic asphalt. Once again, SprayJet technology has acquitted itself with honours in terms of both cleanliness and cost-efficiency.

Hamm tandem rollers paving with low-noise Stone Mastic Asphalt

HAMM tandem rollers paving with low-noise Stone Mastic Asphalt

Freshly renovated old apartment buildings, small cafés, antique dealers and boutiques – little wonder that Munich’s Haidhausen district is a popular place to live. Especially in the “French quarter” between Elsässer Strasse and Lothringer Strasse, the cityscape of the mid-19th century, when Germany experienced an economic boom, has been largely preserved. Yet this tranquillity comes at a price: the majority of the traffic is routed to the edge of the quarter via Orleansstrasse. Here, convoys of cars share the road with busses, cyclists and tramlines. All told, roughly 14,000 vehicles use the two sides of the dual carriageway every day. That not only exerts a heavy load on the road, but also generates a lot of noise.

And so, the Bavarian State capital decided to pave a new wearing course on Orleansstrasse between Rosenheimer Strasse and Orleansplatz using low-noise stone mastic asphalt. The roadworks were one of several rehabilitation projects to reduce traffic noise in the city and were funded within the framework of Economic Improvement Package II.

Impeccable paving in full-road width

For optimum noise abatement, it is important that the number of joints in the asphalt pavement is kept as small as possible. Often, however, this solution cannot be translated into reality, as the ongoing flow of traffic has to be taken into account when rehabilitating a road, meaning that the paving job has to be done in several narrow strips. Contractor Franz Schelle GmbH & Co. KG from Pfaffenhofen was able to avoid this. The company took advantage of the existing closure of a traffic lane on “Orleansstrasse” that had been set up for an expansion of the district heating network. The closure allowed paving in just three strips along the full length of the 550m stretch. This, however, resulted in cramped conditions on this job site, separated from the flowing traffic just by beacons. Klaus Fihn, Site Manager of contractor Schelle, gave a very appropriate description of the situation: “The traffic there is absolute chaos.” His team had to concentrate even harder than usual.

AB 500-2 TV Extending Screed working in full spray width

The preparations were quickly completed. First, the team removed the old wearing and binder courses to an average depth of 13.5cm using Wirtgen milling machines. Then a new binder course was laid. For paving the new wearing course of low-noise stone mastic asphalt (SMA 8 S LA), a VÖGELE SUPER 1800-2 with SprayJet Module moved onto the job site. The paver was combined with an AB 500-2 Extending Screed in TV version and operated in a maximum spray width of 6m. For the 6m application, the screed had been built up with bolt-on extensions. In this configuration, the spray paver placed a perfect wearing course, 2.5cm thick.

Ideal for low-noise wearing course

VÖGELE SprayJet Technology is ideal for placing low-noise wearing course. “In order to create the noise-absorbing cavities, you cannot compact the mix to the same degree as conventional asphalt,” explained Fihn. “Therefore, a durable wearing course with an optimum bond of layers can best be placed using a spray paver.” For the SUPER 1800-2 with SprayJet Module spreads bitumen emulsion and paves asphalt in a single pass. “The conventional method of spraying emulsion and paving asphalt in two operations risks impairing the pavement quality,” explained Fihn. “The layer would have had to be thicker, which, however, given the lower compaction, would have reduced the pavement’s durability.”

Job site and surrounding area stay clean

This is not the only reason for Fihn’s confidence that: “Spray pavers like the SUPER 1800-2 with SprayJet Module from VÖGELE represent the future for inner-city road projects.” Another great merit of the technique is its cleanliness. Thanks to the spray nozzles working with high precision, emulsion is only applied where it is actually needed and nowhere else. The spray pulses are controlled automatically and allow perfect metering. The low spray pressure of just 3 bar minimizes the formation of spray mist. And because the emulsion is immediately overlaid with asphalt, it cannot be damaged by transport vehicles, feeders or pavers. This guarantees a perfect bond of layers. And neither the job site nor surrounding roads are soiled.

Maximum cost-efficiency for contract-letting authority and contractor

Using the SprayJet technology for pavement rehabilitation is highly economical, too. As the wearing course is thinner than for conventional roadworks, up to 50% of the material costs can be saved. Fast progression of the roadworks and a shorter time required until the road can be re-opened to traffic also save time and money, while ensuring the high pavement quality and long service life of the road. The versatility of the technology pays off, too: the SprayJet Module can be installed on the SUPER 1800-2 or removed in just a short time. If a contractor has not booked jobs requiring the SprayJet Module, the machine can be used for conventional paving at any time. In other words: VÖGELE SprayJet Technology combines noise abatement, cost-efficiency and maximum paving quality.

Job site: Munich’s Orleansstrasse, Germany
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