The 3.2 km long BAB 5 section between Hirschberg and Ladenburg in the direction of Frankfurt-Karlsruhe was renewed within six days, which has been owed to always having sufficient cement on site.
According to the Federal Statistical Office, more than 80% of goods are transported across the country. Because of the heavy traffic, motorways should be built sustainably and future-proof. Concrete as a building material guarantees an operating time of around 30 years and is therefore usually the first choice when it comes to renewing the road surfaces of high-traffic routes, as with the new construction of the BAB 5 route section between Hirschberg and Ladenburg.
The Karlsruhe Regional Council had tendered this section of the test in test mode two, i.e. as a day shift. The opposite lane section in the north direction was built last year ¬– albeit in 24-hour operation. With the commissioned construction in daytime operation, the client wanted to check whether the additional effort of a 24/7 installation was worthwhile at all.
"In terms of time, we are absolutely on target, and in my opinion, construction in 24-hour operation is not necessary because the time saved is minimal in relation to the additional effort, especially in such a small construction phase," emphasises Site Manager, Jörg Müller-Rochholz ,from Berger Beton.
Maximum security and stability
His team used around 2 000 m3 of concrete a day, which corresponds to an installation distance of 500 m. This requires 600 to 700 t of cement, i.e. 26 silo trains.
“The cement comes from our factory in Schelklingen. This cement is characterised by a low alkali content, which significantly reduces the risk of an alkali-silica reaction (AKR) and maximises the durability of the concrete,” explains Dr. Klaus Felsch, Product Manager Traffic Infrastructure HeidelbergCement. "In order to avoid construction delays due to delivery bottlenecks – for example due to traffic jams - we did not want to take any risks and installed three buffer silos from us on the mobile mixing plant on site in addition to the three cement silos from Berger Beton," he added. This strategy has proven itself in many construction projects.
"Especially when large quantities are installed, it is advisable to have a sufficiently large buffer quantity of cement available, even if we had no bottlenecks in this case," explains Müller-Rochholz. In addition to the sound logistics, the good cooperation between all those involved was a guarantee for the smooth operation. The location of the mixing plant near the installation section was also an advantage. "The space was narrow, but right on the route, so that the tipping vehicles only had to drive a few kilometres to the installation site," explained Müller-Rochholz.
The installation by the two slipform pavers ran continuously. First, a 22 cm thick layer of sub-concrete was installed and a 5 cm-thick layer of top concrete above. This top concrete consists of an alkali-resistant aggregate with a special resistance to frost and de-icing salt. In a third, final step, the Otto Alte-Teigeler company brushed out the concrete surface and exposed the aggregate. The texture depth achieved in this way is approx. 1 mm. The formation of a washed concrete structure significantly reduces tire road noise. The washed concrete surfaces have a comparable D-stro value of -2.0 db (A). This is also an aspect that stands for sustainability in road construction.
Read the article online at: https://www.worldcement.com/europe-cis/14072020/new-concrete-road-surfacing-for-bab-5-near-ladenburg-using-low-alkali-cement/