'Pumas' flood German tower

An amazing 15,000m3 of concrete was pumped over just 68 hours to form a section of the bottom plate of the tower.

You might think that construction in Europe has ground to a terminal stop – and for the most part you would be right. However, construction on Frankfurt’s Tower 185 (so called because of the projected final height) progress continues unabated.

The first thing a visitor on site might notice is the number of cranes. We counted seven luffing-top machines working on the towers, with a cross-section of models from Leibherr and Wolfkrann.

Meanwhile, a lake of concrete that needs to be moved to help the tower rise beyond its current height of 37m a local contractor pumped 15,056 m³ of concrete within 68 hours in the second section of the huge bottom plate using four large boom truck-mounted concrete pumps.

Story continues below

Advertisement

FEATURED COMMENT Please click here to comment on this article

PUMAS
To do this, a placing boom with a 58 m reach and two 52m units were set up on two pit sides. For reasons perhaps only comprehensible to the lead contractor and to the German sense of humour, these three pumps have been dubbed with the nickname ‘The Pumas’.

During work, the end hose of one of the machines was extended with pipelines, which were connected to an easy to use, hydraulically controlled placing boom with a 20 m reach.

The working range of this boom could be extended again, if necessary through coupling with a mechanical rotary distributor. Three weeks earlier, the first section of the plate was cast with 5,660 m³ concrete – equivalent to two Olympic sized swimming pools.

The building is in Frankfurt’s new Europa quarter between the main train station, the trade fair site and the banking quarter. Tower 185 essentially consists of a multi-storey underground car park, a horseshoe-shaped base building and two high-rise halves with aluminum-glass facade, which enclose a glass centre section.

The developer is Vivico Real Estate who commissioned lead contractor Hochtief Construction AG with completion of the
entire carcass.

The foundation pit was created in advance by groundwork specialist Züblin Spezialtiefbau. Construction of the bottom plate started in March 2009 and the base building is to be completed by autumn 2010 while completion of the 50th story is planned for the end of 2011.

PUMPING
Both for the concrete pumping service and for Putzmeister, who supplied the pumps and booms, Tower 185 is of interest for another reason. For “The Pumas” also have the order to concrete the basement floors, the base building and the two high-rise towers.

For the first time, double-walled, up to 130 bar pressure-resistant pipelines with ZX couplings are going to be used for high-rise concrete pumping in the towers.

Double-walled delivery lines have already been being used on PM truck-mounted concrete pumps for a long time to extend the service life (and thereby to reduce the conversion costs and downtimes), but only in a version limited to 85 bar pressure.

For stationary use, the high-strength, double-walled delivery lines offer the advantage of being able to withstand pressure up to 130 bar for as long as it takes until the inner layer in the pipe is closed.

This means there is no need for regular replacement of the highly stressed delivery line pipes immediately next to the concrete pump at high-rise construction sites. For this first section of the pipeline is subject two the greatest level of wear and the highest pressure.