There's no question that 3D printing is here to stay. However, it is still a developing technology that raises certain questions: is it really effective for massive and large-scale construction? How sustainable is it? Will it go from being an option to becoming the norm in the construction industry? To help clarify the broader picture of 3D printing's place in architecture and construction, we spoke with Alain Guillen, Managing Director and Co-founder of XtreeE, a platform that allows architects to bring their designs to reality through advanced large-scale 3D printing, generating quick and precise shapes without material waste. See below how he and his team see the future of robotics in architecture and why architects should prepare to embrace this new technology, heading for a more efficient but equally creative future.
José Tomás Franco (ArchDaily): Where did your interest in developing large-scale 3D printing for construction come from?
Alain Guillen: XtreeE was born from three graduation projects in the Digital Knowledge department at the Paris-Malaquais School of Architecture. These works were carried out in a university project called Democrite at the Conservatoire National des Arts et Métiers de Paris (CNAM), in partnership with Arts et Métiers ParisTech (ENSAM), INRIA (Institut national de recherche en informatique et en automatique), Sophia Antipolis, and ENSCI-Les Ateliers.
Related ArticleHow Does Spot Work? The Robot That Compares Design to Reality at the Construction Site
At the end of this university project, the whole team decided to try and continue the adventure with the creation of XtreeE. Our main motivation was to develop cutting-edge technologies and create a new market of innovative products for architecture, design, and civil engineering to address the new challenges of today: productivity, sustainability, and quality of the work environment.
JTF: How does the manufacturing process for structural parts work and what differentiates them from non-structural elements?
AG: Our processes rely on large-scale 3D printing of different types of materials, based on a patented XtreeE technology called bi-component extrusion. For non-structural elements, the manufacturing is a simple printing phase, eventually followed by secondary work to get to the final product. As for structural parts we can have several strategies.
The first family of approaches consists in printing a formwork, the structural function of which is limited to resisting the casting of a structural material inside. This was our approach for the Aix-en-Provence pillar back in 2015. The formwork is mostly meant to stay in place and can be associated with various functions such as coating. In this context of cast structural material, we also have access to post-tensioning strategies. This approach was used for the Art&Fact telecommunication pillar and is currently being explored for various other projects.
The second set of strategies for structural parts directly relies on the printed material properties. For instance, we have developed several reinforcement methods to better the tensile behaviour of our concretes. They are now moving out of the lab and we are starting to utilize them for industrial projects.
Today, we are using more and more of our printed materials in a structural fashion. The main obstacles to this are construction regulations, which require us to conduct huge testing campaigns to prove that our printed products are indeed able to withstand the loads they are designed for. Of course, this is very crucial and each step we make in that direction allows us to raise the bar for future projects. We work hand in hand with clients, academics, and regulation authorities to develop global knowledge of such manufacturing techniques.
JTF: Why should architects start considering these systems in comparison to existing ones? Could we say that 3D printing is sustainable?
AG: Our goal is not to replace building techniques that work well as they are, but a big part of the construction industry currently lacks efficiency in regards to product performance and manufacturing.
Robotics brings a potential for complex geometries at a low cost that can benefit architects in many ways: creative freedom of course, but also the possibility of adding functionality to built objects in a more high-performing way without opposing it to aesthetic or architectural concerns.
Even if 3D printing seems to be a “high tech” method, our main concern is environmental. By reducing construction waste associated with traditional formworks, improving the quality of the built products, and greatly facilitating on-site operations, it brings both direct and indirect sustainability to this very impactful sector. We are working towards innovative low-carbon materials and optimized built objects by including life-cycle analysis criteria in our designs.
JTF: Regarding on-site construction logistics, how does traditional construction differ from 3D printed construction?
AG: XtreeE is mostly oriented toward offsite robotic prefabrication. Even if we are considering “direct” printing in the future, we do not think it is very relevant now. What we can do though is bring a printing cell onsite to reduce transport cost, but the printed elements are put in place after their printing. The main benefit of this approach is to enhance quality control and ease delays onsite. In a word we are bringing the advantages of automation that other industries adopted decades ago to the construction sector.
The geometrical freedom and precision offered by 3D printing allow one to add as much functionality to an element as possible, including logistics-oriented features such as dimensional guides or pre-added second works. The purpose is to reduce as much as possible the number of onsite operations and their associated risks.
JTF: What new tools or knowledge should architects learn to become more familiar with 3D printing as a construction system, from the beginning of the design stage?
AG: Mostly parametric design, on any platform. The idea is to integrate as many features as possible at a very early stage so that we can improve efficiency at every step of the project.
The paradigm shift consists in going from a 'linear' design approach, where physical analysis and logistics questions come a bit too late, to a more circular or simultaneous approach, where every actor of the project can discuss with the other around the digital model. 3D printing allows great geometrical freedom so there is much to invent to build better.
JTF: What is the difference between 3D printing with gypsum, clays, and geopolymers? Is it possible to mix them with each other or with other materials?
AG: We are constantly improving our technologies to be able to adapt any material. The goal is to put a material where it is relevant only. Gypsum is particularly suited for indoor architecture, while clay and geopolymer have good sustainable potential either for industrial or architectural products.
JTF: We know that 5 houses in Reims are currently being 3D printed. What is the project about?
AG: Supported by the social landlord Plurial Novilia, the project is located in the heart of the Réma’Vert eco-district in Reims, on a plot of 1000 m2. They are five single-storey houses, mixing off-site 3D concrete printed walls with prefabricated elements.
Last November, the project obtained certification by the CSTB (Centre Scientifique et Technique du Bâtiment: Scientific and Technical Building Centre) for the new 3D concrete printing construction method, through the validation of an ATEx (“Appréciation Technique d’Expérimentation”: Technical Assessment of Experimentation). This is a great milestone for us.
The certification of the 3D printing concept was indeed the essential and unavoidable phase of the Viliaprint project. Until today, French legislation did not allow the use of 3D printed elements as part of the supporting structure of a construction. The favorable opinion of the CSTB has just been delivered, allowing the insurability of the real estate project and, as a direct effect, the possibility of renting the printed houses.
JTF: Considering the evolution of large-scale 3D printing from freestanding elements to complete houses, how do you see the future of this technology?
AG: A near-future will consist of the regulation and normalization of this technology, and in parallel its diversification, both in materials and building systems. We believe we are still at the very beginning of understanding all the possibilities it offers. There is much to learn and most of all much to invent. These approaches could really be the shift the construction sector has been expecting for a long time. Precision, efficiency, control, and sustainability must be the keywords of this new era.
Find out more about the systems and solutions developed by XtreeE, here.