Project data
Country: Austria
Application: Wall, ceiling
Client: voestalpine Stahl Donawitz
Construction company: Lieb Bau Weiz GmbH & Co KG
Products in use
Double railing scaffolding
Modular scaffolding
Floor props
Master PRO
AL2000
AluDEK
DEKplus
PAX
voestalpine has developed an ambitious and feasible step-by-step plan for a green future with greentec steel. In a first step, an electric arc furnace (EAF) will be built at each of the two sites in Linz and Donawitz. With this technology change, the steel and technology group can reduce its emissions by up to 30%. The new EAF at the Donawitz site will be powered by green electricity and will produce high-quality steel for rails, wire rod and seamless tubes.
Lieb Bau Weiz GmbH & Co KG was commissioned to build construction package 3 – the central media building – and relied on RINGER's formwork expertise: High-performance wall and ceiling formwork systems and digital concrete maturity testing ensured safe and efficient implementation. This building essentially houses the hydraulic rooms and the Q-One system, which, as a digital melter, forms the heart of the power supply for the two electric arc furnaces and ensures their precise control. The entire alloy management system is also installed above this media building, which has a total load of 18,400 tonnes when fully filled. Products in use
Massive reinforced concrete structures under demanding conditions
Construction package 3 covers a foundation area measuring 140 m in length and 40 m in width. The building itself is 25 m wide and 30 m high. This reinforced concrete base, on which the alloy management facility will also be built at a later date, will ultimately have a total height of 60 m. To efficiently advance the construction progress, up to 300 m³ of concrete will be processed per week. A total of 8,000 m³ of concrete and 1,600 tonnes of reinforcing steel will be used.
Since the power supply is provided via solid copper rails, the high current creates an extreme magnetic field, which poses the risk of conventional reinforcing steel being pulled out. To prevent this, 28.3 tonnes of anti-magnetic stainless steel were used.
In addition to the strict safety regulations and the need to maintain plant operations throughout the entire construction period, the dimensions of the massive reinforced concrete structures and the limited space available placed high demands on planning and execution. Since the structure is being built in the immediate vicinity of existing voestalpine facilities, precise coordination of the construction work was essential. Particularly challenging was the coordination with the internal transport of liquid steel, which, with a total weight of 1,000 tonnes each, had absolute priority and had to be carried out unhindered at all times.
A total of 80% of the construction project will be completed within just 12 months. This requires precise planning and the use of high-performance formwork systems. To meet these high requirements, Lieb Bau Weiz relied on RINGER's efficient and flexible formwork and scaffolding range as well as its comprehensive expertise. At peak times, the value of RINGER formwork and scaffolding technology on site amounted to 6 million euros.
‘The demanding safety requirements of voestalpine called for a well-thought-out and precise formwork solution. With RINGER's experience and high-quality systems, the Lieb Bau Weiz team was able to work efficiently and, above all, safely, even under the enormous demands and tight space constraints.’
Christoph Lammer, head foreman,
Lieb Bau Weiz GmbH & Co KG
The solid walls of the central media building were constructed using RINGER Master PROformwork. Elements measuring 240 × 300 cm were mainly used for large-area formwork. The wall thicknesses varied between 30 and 60 cm, with only 3 cm remaining between the formwork and the existing structure in one particularly confined area. Due to its one-sided operability, enormous stability and flexible application options, the Master PRO wall formwork system was perfectly suited to this project, ensuring dimensionally accurate and time-efficient implementation.
The highest wall was constructed to a height of 14 metres. To achieve this, a complete formwork side was first erected and then reinforced using RINGER double railing scaffolding. Particular attention was paid to the reinforcement technology in this area. Normally, 30 cm of space is available for reinforcement installation. However, as the walls are up to 60 cm thick, quick brackets were mounted on the reinforcement scaffolding, initially reinforced to 30 cm, then the brackets were removed and the remaining 30 cm were reinforced. The formwork was then closed and secured with puph and pull props. In total, the 14 m high walls were erected in four concreting sections, each with 200 m³ of concrete and 40 tonnes of reinforcing steel. With a permissible fresh concrete pressure of 80 kN/m², this was no problem for Master PRO.
The numerous corner areas also posed special challenges for the planning and formwork system. In order to create the respective angles despite the minimal space available, a special solution was implemented using a combination of 25 Alu Master inner corners, Steel Master elements and DW20 anchors. The front formwork was constructed using Master elements, straightening rails and front anchors to ensure safe load transfer.
The high quality requirements for the concrete surface also made it necessary to use a high-performance formwork facing. Due to the high-quality concrete mix with numerous additives, Master PRO with alkus® solid plastic formwork facing was used. This ensured a uniform and precise concrete surface and proved its durability even under these demanding conditions. Double railing scaffolding for reinforcement work
The ceiling structures of the central media building were constructed in accordance with demanding structural specifications. A total of 4,620 m² of ceiling space with thicknesses between 25 cm and 100 cm was erected, with the top ceiling at a height of 27 m, posing a considerable structural challenge. All ceiling sections contained solidly dimensioned joists, which were cast directly with the ceiling formwork – up to 1.2 m wide and 60 cm high, depending on the location.
