Putzmeister BSA 1409 HP D5 Pumps Concrete for Frankfurt’s U5 Tunnel

“And remember: concrete’s coming on the third!”, calls out the site manager as he takes his leave, grinning. Silvan Borstnar laughs; of course he knows the date – it’s circled in red on his calendar: according to plan, the tunnel concreting for the U5 underground shaft is due to start on the third of the following month. Site manager’s meeting or not, he doesn’t need a reminder for this date.

The excitement is palpable, even though Jochum is on schedule: with a team of four, Managing Director Silvan Borstnar is personally helping ‘underground’ to lay the 500-metre-long delivery line. Professional experience aside: every joint is carefully checked; everything must be secure and watertight.

First joint tunnel project

The extension of the U5 line to the Europaviertel is the first joint underground project between EKS Beton from Frankfurt-Kalbach and Jochum Betonpumpen GmbH from Egelsbach (near Darmstadt). EKS Beton mixes and supplies the ready-mixed concrete, whilst Jochum ensures that the building material reaches its intended destination.

Since the company was founded in 1978, founder Hermann Jochum has frequently worked underground, but a tunnel project of this scale is unprecedented even for Jochum. “But there’s always a first time,” says Silvan Borstnar. The 33-year-old took over as managing director of Jochum Betonpumpen GmbH in 2023. Together with his client, Managing Director Daniel Wojdyno of EKS Beton, he is entering a new business sector with the Frankfurt tunnel project. It is not just about the volume of concrete – the experience gained is crucial, emphasises Silvan Borstnar: “We also want to be at the forefront as a service provider for future engineering projects.”

First underground deployment of the BSA 1409 HP D5

Silvan Borstnar has ordered a new machine specifically for the U5 construction site. Jochum Betonpumpen GmbH is using the new Putzmeister BSA 1409 HP D5 for this purpose. Putzmeister unveiled the new 1400 series for the first time at Bauma 2025. Putzmeister sales representative David Zwadlo: “Our engineers have developed the ‘High Pressure’ stationary pump specifically for building construction applications and long-distance pumping. This closes the gap between the very compact BSA 1409 with a 1.4 m piston stroke and the significantly larger BSA 2109 with a 2.1 m piston stroke.” Following testing, the BSA 1409 HP D5 has been available since 2026.

The BSA 1409 HP D5 is powered by a 180 kW Deutz TCD 6.1 L6 diesel engine. EU Stage V emissions control is designed to reduce noise and exhaust emissions. This is particularly relevant in confined spaces such as Frankfurt’s city centre.

U5 extension due in 2029

On behalf of the City of Frankfurt and VFG Verkehrsgesellschaft Frankfurt am Main, Wayss & Freytag Ingenieurbau is planning the extension of the U5 underground line. The line will connect the main railway station with the Europaviertel from 2029. The extension of the U5 light rail line is a 2.7-kilometre route with four stations. Initial preparatory construction work began as early as 2013. The main construction phase – the structural work for the underground section, including tunnel construction and the ‘Güterplatz’ station – is expected to last until 2029.

The concrete work for the track beds is being carried out by EKS Beton and Jochum Betonpumpen GmbH as subcontractors. The construction period is estimated to last several months.

Amidst Frankfurt’s skyscrapers, this project is taking place ‘underground’: The BSA 1409 HP D5 is situated at the ‘Platz der Republik’ underground station (Düsseldorfer Straße / corner of Mainzer Straße). From there, a DN 125 pipeline runs via a narrow inspection shaft, initially 20 metres down, then a further 30 metres to the entrance of the tunnel bore. At the end of the approximately 450-metre-long ZX pipeline, which is permanently installed in the tunnel, there is a reduction to DN 100 with a manual gate valve. This is followed by a hose line approximately 70 metres long. This allows the installation team to flexibly place the concrete into the shoulder.

First concrete pour in early September

By early September, everything is ready: the pipework has been fully laid and secured, the above-ground site safety barriers are correctly in place, and all approvals have been granted. On the day of the first concrete pour, the clients are on site, as are inspectors and subcontractors. A Putzmeister service technician is also on site to oversee the first concrete pour. At exactly 08:22, the first EKS truck mixer is ready to fill the Putzmeister BSA 1409 HP D5 with slurry for the first time: a water-cement mixture without aggregate used to lubricate the pipeline. Once the slurry has been forced through the pipeline, the actual concreting begins with EKS fresh concrete.

EKS Managing Director Daniel Wojdyno is on site in person to brief his drivers and check the quality of the concrete delivered. No more than 90 minutes may elapse from the mixing of the concrete at the EKS plant to its pouring into the hopper – a logistical challenge in Frankfurt’s city traffic.

Once the first hopper is filled, Borstnar and Wojdyno watch the control display on the Putzmeister pump. Should blockages threaten, the delivery pressure rises rapidly at first. The concrete travels the 500 metres to the track beds without incident. The stationary concrete pump maintains a constant delivery pressure of 30 to 40 bar. Throughout the entire concreting process, Silvan Borstnar remains in constant radio contact with the placement team in the tunnel. On the very first day, around 48 m³ of concrete is placed in just under 5 hours of working time. EKS Managing Director Daniel Wojdyno later writes in his WhatsApp status: “A huge thank you to our fantastic partners who make projects like this possible.”

Cleaning and subsequent operation

Once the concrete pouring is complete, the pipeline is flushed with water down to the reducer. From there, the flushing water is pumped back outside using compressed air. Jochum has specially welded a steel cleaning trough to collect the residual concrete and the flushing water. The remaining hose line is flushed directly in the tunnel into IBC containers provided on site.

In the days that followed, Jochum operators took over the operation of the BSA 1409 HP D5, one of whom was Matthias Nowokowski. “That’s a really good Putzmeister machine,” says concrete pump operator Nowokowski. Daily output varies between 32 and 56 m³ of concrete.