CPC concrete slabs are based on the technology of "carbon pre-stressed concrete," which originated from a long-term research project conducted by the Zurich University of Applied Sciences Winterthur (ZHAW) and Silidur AG, Andelfingen. These panels are reinforced with thin, pre-stressed carbon strands, allowing them to be three to four times thinner and lighter while maintaining the same load-bearing capacity as traditional reinforced slabs.
CPC's innovative approach to concrete panel production reduces material usage by 75% and minimizes the carbon footprint of concrete production. ArchDaily interviewed Professor Josef Kurath from the Department of Architecture Design and Civil Engineering at the Zurich University of Applied Sciences (ZHAW), who collaborated with CPC Construction in developing these concrete panels. We discussed his perspectives on decarbonizing architecture, the inspiration behind the development of CPC panels, a comparison with traditional concrete, and the potential for scalability and accessibility in the future.
Read on to discover John Kurah's insights on decarbonizing the construction industry and the innovative prospects of CPC panels.
Paul Yakubu (ArchDaily): The built environment is responsible for approximately 42% of annual global CO2 emissions. In your opinion, what are the key areas in construction that the building industry should reconsider and innovate in order to reduce these emissions?
Josef Kurath (CPC AG & ZHAW): Concrete and gravel are among the most widely used materials in the construction sector worldwide. Huge quantities of it are being used and this will rise sharply again in the future. These materials are also responsible for a significant proportion of CO2 emissions generated in the construction sector. The components that makeup gravel and concrete are among the most common materials found on the earth's surface worldwide. That's why these are the right raw materials to create buildings and cannot be replaced due to the sheer mass that is used. That is why it is important to use these resources as sparingly as possible in the future, to reuse them again and again, and to keep emissions as low as possible in the manufacturing and construction processes.
PY: What were the initial inspirations behind the research of CPC plates and how did you arrive at pre-stressed carbon strands as a substitute for reinforcement?
JK: As a civil engineer, I know reinforced concrete very well. As a researcher, I have been heavily involved with fiber composites over the past few decades. CFRP (carbon composites) have an enormously high strength in terms of tensile load, know no fatigue, and do not corrode. But they are no stiffer than steel, very delicate to other loads, and not infinitely durable when exposed to the sun. This is due to the matrix. Concrete is incredibly robust in terms of environmental impacts, and mechanical effects and can absorb pressure loads very well. These two materials complement each other incredibly well for these reasons, with the exception of rigidity. If carbon strands are prestressed in concrete, this incompatibility is eliminated and you have a much better building material than reinforced concrete.
PY: What are the current applications of this innovative element, and what are the structural prospects for its integration into architecture? For example, could it potentially replace traditional reinforced concrete entirely in the construction of high-rise buildings within the city?
JK: Today, CPC construction, which is a completely different construction method than today's reinforced concrete construction, is mainly used for simple construction elements in building and civil engineering. These are bridge covers, stair treads, balcony slabs, and first facades of buildings. In recent years, we at the Zurich University of Applied Sciences (ZHAW) have worked with CPC to develop connection types that are tailored to the CPC design. This now enables more complex structures, such as entire bridges, load-bearing slabs, and the load-bearing core of high-rise buildings. Especially with regard to its use in building construction, a number of research projects are underway at the ZHAW, e.g. concerning sound and fire. The CPC construction method could effectively completely replace reinforced concrete construction in building construction without losing the flexibility of reinforced concrete. Since CPC construction is much more sustainable than reinforced concrete construction, up to 4 times less material is needed and the trades in the building are much better separated, this is even a good idea.
PY: In comparison to traditional concrete, CPC panels are three to four times thinner and lighter. This unique characteristic enables the material to behave like a tensile material. Can you envision new forms of design that can be achieved through this innovative behavior of your product?
JK: There is a lot of potential here. We were certainly able to demonstrate this a little on individual smaller buildings such as the "Bridge to the Future" or the "Arch Bank". However, this is a matter for the engineers and architects.
PY: When it comes to scalability, how cost-effective are carbon strips compared to steel reinforcement? Additionally, what methods does your company plan to use to broaden the accessibility of this material?
JK: In the field of bridge covers, small bridges, and similar applications, the CPC construction method is already competitive in the broad market. In the case of high-rise buildings, the construction method is priced in the range of timber buildings, but is still somewhat more expensive than conventional buildings in the broad market. This has to do with the amount of panels produced and the fact that companies still know too little about the construction method. CPC's partner, Holcim AG, is currently producing the CPC large plates in its first plant. These have a size of up to 4.5m x 17m with thicknesses of 40mm and 70mm. With the capacity of this production plant, e.g. approx. 9 medium-sized buildings with a total of approx. 100 apartments per year will be built. Not much for the hardware store. That's why the panels are currently still in the upper price segment for many applications. It is planned to significantly increase production in the next few years. As capacities increase, CPC construction becomes competitive in terms of price, even in conventional house construction. If you include the sustainability aspects, it's clearly more interesting. Due to the difficult approval conditions in the construction industry, this will still take some time.
This article is part of the ArchDaily Topics: Decarbonize Architecture presented by Holcim.
Driven by its purpose to build progress for people and the planet, Holcim is decarbonizing building, while improving living standards for all. Holcim empowers architects and developers across all regions to build sustainably. This series explores how cities of the future can be low-carbon, circular, and resilient.
Every month we explore a topic in-depth through articles, interviews, news, and architecture projects. We invite you to learn more about our ArchDaily Topics. And, as always, at ArchDaily we welcome the contributions of our readers; if you want to submit an article or project, contact us.