Flex slab formwork was used on the first level (400 m²). The side formwork was constructed using AL2000 and Master PRO elements. The 40 cm thick ceiling incorporated 60 cm wide beams, with a supporting scaffolding system reliably transferring the loads. The second ceiling (670 m²) was partially at a height of 14.4 m and was formed using DEKplus, H20 beams and AluDEK. This combination enabled efficient and safe working despite the great height.
The third ceiling (590 m², 50 cm thick) was also constructed using DEKplus, H20 and AluDEK, with additional H20 beams as intermediate layers to optimise the construction height and load distribution. First, the DEKplus ceiling tables were laid as the main formwork, onto which H20 beams were then mounted for additional load transfer. In order to achieve the required construction height, additional H20 beams were then laid crosswise before AluDEK was applied again in the areas between the joists. The intermediate ceiling (330 m², 25 cm) required 55 cm wide joists and was constructed entirely with AluDEK modular ceiling formwork.
The top ceiling level (320 m²) presented one of the greatest challenges with a ceiling thickness of 100 cm at a height of 27 m. A supporting scaffolding system combined with Flex formwork ensured the necessary stability. The intermediate ceiling below remained in place as a static support system to absorb the extreme loads during the concreting and curing phase.
Construction package 3 is divided into two components. The second component was then erected as a mirror image of the first component. All formwork, reinforcement and concreting concepts were adopted identically.
Digital concrete maturity testing for efficient formwork utilisation
A decisive factor in the optimal utilisation of the formwork systems was RINGER's digital concrete maturity testing system. By precisely measuring the concrete compressive strength, it was possible to determine the earliest possible time for stripping the formwork from the very high ceilings.
The concrete maturity measurement is based on continuous recording of the temperature curve during the setting process. For this purpose, sensors were installed directly in the fresh concrete of the ceiling, which provided temperature values in real time via Bluetooth. A user-friendly smartphone app converted this data live into concrete compressive strength. The strength was calculated by the software using a previously determined calibration curve.
Based on this precise measurement data, the RINGER technicians were able to determine the earliest possible formwork removal time for each ceiling for the Lieb Bau Weiz team, thus ensuring efficient formwork utilisation. In addition, the strength data was available online at all times via the smartphone app for the Lieb Bau team, which enabled flexible and optimised construction site coordination.
Efficient construction site logistics with the RINGER extending platform
The RINGER 5-tonne extending platform was used to optimise material transport on the construction site and make work processes more efficient. This robust and flexible platform made it possible to safely transport building materials and formwork elements by crane to the respective floors and store them there temporarily. This optimised the vertical flow of materials and significantly reduced crane times. In addition, the platform enabled the work area to be expanded, creating additional storage and movement space on the individual floors.
Space-saving and safe material supply was crucial, especially when constructing the high ceiling levels. With a load capacity of up to 5 tonnes, it offered sufficient capacity for heavy components, formwork elements and reinforcement materials. A particular advantage was the ease with which the DEKplus ceiling tables could be formed and stripped. By positioning the platform on the respective floor, the ceiling tables could be placed directly at the point of use with the ceiling props already installed and moved to the required location, which significantly accelerated the formwork work.
Thanks to its high load-bearing capacity and easy handling, the platform became an indispensable element for construction site logistics. Assembly by crane and stable fixation by ceiling supports ensured safe use on every floor. In addition, the all-round side protection and the non-slip floor plate made of tear plate ensured maximum safety during loading and unloading.
Other RINGER products in use
In addition to the RINGER formwork systems, other high-performance solutions were used to ensure efficient and safe construction.
The RINGER concrete platform provided a stable and protected working platform for concreting the high walls. Climbing platforms were also used to ensure safe working at great heights.
PAX column formwork was used for the numerous columns in the construction project, which impressed with its ease of use and lack of time-consuming pre-assembly.
To ensure safe access to the various levels, stair towers were erected using RINGER modular scaffolding and double railing scaffolding. These provided workers with safe access to all construction phases.
Teamwork and technology as success factors
With the professional implementation of this project, RINGER once again underlines its expertise in the field of formwork technology for complex industrial buildings. The innovative combination of high-performance wall formwork, flexible ceiling systems and state-of-the-art concrete diagnostics are a decisive factor in ensuring that the Donawitz electric arc furnace can go into operation as planned in spring 2027.
Special thanks go to Mr. Reisenbichler Wolfgang (site manager), Mr. Lammer Christoph (foreman), Mr. Kasper Stefan (assistant foreman) and, above all, the entire construction site team at Lieb Bau Weiz GmbH & Co KG, whose outstanding commitment and expertise have contributed significantly to the successful progress of the construction work.
