Frankfurt's OpernTurm is growing with concrete pumps and a self-acting climbing boom

Ed.Zublin AG is currently erecting an imposing high-rise project, the OpernTurm, in the centre of Frankfurt am Main at a breathtaking speed. Including its base plate, around 55,000 m³ of concrete will be incorporated in the 170 m tower. The main players in the speedy construction progress are, among others, Europe's largest truck-mounted concrete pump M 63-5, a stationary high pressure concrete pump BSA 2109 as well as a stationary boom MX-32-4, on redeveloped tubular columns, with a climbing system.

The new development from tower building and podium in front is located precisely opposite Frankfurt's Alte Oper, which is steeped in tradition, and will, once complete, blend harmoniously into the surrounding architecture. In the three basement floors, the OpernTurm has 580 car parking spaces, and approximately 67,000 m² office and business space is rented over the 42 upper floors. The project developer is the American estate agency Tishman Speyer, which has already formed a striking image with the construction of the Frankfurt MesseTurm in the metropolis on the River Main. As the main contractor, Ed.Zublin AG is in charge of turnkey-ready construction work. Construction began in summer 2007 and is expected to be complete by the end of 2009.

The order for concrete delivery, both for the base plate and for construction of the building itself, with 46 floors, was given to the concrete pumping service "Die Pumas". After extensive foundation work by Ed.Zublin Spezialtiefbau GmbH (in consortium), three truck-mounted concrete pumps from the Lorscher pumping service with 42, 52 and 63 metre booms took on the task of concrete delivery for the mighty 3.0 - 4.5 m base plate in July 2007. Due to the highly restricted space available, setting up the large boom concrete pump was far from easy: while there was space for the M 42-5 and M 63-5 with one-side support on a makeshift ramp or on the very busy Bockenheimer Landstrasse, the third machine had to be set up on a specially-erected heavy-load frame. Three consecutive days and nights were allocated for installing the 5,660 m³ concrete (property class C 30/35). The Putzmeister M63-5, the largest truck-mounted concrete pump in Europe, alone delivered 2,000 m³ of the total volume within 24 hours without any problems. In consideration of performances at the neighbouring Alte Oper, a 20-hour break from concreting operations, which lasted several days, was accepted. It was thanks to finely-balanced concreting logistics that concrete was transported by truck mixer through the heavy inner-city traffic without any obstacles.

In addition to a large fleet of truck-mounted concrete pumps (33 machines), the pumping service "Die Pumas" also has 5 stationary concrete pumps and 7 stationary booms. This leaves the company in the best possible position to take on concrete delivery tasks for demanding high rise projects. At Frankfurt's OpernTurm, "Die Pumas" are using the new Putzmeister tubular column system RS 850 with a simplified, automated climbing system that carries the stationary boom with 32-metre outriggers for the first time.

Central constructional elements of the OpernTurm are two building cores, which will, when the building is complete, accommodate the stair wells, lift shafts and supply lines. During the building phase, the two cores are always two to three stories ahead of the floors. Both the two cores and the floors are made of concrete of property class C50/60 with a maximum particle size of 16 mm. The concrete batches, delivered by three mixing apparatus, are regularly monitored on the construction site by a laboratory.

During construction of the OpernTurm, the stationary boom climbs upwards, in line with construction progress, not inside one of the building shafts but between the two cores, through holes in the floor. A tubular column and boom were installed after the third floor was completed, i.e. at the height of level "0" (ground floor). Since then, the concrete placing boom has stood freely, without ballast, on a tubular column 16 m above the last floor guide. Due to its higher position, the boom not only reaches every point of the floors, each of which are 1,800 m2, but also the formworks of the building cores, which are three levels higher. The stationary boom is connected to the stationary concrete pump by means of an approximately 80 m long ground line (DN 125). Later on, as the building height increased, the ground line was continued as a riser up to 170 m.