From research to industrial application

The construction, erection, modernisation and operation of residential and non-residential buildings account for 40 per cent of greenhouse gas emissions in Germany. 

Carbon concrete enables significantly slimmer, lighter and more durable structural elements than traditional reinforced concrete construction. As carbon does not corrode, the concrete cover can be significantly reduced, leading to a substantial decrease in the quantities of cement, gravel and sand required. Overall, this already enables savings of up to 80 per cent in resource use today. 

In combination with CO₂-mineralised aggregates and additional CO₂-storing materials, components produced at the C-Factory will in future even serve as carbon sinks.

Carbon concrete construction has been the subject of intensive research over the past two decades and has been successfully tested in initial construction projects – including the Carbon Concrete CUBE in Dresden, the world’s first building made of carbon concrete. The automated manufacturing processes used there were developed and tested at theCarbon Concrete Technical Centre Germany at the FTZ of HTWK Leipzig. The C-Factory now marks the decisive step: the transition of this technology to industrial, scalable production.

C-Factory – Prototype, fully automated production line

The establishment of the C-Factory will see the development of the first prototype, fully automated production line for large-format carbon concrete components, as well as the first-ever integration of CO₂-storing building materials.

Over the next four years, the pilot plant in Leipzig will be built, commissioned and used to manufacture various demonstration components. It will serve as a benchmark for future carbon concrete plants and as the basis for the industrial scaling of a climate-friendly construction method. The components and production processes developed at the C-Factory can be transferred to different sites. 

Consortium leadership

Dr Alexander Kahnt, Managing Director of Kahnt & Tietze GmbH, explains: “The success of this project is down to the outstanding work of my team in Leipzig. We are all motivated by the goal of significantly reducing emissions in the construction industry with the C-Factory.”

Dr.-Ing. Matthias Tietze, also Managing Director of Kahnt & Tietze GmbH, adds: “We are bringing a technology – which until now has mainly existed in research and pilot projects – into industrial reality. With the C-Factory, we are laying the foundations for the cost-effective and scalable construction of buildings.”

Both managing directors studied at HTWK Leipzig and completed their doctoral degrees through a collaborative programme at TU Dresden. Dr Alexander Kahnt, Eng., laid the foundations in building physics and structural engineering for slim carbon concrete components with his doctoral thesis on ‘The Building Envelope of the Future’. Dr.-Ing. Matthias Tietze completed his doctoral thesis on the topic ‘The economic value chain of carbon concrete – using the example of double-wall semi-precast construction’ and focused on the cost-effective implementation of this construction method. 

After completing his studies, Dr.-Ing. Tietze worked at TU Dresden on the C3 – Carbon Concrete Composite project at the Institute of Solid Construction under the supervision of Prof. Dr.-Ing. Manfred Curbach. Kahnt established the ‘Sustainable Construction’ research group at the Institute of Concrete Structures at HTWK Leipzig under the leadership of Prof. Dr.-Ing. Klaus Holschemacher. 

For many years, they have all been united by the goal of transferring carbon concrete construction from research into practical application.

Together, they founded Kahnt & Tietze GmbH, based at HTWK Leipzig, to implement new materials, construction methods and manufacturing technologies on an industrial scale at the C-Factory.

The Leipzig Research and Transfer Centre (Forschungs- und Transferzentrum Leipzig e. V.) at HTWK Leipzig is supporting the industrial upscaling of innovative carbon concrete technology

HTWK Leipzig is contributing to the development of the C-Factory through its Research and Transfer Centre (FTZ). Since 2014 – with funding from the Carbon Concrete Composite (C3) research initiative – researchers have been developing carbon concrete construction methods in numerous individual projects. With the opening of the university’s Carbon Concrete Technology Centre Germany in 2022, researchers were able to design and test manufacturing processes for the new components. At the Carbon Concrete Technology Centre Germany, staff from the Institute of Concrete Structures, led by Prof. Dr.-Ing. Klaus Holschemacher, are working on an interdisciplinary basis with the Institute of Process Automation and Embedded Systems, led by Prof. Dr.-Ing. Tilo Heimbold.

The C-Factory now marks the decisive step towards widespread application. Kahnt & Tietze GmbH, a spin-off from HTWK Leipzig, is acting as the initiator and is taking the lead in the consortium. This move to bridge the gap to the market is to be achieved in particular through close collaboration between the FTZ at HTWK Leipzig and Kahnt & Tietze GmbH, as well as with other partners, in order to systematically expand the continuous automation of key process steps.

Prof. Dr.-Ing. Klaus Holschemacher, Director of the Institute for Concrete Structures (IfB) at HTWK Leipzig, explains: “With the Carbon Concrete Technology Centre Germany, we have been able to combine the theoretical foundations developed in Leipzig as part of the various C3 research projects on carbon concrete with the requirements of a practical, automated manufacturing technology. The building material that gives the technical centre its name is more resource-efficient and durable than the reinforced concrete used worldwide to date; it is also recyclable and can even be used for multiple purposes.”

For the FTZ, the project represents an important milestone in technology transfer. The manufacturing processes for producing carbon concrete components – the development of which was supported in particular by research funding from the Saxon State Ministry of Science, Culture and Tourism – are thus being translated into marketable applications.

Prof. Dr.-Ing. Tilo Heimbold, project manager of the C-Factory and also scientific director of the Research and Transfer Centre, explains: “We have many years’ experience in the automation of manufacturing processes for industry. In this project, we are specifically applying this experience to the construction sector in order to increase productivity and quality whilst reducing emissions. In doing so, we are laying the vital foundations for Germany to remain competitive as a business location.”